M.project Part2

Chapter 1

COMPANY PROFILE

1.1 INTRODUCTION

Tecumseh Products India Private Limited (TPIPL) is a wholly owned subsidiary of

Tecumseh Products Company (TPC), USA. TPIPL has two plants in India, one at Ballabgarh

near New Delhi and the other at Balanagar Industrial Estate in Hyderabad.

Tecumseh Products Company (TPC) is a full line, independent global manufacturer of

hermetic compressors for air conditioning and refrigeration products, gasoline engines and

power train components for lawn and garden applications, industrial pumps, and small

electric motors.

The facility at Hyderabad has been setup through the acquisition of Siel Compressors

Ltd. Hyderabad. TPIPL is now the largest independent manufacturer of compressors in India.

The facility is both ISO 9001 and 14001 certified. One of the four global Technology

Development Centers (TDC) of TPC is located in this facility. In-house Application

Engineering Testing facility is well equipped to optimize and ensure performance

improvement of the appliance.

The facility at Hyderabad is engaged in the manufacture of the following series of

compressors for different applications as mentioned below.

1. Reciprocating hermetic compressors

AW series (12000 – 42000 BTU/hr) - Air conditioning Application

AK series (5500 – 1000BTU/hr) - Commercial refrigeration Application

2. Rotary compressors (18000 – 26500 BTU/hr)

RN Series - Air conditioning application

RK Series – Commercial Refrigeration& Low end Air Conditioning

Application

The facility at Ballabgarh is engaged in the manufacture of the following series of

compressors for different applications as mentioned below.

THK Series Reciprocating compressors – Refrigeration application

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1.2 GLOBAL PRESENCE

1.3 CERTIFICATIONS

2

Tecumseh, USA

Tecumseh

Do Brasil

Vecomesa Venezuela

,

Venezuela

TPC, Canada

Canada

Tecumseh India

,

India

Tecnamotor Italy

,

Italy

ARCELIK Turkey

,

Turkey

Tecumseh

Europe

Chapter 2

INTRODUCTION TO COMPRESSORS

2.1 DEFINITION OF COMPRESSOR

A compressor is a mechanical device that is used to increase the pressure or compress

the fluid. In refrigeration and heating system it is the most essential component. It

pressurizes a gas in order to turn it into a liquid, thereby allowing heat to be removed or

added. The development of compressors began during the late 1800s and matured in early

1900s. There are various different kinds of compressors in the market today.

2.2 TYPES OF COMPRESSORS

The tree diagram shows the various types of compressors drawn below.

Fig: 2.1 Types of compressors

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As shown in Figure.2.1, there are two basic compressor types: positive-displacement

and dynamic.

In the positive-displacement type, a given quantity of air or gas is trapped in a

compression chamber and the volume it occupies is mechanically reduced, causing a

corresponding rise in pressure prior to discharge. At constant speed, the air flow remains

essentially constant with variations in discharge pressure.

Dynamic compressors impart velocity energy to continuously flowing air or gas by

means of impellers rotating at very high speeds. The velocity energy is changed into pressure

energy both by the impellers and the discharge volutes or diffusers. In the centrifugal-type

dynamic.

2.3 DIFFERENT TYPES OF COMPRESSORS MANUFACTURE IN

TECUMSEH, HYDERABAD

SI.NoType of

compressorSeries

Capacity

in BTU/hr (British

Thermal Unit)

Application

1. Reciprocating

compressors

AW series

AK series

12000 – 42000

5500 – 10000

Air conditioning

Application.

Commercial refrigeration

Application

2. Rotary

compressors

RN series

RK series

18000 – 26500

18000 – 26500

Air conditioning

application

Commercial Refrigeration

& Low end Air

Conditioning Application

Table 2.1

The company given different names based on their convenience. AW and AK are

reciprocating compressors where as RN and RK are rotary compressors. Normally

reciprocating compressors pressurize more air than rotary and these compressors are used

where we need more air.

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2.4 COMPONENTS OF A COMPRESSOR

Physically it has 3 main sub-assemblies viz. the pump kit, motor and housing.

Fig: 2.2 Components of a compressor

The manufacture of the compressor consists of three different processes which are

done at three different locations which are called

1. Machine shop

2. Motor shop

3. Assembly shop

There exists a different department which checks the accuracy of the components

inspects the error level and keeps a tab on the quality of the products obtained. This

department works very hard to maintain the quality level of the company and to satisfy their

customer’s needs. This department is the Quality control department. They check whether the

components are according to the required specifications or not after every process. The

system followed by the Quality department is very systematic and it can be observed that

they do the processes in a very meticulous manner.

In the machine shop, the parts which are outsourced according to the specification

provided by the Tecumseh Company are worked on according to the desired dimensions.

Since the company has outsourced most of its components from casting plants located at

different corners of the country, it saves time involving the gathering of raw materials and

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Housing

Pump Kit

Motor

then casting the materials into the required moulds. Most of the work done is this company is

done by machines which reduce the human error to a bare minimum. Due to the use of the

machines, the efficiency of the company has increased and it has also increased the

productivity of the company. Since the machines work continuously and mostly there is

contact in between moving parts, lots of heat is generated. To reduce the damages caused due

to the heat, coolants are used at every machine. The coolant which is used maximum in the

manufacture of rotary compressor is Tech cool 3900 sometimes mixed along with water.

The main function of motor shop is to manufacture the rotor and stator. After the

manufacture of rotor and stator, it is sent to the assembly shop. In comparison to the machine

shop, this shop has less number of operations. Though the number of operations is very less,

each operation has its own significance and without that operation, the working of

compressor becomes faulty. The machines used in RN rotor motor shop are completely

automated and hence we can find very few people working at the RN-motor shop. The

equipment used at the motor shop does very meticulous tests which confirm the perfect

working of the stator and it reduces the number of faulty pieces. If the components fail these

tests, the components are rejected and sent back. The equipment used in this shop is

considered the latest equipment in the world.

Assembly shop is the final stage in the compressor manufacture. This shop reflects

the company’s efficiency and productivity. In this shop as well, we can see that machines are

used in every operation. Assembly shop’s activities are further divided into three sub lines-

kit line, terminal line, cylinder head and valve plate sub-assembly. In this shop, various kinds

of operations can be observed from turning to painting, welding to cooling, etc. Testing is

done at many stages. Testing is done at one stage which is called pre-testing which checks

before the assembly of the final product. Then testing is also done before the kit is sent to the

customers. The compressors are painted and done tests on to check leakage and then are

packed according to the customer’s requirements.

Next chapter deals with the types of reciprocating compressors manufactured in

Tecumseh and discuss about the main components of machine shop and their machining

operations.

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Chapter 3

RECIPROCATING COMPRESSORS

3.1 INTRODUCTION

Reciprocating compressors can be classified into two types. They are single acting

reciprocating compressors and double acting reciprocating compressors. Company divided

these into AK series (Single acting) and AW series (Double acting).

3.2 MACHINE SHOP

The place where various operations such as finishing operations are done on the

different components of compressor is called the Machine Shop. The AK or AW

Reciprocating compressor consists of five main components.

1. Crank Case

2. Crank Shaft

3. Piston

4. Connecting Rod

5. Out Bore Bearing

3.2.1. CRANK CASE

Crankcase is the main component of the compressor. It is made up of cast iron whose

hardness value is 170-229 BHN. It houses cylinders, pistons, crankshaft, connecting rod,

OBB and cylinder head. It may have a single or multi-cylinder depending on the output. The

entire compression of gas (refrigerant) takes place in cylinder bore of crank case.

AK model AW model

Fig.3.1 Crank case

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3.2.2 CRANK SHAFT

The crankshaft is made of either forged alloy steel or out of spheroid Grey Iron

casting. The portions of shaft that work inside the bearings are called ‘journals’. The

crankshaft should be strong enough to take the thrust of the piston during compression

without getting distorted. The reciprocating motion of the piston is made possible by the

‘crank’ of the crankshaft. The piston-end of the connecting rod is attached to the piston by the

piston pin, which is tightly fitted in the position.

In AK type one Portion of the shaft is provided with eccentricity to form throws to

which the connecting rods are attached. As the crank shaft rotates, the pistons reciprocate

forward and backward. In AW type there are two kinds of pins and journals called the short

end pin, long end pin and the short end journal and the long end journal.

AK model AW model

Fig.3.2 Crank shaft

3.2.3 PISTON

Piston is a cylindrical metal plug that reciprocates in the cylinder. They are

made of Cast Iron or Aluminum alloy. The clearance between the cylinder and the piston

must be less so that it should not allow the flow back of discharge gas from the top of the

piston to the crankcase. At the same time that gap must be filled with oil film to provide

lubrication. For bigger compressors, pistons are fitted with piston rings, so that when they get

worn out, only the rings have to be changed. It sucks in the low pressure gas through the

suction valve, compresses it and pushes it out through the discharge valve.

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AK model AW model

Fig.3.3 Piston

3.2.4 CONNECTING ROD

The connecting rod, as the name suggests connects the crank shaft and the piston

and is an important component required to convert the rotation of crank shaft to the

reciprocating motion of piston. It is made of Aluminum for it should add least possible inertia

to the piston-crank shaft system.

AK model AW model

Fig.3.4 Connecting rod

3.2.5 OUT BOARD BEARING

This, as the name suggests is one of the bearings which support the crank shaft

during its rotation. This is fitted to the crank case and supports the lower end of the crank

shaft. This is a casting. A bronze bush is fitted in the shaft hole for friction free rotation. This

is fitted to the crank case with three screws.

AK model AW model

Fig.3.5 Out Board Bearing

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3.3 VALVE PLATE SUB-ASSEMBLY

This is the most crucial component from the designing, manufacturing and

functional point of view (in addition the project has lots to do with this). This is an assembly

of many parts.

The valve plate contains the valves, the discharge valve and the suction valve.

Valve is an arrangement which allows the flow (of gas in case of a gas compressor) only in

one direction. The suction valve allows gas to flow only from the suction muffler to the

piston chamber (during suction stroke) and the discharge valve allows the compressed gas to

flow only from the piston chamber to the discharge muffler (during the compression stroke).

E.V.R & EV L Suction Valve

Rivet

Discharge side of valve plate Suction side of valve plate

Fig.3.6 Valve Plate

3.4 GASKET

There are two gaskets installed in the pump kit to prevent leaks by sealing the metal

to metal contact areas. One of them, a rubber gasket cut in suitable pattern is placed between

the valve plate and the crank case. The second, a rubberized metal gasket (Buna –N) cut in

suitable pattern is placed between valve plate and the cylinder head.

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Rubber Gasket Rubberized Metal Gasket

Fig.3.7

3.5 MUFFLERS

Mufflers are components attached to the compressor to reduce noise during its

functioning by modifying the flow pattern of fluid. There are two mufflers in the pump kit. A

discharge muffler which reduces noise of the discharge gases and the other is suction muffler

which reduces noise of the suction gases.

The discharge muffler is built within the crank case as two cylindrical chambers

and the suction muffler is a rectangular chamber fixed to the cylinder head at the inlet hole.

3.6 CYLINDER HEAD

The cylinder head is a heavy metal casting. The cylinder bore containing the piston

and the cylinder head lie on either side of the valve plate. This acts as a directing gateway for

the incoming and outgoing gases.

The molding has two pathways, one which leads the incoming low pressure gas

from the suction muffler to the suction holes and the other which leads the high pressure

output gases from the discharge holes to the discharge muffler.

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3.7 MANUFACTURING OF COMPRESSOR COMPONENTS

In Tecumseh input components are castings. Every component of compressors needs

to undergo certain operations before going to assemble so the components of compressor

undergo various operations at different machines. The following tables give the details about

various operations of different component with cycle time also.

