Six Sigma in the Automotive Industry

Introduction• Six Sigma (6σ) is a set of techniques and tools for process improvement.

• It was introduced by Bill Smith at Motorola in 1986.

• It seeks to improve the quality of the output of a process by identifying andremoving the causes of defects and minimizing variability in manufacturing andbusiness processes.

• It uses a set of quality management methods, mainly empirical, statisticalmethods, and creates a special infrastructure of people within the organizationwho are experts in these methods.

• A six sigma process is one in which 99.99966% of all opportunities to producesome feature of a part are statistically expected to be free of defects (3.4defective features per million opportunities) Source – Motorola.com

Concept of 1.5σ Shift• The 6σ levels can only be achieved in the short term for a process

• When the process was done for a longer time frame, the sigma level of 4.5 was only found to be achievable

• Thus the 6σ level essentially is 4.5σ + 1.5σ shift from the central value.

• Thus rather than achieving 2 DPBO, six sigma can only achieve 3.4 DPMO

Source - Tennant, Geoff (2001). SIX SIGMA: SPC and TQM in Manufacturing and Services

Methodologies of Six Sigma - DMAIC• DMAIC• Used for projects aimed at improving an existing business process

• Define the system, the voice of the customer and their requirements, and the project goals, specifically.

• Measure key aspects of the current process and collect relevant data; calculate the 'as-is' Process Capability.

• Analyze the data to investigate and verify cause-and-effect relationships. Determine what the relationships are,and attempt to ensure that all factors have been considered. Seek out root cause of the defect underinvestigation.

• Improve or optimize the current process based upon data analysis using techniques such as design ofexperiments, poka yoke or mistake proofing, and standard work to create a new, future state process. Set up pilotruns to establish process capability.

• Control the future state process to ensure that any deviations from the target are corrected before they result indefects. Implement control systems such as statistical process control, production boards, visual workplaces, andcontinuously monitor the process. This process is repeated until the desired quality level is obtained.

Source - De Feo, Joseph A.; Barnard, William (2005). JURAN Institute's Six Sigma Breakthrough and Beyond – Quality Performance Breakthrough Methods

Methodologies of Six Sigma - DMADV• DMADV

• Used for projects aimed at creating new product or process designs

• Define design goals that are consistent with customer demands and the enterprise strategy.

• Measure and identify CTQs (characteristics that are Critical To Quality), measure product capabilities, production process capability, and measure risks.

• Analyze to develop and design alternatives

• Design an improved alternative, best suited per analysis in the previous step

• Verify the design, set up pilot runs, implement the production process and hand it over to the process owner(s)

Source - De Feo, Joseph A.; Barnard, William (2005). JURAN Institute's Six Sigma Breakthrough and Beyond – Quality Performance Breakthrough Methods

Six Sigma at Maruti Suzuki• Maruti Suzuki India (MSIL), the country’s largest passenger cars manufacturer has implementedprinciples of Poka Yoke, TQM and by extension, 6σ principles since its inception in 1984.

• MSIL started a programme called Maruti Centre for Excellence (MACE) – involving 21 of its componentvendors -- to replicate best practices from the shop floor of MSIL which translates into better quality andbetter productivity, to combat the issues of recalls and defective components that other carmanufacturers were facing.

• MACE was started with a corpus fund of ₹10 crore from MSIL and the vendors contributing ₹25 lakh eachand identified areas where the vendors can improve in quality on global levels and also follow someparameters of operations.

• The company helps the suppliers deploy lean processes to improve productivity and reduce resourcewastages. There are four main activities -- training, audit, implementation and up-gradation of smallervendors who supply to these tier-I suppliers so that the quality is maintained in the chain of products.

Source – The Hindu Businessline

Six Sigma at Maruti Suzuki (Contd.)• Based on some basic requirements, MSIL decides on certain topics and train both blue collared as well as the white collared employees in the vendors’ factories.

• Then, the team audits which quality systems are to be followed in every operation. For every operation, there is a prescribed ways of doing it as the quality standard is the backbone of the company in how it operates.

• It is the implementation of lean manufacturing system at its vendors -- based on what Maruti has in-house production systems -- based on Suzuki Motor Japan and Toyota Quality Management (TQM), which means improving the productivity, eliminating the waste and reducing the defects.

• The company through implementing lean manufacturing systems has 720 projects completed so far for productivity improvement, quality, inventory control and energy conservation. MACE has worked with 146 tier-II vendors for overall improvement in performance resulting in reduction in rejections from 10,933 to 1,180 products per month and defect reduction from 432 to 146 per month.

