Cycletime Reduction

8/13/2019 Cycletime Reduction

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CYCLETIMEREDUCTION


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CYCLETIME REDUCTION

The Definition of Cycletime

There are two general definitions of Cycletime1. Time between beginning of production and completion of production.2. Time between the completion of the last product and completion ofthe next product.

While the scope of this Course covers BOTH areas, for purposes ofclarity, we will refer to definition 1 as leadtime and 2 as

cycletime.

Process1

Process2

Inspection Pack

Cycletime = Leadtime Cycletime

WIP WIP


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CYCLETIME REDUCTIONThe Definition of Cycletime

Process1

Process2

Inspection Pack

Leadtime

The leadtime starts the moment the piece parts are withdrawn fromStore and ends when the product is completed.The elements involved : waiting time, processing time, conversion orset-up time, transportation time and documentation time.To effectively reduce leadtime and cycletime, we would need toreduce/eliminate each of these elements.

Cycletime

WIP WIP


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CYCLETIME REDUCTION

The Definition of Cycletime

Cycletime = Available Production Time

Number of Products Produced

= Production Efficiency

Cycletime can be measured for the whole Production Line, for eachindividual Product or even Model.


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CYCLETIME REDUCTIONImportance of Cycletime

ReductionTechnology is constantly obsoleteTodays Product Lifecycles 3 12 monthsInventory is moneyRisk of inventory obsolescence highTodays Customers want- increased flexibility- low obsolescence riskThese goals can be achieved with reduced cycletime

A short cycletime is an organizations COMPETITIVE EDGE


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CYCLETIME REDUCTION

Theory of ConstraintsIn a Production line, identifythe bottleneck (D).Increase the bottleneck (D)

capacity. Bottleneck shifts toB.Increase the bottleneck (B)capacity.

To increase the effectivecapacity, focus on theconstraint (bottleneck) area.

Effective capacity

A DB C

Effective capacity

Effective capacity


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CYCLETIME REDUCTION

Theory of ConstraintsConstraints Product flowCycletime

To REDUCE Cycletime, production flow constraints

need to be eliminated or reduced.These constraints are :

Process1

Process2

Inspection Pack

WIP WIP


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CYCLETIME REDUCTION

Cycletime Analysis ToolsThree main tools used to analyze cycletime are:

1. Flow DiagramTo analyze the actual product flow.

2. Operations ChartTo analyze every production step and part used.

3. Process ChartTo study all the handling, inspection, operations, storageand delays as the product flows from raw materials tofinished goods.


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CYCLETIME REDUCTION

Cycletime Analysis ToolsThese tools are the macro analysis tools in that theyare used to analyze the overall operations.

Process1

Process2

Inspection Pack

WIP WIP


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CYCLETIME REDUCTIONCycletime Analysis Tools : Flow

DiagramWhat it is : A diagram that shows the path traveled bythe product as it flows through from Receiving toProduction to Shipping.

How to develop :1. Start with an existing or proposed scaled layout.2. Each step in the actual or proposed production flow is plotted

onto the layout, with arrows showing the direction of flow.


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Example : A current production layout.

Receiving

& IssuingStore

Shipping

Finished

GoodsStore

WI P

( K i t s )

Process1

WIP

Assembly Flow Inspection

WIP Awt.OQA

WIP Awt.Pack

Pack

OQA Room

Actual Product Flow


Diagram


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The Flow Diagram will be able to identify issues suchas :

Cross Traffic where flow lines cross

Backtracking where material flows backwardDistance product travelled.


Diagram


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Cross Traffic and Backtracking

Receiving

& IssuingStore

Shipping

Finished

GoodsStore

WI P

( K i t s )

Process1

WIP

Assembly Flow Inspection

WIP Awt.OQA

WIP Awt.Pack

Pack

OQA Room

Actual Product Flow

Backtracking

Cross Traffic


Diagram


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CYCLETIME REDUCTIONCycletime Analysis Tools : OperationsChart

What it is : A chart showingthe raw material,the purchased piece parts,

the fabrication/sub-assembly sequence,the assembly sequence,the equipment needs andthe time standards

to produce a finished product.