COMPONENT: CONNECTING ROD

Operation Cycle time in sec

START (Receipt of connecting rod) Burnishing Jet washing END

- 05 03 -

COMPONENT: PISTON


START (Receipt of pistons) Rough grinding Fine boring Pin bore ID chamfer, External chamfer/Deburr Grooving, Crown chamfer, Shirt chamfer Engraving and oil hole drilling Lock pin hole drilling and chamfering Diamond reaming Finish grinding MIP(magnesium iron phosphate) coating Buffing END

- 06 21 20 13 18 17 12 06 06 04 -

COMPONENT: OBB


START (Receipt of OBB) Oil stone Fine boring / Demurring Burnishing Bullows cleaning

- 15 40 08 20

COMPONENT: CRANK CASE

12


START (Receipt of crank cases) Stator side machining Rough boring Bush fitting OBB side machining Fine boring Slot milling Manual demurring ADA washing Air blow all tapped holes Crank bore burnishing Honing Bellows cleaning END

- 58 42 25 32 30 30 20 33 20 10 54 24 -

COMPONENT: CRANK SHAFT


START (Receipt of crank shaft) Jet cleaning of shafts Shot blasting Straightening Air cleaning and Jet cleaning Journal rough grinding Journal finish grinding Thrust face grinding Pin grinding SE Pin grinding LE Oil hole cleaning MIP Pin buffing Journal and hand buffing Jet and bullows cleaning END

- 12 12 18 10 35 28 30 50 50 26 20 09 12 30 -

Next chapter deals with the manufacturing process of rotary compressors and working

of compressors and discuss about the gauges used in the company. This chapter also discuss

about the kit assembly, external parts of compressor, main assembly and tests performed for

compressors.

Chapter 4

13

ROTARY COMPRESSORS

4.1INTRODUCTION TO RN-ROTARY COMPRESSOR

RN compressor consists of five components. In this compressor, roller rotates and

along with the roller the crankshaft moves up and down, in turn causing the rotator motion.

Thus, it can be observed how the compressor got its name.

4.1.1 RN-MACHINE SHOP

The place where various operations such as finishing operations are done on the

different components of the rotary compressor is called the Machine Shop. This part of the

project describes all the processes in detail that are performed in the machine shop. The RN

rotary compressor consists of five main components.

1. Crank shaft

2. Roller

3. Out Board Bearing ( OBB)

4. Main Bearing (MB)

5. Cylindrical block.

The five components are manufactured in the machine shop.

4.1.2 RN-MOTOR SHOP

The place where the stator part of the compressor is made or manufactured is called

Motor shop. It is so called because it deals with the electronics part of the compressor and it

shows the specific details of the making of the stator component of the rotary compressor.

4.2 GAUGES

14

We use different gauges to measure different parameters of components after some

operations to check whether the parameters are in specifications or not. In Tecumseh

Company all gauges are air gauges in all machine shop.

The following are some of the gauges using in company.

1. Air gauge

2. Deck height gauge

3. Height gauge

4. Vernier calipers

4.3 KIT ASSEMBLY

After successful completion of different operations on different components, all

components send to assembly section where all components put together and made them a

single component called kit. In this assembly they do not assemble external parts of

compressor only kit assembly. Before going to assemble all components they check the

specifications of components and from those specifications they provide one grading and

according to they assemble.

Fig. 4.1 pump kit

Here grading plays major role in assembly because similar grading components only

assemble together not different grading components. The grading to each component is given

based on value came from the gauge used to check parameters of component. Grading will

provide only to components which undergone different operations at machine shop.

4.4 EXTERNAL PARTS OF COMPRESSOR

Compressor has some external parts which are visible from outside. Some of these

external parts protect internal parts of compressor. The name of external parts names given

below and these parts are combined together by various operations at different machines.

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1. Housing

2. Top cap

3. Bottom cap

4. Discharge adopter on top cap

5. Suction adopter on housing

6. Three phase terminal on top cap

4.5 MAIN ASSEMBLY

Here we explain about the assembly of RN compressors only. The following gives the

details about assembly of external parts and their operations before going to put together.

Here every operation contains one respective code for convenience. It also explains about

different tests through which a compressor will undergo. This process is up to final packing.

1310 – Rough expand

The housing is placed on a 9-finger expander machine and expanded to required

dimensions.

1320 – Finish ends

The sharp corners on both the ends are broken and given a smooth finish.

1330 – Pierce suction hole, punch witness mark

The hole for suction is made at the bottom of the housing using a pierce machine.

Then a witness mark is punched at 20 from the hole.

1340 – Pierce weld holes

Three weld holes are pierced by pierce machine at given distance from the suction

hole. This distance is measured using hole position gauge.

1345 – Housing degreasing

The degreasing of housing, top cap and bottom cap are done in four stages. First they

are cleaned with diver spray, then DM water and Grisiron 8517. Then they go through a hot

air blow-off.

1350 – Weld suction adapter

The suction adapter is welded into the suction hole and the ID of the adapter is ball

burnished.

1360 – Weld accumulator bracket

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A bracket is welded to the housing for holding the accumulator in place after

assembly.

1370 – Final expand, stamp housing code

The hosing is expanded once again finally using expander machine. Then the code of

the housing is stamped on it.

1400 – Housing finish wash

This wash is done in a 3-stage washer using the chemical Grisiron 8517 and then 4th

stage hot air blow-off is done. During this wash the conveyor speed should not exceed

1m/min.

4.5.1 HOUSING TOP CAP SUB-ASSEMBLY

1510 – Braze discharge tube

The discharge tube and silver braze ring (40% silver alloy) are loaded on top cap and

brazed.

1520 – Hanger bracket welding

A bracket is welded opposite to the terminal hole for hanging purposes.

1530 – Weld cover stud

A stud is welded beside the terminal hole.

1540 – Wash

The top cap is washed in Grisiron 8517 and degreased.

1550 – Weld terminal

The electric terminal is placed in the terminal hole and welded.

4.5.2 TERMINAL ASSEMBLY

2010 – Rotor & Kit assembly

Rotor is heated to 190oC (max.) and is placed on the crank shaft of the kit and is then

cooled to room temperature.

2030 – Stator & Housing assembly

Housing is heated to 3700C (2570C to 3730C) and then stator is dropped into it.

2040 – Cool down

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The stator–housing assembly is cooled for 45 min. to 280C.

2050 – Electric parameters check of stator & bar code

Three tests – Continuity test, Hi-Pot test and Insulation Resistance test are done. In

continuity test the compressor is run at normal voltage and resistance, common, start and run

currents are checked. In Hi-Pot test, a high potential of 1865V is applied for 1 sec. Then the

insulation resistance is verified at 500V D.C. This should not be less than 2 Mohm.

2060 – Assemble Kit/Rotor to Housing/Stator

The rotor-kit sub assembly is placed into the housing-stator assembly.

2065 – Bottom cap assembly onto housing

A magnet is attached to the bottom cap and is assembled by gentle malleting to the

housing. The magnet is for attracting any rust or other magnetic particles present inside the

compressor.

2070 – Weld Main Bearing to Housing

The main bearing in the kit is welded to housing at the suction adapter using welder

machine.

2080 – Check air gap

After removing the air gap can, this was placed between stator and rotor, the air gap

created by it is checked by Air Gap Feeler gauge.

2090 – Install O-Ring and Plug suction hole

Using insertion tool, install O-Ring in O-Ring groove in cylinder block.

Install plug into suction hole using plug pusher.

Note: O-Ring should not be punctured & inserted in correct position. Apply little “Shell

Tellus 68” oil on the O-Ring for easy entry.

2095 – Connect stator to top cap terminal

The cluster box of the stator is connected to the electric terminal in the top cap sub

assembly.

2096 – Continuity test

Apply run voltage of 160V for 1 sec for main winding and say OK if compressor

doesn’t buzz.

2110 – Press top & bottom caps into housing

Both the caps just placed on the compressor are pressed tightly onto it.

2120 - Seam weld top & bottom caps to housing

Both the caps are seam welded carefully by an automatic welder. Hydrostatic test of

welder is to be done once in a week

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2130 – Remove plug from suction and assemble accumulator

The plugs put earlier for avoiding moisture from entering the compressor are removed

and the accumulator is inserted into the suction adapter, rotating as tube is inserted. It should

be done gently; otherwise the O-Ring will be punctured.

2140 – Braze accumulator to suction adapter

The accumulator assembled to suction adapter is brazed (welding at lower flame)

using solder wire and dual tipped torch.

2150 – Assemble plugs to suction & discharge tubes

Plugs are placed to the suction tube on the accumulator and the discharge tube on the

main compressor.

2160 – Weld base plate to compressor

A triangular base plate is welded to the compressor.

2170 – Bubble tank leak test

The compressor is passed into water at high pressure and checked for any leakages. If

one hole is leaking the compressor is sent for redoing the weld, but if two or three holes are

leaking the compressor is rejected.

2180 – Install paint shields

4.6 DIP PAINT AND VACUUM DEHYDRATION

2310 – Compressor pre-treatment- Zinc Phosphate (before paint)

The compressor is pre-treated with Zinc Phosphate as a protective layer.

2320 – Dip paint process

The compressors are dipped into a black epoxy/amino paint with 30-45% (V/V)

thinner.

2330 – Paint Baking

The compressors dip painted are now baked at 1750C for 2.5 hrs. If done at lower

temperatures yellow marks are formed.

2340 – Vacuum Dehydrate compressor

The compressor is dehydrated to remove any moisture remaining inside it. This

process is done for 20 min. Then a Residual Moisture Test is done which takes about 3 hrs.

To pass this test the moisture should be less than 75 mg. If rejected it is heated to 1200C and

dehydration is done.

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4.7 OIL LINE AND PACKING FINAL TEST

2510 – Remove all plugs

The suction plugs and discharge plugs are removed by plug remover.

2520 – Oil charge/ Oil processing

650 ml of oil (for 22K model) is filled into the compressor.

2525 – Electric testing/Strap Tightening

Three tests are done – continuity test, high potential (Hi-Pot) test, insulation

resistance.

2530 – Performance test

High Voltage: Start at 250V for 3 sec

Pump Up: Measure voltage, wattage, amperage after reaching 300 psi discharge

pressure.

Ground fault detection: Current leak during run has to be less than 6 mA.

Leak back test: When discharge pressure is 225 +/- 5 psi. Pressure rise on suction is 5

psi.

Low Voltage start: Both suction and discharge at 175 +/- 5 psi and has to start at less

than 120 volts current.

Locked rotor test: At rated voltage when auxiliary winding is cut off, if compressor

buzzes, indication of fail.

2540 – Rubber plug and N2 charge

Rubber plugs are put and Nitrogen is charged with 5-10 psig. Dry Nitrogen is used for

this purpose.

2550 – Assemble terminal parts per bill of material

The components are installed with a protective cover as per bill of material.

2560 – Single Packing

For single packing cardboard cartons are used.

2570 – Multiple Packing

The compressors are packed in 2-3 layers. Polythene covers and rings are placed over

the compressors and cardboard is placed between each layer.

2580 – Wrap and Seal

The conveyor will skid the packages into a stretch wrapper and it will be automatically

wrapped. The use of Instapack foam for packing has been eliminated as an environmental

initiative and has been replaced by paper and cardboard packing.

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4.8 WORKING OF COMPRESSOR

4.8.1 RECIPROCATING COMPRESSOR

A reciprocating compressor uses the reciprocating action of a piston inside a cylinder

to compress refrigerant. As the piston moves downward, a vacuum is created inside the

cylinder. Because the pressure above the intake valve is greater than the pressure below it, the

intake valve is forced open and refrigerant is sucked into the cylinder. After the piston

reaches its bottom position it begins to move upward.

Fig: 4.2 working of reciprocating compressor

The intake valve closes, trapping the refrigerant inside the cylinder. As the piston

continues to move upward it compresses the refrigerant, increasing its pressure. At a certain

point the pressure exerted by the refrigerant forces the exhaust valve to open and the

compressed refrigerant flows out of the cylinder. Once the piston reaches it top-most

position, it starts moving downward again and the cycle is repeated.

4.8.2 ROTARY COMPRESSORS

In a rotary compressor the refrigerant is compressed by the rotating action of a roller

inside a cylinder. The roller rotates eccentrically (off-centre) around a shaft so that part of the

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roller is always in contact with the inside wall of the cylinder. A spring-mounted blade is

always rubbing against the roller. The two points of contact create two sealed areas of

continuously variable volume inside the cylinder. At a certain point in the rotation of the

roller, the intake port is exposed and a quantity of refrigerant is sucked into the cylinder,

filling one of the sealed areas.

Fig.4.3 working of rotary compressor

As the roller continues to rotate the volume of the area the refrigerant occupies is

reduced and the refrigerant is compressed. When the exhaust valve is exposed, the high-

pressure refrigerant forces the exhaust valve to open and the refrigerant is released. Rotary

compressors are very efficient because the actions of taking in refrigerant and compressing

refrigerant occur simultaneously.

Next chapter deals with the role of quality control, 7 QC tools used in the statistical

process control and discuss the gauge repeatability and reproducibility.

22

Chapter 5

QUALITY CONTROL

5.1 INTRODUCTION

The managerial process during which actual process performance is evaluated and

actions are taken on unusual performance. It is a process to ensure whether a product meets

predefined standards and requisite action taken if the standards are not met.