Source – The Hindu Businessline

Six Sigma at Maruti Suzuki (Contd.)• The MACE program also aims at achieving Zero Defects and has been successful. It has been able to address the issue of ensuring high quality even at the hands of contract labourers.

• One of the steps taken was the installation of visual and audio alarms at the production lines which would go off whenever a worker took an incorrect component during assembly.

• Through such programmes, many of its vendors have now got ‘zero rejection’ in its parts and wastage is also controlled. For example, part of the MACE since its inception, Superfine Components is been supplying parts to MSIL with zero rejection, continuously over the last three years.

• MSIL through MACE sends its counsellors to other factories as part of the MoU with Ministry of Micro, Small and Medium Enterprises (MSME). MACE has also become part of Quality Council of India for such activities and has tied up with Kaizen Institute India in Ahmedabad, Gujarat.

Source – The Hindu Businessline

Six Sigma at Tata Motors• The quality improvement project at Tata Engineering operates under the umbrella of the Tata Business Excellence Model, an open-ended framework that drives business excellence in group companies. But the main component of the quality undertaking is Six Sigma.

• Tata Engineering set up a strong Six Sigma organisation and established a robust audit and monitoring mechanism to ensure that targets were met and sustained. A large number of teams were put in place to implement the project.

• There was one at the apex level to oversee the overall implementation and others at the company’s plants in Jamshedpur, Pune and Lucknow.

• A filtering procedure was created to identify and isolate problems. Firstly, the CTQ features at the aggregate level — body, engine, paint, gearbox, axle, etc — were considered.

Source – Tata website

Six Sigma at Tata Motors – Contd.• Next in line were product audits, process audits and independent audits, which were later matched to customer needs. Coming under the Six Sigma microscope were three process levels: manufacturing, support services and plant support services.

•Then came the components, and after that the supplier-level CTQ characteristics. The improvement processes followed: skill enhancement, process mapping, cause-and-effect analysis, failure-mode-and-effect analysis (which helps anticipate problems and puts pre-emptive corrective measures in place).

Source – Tata website

Six Sigma Implementation Case Study• “Implementation of a Lean Six Sigma Project in a Production Line” by Valter R. Morais, Sérgio D. Sousa, Member, IAENG and Isabel Lopes. Published in Proceedings of the World Congress on Engineering 2015 Vol II.

• The Case dealt with the improvement of the sigma level of a production line that manufactures shock absorbers for Yamaha and Honda.

• The line efficiency index was found out to be 77.8%. However, this didn’t reflect all the unplanned stoppages. Causes of Adjustments problems, product quality problems and equipment failure were listed as the main causes.

• The process improvements were brought in place and the sigma level was shown to have increased from 2.48 to 3.45.

Six Sigma Implementation Case Study – Contd.• A reduction in the settings from 72 minutes to 12 minutes was achieved. The rejection decreases from 3,9% to 1.9%.

•With the new balancing of 17 seconds and 84.31% efficiency, the new production capacity is 3035 units/day. This easily fulfilled the 2200 units/day demand. The improvements implemented were:

1) Grouping operations: Design a new layout for the machining process.

2) Redo the line balancing and provide training to employees.

3) Assess the new line capacity and performance

Strategic Enhancement of Quality through 6σ: A Case Study International Journal of Engineering Trends and Technology (IJETT) - Volume4 Issue6- June 2013

Rajendra M. Belokar, Jagbir Singh (Department of Production Engineering, PEC University of Technology Chandigarh, India)

The aim of Six Sigma methodology is to improve the quality by reducing the number of defects as much as possible.

This case study was conducted at Caparo Maruti Ltd, BAWAL which mainly manufactures various sheet metal parts and components associated with automobiles.

focus is mainly on manufacturing of one of the sheet metal parts i.e. Panel component wheel housing inner left hand (LH) & right hand (RH) sheet metal part for G model (Maruti Suzuki SWIFT)

DMAIC Approach- Define Phase The main material used in manufacturing the inner wheel housing part is cold rolled continuous annealed steel material in the form of metal sheet.

These metal sheets are bought from their vendor companies mainly from Tata Steel, BhushanSteel and Essar etc.

Major steps for making the inner wheel housing part, we have to do various operations on the metal sheets in different compartments or shops Drawing (Press Shop)

Trimming & piercing (Press Shop)

Trimming & Cam piercing (Press Shop)

restrike & parting operations (Press Shop)

Projection and Spot welding (Weld Shop)

Define Phase

Process flow diagram (PFD)

Measure Phase All the finished inner wheel housing parts were tested for quality by using visual inspections.

Mainly three types of inspections are conducted on all the parts before dispatching to customers.

(a) on processing visual inspection

(b) fitment inspection by manually checking fixture

(c) pre- dispatch visual inspection

Data on the basis of these inspections was collected for 10 months.