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How to develop :1. Identify purchased vs. sub-assembled piece parts.2. Determine the operations required to fabricate each part and its sequence of

operations.

3. Determine the sequence of assembly for ALL piece parts.4. Identify the base part (raw PCB). This is the 1 st part that starts the assembly

process. Put that part on a horizontal line at the far right top of the page. On avertical line extending down from the right side of the horizontal line, place a circlefor each operation. Beginning with the first operation, list all operations down tothe last operation.

5.Place the 2

nd

part to the left of the 1st

part and the 3rd

part to the left of the 2nd

partetc. All of the fabrication steps are listed below the parts with a circle representingeach operation.

6. Draw a horizontal line from the bottom of the last operation of the 2 nd part to thepoint above the operation where it joins the 1 st part, and so on.


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Example :Base Part1st Part /

2nd Part3rd Part4 th Part

Sub-assemble 4 th Part to 3 rd Part

Assemble 1 st and 2 nd Parts andsub-assemble 3 rd and 4 th Parts

Operations tofabricate 4 th Part

Parts to be fabricatedPurchased Piece Part



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How to develop : cont.7. Introduce all the purchased piece parts on horizontal lines above the assembly

operation circle where they are placed on the assembly.8. Put time standards, operation numbers, and operation descriptions next to and in

the circle.9. Sum total the hours per 1,000 units and place these total hours at the bottom right

under the last assembly or pack-out operation.

Example : PCB

05

10

Solder paste

Solder pasteprinting

Caps 0012 (4)

Res. 0120 (3)

SMDplacement

4002.5

250

4

Operation number

Operationdescription

Units per hour

Number ofhours to

complete 1,000units

6.5 hours



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From the Operations Chart, the theoretical productleadtime can be determined.The difference between the actual leadtime and the

theoretical leadtime is the leadtime GAP.It is only through process and operations improvementthat the theoretical leadtime can be improved.



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CYCLETIME REDUCTIONCycletime Analysis Tools : Process Chart

What it is : A chart that shows all the handling,inspection, operations, storage, and delays that occurto one part as it moves through the Production process.How to develop : Conventional symbols are used to describe theprocess steps.

Symbol Description Indicates Meaning

D

Circle

Square Arrow

Triangle

Big D

Operation

InspectionTransportation

Storage

Delay

Performing work on a part

Used for quality control workUsed when moving material

Used for long term storage

Used for short term storage


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Sample Process ChartingPROCESS CHART

PRESENT METHOD PROPOSED METHOD DATE : PAGE /

PART DESCRIPTION :

OPERATION DESCRIPTION :

SUMMARY PRESENT PROPOSED DIFFERENCE ANALYSIS : FLOW NO. TIME NO. TIME NO. TIME DIAGRAM

OPERATIONS WHY WHEN ATTACHED

TRANSPORT WHAT WHO

INSPECTIONS WHERE HOW

DELAYS

STORAGES STUDIED BY :

DIST. TRAVELED FT. FT. FT. STEP DETAILS OF PROCESS METHOD OPERATION TRANSPORT INSPECTION DELAY STORAGE DISTANCE QTY HRS/UNIT TIME CALCULATIONS

1

2

DD

D

1

2

3

4 5 6

7 8 9 10 11 12 13



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The main sections :1. Select either present method or proposed method, date and page.2. Describe the name of part and specifications if relevant.3. Record the limits of the study (example : from Receiving to FG).4. Record under the PRESENT column for study of current operations. To come

up with a new proposal, use the PROPOSED column. 5. For each step, the 5Ws and 1H are asked, starting with Why. Try to

Eliminate every step possible orCombine the steps orChange the sequence of operations to improve the product flow.

6. A Flow Diagram should be attached if available.7. Describe what happens in each step.8. Methods of transportation or storage are described (eg. by pallet).9. Symbols shade the appropriate symbol related to the step.