5.2 ROLE OF QUALITY CONTROL

Quality Control measures both products and processes for conformance to quality

requirements (including both the specific requirements prescribed by the product

specification, and the more general requirements prescribed by Quality Assurance); identifies

acceptable limits for significant Quality Attributes; identifies whether products and processes

fall within those limits (conform to requirements) or fall outside them (exhibit defects); and

reports accordingly. Correction of product failures generally lies outside the ambit of Quality

Control. The defects due to leaks in compressor pump kits is a Quality Control related

problem.

The recent advancements in Operations Management and Quality Control have

brought revolutionary techniques to solve problems related to Quality Control. These are the

7QC tools and 6-Sigma tools, to name a few. These tools fall under the category of Statistical

Process Control (SPC).

5.3 STATISTICAL PROCESS CONTROL

Statistical Process Control (SPC) is a collection of statistical techniques that are used

to monitor critical parameters and reduce variations. We used SPC to achieve process

stability and improve the capability through reduction of variability. Often the term

"Statistical Quality Control" is used interchangeably with "Statistical Process Control." The

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objective of SPC is to get a process under control. This is done by identifying and eliminating

any specific causes of variation not associated with the process itself. A process that is in

control will constantly perform within its own natural limits.

SPC can be broken into two components: process control and acceptance sampling. In

process control, SPC involves these seven tools:

1. Histogram,

2. Check Sheet,

3. Pareto Chart,

4. Cause and Effect Diagram,

5. Defect Concentration Diagram,

6. Scatter Diagram and

7. Control Chart

These tools often called "The 7 QC tools." Most of the tools help us to identify a

problem in the process. Acceptance sampling is used to reduce variation in the process by

using statistical sampling techniques to select the proper sampling size and to interpret

whether our whole product should be accepted or rejected.

5.4 7QC TOOLS

Seven QC tools are fundamental instruments to improve the quality of the product.

They are used to analyze the production process, identify the major problems, control

fluctuations of product quality, and provide solutions to avoid future defects. Statistical

literacy is necessary to effectively use the seven QC tools. These tools use statistical

techniques and knowledge to accumulate data and analyze them.

Seven QC tools are utilized to organize the collected data in a way that is easy to

understand and analyze. Moreover, from using the seven QC tools, any specific problems in a

process are identified with 6 sigma Tools like process mapping & FMEA.

7QC tools always include

Check Sheet is used to easily collect data. Decision-making and actions are taken

from the data.

24

Pareto Chart is used to define problems, to set their priority, to illustrate the

problems detected, and determine their frequency in the process.

Cause-and-Effect Diagram (Fishbone Diagram) is used to figure out any possible

causes of a problem. After the major causes are known, we can solve the problem

accurately.

Histogram shows a bar chart of accumulated data and provides the easiest way to

evaluate the distribution of data.

Scatter Diagram is a graphical tool that plots many data points and shows a pattern

of correlation between two variables.

Flow Chart shows the process step by step and can sometimes identify an

unnecessary procedure.

Control Chart provides control limits which are generally three standard deviations

above and below average, whether or not our process is in control.

These tools help us identify the critical areas of defects and helps solve the problem

efficiently and effectively. The above tools proved to be highly efficient when effectively

apply to the present problem in Quality Control of compressors pump kits.

5.5 GAUGE REPETABILITY AND REPRODUCIBILITY

• Repeatability: It is the variability of measurements obtained by one person while

measuring the same parameter repeatedly.

• Reproducibility: It is the variability of measurement system caused by differences in

operator behavior.

Next chapter deals with the process capability and machine capability and conditions

for the process capability and machine capability.

25

.

Chapter 6

PROCESS CAPABILITY & MACHINE CAPABILITY

6.1 PROCESS CAPABILITY

Process capability is the long-term performance level of the process after it has been

brought under statistical control. In other words, process capability is the range over which

the natural variation of the process occurs as determined by the system of common causes.

Process capability is also the ability of the combination of people, machine, methods,

material, and measurements to produce a product that will consistently meet the design

requirements or customer expectation.

6.1.1 PROCESS CAPABILITY STUDY

Process capability study is a scientific and a systematic procedure that uses control

charts to detect and eliminate the unnatural causes of variation until a state of statistical

control is reached. When the study is completed, you will identify the natural variability of

the process.

6.1.2 NECESSITY OF KNOWING THE CAPABILITY OF OUR PROCESSES

Process capability measurements allow us to summarize process capability in terms of

meaningful percentages and metrics. To predict the extent to which the process will be able to

hold tolerance or customer requirements. Based on the law of probability, you can compute

how often the process will meet the specification or the expectation of your customer.

It helps you choose from among competing processes, the most appropriate one for

meeting customers' expectation. Knowing the capability of your processes, you can specify

better the quality performance requirements for new machines, parts and processes.

26

6.1.3 NECESSITY OF KNOWING THE CAPABILITY OF OUR SUPPLIER'S

PROCESSES

To understand hidden supplier costs. Suppliers may not know or hide their natural

capability limits in an effort to keep business. This could mean that unnecessary costs could

occur such as sorting to actually meet customer needs. To be pro-active, For example, Cpk

estimation made using injection molding pressure measurements during a molding cycle may

help reveal a faulty piston pressure valve ready to malfunction before the actual molded part

measurements go out of specifications.

6.1.4 MEASURES OF PROCESS CAPABILITY - PROCESS CAPABILITY INDICES

Cp, Cpl, Cpu and Cpk are the four most common and timed tested measures of

process capability.

Process capability indices measure the degree to which your process produces output

that meets the customer's specification.

Process capability indices can be used effectively to summarize process capability

information in a convenient unit less system.

Cp and Cpk are quantitative expressions that personify the variability of your process

(its natural limits) relative to its specification limits (customer requirements).

Following are the graphical details and equations quantifying process capability

27

A minimum of four possible outcomes can arise when the natural process variability is compared with

the design specifications or customer expectations:

Case 1: Cpk > 1.33 (A Highly Capable Process)

This process should produce less than 64 ppm. This process will produce conforming

products as long as it remains in statistical control. The process owner can claim that the customer

should experience least difficulty and greater reliability with this product. This should translate into

higher profits.

Note: Cpk values of 1.33 or greater are considered to be industry benchmarks. This means that the

process is contained within four standard deviations of the process specifications.

Case 2: Cpk = 1 to 1.33 (A Barely Capable Process)

This process will produce greater than 64 ppm but less than 2700 non-conforming

ppm. This process has a spread just about equal to specification width. It should be noted that

28

if the process mean moves to the left or the right, a significant portion of product will start

falling outside one of the specification limits. This process must be closely monitored.

Case 3: Cpk < 1 (The Process is not Capable)

This process will produce more than 2700 non-conforming ppm. It is impossible for

the current process to meet specifications even when it is in statistical control. If the

specifications are realistic, an effort must be immediately made to improve the process (i.e.

reduce variation) to the point where it is capable of producing consistently within

specifications.

Case 4: Cpk < 1 (The Process is not Capable)

This process will also produce more than 2700 non-conforming ppm. The variability

(s) and specification width is assumed to be the same as in case 2, but the process average is

off-center. In such cases, adjustment is required to move the process mean back to target. If

no action is taken, a substantial portion of the output will fall outside the specification limit

even though the process might be in statistical control.

29

6.2 MACHINE CAPABILITY

Machine capability is the ability of machine to produce a product that will

consistently meet the design requirements or customer expectation.

6.2.1 MACHINE CAPABILITY INDEX (Cm)

Machine capability index which gives capability of the machine to meet the tolerance,

is expressed in terms of a ratio as follows.

Cm = (Tolerance) ٪ (6 sigma for machine)

Since process capability index should be greater than 1.33, it may be preferable to

achieve an index of 1.67 or even 2 for machine capability. However, if improvement in

machine capability involves expensive modification, check overall process variation before

making such modifications. If variation from other factors such as material, method, man is

negligible, then machine capability index of 1.50 to 1.66 may be sufficient for the process.

Next chapter deals with the results of gauge repeatability and reproducibility, machine

capability and process capability reports in AW machine shop and RN assembly.

30

Chapter 7

PROCESS CAPABILITY REPORTS OF DIFFERENT SHOPS

7.1 AW MACHINE SHOP

The components of AW series compressors undergo different types of operations

before going to kit assembly in the AW machine shop which already discussed in chapter 3.

Among various operations only critical operations are considered for doing this project.

Critical operations are defined as the operations which directly effect the quality of the

product.

The quality of the product mainly depends on the machine capability and process

capability, which are discussed in chapter 6. So, the quality is controlled by providing the

better capable processes.

Before going to know about the process capability and machine capability, first check

the gauge repeatability and reproducibility of the gauges used in those critical operations for

measuring the specifications of the parameter.

7.1.1 GRR (GAUGE REPEATABILITY & REPRODUCIBILITY) REPORTS

For calculating the GRR there are some standard formulas provided. In this project

Microsoft excel sheet is used to calculate the values of GRR. In this a Microsoft excel sheet is

created such that it has the all formulas for calculating GRR and give final value of GRR just

by entering the measured values of the parameters.

7.1.1.1 CONDITIONS FOR GRR TEST

1. GRR is less than 10 % and NDC (No. of Distinct Categories) is greater than 5 -

Measurement system can be used for SPC study.

2. GRR between 10% to 30% & NDC (No. of Distinct Categories) is greater than 5 -

Measurement system can be used for detection purpose only.

3. GRR above 30 % - Error - Measurement system stands rejected.

31

7.1.1.2 FORMULAS FOR GRR

Operators : A,B & C

No. of Trails, r = 3

No. of Parts, n=10

Gauge Repeatability and Reproducibility, GRR =

o Repeatability - Equipment variation, EV = Rbar * K₁

K₁ = 0.5908 Rbar = (Ra + Rb +Rc)/3 Ra = , Rb = & Rc =

Range,Rai= Rbi = Rci = (Max. value during the trails – Min value during the trails) for part i.o Reproducibility - Appraiser Variation, AV =

Xdiff = Max(Xj) – Min(Xj), where j stands for operator

where Xj = average of all values collected by operator j.

% GRR = 100 ( GRR/ TV)

o Total Variation, TV =

o Part Variation, PV = Rp * K₃

o K₃ = 0.3146

o Rp = Max(Ai) – Min(Ai), where I stands for part

o Average, Ai = (Rai+ Rbi + Rci) / 3 No. of Distinct Categories, NDC = 1.41 (PV / GRR)

By using above formulas GRR can be calculated.

7.1.1.3 GRR TABLE

It contains following data

32

Parameter is to be measured

Part name

Specification of parameter

Collected data

GRR report of Crank case- cylinder bore diameter on Honing Machine 1

The following table 7.1 shows the GRR sheet for the gauge which is used at honing

machine1. In this machine, honing operation is done for the crank case cylinder bore

diameter. The specification of the cylinder bore diameter is 1.5494/1.5506, it means for

honing operation the lower specification limit is 1.5494 and upper specification limit is

1.5506. Here Air gauge is used to measure the specifications. All the readings are in inches

which are mentioned in the following tables. In which three operators say A, B & C are taken

the readings in three trails for ten different parts or samples. The shaded area in the table

represents the values generated by Microsoft excel. At the end of the table GRR (Gauge

Repeatability and Reproducibility) and NDC (No. of Distinct Categories) values are

provided. This Explanation is similar for all GRR tables but parameter and machine are

changed.