Out of the 283470 units tested, 283305 units passed all the tests and 165 failed in tests.

major defects come mainly due to poor environmental condition regarding to sheet metal parts, press & welding failure are in (a) Red rust, (b) Nut out, (c) Part bend or damage, (d) Spot Dent, (e) Part mismatch, (f) Spot Burn (g) Cracking & Necking (h) Welding offset

Measure PhasePeriod 01-04-2012 to 31-01-2013 % Failed in

Total Units Tested 283470

Units Passed 283305

Units Failed 165 (0.0582%)

Units Failed in Red rust 96 58.18

Units Failed in Nut Out 27 16.36

Units Failed in Part bend or damage 21 12.72

Units Failed in Spot burn 9 5.45

Units Failed in Part mismatch 5 3.03

Units Failed in spot dent 4 2.42

Units Failed in cracking & Necking 2 1.21

Units Failed in Welding offset 1 .6

Measure PhaseDefects per Million opportunities:-

DPMO= (165 * 1000000)/(283470 * 8)

= 73

i.e Sigma Level of Approximately 5.393

Conformance Level (%)

Defects per Million opportunities

Sigma Level

30.85 691500 1

69.15 308500 2

93.3 66800 3

97.73 22700 3.5

99.38 6200 4

99.795 2050 4.375

99.87 1300 4.5

99.94 600 4.75

99.977 230 5

99.997 30 5.5

99.99966 3.4 6

Analyze Phase The Pareto diagram and Line diagram reveals major defect is red rust appearance on sheet metal part.

This defect occurs on metal sheets mainly due to a long contact with moisture air.

This type of defect comes under appearance related category.

This defect may be produced on both raw material sheets and manufactured parts which may be easily known only by visual inspection.

The potential failure mode of inner wheel housing parts due to red rust are:- rusty sheets metal part gives a red appearance which indicates that corrosion must be produced on parts

throughout the life.

part will become functionally weak in strength after some time

part life will become small as compare to others

other defects may be occurred like cracks in part

painting defects will be occurred

Pareto and Line Chart for defects

Analyze Phase These potential effects of failures occurs on the surface of inner wheel housing parts which is very critical mainly for maintenance, accidental & safety purposes throughout the life.

If we are able to eliminate the major failure which may be occurred due to red rust, the defective level can be brought down to 0.0243 % from the present level of 0.0582%.

The principle of Pareto diagram also states that investment in improvement of vital few yields better than compared to investment in trivial many. Hence inner wheel housing defect, red rust appearance on sheet metal surface was taken up for investigation.

The major causes for red rust appearance was:-1. Lacking of awareness regarding to inventory stock.2. Store supervisor negligence or improper arrangement of raw material sheets in inventory stock.3. Raw material storage in open space4. Due to bad environmental condition like rain.5. Due to moisture presence in surrounding of raw material.6. Storage method not good.7. More carbon presence in component

Analyze Phase• Ishikawa

Diagramme for Red rusting

• Defected parts due to red rust appearance account 0.0339 %

Improve Phase The causes for red rust were analyzed and found that it is due to the bad environmental conditions like due to rain and moisture air only.

The material used is high quality cold rolled continuous annealed steel sheets as a raw material bought from their reputed vendor companies, mainly from Tata Steel Ltd. and others. Firstly, this raw material must be deeply examined before it is introduced in the manufacturing process. Hence defects due to material will be ruled out.

The improvement can be brought into the product by using anti rust oil spray techniques on raw material if necessary before introducing in manufacturing process by which we can improve quality of our product.

If only the red rust appearance failure in inner wheel housing parts were eliminated, the improvement in Sigma level will be from 5.393 to 5.5

ControlNEW DPMO= (69*1000000)/(8*283470)=30

Sigma level of Approximately 5.5 Defective level can also be brought down to 0.0243% (From 0.0582 %).

Once the solution is implemented, the next step is to place the necessary control to assure that the improvements are maintained long-term. This involves monitoring the key process metrics to promote continuous improvement.

Summary Of Case Study• Pareto diagram revealed major failures in red rust appearance test. 58.18% inner wheel housing parts failed in red rust appearance test.

• substantial improvement in the process can be achieved through the elimination of red rust appearance failures.

• reasons for red rust appearance failures were identified and solutions were recommended to the management for improvement.

• This may improve the process from Sigma level of 5.393 to 5.5

Introduction

In this era of globalization, it is proven fact that organizations that are able to use resources effectively will be market leader and rest will be followers

Automotive industry is not far from it

World class manufacturing has been achieved by

1. Productivity

2. Quality

3. Delivery

4. Flexibility

5. cost