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The main sections :10. This is recorded when the transportation symbol is used. Specify unit of

measurement.11. Quantity refers to many things :

a. Operations Pieces per hourb. Transportation Number of pieces moved at a timec. Inspection Pieces per hour and/or frequency of inspectiond. Delays Number of pieces waitinge. Storage How many pieces per storage unit

12. Hours per unit time spent per piece at that step. Used only for operations,

transportation and inspection.13. Time calculations column provided to compute time spent.

Once all the sections are completed, return to complete the Summary.Use your Process Chart analyze and identify improvement opportunities.



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CYCLETIME REDUCTIONMethods of Analyzing Cycletime

Five main charts are used to micro analyzecycletime of operations :

Operations Analysis ChartOperator/Machine ChartGang ChartMulti-Machine Chart

Left/Right Hand Chart


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These charts are used to analyze and breakdown eachoperation into its separate micro elements.

Process1

Process2

Inspection Pack

WIP WIP

CYCLETIME REDUCTIONMethods of Analyzing Cycletime


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CYCLETIME REDUCTIONMethods of Analyzing Cycletime :Multi

Activity ChartWhat it is : It is a standard Chart Format used to createthe

Operations analysis chartOperator/machine chart

Gang chartMultimachine chartLeft-hand/right-hand chart

The chart is separated into 15 different sections.


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Activity ChartMULTI ACTIVITY CHART

OPERATOR/MACHINE GANG MULTI MACHINELEFT HAND/RIGHT HAND OPERATIONS

OPERATION NO. PART NO. OPERATION DESCRIPTION :

DATE : TIME :

BY :

ACTIVITY TIME IN ACTIVITY SECONDS

TOTAL UTILIZATION : TOTAL UTILIZATION :

% UTILIZATION : % UTILIZATION :

TOTAL NORMAL TIME IN SECONDS PER UNIT :

+ % ALLOWANCE :

STANDARD TIME :

HOURS PER UNIT :

PIECES PER HOUR :

1

2 34 5

6

7

8 8

9 9

10 10

1112

1314

15


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Activity ChartThe main sections :

1. Tick or cross the appropriate box on the chart being created.2. The operation number for the particular operation (if available).3. The product part number.4. The date of the study, include day, month and year.

5. The time the study started.6. Record the name of the person who is conducting the study.7. Operation described in clear terms.8. Activity will represent different things for different charts

1. Operations analysis use LEFT column only2. Operator/machine LEFT column for Operator, RIGHT for Machine3. Gang LEFT column for Operator 1, RIGHT for Operator 24. Multimachine 2 charts are taped next to each other. On the 1 st chart, LEFT

column for Operator, RIGHT for Machine 1. On the 2 nd chart, LEFT column forMachine 2, RIGHT column for Machine 3.

5. L-H/R-H LEFT column for Left Hand, RIGHT for Right Hand


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The main sections :9. These are the activity areas where the actual activities are recorded.10. Total Utilization is how much time this activity was working. Idle time is

NOT included.% Utilization is the total utilization divided by the total time of thatactivity.

11. Total normal time is how long it takes each activity to complete a cycleand includes both working time and idle time.

12. Allowances are the time added to normal time to make the timestandards realistic. These include personal time, fatigue and delays. A

ballpark figure of 10% is typically used.13. Standard time = normal time + allowances (in secs/unit).14. Hours per unit = standard time (secs/unit)/(3600 secs/hour)15. Pieces per hour = inverse of hours per unit = 1/(hours per unit)


Activity Chart


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CYCLETIME REDUCTIONMethods of Analyzing CycletimePieces Per Hour Cycletime

Pieces Per Hour Cycletime

1 Hour

Cycletime

Cycletime


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CYCLETIME REDUCTIONMethods of Analyzing Cycletime :Operations

Analysis ChartWhat it is : A chart used to describe

a single activityusually one operator using tools 100% operator controlledExample : Packing operation.