GRR ( III EDITION)

DATA COLLECTION SHEET

Part Name: Crank Case Gauge name: Air gauge Date: 28/02/2010 Machine : Honing 1

Parameter: cylinder bore dia Spec: 1.5494/1.5506 Performed by: JNTU students

Operator

PART

Trial 1 2 3 4 5 6 7 8 9 10

A – 1 1.55070 1.55000 1.54965 1.54980 1.54995 1.55000 1.55165 1.55000 1.54985 1.54945 Avg. 1.5501

A – 2 1.55070 1.55000 1.54965 1.54980 1.54985 1.55000 1.55165 1.55000 1.54980 1.54945 Avg. 1.5501

A – 3 1.55070 1.55000 1.54965 1.54980 1.54985 1.54995 1.55160 1.55000 1.54980 1.54945 Avg. 1.5501

Average 1.5507 1.5500 1.5497 1.5498 1.5499 1.5500 1.5516 1.5500 1.5498 1.5495 X a 1.5501

Range 0.0000 0.0000 0.0000 0.0000 0.0001 0.0001 0.0000 0.0000 0.0000 0.0000 R a = 0.00002

B -1 1.55075 1.55000 1.54965 1.54980 1.54985 1.54995 1.55165 1.55000 1.54985 1.54950 Avg. 1.5501

B -2 1.55075 1.55000 1.54965 1.54985 1.54985 1.55000 1.55165 1.55000 1.54985 1.54950 Avg. 1.5501

B -3 1.55070 1.54995 1.54965 1.54980 1.54985 1.54995 1.55160 1.55000 1.54980 1.54945 Avg. 1.5501

Average 1.5507 1.5500 1.5497 1.5498 1.5499 1.5500 1.5516 1.5500 1.5498 1.5495 X b = 1.5501

33

Range 0.0001 0.0001 0.0000 0.0000 0.0000 0.0001 0.0000 0.0000 0.0000 0.0001 R b = 0.00004

C – 1 1.55075 1.55000 1.54965 1.54980 1.54985 1.54995 1.55165 1.55000 1.54980 1.54950 Avg. 1.5501

C – 2 1.55075 1.55000 1.54965 1.54985 1.54985 1.55000 1.55165 1.55000 1.54985 1.54950 Avg. 1.5501

C – 3 1.55070 1.55000 1.54965 1.54980 1.54980 1.54995 1.55160 1.55000 1.54980 1.54945 Avg. 1.5501

Average 1.5507 1.5500 1.5497 1.5498 1.5498 1.5500 1.5516 1.5500 1.5498 1.5495 Xc = 1.5501

Range 0.0001 0.0000 0.0000 0.0000 0.0000 0.0001 0.0000 0.0000 0.0000 0.0001 Rc = 0.00003

Part

Average1.5507 1.5500 1.5497 1.5498 1.5499 1.5500 1.5516 1.5500 1.5498 1.5495

% GRR – 2.86 NDC- 51

Table 7.1

From the above table 7.1 GRR is less than 10% and NDC is greater than 5. So, from

the conditions of GRR test, it is found that the Measurement system can be used for

SPC (statistical process control) study.

GRR report of Crank case- cylinder bore diameter on Honing Machine 2

GRR ( III EDITION)


Part Name: Crank Case Gauge name: Air gauge Date: 28/02/2010 Machine : Honing 2

Parameter: cylinder bore dia Spec: 1.5494/1.5506 Performed by: JNTU students

Operator PART

Trial 1 2 3 4 5 6 7 8 9 10

A – 1 1.55170 1.55030 1.55025 1.55010 1.54995 1.54985 1.55010 1.55015 1.54950 1.55018 Avg. 1.5502

A – 2 1.55170 1.55030 1.55025 1.55010 1.55000 1.54990 1.55010 1.55015 1.55000 1.54950 Avg. 1.5502

A – 3 1.55170 1.55030 1.55025 1.55010 1.54990 1.54990 1.55010 1.55015 1.55000 1.54950 Avg. 1.5502

Average 1.5517 1.5503 1.5503 1.5501 1.5500 1.5499 1.5501 1.5502 1.5498 1.5497 X a 1.5502

Range 0.0000 0.0000 0.0000 0.0000 0.0001 0.0001 0.0000 0.0000 0.0005 0.0007 R a = 0.00013

B -1 1.55160 1.55030 1.55025 1.55010 1.54990 1.54990 1.55010 1.55015 1.54995 1.54950 Avg. 1.5502

B -2 1.55175 1.55030 1.55030 1.55010 1.54995 1.54990 1.55010 1.55015 1.55000 1.54950 Avg. 1.5502

B -3 1.55175 1.55030 1.55025 1.55010 1.54995 1.54990 1.55010 1.55015 1.55000 1.54950 Avg. 1.5502

Average 1.5517 1.5503 1.5503 1.5501 1.5499 1.5499 1.5501 1.5502 1.5500 1.5495 X b = 1.5502

Range 0.0001 0.0000 0.0001 0.0000 0.0000 0.0000 0.0000 0.0000 0.0001 0.0000 R b = 0.00003

C – 1 1.55165 1.55030 1.55030 1.55015 1.54995 1.54990 1.55015 1.55015 1.55000 1.54950 Avg. 1.5502

C – 2 1.55175 1.55030 1.55030 1.55010 1.54995 1.54990 1.55010 1.55015 1.55000 1.54950 Avg. 1.5502

34

C – 3 1.55170 1.55030 1.55030 1.55015 1.54995 1.54990 1.55010 1.55015 1.55000 1.54950 Avg. 1.5502

Average 1.5517 1.5503 1.5503 1.5501 1.5500 1.5499 1.5501 1.5502 1.5500 1.5495 Xc = 1.5502

Range 0.0001 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 Rc = 0.00002

Part Average 1.5517 1.5503 1.5503 1.5501 1.5499 1.5499 1.5501 1.5502 1.5499 1.5496

% GRR – 5.46 NDC- 26

Table 7.2




GRR report of Crank Shaft- S.E pin diameter on Parishudh S.E Machine

GRR ( III EDITION)


Part Name: Crank Shaft Gauge name: Air gauge Date: 28/02/2010 Machine : Parishudh

S.E

Parameter: S.E pin diameter Spec: 1.4371/1.4376 Performed by: JNTU students

Operator

PART

Trial 1 2 3 4 5 6 7 8 9 10

A – 1 1.43725 1.43730 1.43785 1.43735 1.43730 1.43735 1.43725 1.43665 1.43740 1.43725 Avg. 1.4373

A – 2 1.43740 1.43730 1.43785 1.43735 1.43740 1.43730 1.43725 1.43670 1.43730 1.43725 Avg. 1.4373

A – 3 1.43740 1.43725 1.43780 1.43735 1.43730 1.43735 1.43720 1.43665 1.43725 1.43725 Avg. 1.4373

Average 1.4374 1.4373 1.4378 1.4374 1.4373 1.4373 1.4372 1.4367 1.4373 1.4373

X a 1.4373

Range 0.0002 0.0001 0.0001 0.0000 0.0001 0.0000 0.0000 0.0001 0.0002 0.0000R a = 0.0000

7

B -1 1.43745 1.43740 1.43780 1.43740 1.43735 1.43750 1.43725 1.43675 1.43675 1.43730 Avg. 1.4373

B -2 1.43745 1.43730 1.43780 1.43740 1.43735 1.43735 1.43725 1.43670 1.43670 1.43725 Avg. 1.4373

B -3 1.43730 1.43725 1.43780 1.43730 1.43730 1.43735 1.43725 1.43665 1.43740 1.43725 Avg. 1.4373

Average 1.4374 1.4373 1.4378 1.4374 1.4373 1.4374 1.4373 1.4367 1.4370 1.4373

X b =1.4373

Range 0.0001 0.0002 0.0000 0.0001 0.0000 0.0002 0.0000 0.0001 0.0007 0.0001R b = 0.0001

4

C – 1 1.43745 1.43730 1.43780 1.43740 1.43735 1.43740 1.43730 1.43655 1.43740 1.43725 Avg. 1.4373

C – 2 1.43740 1.43740 1.43785 1.43740 1.43740 1.43745 1.43720 1.43655 1.43740 1.43725 Avg. 1.4373

C – 3 1.43730 1.43730 1.43780 1.43730 1.43730 1.43745 1.43725 1.43655 1.43730 1.43715 Avg. 1.4373

35

Average 1.4374 1.4373 1.4378 1.4374 1.4374 1.4374 1.4373 1.4366 1.4374 1.4372

Xc =1.4373

Range 0.0001 0.0001 0.0001 0.0001 0.0001 0.0000 0.0001 0.0000 0.0001 0.0001Rc = 0.0000

8

Part

Average 1.4374 1.4373 1.4378 1.4374 1.4373 1.4374 1.4372 1.4366 1.4372 1.4372

% GRR – 15.97 NDC- 9

Table 7.3

From the above table 7.3 GRR is between10- 30% and NDC is greater than 5. So,

from the conditions of GRR test, it is found that Measurement system can be used for

detection purpose only.

GRR report of Crank Shaft- L.E pin diameter on Parishudh L.E Machine

GRR ( III EDITION)


Part Name: Crank Shaft Gauge name: Air gauge Date: 28/02/2010 Machine : Parishudh

L.E

Parameter: L.E pin diameter Spec: 1.4371/1.4376 Performed by: JNTU students

Operator

PART

Trial 1 2 3 4 5 6 7 8 9 10

A – 1 1.43750 1.43785 1.43745 1.43750 1.43735 1.43750 1.43745 1.43660 1.43745 1.43750 Avg. 1.4373

A – 2 1.43745 1.43780 1.43740 1.43745 1.43730 1.43740 1.43740 1.43655 1.43745 1.43745 Avg. 1.4373

A – 3 1.43740 1.43780 1.43740 1.43745 1.43735 1.43750 1.43745 1.43665 1.43745 1.43745 Avg. 1.4373

Average 1.4375 1.4378 1.4374 1.4375 1.4373 1.4375 1.4374 1.4366 1.4375 1.4375 X a 1.4373

Range 0.0001 0.0001 0.0000 0.0001 0.0000 0.0001 0.0000 0.0001 0.0000 0.0001R a = 0.00007

B -1 1.43745 1.43780 1.43745 1.43750 1.43740 1.43745 1.43745 1.43660 1.43750 1.43750 Avg. 1.4373

B -2 1.43750 1.43780 1.43740 1.43750 1.43740 1.43740 1.43745 1.43665 1.43745 1.43750 Avg. 1.4373

B -3 1.43740 1.43780 1.43740 1.43750 1.43735 1.43740 1.43745 1.43655 1.43745 1.43750 Avg. 1.4373

Average 1.4375 1.4378 1.4374 1.4375 1.4374 1.4374 1.4375 1.4366 1.4375 1.4375X b = 1.4373

Range 0.0001 0.0000 0.0000 0.0000 0.0001 0.0000 0.0000 1.4375 0.0001 0.0000R b = 0.00014

C – 1 1.43735 1.43780 1.43740 1.43745 1.43730 1.43740 1.1.4373 1.43660 1.43740 1.43740 Avg. 1.4373

C – 2 1.43735 1.43780 1.43730 1.43745 1.43735 1.43735 1.43740 1.43665 1.43740 1.43745 Avg. 1.4373

C – 3 1.43740 1.43780 1.43740 1.43745 1.43740 1.43740 1.43740 1.43660 1.43745 1.43745 Avg. 1.4374

Average 1.4374 1.4378 1.4374 1.4375 1.4374 1.4374 1.4374 1.4366 1.4374 1.4374 Xc 1.4374

36

=

Range 0.0001 0.0000 0.0001 0.0000 0.0001 0.0001 0.0000 0.0000 0.0000 0.0000 Rc = 0.00004

Part

Average 1.4374 1.4378 1.4374 1.4375 1.4374 1.4374 1.4374 1.4366 1.4374 1.4375

% GRR – 9.49 NDC- 15

Table 7.4




GRR report of Piston OD grinding on Micron Machine

GRR ( III EDITION)


Part Name: Piston Gauge name: Air gauge Date: 02/03/2010 Machine : Micron

Parameter: Piston OD grinding Spec: 1.5490/1.5500 Performed by: JNTU students

Operator PART

Trial 1 2 3 4 5 6 7 8 9 10

A – 1 1.54895 1.54935 1.54955 1.54945 1.54920 1.54940 1.54970 1.54865 1.54975 1.54905 Avg. 1.5493

A – 2 1.54900 1.54935 1.54955 1.54950 1.54925 1.54940 1.54975 1.54870 1.54975 1.54910 Avg. 1.5493

A – 3 1.54900 1.54940 1.54955 1.54950 1.54925 1.54945 1.54975 1.54865 1.54975 1.54905 Avg. 1.5493

Average 1.5490 1.5494 1.5496 1.5495 1.5492 1.5494 1.5497 1.5487 1.5498 1.5491 X a 1.5493

Range 0.0000 0.0001 0.0000 0.0001 0.0001 0.0000 0.0000 0.0000 0.0000 0.0000R a = 0.00004

B -1 1.54895 1.54935 1.54955 1.54950 1.54915 1.54935 1.54975 1.54870 1.54975 1.54905 Avg. 1.5493

B -2 1.54900 1.54940 1.54955 1.54950 1.54925 1.54945 1.54975 1.54870 1.54975 1.54910 Avg. 1.5493

B -3 1.54900 1.54940 1.54955 1.54950 1.54925 1.54945 1.54975 1.54870 1.54975 1.54905 Avg. 1.5493