MULTI ACTIVITY CHART OPERATOR/MACHINE GANG MULTI MACHINE

LEFT HAND/RIGHT HAND OPERATIONS


DATE : TIME :

BY :


X100 AX250

Feb.26,05 0930Bruce Lee

Packing operation for shipment.

CYCLETIME REDUCTION


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CYCLETIME REDUCTIONMethods of Analyzing CycletimeOperations Analysis Chart

SECONDS

This side is left blank

Activity ActivityFold carton box, insert kimcell.

Insert PCBA and pack into carton.Idle.

1047

These activities need to beanalyzed, for example :

Why 10 secs to preparebox? Can it be preparedahead of time?

Why idle time of 7 secs?How to eliminate this? Whatcan operator do if cannoteliminate?

CYCLETIME REDUCTION


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CYCLETIME REDUCTIONMethods of Analyzing CycletimeOperations Analysis Chart




+ % ALLOWANCE :

STANDARD TIME :

HOURS PER UNIT :

PIECES PER HOUR :

14 secs67%

21 secs

10%

24 secs0.0067

150

CYCLETIME REDUCTION


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CYCLETIME REDUCTIONMethods of Analyzing CycletimeOperator/Machine Chart

What it is : A chart that shows the activities andinter-relationship of the operator and themachine. The chart shows what each is doing

at any moment in time.Example : An operator running a marking machine.MULTI ACTIVITY CHART

OPERATOR/MACHINE GANG MULTI MACHINELEFT HAND/RIGHT HAND OPERATIONS


DATE : TIME :

BY :


X

75 BY300Feb.26,05 1500

Jackie ChanInk marking EPROM.

Operator Ink Mark Machine

CYCLETIME REDUCTION


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SECONDSOperator Ink Mark Machine

Load EPROM. Idle.Mark unit.Idle.

57

Unload EPROM.45 Inspect EPROM. Idle.

579

The high percentage of idle timerepresents a waste of capacity.How to minimize?

Can the work sequence berearranged to utilize the idletime to do inspection?

Can the inspection beeliminated to reduce thecycletime?

CYCLETIME REDUCTION


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+ % ALLOWANCE :

STANDARD TIME :

HOURS PER UNIT :

PIECES PER HOUR :

14 secs 7 secs67% 33%

21 secs10%

24 secs0.0067

150

CYCLETIME REDUCTION


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CYCLETIME REDUCTIONMethods of Analyzing CycletimeGang Chart

What it is : A chart to show the activities of two or morepeople when their activities intertwine. When more thantwo people are involved, tape two or more charts side byside.

Example : Solder joint touch-up and inspection.




DATE : TIME :

BY :


X

851700Feb.26, 05

LT800Solder joint touch-up and inspection.

Ali Bakar

Touch-up operator Inspection operator


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CYCLETIME REDUCTION


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CYCLETIME REDUCTIONMethods of Analyzing CycletimeGang Chart




+ % ALLOWANCE :

STANDARD TIME :

HOURS PER UNIT :

PIECES PER HOUR :

26 secs

49%

27 secs

51%53 secs

10%

59 secs0.016

63

CYCLETIME REDUCTION


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CYCLETIME REDUCTIONMethods of Analyzing CycletimeMulti-Machine Chart

What it is : A chart similar to the operator/machine chartexcept that additional charts are taped to the side of the1 st chart. On these additional charts, each additionalmachine takes up one column.

Example : 1 operator running 3 ink markers.

Operator Machine 1 Machine 2 Machine 3

CYCLETIME REDUCTION


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CYCLETIME REDUCTIONMethods of Analyzing CycletimeLeft/Right Hand Chart

What it is : A chart that tracks the separate activities ofeach hand of an operator. Each hands activity isbroken down into detailed elements.

Example : Operator inserting PTH components into PCBA.




DATE : TIME :

BY :


X

65 AT540Feb.26, 05 1030

MuruPTH insertion into PCBA.

Left Hand Right Hand

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SECONDSLeft Hand Right HandPick-up PCBA. Pick-up component.

Align and insert component intoPCBA.

Idle (Holding PCBA).

Idle.Pass PCBA to next operation.

Idle.

5 5

12 12

413 9

CYCLETIME REDUCTION


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+ % ALLOWANCE :

STANDARD TIME :

HOURS PER UNIT :

PIECES PER HOUR :

5 secs17%

21 secs70%

30 secs10%

33 secs0.009109

CYCLETIME REDUCTION


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CYCLETIME REDUCTIONMethods of Cycletime ReductionWork Station Design

Having a work station that is designed to ease the taskof the operator will help in maximizing work efficiency =reducing cycletime.

A well designed work station supports motion economy.

Process1

Process2

Inspection Pack

WIP WIP


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CYCLETIME REDUCTION


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Some key considerations :Work table height should beconstant and ideally at elbow

height of the seated person.

Use chairs which can be

adjusted for height.Chairs should be comfortablewith back supports.

CYCLETIME REDUCTION
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Some key considerations :Frequently used tools should belocated nearby the work station.Incorporate fixtures to replace thehuman hand for holding parts asmuch as possible.Locate reject bins or baskets closeto the work station to preventunnecessary movement by theoperator.Use chutes to take advantage ofgravity to move parts.

CYCLETIME REDUCTION
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Some key considerations : Align the work station to the product flow.

CYCLETIME REDUCTION


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CYCLETIME REDUCTIONMethods of Cycletime ReductionMotion Economy

Economic motion minimizes processing time andhence contributes to cycletime reduction.This is strongly related to and supported by workstation design.

Process1

Process2

Inspection Pack

WIP WIP

CYCLETIME REDUCTION


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Some key considerations :The hands should :

1. Operate as mirror images2. Start and stop motions at the

same time3. Move in opposite directions4. Be working at all times.

Use fixtures to replace handsholding parts where possible.Use foot operated controldevices where possible to freeup the hands.

CYCLETIME REDUCTION


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Some key considerations :Use ballistic motions where possible :fast motions using one set of musclesand not trying to end the motion using

other muscles, example, throwing apart into a bin.Use controlled motions, i.e. whichrequire control at the end of the motion,only for activities needing safety or

quality considerations.Use curved continuous motions insteadof separate linear motions.

CYCLETIME REDUCTION


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CYCLETIME REDUCTIONMethods of Cycletime ReductionLine Balancing

One technique which sees almost immediate impact in acycletime reduction exercise is line balancing. Bybalancing the production line, obvious line imbalances orbottlenecks can be removed. This increases the effectiveline capacity and reduces cycletime.Refer to section on Theory of Constraints.

Process1

Process2

Inspection Pack

WIP WIP

CYCLETIME REDUCTION


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CYCLETIME REDUCTIONMethods of Cycletime ReductionRemoving NVA

Non-Value-Added activities are activities that do not addvalue to the product. They just add cost .Major NVA activities are inspection, product movementand waiting time. By removing or reducing theseactivities, the cycletime is reduced accordingly. Waitingtime is one of the major contributors to long cycletime .

Process1

Process2

Inspection Pack

WIP WIP

CYCLETIME REDUCTION


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While removing inspection needs to be justified with qualityimprovement, others such as eliminating a staging area(shown below), can be easily justified.

ISSUING STORE

ISSUING STORE

STAGING AREA

PRODUCTION LINE

PRODUCTION LINE

CYCLETIME REDUCTION


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Examples of elimination of handling and transportation.Improvement from A to D.

Double Handling

Transportation

Inventory on conveyor

No waiting

A

B

C

D

CYCLETIME REDUCTION


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CYCLETIME REDUCTIONMethods of Cycletime ReductionQuick Set-ups

In handling multiple models, the process ofchanging from one model to the next is NVA. Itadds up to the product leadtime and hence,cycletime.Quick set-ups, therefore, reduce productcycletime.