Average 1.5490 1.5494 1.5496 1.5495 1.5492 1.5494 1.5498 1.5487 1.5498 1.5491X b = 1.5493

Range 0.0000 0.0001 0.0000 0.0000 0.0001 0.0001 0.0000 0.0000 0.0000 0.0000R b = 0.00003

C – 1 1.54900 1.54940 1.54955 1.54945 1.54920 1.54940 1.54975 1.54870 1.54975 1.54905 Avg. 1.5493

C – 2 1.54900 1.54940 1.54955 1.54950 1.54925 1.54945 1.54975 1.54870 1.54975 1.54910 Avg. 1.5493

C – 3 1.54900 1.54935 1.54955 1.54950 1.54920 1.54940 1.54975 1.54870 1.54975 1.54905 Avg. 1.5493

Average 1.5490 1.5494 1.5496 1.5495 1.5492 1.5494 1.5498 1.5487 1.5498 1.5491 Xc 1.5493

37

=

Range 0.0000 0.0001 0.0000 0.0001 0.0001 0.0000 0.0000 0.0000 0.0000 0.0000 Rc = 0.00003

Part

Average 1.5490 1.5494 1.5496 1.5495 1.5492 1.5494 1.5497 1.5487 1.5498 1.5491

% GRR – 5.98 NDC- 24

Table 7.5




GRR report of Connecting Rod crank bore on XLO - 732 Machine

GRR ( III EDITION)


Part Name: Piston Gauge name: Air gauge Date: 02/03/2010 Machine : Micron

Parameter: Piston OD grinding Spec: 1.4382/1.4386 Performed by: JNTU students

Operator PART

Trial 1 2 3 4 5 6 7 8 9 10

A – 1 1.43855 1.43875 1.43860 1.43840 1.43850 1.43880 1.43880 1.43815 1.43880 1.43875 Avg. 1.4386

A – 2 1.43860 1.43880 1.43865 1.43840 1.43850 1.43875 1.43880 1.43815 1.43880 1.43875 Avg. 1.4386

A – 3 1.43855 1.43880 1.43865 1.43845 1.43850 1.43880 1.43880 1.43815 1.43880 1.43875 Avg. 1.4386

Average 1.4386 1.4388 1.4386 1.4384 1.4385 1.4388 1.4388 1.4382 1.4388 1.4388 X a 1.4386

Range 0.0001 0.0001 0.0000 0.0001 0.0000 0.0001 0.0000 0.0000 0.0000 0.0000 R a = 0.00003

B -1 1.43860 1.43875 1.43865 1.43840 1.43850 1.43880 1.43880 1.43820 1.43880 1.43875 Avg. 1.4386

B -2 1.43860 1.43880 1.43865 1.43845 1.43850 1.43880 1.43880 1.43815 1.43880 1.43875 Avg. 1.4386

B -3 1.43860 1.43880 1.43865 1.43845 1.43850 1.43880 1.43880 1.43815 1.43880 1.43875 Avg. 1.4386

Average 1.4386 1.4388 1.4387 1.4384 1.4385 1.4388 1.4388 1.4382 1.4388 1.4388 X b = 1.4386

Range 0.0000 0.0001 0.0000 0.0001 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 R b = 0.00002

C – 1 1.43855 1.43880 1.43860 1.43840 1.43845 1.43880 1.43885 1.43815 1.43880 1.43875 Avg. 1.4386

C – 2 1.43855 1.43880 1.43865 1.43840 1.43850 1.43880 1.43885 1.43815 1.43880 1.43875 Avg. 1.4386

C – 3 1.43860 1.43875 1.43860 1.43845 1.43850 1.43875 1.43880 1.43820 1.43880 1.43875 Avg. 1.4386

Average 1.4386 1.4388 1.4386 1.4384 1.4385 1.4388 1.4388 1.4382 1.4388 1.4388 Xc = 1.4386

38

Range 0.0001 0.0001 0.0000 0.0001 0.0000 0.0001 0.0000 0.0000 0.0000 0.0000 Rc = 0.00004

Part

Average 1.5490 1.5494 1.5496 1.5495 1.5492 1.5494 1.5497 1.5487 1.5498 1.5491

% GRR – 8.09 NDC- 17

Table 7.6

From the above table 7.6 GRR is less than 10% and NDC is greater than 5. So, from the

conditions of GRR test, it is found that the Measurement system can be used for SPC

(statistical process control) study.

7.1.1.4 SUMMARY SHEET FOR GRR TEST

S.NO COMPONENT MACHINE PARAMETER GRR NDC

TEST

(PASS/

FAIL)

1 CRANK CASEHONING - 1 (OLD) CYL. BORE DIA 2.76 51 P

HONING - 2(NEW) CYL. BORE DIA 5.46 26 P

2 CRANK SHAFTPARISHUDH S.E S.E PIN DIA 15.97 9 F

PARISHUDH L.E L.E PIN DIA 9.49 15 P

3 PISTON MICRON OD GRINDING 5.98 24 P

4CONNECTING

RODXLO – 732 CRANK BORE DIA 8.09 17

P

Table 7.7 Summery sheet for GRR test

From the above table 7.7

It is clear that the gauges available at the machines say Honing-1, Honing -2,

Parishudh L.E, Micron and XLO – 732 are satisfy the first condition (GRR % less

than 10 % and NDC greater than 5) of GRR test. So, these gauges can be used for

SPC study.

But the gauge at Parishudh S.E machine satisfies the second condition (GRR between

10% to 30% & NDC greater than 5) of GRR test. So, this gauge can be used for

detection purpose only.

7.1.2 MACHINE CAPABILITY REPORTS

To know the capabilities of various machines, the machine capability test is

performed. To perform this test some standard form of collection data table and formulas are

39

used. This work is done on Microsoft excel by creating a excel sheet such that it contains the

formulas for calculating machine capability.

7.1.2.1 CONDITION FOR MACHINE CAPABILITY TEST

The capability of the machine should be greater than 2, for the machine to be in good

working condition.

7.1.2.2 FORMULAS FOR CALCULATING MACHINE CAPABILITY

No. of times readings are taken (by providing some interval between them), n = 10

Range , Ri = Max value – Min value

Average of all ranges, Rbar =

Constant, d ₂ = 2.326 Sigma = Rbar / d₂

6Sigma = 6 * Sigma Tolerance =USL – LSL

o USL – Upper Specification Limit o LSL – Lower Specification Limit

Machine Capability = Tolerance / 6Sigma7.1.2.3 PROCEDURE FOR CALCULATING MACHINE CAPABILITY

Collect the data for different parameters from different machines in time intervals.

Enter the data in the Microsoft excel sheet as shown in following table.

The Microsoft excel sheet automatically generates the machine capability values, in

which we provide the formulas for calculating machine capability.

Machine Capability Report of Honing1 Machine (CYLINDER BORE DIA) (Spec: 1.5494/1.5506)

The following table 7.8 shows the machine capability sheet for Honing Machine1. In

this machine, honing operation is done for the crank case cylinder bore diameter. In this table

first column shows the serial number, second column shows the time at which readings are

taken, next column shows the samples or work pieces readings taken during the time

40

mentioned in the column2. The range column shows the difference in the maximum reading

and minimum reading in the corresponding row. R bar is the average of all ranges. d₂ is

constant. Tolerance is the difference between the specification limits. For sigma, 6sigma and

machine capability formulas are provided earlier. As mentioned in the procedure 7.1.2.3,

after entering all values in excel sheet it generates machine capability values. From these

tables capability value is taken for the test. This explanation is similar for all AW and RN

tables drawn in following pages, but machines are different.

S.NO

TimeSamples

Range R bar d2 Sigma 6

SigmaToleranc

ecapability

1 2 3 4 5

1 9:45 1.55000 1.55005 1.54995 1.54995 1.54990 0.00015

0.00029 2.326 0.00013 0.00076 0.0012 1.577

2 11:15 1.55020 1.55010 1.55000 1.54980 1.54965 0.00055

3 11:45 1.54990 1.55025 1.55015 1.55000 1.54990 0.00035

4 12:15 1.55020 1.55025 1.55020 1.55010 1.55005 0.00020

5 12:45 1.55020 1.55015 1.55000 1.55015 1.55010 0.00020

6 13:45 1.54995 1.55010 1.55005 1.55005 1.54995 0.00015

7 14:15 1.54990 1.55015 1.55005 1.55025 1.55020 0.00035

8 14:45 1.54990 1.54955 1.54955 1.54945 1.54925 0.00065

9 15:15 1.54980 1.54980 1.54970 1.54955 1.54960 0.00025

10 15:45 1.54995 1.54990 1.54995 1.54990 1.54985 0.00010

Table 7.8

From the table 7.8 it is found that machine capability is less than 2. So, the required

condition for machine capability test is not satisfied.

Machine Capability Report of Honing2 Machine ( CYLINDER BORE DIA) (Spec:

1.5494/1.5506 )

S.NO

TimeSamples


SigmaTolera

nceCapabil

ity1 2 3 4 5

1 9:50 1.55015 1.55005 1.55005 1.54995 1.54995 0.00020

0.00014 2.326 0.00006 0.00037 0.0012 3.208

2 11:20 1.55000 1.54995 1.54985 1.54980 1.54980 0.00020

3 11:50 1.55000 1.54995 1.55005 1.55000 1.55015 0.00020

4 12:20 1.54990 1.55000 1.55005 1.54990 1.54990 0.00015

5 12:50 1.54995 1.54995 1.54995 1.54990 1.54995 0.00005

6 13:50 1.55000 1.54995 1.54995 1.54995 1.54990 0.00010

7 14:20 1.54995 1.54990 1.54995 1.55000 1.54990 0.00010

41

8 14:50 1.54995 1.54995 1.55000 1.54985 1.54990 0.00015

9 15:20 1.55005 1.55000 1.55005 1.55000 1.55015 0.00015

10 15:50 1.55000 1.54995 1.54990 1.54985 1.54985 0.00015

Table 7.9

From the table 7.9 it is found that machine capability is greater than 2. So, the

required condition for machine capability test is satisfied.

Machine Capability Report of Parishudh S.E Machine (Crank Shaft) (Spec:

1.4371/1.4376)

S.NO

TimeSamples


SigmaToleranc

ecapabili

ty1 2 3 4 5

1 12:20 1.43730 1.43735 1.43735 1.43735 1.43730 0.00005

0.00005 2.326 0.00002 0.00013 0.0005 3.877

2 12:50 1.43730 1.43730 1.43730 1.43730 1.43730 0.00000

3 13:45 1.43730 1.43725 1.43735 1.43725 1.43730 0.00010

4 14:45 1.43730 1.43735 1.43735 1.43730 1.43735 0.00005

5 15:10 1.43730 1.43730 1.43725 1.43730 1.43725 0.00005

6 15:35 1.43730 1.43730 1.43730 1.43735 1.43735 0.00005

7 16:00 1.43735 1.43735 1.43735 1.43730 1.43730 0.00005

8 16:25 1.43730 1.43725 1.43725 1.43725 1.43730 0.00005

9 16:50 1.43730 1.43735 1.43735 1.43735 1.43730 0.00005

10 17:50 1.43730 1.43730 1.43730 1.43725 1.43725 0.00005

Table 7.10

From the table 7.10 it is found that machine capability is greater than 2. So, the required

condition for machine capability test is satisfied.

Machine Capability Report of Parishudh L.E Machine (Crank Shaft) (Spec:

1.4371/1.4376)

S.NO

TimeSamples


SigmaToleranc

ecapabili

ty1 2 3 4 5

1 12:25 1.43740 1.43735 1.43735 1.43735 1.43735 0.00005

0.00006 2.326 0.00003 0.00015 0.0005 3.2312 12:55 1.43735 1.43735 1.43730 1.43735 1.43740 0.00010

3 13:50 1.43735 1.43730 1.43735 1.43730 1.43730 0.00005

4 14:50 1.43735 1.43730 1.43735 1.43735 1.43735 0.00005

42

5 15:15 1.43735 1.43735 1.43730 1.43730 1.43730 0.00005

6 15:40 1.43735 1.43735 1.43735 1.43740 1.43735 0.00005

7 16:05 1.43735 1.43735 1.43740 1.43740 1.43745 0.00010

8 16:30 1.43735 1.43735 1.43735 1.43735 1.43730 0.00005

9 16:55 1.43735 1.43735 1.43735 1.43730 1.43730 0.00005

10 17:20 1.43735 1.43740 1.43740 1.43740 1.43735 0.00005

Table 7.11

From the table 7.11 it is found that machine capability is greater than 2. So, the

required condition for machine capability test is satisfied.

Machine Capability Report of EMT Machine ( Piston deck height) (Spec: 0.8403/0.8443)

S.NO

TimeSamples


SigmaToleran

cecapabil

ity1 2 3 4 5

1 13:20 0.8468 0.8443 0.8458 0.8453 0.8443 0.0025

0.00265 2.326 0.00114 0.00684 0.004 0.585

2 13:50 0.8468 0.8458 0.8458 0.8453 0.8443 0.0025

3 14:40 0.8468 0.8463 0.8453 0.8448 0.8443 0.0025

4 15:05 0.8468 0.8443 0.8468 0.8453 0.8413 0.0055

5 15:30 0.8463 0.8443 0.8438 0.8463 0.8463 0.0025

6 15:55 0.8468 0.8468 0.8473 0.8438 0.8458 0.0035

7 16:20 0.8468 0.8468 0.8443 0.8453 0.8463 0.0025

8 16:45 0.8458 0.8458 0.8463 0.8473 0.8453 0.0020

9 17:10 0.8468 0.8458 0.8473 0.8453 0.8458 0.0020

10 17:35 0.8458 0.8468 0.8458 0.8463 0.8463 0.0010

Table 7.12



Machine Capability Report of TU-2065 Machine ( Piston deck height) (Spec:

0.7938/0.7958)

S.NO

TimeSamples


SigmaToleranc

ecapabili

ty1 2 3 4 5

1 13:00 0.7955 0.7940 0.7965 0.7945 0.7965 0.0025

0.00260 2.326 0.00112 0.00671 0.002 0.2982 13:40 0.7965 0.7940 0.7965 0.7950 0.7950 0.0025

3 14:15 0.7960 0.7940 0.7965 0.7950 0.7960 0.0025

43

4 14:55 0.7960 0.7965 0.7965 0.7965 0.7955 0.0010

5 15:20 0.7970 0.7935 0.7960 0.7945 0.7910 0.0060

6 15:45 0.7965 0.7940 0.7960 0.7950 0.7930 0.0035

7 16:10 0.7940 0.7950 0.7955 0.7950 0.7960 0.0020

8 16:35 0.7955 0.7975 0.7950 0.7960 0.7950 0.0025

9 17:00 0.7970 0.7970 0.7960 0.7955 0.7960 0.0015

10 17:25 0.7955 0.7950 0.7960 0.7965 0.7970 0.0020

Table 7.13



7.1.2.4 SUMMARY SHEET FOR MACHINE CAPABILITY TEST

S.NO COMPONENT MACHINE PARAMETER MACHINE CAPABILITY

1 CRANK CASEHONING - 1 (OLD) CYL. BORE DIA 1.57

HONING - 2(NEW) CYL. BORE DIA 3.21

2 CRANK SHAFTPARISHUDH S.E S.E PIN DIA 3.87

PARISHUDH L.E L.E PIN DIA 3.23

3 PISTONEMT DECK HEIGHT 0.59

TUPELO 2065 DECK HEIGHT 0.30

Table 7.14: Summary sheet for Machine Capability test


It is clear that the machine capabilities of Honing2, Parishudh SE and Parishudh LE

machines are greater than the required capability 2. Therefore they satisfies the

condition for the for machine capability test.

But the machine capabilities of Honing1, EMT and TUPELO2065 are less than 2. So,

the required condition for machine capability test is not satisfied.

7.1.3 PROCESS CAPABILITY REPORTS

44

To know the capabilities of various processes, process capability test is performed. In

this test first readings are collected and process capability charts for the collected data are

drawn. The readings are nothing but process specification for example diameter of the

cylinder bore.

For drawing the process capability charts MTAB software is used. This software

automatically generates the process capability charts for the given set of values.

This software needs the following information for drawing the process capability

charts.

Collected data

Lower specification limit

Upper specification limit

Title for the graph

So that the MTAB software generates the process capability charts. Through this

chart values of process capability (Cp) and process capability index (Cpk) are found.

7.1.3.1 CONDITIONS FOR THE PROCESS CAPABILITY TEST

1. Process capability index (Cpk) is greater than 1.33 - A Highly Capable Process.

2. Process capability index (Cpk) is between 1 to 1.33 - A Barely Capable Process.

3. Process capability index (Cpk) is less than 1 - The Process is not capable.

7.1.3.2 PROCEDURE FOR CALCULATING PROCESS CAPABILITY

Collect the data for different processes.

Enter the values in MTAB soft ware.

Enter the specification limits for the given parameters.

Enter the title of the graph.

Then MTAB automatically generates the process capability charts. From which the

process capability (Cp) and process capability index (Cpk) are taken.

7.1.3.3 COLLECTION DATA AND PROCESS CAPABILITY GRAPHS

45

Collected Data for Crank Case cylinder Bore

The following table 7.15 shows the collected values for drawing the process

capability charts. In this table the parameter is crank case cylinder bore diameter. AW crank

case has two cylinder bores, they are called top bore and bottom bore. In table first column

shows the serial number, second and third columns show the readings of top and bottom bore

on Honing machine1 and next two columns show the readings of top and bottom bore on

Honing machine2. All the readings are taken in inches and measured by using Air gauges.

The specification of the parameter is 1.5494/1.5496. This explanation is similar for all AW

and RN tables but the parameters and machines are different.

PARAMETER : CYLINDER BORE DIA

Specification : 1.5494/1.5506 Date : 03 / 03 / 10

MACHINE HONNING 1 HONNING 2 MACHINE HONNING 1 HONNING 2

S.NO TOP BOTTOM TOP BOTTOM S.NO TOP BOTTOM TOP BOTTOM

1 1.54995 1.54995 1.54990 1.54990 26 1.55020 1.55020 1.54990 1.54990

2 1.54990 1.54975 1.54980 1.54980 27 1.55005 1.54950 1.54980 1.54980

3 1.54975 1.54950 1.54990 1.54985 28 1.55020 1.55025 1.54980 1.54980

4 1.54975 1.54970 1.54985 1.54990 29 1.54995 1.55000 1.54980 1.54985

5 1.55000 1.54990 1.54985 1.54985 30 1.54990 1.54995 1.54990 1.54995

6 1.54985 1.54970 1.54990 1.54990 31 1.54995 1.54995 1.54995 1.54995

7 1.54985 1.54975 1.54980 1.54985 32 1.54995 1.54970 1.55000 1.55000

8 1.54990 1.54985 1.55000 1.54990 33 1.54970 1.54965 1.54995 1.54995

9 1.54990 1.59800 1.54985 1.54990 34 1.54995 1.54990 1.55005 1.55005

10 1.54980 1.54985 1.54980 1.54980 35 1.54995 1.54960 1.55000 1.55000

11 1.54995 1.55000 1.54985 1.54990 36 1.54965 1.54965 1.55005 1.55000

12 1.55025 1.55005 1.54995 1.54995 37 1.54970 1.54975 1.54985 1.54985

13 1.54990 1.54985 1.54990 1.54990 38 1.54975 1.54970 1.54990 1.54990

14 1.54995 1.55000 1.54980 1.54985 39 1.54965 1.54950 1.54995 1.54995

15 1.54985 1.54985 1.54990 1.54985 40 1.54975 1.54990 1.54990 1.54990

16 1.55005 1.55000 1.54995 1.54990 41 1.54960 1.54960 1.54995 1.54995

17 1.54990 1.54975 1.54980 1.54975 42 1.54950 1.54965 1.54985 1.54980

18 1.54995 1.55005 1.54995 1.54975 43 1.54990 1.54990 1.54980 1.54985

19 1.54985 1.54985 1.54970 1.54960 44 1.54965 1.54990 1.54980 1.54980

46

20 1.55005 1.54970 1.54995 1.54950 45 1.54940 1.54965 1.54990 1.54990

21 1.55010 1.55010 1.54985 1.54985 46 1.54970 1.54970 1.54985 1.54985

22 1.55005 1.55005 1.54990 1.54990 47 1.54985 1.54995 1.54985 1.54980

23 1.54985 1.54985 1.54995 1.54990 48 1.54940 1.54935 1.54990 1.54980

24 1.55015 1.54990 1.54990 1.54990 49 1.55035 1.55035 1.55000 1.54995

25 1.54995 1.54995 1.54985 1.54980 50 1.55015 1.54995 1.54980 1.54980

Table 7.15

Process Capability Graphs for Crank Case Cylinder Bore Diameter

The process capability graph explains the following points and this is common to all

process capability graphs drawn in following pages, but operation is different.

The LSL dotted vertical line shows the lower specification limit for the given

parameter. Here the parameter is cylinder bore diameter.

The USL dotted vertical line shows the upper specification limit for the given

parameter.

The rectangular bar in between the LSL and USL show the number of parts with in

the limit or specification.

The rectangular bars out side the LSL or USL show the number of parts out of the

limits.

If the rectangular bars show on left side of the LSL means the parts are in under size

and if they show on right side of the USL means the parts are in over size.

From this graph we obtain the process capability (Cp) and process capability index

(Cpk). These values are circled in the graph.

47

Graph 7.1

The above graph 7.1 obtains by entering the input values such are specifications of

cylinder bore diameter, upper specification limit and lower specification limit in MTAB.

From The above graph 7.1 Cp = 1.21 and Cpk = 0.84 of top bore diameter of

crank case at honing machine1

The graphs drawn below are followed by their corresponding Cp and Cpk values.

Graph 7.2

48

From The above graph 7.2 Cp = 0.93 and Cpk = 0.58 of bottom bore diameter of

crankcase at honing machine1

Graph 7.3

From The above graph 7.3 Cp = 2.53 and Cpk = 1.78 of top bore diameter of

crankcase at honing machine2

Graph 7.4

49

From The above graph 7.4 Cp = 2.90 and Cpk = 1.98 78 of bottom bore diameter

of crankcase at honing machine2

Collected Data for Piston Deck Height

PARAMETER :Deck Height MACHINE : TUPELO – 2065

SPECIFICATION :( Deck height : 0.8238 / 0.8258" )

Fixtures

Deck Height

(0.8238/0.8258)

Deck Height

(0.8238/0.8258)

Deck Height

(0.8238/0.8258)

Deck Height (0.8238/0.825

8)

Deck Height

(0.8238/0.8258)

Deck Height

(0.8238/0.8258)

Deck Height

(0.8238/0.8258)

Deck Height

(0.8238/0.8258)