Process1

Process2

Inspection Pack

WIP WIP

CYCLETIME REDUCTION


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Internal setup : Setup activities done on the machine while themachine is down.

Example : Changing over of tools, dies, jigs and materials whi lethe mach ine i s down .

External setup : Setup activities done before and after themachine is down and do not add to the machine downtime.

Example : Prepar ing in advanc e the necessary jigs, tools, thenext die and materials and removing the detached die and jigsaf ter the m achine i s u p .

Machine down Machine up

Internal setup change tool,die, materials

External setup prepare tool,die, materials

External setup remove

detached tool, die

CYCLETIME REDUCTION


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Steps in Shortening Set-up Time

1. Separate the internal set-up tasks from the external set-up tasks

Example :Typical External Set-up Tasks Typical Internal Set-up Tasks

Preparation of dies, fixtures etc. Transfer of dies

Attachment and detachment Adjustment of location, height,

pressure, etc. Test run

2. Convert internal set-up to external set-up

Example : Preheating dies is a way of converting internalset-up to external set-up

CYCLETIME REDUCTION


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3. Improve internal set-up

Example 1 : Reduce internal set-up by eliminating adjustment

StandardizedDie Height

Blocks

Locating Pin

CYCLETIME REDUCTION


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88B

ColorcodingMachine

Address

Die storage area

(close to the point of use)

4. Improve external set-upReduce/eliminate time wasted searching for tools, dies and fixtures bydesignating areas by color coding shelves and assigning addresses for eachstorage area.

Reduce time wasted in transferring dies by storing frequently used dies closeto the machine.

CYCLETIME REDUCTION


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Methods of Cycletime ReductionLot Size Reduction

Typically, the larger the lot size, the longer the waitingtime. Traditionally, large lot sizes were preferred due tohigh set-up times. However, with large lot sizes, WIPbuilds up and product cycletime lengthens.Reducing lot size reduces product cycletime.

Process1

Process2

Inspection Pack

WIP WIP

CYCLETIME REDUCTION


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Methods of Cycletime ReductionLot Size Reduction

Example : Processing time 1 min./unit

A B C

A B C

A B C

A B C

A B C

A B C

Lot size : 3 Lot size : 1Time Time

0 min 0 min

3 min1 min

A B C

A B C

6 min

9 min

2 min

3 min

A B C4 min

A B C5 min

CYCLETIME REDUCTION


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Methods of Cycletime ReductionParallel Processing

Parallel processing means processing 2 or moreoperations at the same time. In set-up time language, itmeans converting internal time to external time.Parallel processing, therefore, reduces set-up time.

Process1

Process2

Inspection Pack

WIP WIP

CYCLETIME REDUCTION


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Example : Reducing internal set-up by using ParallelOperations

1 2 3 4 5 6 7machine stop machine start

Step No. OperationInternal /External

Required time(min) Performed by

1 Look for new die I 3 Operator2 Transfer new die I 10 Operator3 Remove used die I 2 Operator4 Attach new die I 2 Operator5 Transfer new material I 10 Operator6 Adjust I 20 Operator7 Transfer used die I 10 Operator

Before improvement (Total Internal Set-up Time : 57 Min)

Parallel Operations on a Press Machine

CYCLETIME REDUCTION


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1 2 5 4 6a 7

machinestop

machinestart

Step No. Operation

Internal /

External

Required time

(min) Performed by1 Look for new die E 3 Assistant2 Transfer new die E 10 Assistant5 Transfer new material E 10 Assistant4 Attach new die * I 2 Assistant

6a Adjust ** I 7 Assistant3 Remove used die * I 2 Operator

6b Adjust ** I 8 Operator

After improvement (Total Internal Set-up Time : 10 Min)

3 6b

(Set-up assistant)

(Operator)

7 Transfer used die E 10 Assistant

Note : *, ** : conduct operations simultaneously

CYCLETIME REDUCTION


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Methods of Cycletime ReductionWIP Reduction

Work In Progress (WIP) or inventory, when not beingprocessed, is accumulating cycletime. Therefore, toreduce cycletime, drive down WIP.