1LL 3LL 3RL 3RR 4LL 4LR 4RL 4RR

1 0.8240 0.8265 0.8240 0.8250 0.8255 0.8260 0.8260 0.8250

2 0.8250 0.8260 0.8245 0.8255 0.8250 0.8250 0.8255 0.8250

3 0.8250 0.8265 0.8240 0.8250 0.8245 0.8245 0.8265 0.8250

4 0.8240 0.8280 0.8250 0.8250 0.8255 0.8250 0.8215 0.8245

5 0.8250 0.8265 0.8255 0.8240 0.8250 0.8260 0.8250 0.8245

6 0.8245 0.8265 0.8240 0.8255 0.8250 0.8250 0.8255 0.8245

7 0.8245 0.8250 0.8245 0.8255 0.8260 0.8250 0.8250 0.8245

8 0.8250 0.8255 0.8245 0.8250 0.8245 0.8260 0.8270 0.8245

50

9 0.8250 0.8260 0.8240 0.8240 0.8250 0.8255 0.8260 0.8250

10 0.8250 0.8255 0.8245 0.8250 0.8245 0.8255 0.8255 0.8245

11 0.8245 0.8260 0.8240 0.8255 0.8250 0.8255 0.8260 0.8250

12 0.8250 0.8260 0.8245 0.8250 0.8250 0.8250 0.8260 0.8245

13 0.8245 0.8255 0.8260 0.8250 0.8245 0.8255 0.8255 0.8255

14 0.8245 0.8260 0.8245 0.8240 0.8250 0.8255 0.8260 0.8245

15 0.8240 0.8250 0.8265 0.8250 0.8250 0.8250 0.8260 0.8250

16 0.8240 0.8265 0.8250 0.8255 0.8240 0.8255 0.8260 0.8260

17 0.8240 0.8255 0.8250 0.8250 0.8255 0.8260 0.8265 0.8255

18 0.8245 0.8260 0.8255 0.8265 0.8250 0.8255 0.8260 0.8255

19 0.8245 0.8250 0.8255 0.8250 0.8245 0.8255 0.8265 0.8255

20 0.8245 0.8260 0.8250 0.8265 0.8255 0.8260 0.8260 0.8260

21 0.8245 0.8260 0.8260 0.8260 0.8250 0.8260 0.8265 0.8250

22 0.8240 0.8260 0.8255 0.8250 0.8245 0.8255 0.8265 0.8255

23 0.8240 0.8255 0.8255 0.8255 0.8240 0.8250 0.8265 0.8255

24 0.8240 0.8260 0.8250 0.8260 0.8240 0.8250 0.8260 0.8245

25 0.8240 0.8255 0.8250 0.8260 0.8250 0.8250 0.8255 0.8260

26 0.8245 0.8255 0.8255 0.8260 0.8250 0.8255 0.8260 0.8255

27 0.8245 0.8255 0.8250 0.8260 0.8250 0.8255 0.8265 0.8260

28 0.8245 0.8255 0.8255 0.8260 0.8250 0.8255 0.8260 0.8250

29 0.8245 0.8255 0.8250 0.8265 0.8245 0.8260 0.8265 0.8250

30 0.8240 0.8260 0.8245 0.8265 0.8250 0.8250 0.8260 0.8250

31 0.8245 0.8250 0.8250 0.8260 0.8245 0.8250 0.8260 0.8250

32 0.8245 0.8255 0.8250 0.8255 0.8250 0.8250 0.8260 0.8255

33 0.8240 0.8255 0.8250 0.8255 0.8245 0.8260 0.8265 0.8255

34 0.8245 0.8265 0.8250 0.8260 0.8245 0.8245 0.8265 0.8245

35 0.8245 0.8255 0.8250 0.8260 0.8250 0.8250 0.8260 0.8250

36 0.8240 0.8250 0.8250 0.8255 0.8240 0.8250 0.8260 0.8245

37 0.8240 0.8255 0.8255 0.8245 0.8240 0.8250 0.8260 0.8245

38 0.8240 0.8250 0.8250 0.8260 0.8240 0.8245 0.8265 0.8245

39 0.8240 0.8260 0.8255 0.8260 0.8245 0.8250 0.8260 0.8245

40 0.8245 0.8255 0.8250 0.8260 0.8245 0.8245 0.8265 0.8245

41 0.8245 0.8255 0.8250 0.8245 0.8250 0.8245 0.8260 0.8245

51

42 0.8245 0.8260 0.8255 0.8200 0.8250 0.8250 0.8260 0.8240

43 0.8245 0.8255 0.8255 0.8240 0.8240 0.8240 0.8250 0.8240

44 0.8235 0.8255 0.8250 0.8240 0.8240 0.8245 0.8260 0.8245

45 0.8230 0.8240 0.8250 0.8255 0.8250 0.8250 0.8255 0.8250

46 0.8230 0.8250 0.8245 0.8260 0.8240 0.8245 0.8255 0.8250

47 0.8245 0.8260 0.8255 0.8250 0.8240 0.8245 0.8260 0.8250

48 0.8255 0.8250 0.8250 0.8250 0.8245 0.8240 0.8260 0.8250

49 0.8245 0.8250 0.8250 0.8250 0.8245 0.8245 0.8260 0.8250

50 0.8245 0.8255 0.8255 0.8250 0.8240 0.8245 0.8260 0.8250

51 0.8245 0.8250 0.8250 0.8250 0.8245 0.8245 0.8260 0.8250

52 0.8245 0.8250 0.8250 0.8255 0.8245 0.8240 0.8255 0.8250

53 0.8250 0.8255 0.8250 0.8250 0.8240 0.8245 0.8260 0.8250

Table 7.16

Process Capability Graphs for Piston Deck Height

Graph 7.5

52

From The above graph 7.5 Cp = 1.22 and Cpk = 0.71of Piston deck height at

fixture 1LL of TU-2065 machine

Graph 7.6

From The above graph 7.6 Cp = 0.65 and Cpk = 0.09 of Piston deck height at

fixture 3LL of TU-2065 machine.

Graph 7.7

53


fixture 3RL of TU-2065 machine

Graph 7.8


fixture 3RR of TU-2065 machine

Graph 7.9

54


fixture 4LL of TU-2065 machine

Graph 7.10


fixture 4LR of TU-2065 machine

55

Graph 7.11

From The above graph 7.11 Cp = 0.67 and Cpk = -0.08 of Piston deck height at

fixture 4RL of TU-2065 machine

Graph 7.12


fixture 4RR of TU-2065 machine

Collected Data for Crank Shaft Pin Grinding

Specification : 1.4371 / 1.4376"

Machine : Parishudh S.E , Parishudh L.E03/03/2010

S.NO PARISHUDH

S.EPARISHUDH

L.E S.NO PARISHUDH

S.EPARISHUDH

L.E

1 1.4374 1.43745 26 1.4373 1.4374

2 1.43735 1.43745 27 1.4374 1.4374

3 1.43735 1.4374 28 1.43735 1.43745

4 1.4373 1.4374 29 1.4374 1.4374

5 1.4374 1.4374 30 1.43735 1.4374

6 1.43735 1.4374 31 1.4373 1.4374

7 1.43735 1.4374 32 1.4373 1.43735

8 1.43735 1.4374 33 1.4373 1.4374

9 1.43735 1.4374 34 1.4373 1.4374

56

10 1.4375 1.43755 35 1.43735 1.4374

11 1.43735 1.43745 36 1.43735 1.43745

12 1.43735 1.43735 37 1.43735 1.43735

13 1.4374 1.4374 38 1.43735 1.43745

14 1.4374 1.4375 39 1.43735 1.43735

15 1.4374 1.43735 40 1.43735 1.43735

16 1.4374 1.43745 41 1.4373 1.4374

17 1.43725 1.4373 42 1.43735 1.4374

18 1.4374 1.43745 43 1.4373 1.4374

19 1.4373 1.43735 44 1.43735 1.43745

20 1.43735 1.43745 45 1.43735 1.4374

21 1.43735 1.4373 46 1.43735 1.43735

22 1.43735 1.43735 47 1.4373 1.43745

23 1.43735 1.4374 48 1.4373 1.43745

24 1.4374 1.43735 49 1.4373 1.43745

25 1.43735 1.4374 50 1.4373 1.43745

Table 7.17

Process Capability Graphs for Crank Shaft Pin Grinding

57

Graph 7.13

From The above graph 7.13 Cp = 2.56 and Cpk = 2.54

Graph 7.14

From The above graph Cp = 1.21 and Cpk = 0.84

7.1.3.4 SUMMARY SHEET FOR PROCESS CAPABILITY TEST

58

S.NO COMPONENT MACHINE PARAMETER Cp Cpk

1 CRANK CASE

HONNING 1 ( OLD ) CYL .BORE DIATOP 1.21 0.84

BOTTOM 0.93 0.58

HONNING 2 ( NEW ) CYL .BORE DIATOP 2.53 1.78

BOTTOM 2.9 1.98

2 PISTON TUPELLO 2065 DECK HEIGHT

1LL 1.22 0.71

3LL 0.65 0.09

3RL 0.7 0.61

3RR 0.54 0.3

4LL 0.8 0.7

4LR 0.91 0.64

4RL 0.67 -0.08

4RR 1.15 0.96

3 CRANK SHAFTPARISHUDH S.E S.E PIN DIA 2.56 2.54

PARISHUDH L.E L.E PIN DIA 1.87 1.46

Table 7.18 Process Capability report


The process capabilities of the processes which are done on the Honing 2, Parishudh

S.E and Parishudh L.E machines are satisfactory values that means these values are

greater than 1.33 (which is the condition of process capability test). So, these are

highly capable processes.

The process capabilities of the processes which are done on the Honing 1 and

TUPELO – 2065 machines are not satisfactory values. The Cpk of these processes are

less than 1.33. So, these processes are not capable.

Among the above all operations, the operations performed at fixtures 3LL (Cpk

is 0.08) and 4RL (Cpk is -0.09) in the TUPELO 2065 considered in this project,

because these have very less process capabilities among all.

7.1.3.5 CAUSE AND EFFECT DIAGRAM:

59

In this process the parameter is piston deck height. So, it is important to know what

the causes are and how they effect on the piston deck height.

Fig.7.1 Cause and Effect Diagram

From the cause and effect diagram it is concludes that

There are six variables to cause the problems in the process. They are Men, Machine,

Material, Method, Environment and Measurement

Men: Because of improper training, motivation, lack of attention of operator while

working causes the problems in the process.

60

Machine: Improper alignment of OBB (out board bearing), variations in clamping of

the component (due to manual clamping) and variations in the spindle alignment

causes the piston deck height variation.

Material: Hardness of the material and variation in the piston squareness causes the

variations in the piston deck height

Method: Due to the improper chips cleaning and improper locking of end stopper

piston deck may be vary.

Environment: Poor ventilation and model mix-up (when different types models are

available) causes the variations in the piston deck height.

Measurement: Due to the improper calibration of gauges and dials, improper

mastering (master piece is provided for basic adjustment), operator skills to measure

the deck height causes the variations in the piston deck height.

7.1.3.6 ACTION PLANS FOR THE PROBLEM

After knowing the causes for piston deck height variation, following action plans are

applied. The action plans are

1. Alignment and geometrical parameters of all spindles: In this step the realignment

of all spindles is done.

2. Alignment of all Fixtures and V blocks: In this step the realignment of all fixtures

and V blocks is done.

3. Inspection of Top and Bottom guide bushes: In this step inspection of the top and

bottom guide bushes with respect to the parallelism, squareness is done.

4. To provide proper coolant: In this step sufficient coolant is provided to remove the

chips form fixtures and V blocks.

5. To change the clamping springs: In this step the clamping springs are changed (here

clamping of the component is done by spring force).

6. To change the cutting tools: In this step the cutting tools say Drill bit and Reamers

are changed.

61

7. Component trails and corrections: In this step data is collected for the components

which are out from the machine, then adjusted the parameters if any adjustment

required during the starting of process.

7.1.3.7 AFTER APPLYING ACTION PLAN

PARAMETER :Deck Height MACHINE : TUPELO – 2065

SPECIFICATION :( Deck height : 0.8238 / 0.8258" )

Fixtures

S.NO

Deck Height (0.8238/0.8258)

Deck Height (0.8238/0.8258) Fixtures

S.NO

Deck Height (0.8238/0.8258)

Deck Height (0.8238/0.8258)

3LL 4RL 3LL 4RL

1 0.8255 0.8240 20 0.8250 0.8245

2 0.8250 0.8240 21 0.8255 0.8245

3 0.8250 0.8240 22 0.8255 0.8240

4 0.8250 0.8240 23 0.8250 0.8245

5 0.8255 0.8245 24 0.8250 0.8240

6 0.8255 0.8240 25 0.8250 0.8240

7 0.8255 0.8240 26 0.8250 0.8245

8 0.8250 0.8245 27 0.8255 0.8245

9 0.8245 0.8245 28 0.8255 0.8240

10 0.8250 0.8245 29 0.8250 0.8245

11 0.8260 0.8240 30 0.8255 0.8245

12 0.8245 0.8245 31 0.8255 0.8245

13 0.8255 0.8245 32 0.8260 0.8245

14 0.8255 0.8240 33 0.8255 0.8240

15 0.8255 0.8240 34 0.8255 0.8240

16 0.8260 0.8240 35 0.8255 0.8240

17 0.8255 0.8240 36 0.8255 0.8240

18 0.8250 0.8240 37 0.8250 0.8240

19 0.8250 0.8245 38 0.8255 0.8240

Table 7.19

62

After applying action plans again the data has been collected to calculate the process

capability by drawing process capability graphs which are shown below. These graphs are

drawn using the procedure explained in 7.1.3.2 earlier.

Process Capability Charts for Piston Deck Height After Applying Action Plan

Graph 7.15


Graph 7.16


63

7.1.3.7 COMPARISON OF PROCESS CAPABILITIES FOR TUPELO 2065

FIXTURE BEFORE ACTION PLAN AFTER ACTON PLAN

Cp Cpk Cp Cpk

3LL 0.65 0.09 1.06 0.59

4RL 0.67 -0.08 1.31 0.54

Table 7.20

From the above table 7.20 it is concluded that

For the fixture 3LL the process capability (Cp) is increased from 0.65 to 1.06 and

process capability index (Cpk) is increased from 0.09 to 0.59.