Process1

Process2

Inspection Pack

WIP WIP

CYCLETIME REDUCTION


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Raw material Finished productsto customers

Sea of inventory

Poor

scheduling

Machinebreakdown Quality

problems

Absenteeism

Long set-up times

Inventory Covers Problems

CYCLETIME REDUCTION


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The only justifiable WIP is that which isused to prevent a process from beinglinedown.For example, the WIP shown should onlyserve to prevent Process 2 from stoppingbecause of instability in Process 1 due to :

Machine downtimeLow yieldsQuality issuesBatch processing waiting time

However, as WIP represents waitinginventory and should be driven down.

Process1

Process2

WIP

CYCLETIME REDUCTION


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Methods of Cycletime ReductionFIFO

FIFO stands for First In First Out. This is a flow sequence where thefirst product processed flows through and gets completed first, andso on.By implementing FIFO, no WIP gets bypassed and line issues areforced to be addressed, easing the subsequent product flow and

hence reducing cycletime.The only time FIFO should be bypassed is when there is anabnormal lot such as extremely low yield lot, quality question etc.

Process1

Process2

Inspection Pack

WIP WIP

CYCLETIME REDUCTION


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Methods of Cycletime ReductionKanbans

A Kanban is a card used in the Toyota Production System or JIT. Itis used to request or pull materials in a Pull Production System.In Malaysia, typically Kanban squares are used in the place ofKanban cards. By defining the Kanban quantity, WIP, productionflow and hence cycletime can be controlled.

Process1

Process2

Inspection Pack

WIP WIP

CYCLETIME REDUCTION


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An in fo rmat ion sys tem tha t ha rmo nious ly con t ro l s theprodu c t ion o f the

necessary p rod uc t s in the

necessary qu ant i t ies at the

necessary t im e in

every p roc ess o f a f ac to ry and a l so amo ng c om panies

It u t i l izes a pul l sys tem that i s d ic ta ted by cus tom er orders

I t is a sub -sys tem tha t suppo r t s the Toyota Produc t ionSys tem or l ean m anufac tu r ing

What is the Kanban system?

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PROCESS 1 PROCESS 2 FG CUSTOMERFG STOREWIPWIP

123

Cus tom er p laces o rderand FG Store ships FGavailable to Custo m er.

At the same t im e, aWi thdrawal Kanban i s

i s sued f rom FG Store toKanban loca t ion o f

Process 2 and WIP f romProcess 2 is pulled to

FG Store

Process 2 receives aProduc t ion Order ing

Kanban f rom i t sKanb an locat ion .

It s t a r ts p rodu c t ion

and a t the same t im eissu es a Withd rawalKanban to Kanban

loca t ion o f P rocess 1

Process 1 receives aProduc t ion Order ing

Kanban f rom i t sKanb an loc at ion.

It s t a rt s p ro duc t ion

and a t the same t im eissu es a Withdraw alKanban to Kanban

loc at ion of Raw Mat lStore

CYCLETIME REDUCTION


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Methods of Cycletime ReductionLeveled Production

When there are two models to a product, say models Aand B. Typically, these models will be loaded as A,A,A,Athen B,B,B,B. In leveled production, the loading is

A,B,A,B,A,B,A,B.

The advantage of leveled production with regards tocycletime is huge if A and B are sold as a set.

Process1

Process2

Inspection Pack

WIP WIP

CYCLETIME REDUCTION


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Methods of Cycletime ReductionLeveled Production

Example : Models A and B (a set) are processed through Processes1 and 2. Each take 1 minute to process for each process. Two setsare processed.