For the fixture 4RL the process capability (Cp) is increased from 0.67 to 1.31 and

process capability index (Cpk) is increased from -0.08 to 0.54.

64

7.2 ROTARY ASSEMBLY (RN SERIES)

The components of RN series compressors undergo different types of operations in

the RN assembly shop. Among them only the critical operations are considered for doing this

project. Critical operations are defined as the operations which directly effect the quality of

the product. The process capability for all critical operations calculated by using the

procedure explained in 7.1.3.2. Data is collected as explained in the table 7.15.

7.2.1 COLLECTION DATA AND PROCESS CAPABILITY GRAPHS:

For Initial Expansion Operation on Housing

rough expansion Machine

For Final Expansion Operation On Housing

Final expander Machine

HOUSING INNER DIAMETER (Spec:5.883/5.893)HOUSING INNER DIAMETER (Spec:5.898/5.903)

SI.NO1st

END SI.NO1st

END SI.NO1st

END SI.NO1st

END SI.NO1st

END SI.NO1st

END

1 5.865 21 5.888 41 5.886 1 5.9015 21 5.9035 41 5.886

2 5.856 22 5.888 42 5.888 2 5.9065 22 5.9035 42 5.888

3 5.886 23 5.8885 43 5.8825 3 5.907 23 5.905 43 5.8825

4 5.874 24 5.8875 44 5.888 4 5.904 24 5.901 44 5.888

5 5.8815 25 5.884 45 5.887 5 5.91 25 5.902 45 5.887

6 5.886 26 5.8815 46 5.888 6 5.904 26 5.901 46 5.888

7 5.886 27 5.8865 47 5.888 7 5.902 27 5.9045 47 5.888

8 5.8825 28 5.8875 48 5.888 8 5.9035 28 5.9065 48 5.888

9 5.8835 29 5.8805 49 5.8865 9 5.912 29 5.9065 49 5.8865

10 5.886 30 5.883 50 5.8875 10 5.904 30 5.92 50 5.8875

11 5.886 31 5.8855 11 5.908 31 5.9045

12 5.8875 32 5.888 12 5.904 32 5.904

13 5.8835 33 5.8865 13 5.907 33 5.9095

14 5.8815 34 5.8855 14 5.9045 34 5.9045

15 5.8845 35 5.8865 15 5.9045 35 5.9245

16 5.8845 36 5.888 16 5.904 36 5.912

17 5.8805 37 5.886 17 5.9095 37 5.903

18 5.8865 38 5.8875 18 5.9095 38 5.9045

19 5.886 39 5.884 19 5.901 39 5.907

20 5.888 40 5.8855 20 5.904 40 5.9045

Table 7.21

65

Graph 7.17


Graph 7.18

From The above graph 7.17 Cp = 0.17 and Cpk = -0.24

66

For Suction hole making Operation

SUCTION HOLE ID (Spec: 0.88-0.883) SI.No ID SI.No ID SI.No ID

1 0.8805 17 0.8805 33 0.881

2 0.8805 18 0.883 34 0.882

3 0.8825 19 0.8805 35 0.882

4 0.8805 20 0.882 36 0.8805

5 0.8805 21 0.8805 37 0.8815

6 0.8805 22 0.8805 38 0.8805

7 0.8825 23 0.8805 39 0.8805

8 0.8805 24 0.881 40 0.883

9 0.8805 25 0.881 41 0.8805

10 0.8805 26 0.8815 42 0.8805

11 0.8805 27 0.8805 43 0.8825

12 0.881 28 0.883 44 0.8805

13 0.8825 29 0.8805 45 0.8805

14 0.8825 30 0.882 46 0.8805

15 0.8805 31 0.882 47 0.8805

16 0.8825 32 0.8805

Table 7.22

Graph 7.19


67

For Puddle hole making Operation On 3-hole piercing Machine:

PUDDLE HOLE ID (Spec: 0.88-0.883) SI.No ID SI.No ID SI.No ID

1 0.245 17 0.2525 33 0.2475

2 0.257 18 0.2545 34 0.251

3 0.24885 19 0.249 35 0.249

4 0.245 20 0.248 36 0.246

5 0.2505 21 0.253 37 0.247

6 0.253 22 0.2485 38 0.2505

7 0.249 23 0.247 39 0.253

8 0.254 24 0.251 40 0.2455

9 0.2485 25 0.252 41 0.2485

10 0.2475 26 0.249 42 0.2455

11 0.2455 27 0.247 43 0.2445

12 0.2445 28 0.246 44 0.2465

13 0.253 29 0.247 45 0.2445

14 0.2575 30 0.2525 46 0.2485

15 0.2515 31 0.246 47 0.246

16 0.251 32 0.249

Table 7.23

Graph 7.20


68

7.2.2 SUMMARY SHEET FOR PROCESS CAPABILITY TEST

SL.NO

OPERATIO

N NO OPERATION PARAMETER SPECIFICATION Cp Cpk

1 1310 Housing Expansion ID 5.893-5.883 0.6 0.44

2 1330 Suction hole making ID 0.883-0.880 0.55 0.42

3 1340 Puddle holes making ID 0.255-0.245 0.5 0.41

4 1370

Final Expansion of

Housing ID 5.903-5.899 0.2 0.14

Table 7.24 Process Capability reports before action plan

From above table 7.24

The process capabilities of all operations are not satisfactory because the values of

Cpk are less than 1.33. So, from the conditions of process capability test these process

are not capable for the future operations

7.2.3 ACTION PLANS

From the above reports some problems are found and to avoid these problems the

following action plans are applied.

The action plans are

Tools changed

Spacers changed

Dice punch changed

Expansion mandrel changed

Hole punch reference changed

Reference taken at dual location

Expansion dimension changed at both initial and final

Inspection implemented at both side of housing

69

7.2.4 COLLECTION DATA AND PROCESS CAPABILITY GRAPHS AFTER

ACTION PLAN

For Initial Expansion Operation on Housing

rough expansion Machine

For Final Expansion Operation On Housing

Final expander Machine

HOUSING INNER DIAMETER (Spec:5.883/5.893)HOUSING INNER DIAMETER (Spec:5.898/5.903)

SI.NO1st

END SI.NO1st

END SI.NO1st

END SI.NO1st

END SI.NO1st

END SI.NO1st

END

15.891

215.888

415.888

15.9010

215.9000

415.9010

25.892

225.888

425.889

25.9010

225.9010

425.9000

35.89

235.888

435.889

35.9010

235.9010

435.9010

45.89

245.888

445.8885

45.9010

245.9010

445.9010

55.89

255.888

455.889

55.9010

255.9000

455.9010

65.891

265.885

465.89

65.9010

265.9010

465.9010

75.89

275.8885

475.888

75.9020

275.9010

475.9020

85.886

285.888

485.8905

85.9010

285.8990

485.9010

95.886

295.888

495.8905

95.9010

295.9000

495.9000

105.887

305.888

505.891

105.9000

305.9000

505.9000

115.888

315.884

115.9010

315.8990

125.888

325.8885

125.9000

325.9000

135.888

335.888

135.9000

335.8990

145.884

345.888

145.9020

345.9010

155.8865

355.888

155.9000

355.9010

165.886

365.8885

165.9000

365.9010

175.888

375.888

175.9000

375.9000

185.888

385.888

185.9000

385.9020

195.888

395.888

195.9010

395.9010

205.888

405.888

205.9000

405.9000

Table 7.25

70

After applying action plans again the data has been collected to calculate the process

capability by drawing process capability graphs which are shown below. These graphs are

drawn using the procedure explained in 7.1.3.2.

Graph 7.21


Graph 7.22


For Suction hole making Operation On Suction hole piercing Machine

71

SUCTION HOLE ID (Spec: 0.88-0.883)SI.No ID SI.No ID SI.No ID

1 0.8810 17 0.8820 33 0.8815

2 0.8810 18 0.8815 34 0.8820

3 0.8815 19 0.8815 35 0.8820

4 0.8810 20 0.8820 36 0.8810

5 0.8815 21 0.8815 37 0.8815

6 0.8810 22 0.8815 38 0.8815

7 0.8820 23 0.8815 39 0.8815

8 0.8815 24 0.8815 40 0.8810

9 0.8815 25 0.8815 41 0.8815

10 0.8810 26 0.8815 42 0.8815

11 0.8815 27 0.8810 43 0.8820

12 0.8810 28 0.8820 44 0.8815

13 0.8820 29 0.8815 45 0.8810

14 0.8820 30 0.8820 46 0.8815

15 0.8815 31 0.8820 47 0.8810

16 0.8820 32 0.8810

Table 7.26

Graph 7.23


For Puddle hole making Operation On 3-hole piercing Machine:

72

PUDDLE HOLE ID (Spec: 0.88-0.883) SI.No ID SI.No ID SI.No ID

1 0.250 17 0.250 33 0.250

2 0.250 18 0.250 34 0.250

3 0.249 19 0.249 35 0.249

4 0.250 20 0.248 36 0.250

5 0.250 21 0.250 37 0.250

6 0.250 22 0.249 38 0.250

7 0.249 23 0.250 39 0.250

8 0.250 24 0.250 40 0.250

9 0.249 25 0.250 41 0.249

10 0.250 26 0.249 42 0.250

11 0.250 27 0.250 43 0.250

12 0.250 28 0.250 44 0.250

13 0.250 29 0.250 45 0.250

14 0.250 30 0.250 46 0.249

15 0.250 31 0.250 47 0.250

16 0.250 32 0.249

Table 7.27

Graph 7.24

From The above graph Cp = 0.50 and Cpk = 0.41

73

7.2.5 SUMMARY SHEET FOR PROCESS CAPABILITY TEST AFTER ACTION

PLAN

SL.NO

OPERATION

NO OPERATION PARAMETER SPECIFICATION Cp Cpk

1 1310 Housing Expansion ID 5.893-5.883 1.26 1.19

2 1330 Suction hole making ID 0.883-0.8800 1.44 1.44

3 1340 Puddle holes making ID 0.255-0.245 2.79 2.63

4 1370

Final Expansion of

Housing ID 5.903-5.899 1.16 1.11

Table 7.28 Process Capability and Machine Capability reports after action plan

From the above table7.28 it is concluded that

For Housing Expansion the process capability (Cp) is increased from 0.60 to 1.26 and

process capability index (Cpk) is increased from 0.44 to 1.19

For the Suction hole making the process capability (Cp) is increased from 0.55 to 1.44

and process capability index (Cpk) is increased from 0.42 to 1.44.

For Puddle holes making the process capability (Cp) is increased from 0.50 to 2.79

and process capability index (Cpk) is increased from 0.41 to 2.63

For the Final Expansion of Housing the process capability (Cp) is increased from 0.2

to 1.44 and process capability index (Cpk) is increased from 0.14 to 1.11.

74

CONCLUSION

In this project, the manufacture of the compressor has been studied in detail. It has

been observed that the company inputs are castings. So, for these castings finishing

operations are done on the respected machine shops and then the components are assembled

according to the requirement while performing various tests on them to check the quality,

whether the parts have been machined according to the required specifications or not. Every

operation has its own specifications which the component must meet.

Quality of the product depends upon the process capability and machine capability.

So, to improve the quality in the AW machine shop and RN assembly the process capability

and machine capability are studied for critical operations of compressors during the

manufacturing process.

In the AW machine shop process capability for critical operations are calculated.

Process capability of piston deck height is found to be low for fixtures 3LL and 4RL at

tupelo-2065 machine. After applying action plans for the fixture 3LL the process capability

(Cp) is increased from 0.65 to 1.06 and process capability index (Cpk) is increased from

0.09 to 0.59. Similarly for the fixture 4RL the process capability (Cp) is increased from 0.65

to 1.06 and process capability index (Cpk) is increased from 0.09 to 0.59.

Similarly in the RN assembly, action plans are applied to the critical operations, by

this the process capability(Cp) is increased for puddle hole making operation from 0.50 to

2.79 and process capability index (Cpk) is increased from 0.41 t0 2.63.

Finally the process capabilities of these critical operations which are not in desirable

limits are improved by applying the different actions plans for different operations in AW

machine shop and RN assembly. So, the quality and performance of compressors are

improved.

75

BIBLIOGRAPHY

www.tecumsehindia.com

www.mastermachines.com

www.intinidia.com

www.4shared.com

Automation, Production Systems and Computer – Integrated Manufacturing by

Mikell P.Groover, PHI.

76

http://www.4shared.com/

http://www.intinidia.com/

http://www.mastermachines.com/

http://www.tecumsehindia.com/

Documents

M.project Part2