1 2

1 2

1 2

1 2

1 2

1 2

1 2

1 2 AB

A A

TimeTime

1 min 1 min

2 min2 min A A AB

3 min 3 min A AB B A

4 min 4 min

A

B B A A B A

Set completion : 4 min Set completion : 3 min

CYCLETIME REDUCTION


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Methods of Cycletime ReductionEliminating Wastes

Wastes are elements in the Production area that addcost but not value. Eliminating these wastes will see thecycletime drop tremendously.

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Methods of Cycletime ReductionEliminating Wastes

Kiyo shi Suzaki refined waste classification into sevencategories :

Waste from overproduction Waste of waiting time Transportation waste Processing waste Inventory waste Waste of motion Waste from product defects

Henry Ford , If it doesnt add value, its waste .

CYCLETIME REDUCTION
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Methods of Cycletime ReductionFlow Smoothing / Layout

Like water flowing through a pipe, a short and directproduction layout will tend to produce a smooth and fastproduction flow.Use a product-centric layout instead of a process-centriclayout to shorten product cycletime.

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Methods of Cycletime ReductionFlow Smoothing / Layout

Layout/flow guidelines :Product should flowtowards the shipment area.No backflow wherepossible.No cross flows.Do not use excess floorspace.

Keep area compact anddefined.Identify all inventory areasand kanbans.

S HI P ME NT

S HI P ME NT

S HI P ME NT

WALLED OFFFOR FUTUREEXPANSION

S HI P ME NT

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Methods of Cycletime Reduction5 S

A properly executed 5S environment can help reducecycletime.

A neat and properly defined work area means thattools and parts can be easily found. Searching time

and waiting time can be minimised or eliminatedresulting in reduced cycletime.

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CYCLETIME REDUCTIONCycletime Simulation

A cycletime simulation can reveal the theoreticalleadtime and cycletime for the product. This will be thetheoretical limit for the product cycletime.

1. Define the lot size, the processes and the UPH for each process.2. Compute the lot completion time for each process.3. List the Processes down the first column.4. List an Hour timeline across the top row.5. Plot the Lots as they move diagonally down from top left to bottom

right of the table.

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Lot Size : 3,000 Process Assembly Mark Test

UPH 1,200 2,000 1,500

Lot Completion Time 2.50 1.50 2.0

Lot Completion Time = Lot SizeUPH

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2

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Timeline (hr)Process

Assembly

Mark

Test

1 2 3 4 5 6 7 8 9 10 11

Lot 1

Lot 1

Lot 1

Lot 2

Lot 2

Lot 2

Lot 3

Lot 3

Lot 3

Leadtime = 6hrsCycletime= 2.5hrs Cycletime

3

4

5

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CYCLETIME REDUCTIONCycletime Metrics

Metrics related to cycletime are :Total leadtimeCycletimeProcess Cycle Efficiency (PCE)

Workstation Turnover Time (WTT)

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Total Leadtime Cycletime

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PCE WTT

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Total LeadtimeUnit of measurement weeks/days/shifts/hours/minsTotal leadtime can be :

measured (from time piece parts are issued to receivingcompleted product at Finished Goods)computed from Littles Law :

Total Leadtime (time) =WIP (units)

Average Completion Rate

Effective Line Capacity(units/time)

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CycletimeUnit of measurement weeks/days/shifts/hours/mins

Although cycletime is defined as the time taken for the next product to be produced, the average cycletime is generally

computed as follows :

Cycletime (time/unit)= Available Production Time (time)

Number of Products Produced (unit)

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Process Cycle Efficiency (PCE)PCE indicates how efficiently the process is converting WIP intofinished products.PCE is a ratio.

Any process with low PCE will have large NVA activities andhence opportunities to for cycletime reduction.It is common to get PCEs of less than 10% before improvement. The Process Chart can be used to collect the required data forValue-Add Time.

PCE = Value-Add Time (time)

Total Leadtime (time)

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Workstation Turnover Time (WTT)It is the time taken to set-up and perform one cycle ofwork at a specified workstation.Unit of measurement - hours/mins/secs.

WTT =Summation of (set-up time + process time) at the

workstation

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Cycletime Reduction