Análisis estadístico

Poka-yoke can be implemented at any step of a manufacturing process where something can go wrong or an error can be made. For example, a jig that holds pieces for processing might be modified to only

Dept of MBA, SJBIT Page 102 allow pieces to be held in the correct orientation, or a digital counter might track the number of spot welds on each piece to ensure that the worker executes the correct number of welds.

Shigeo Shingo recognized three types of poka-yoke for detecting and preventing errors in a mass production system:

1. The contact method identifies product defects by testing the product's shape, size, color, or other physical attributes.

2. The fixed-value (or constant number) method alerts the operator if a certain number of movements are not made.

3. The motion-step (or sequence) method determines whether the prescribed steps of the process have been followed.

Either the operator is alerted when a mistake is about to be made, or the poka-yoke device actually prevents the mistake from being made. In Shingo's lexicon, the former implementation would be called awarning poka-yoke, while the latter would be referred to as a control poka-yoke.

Shingo argued that errors are inevitable in any manufacturing process, but that if appropriate poka-yokes are implemented, then mistakes can be caught quickly and prevented from resulting in defects. By eliminating defects at the source, the cost of mistakes within a company is reduced

**** End of Module 7****

Dept of MBA, SJBIT Page 103 Module 8

Introduction to Six Sigma Historical developments, statistical framework for six sigma, DPU and DPMO concepts, DMAIC methodology, Training for Six Sigma, Benefits of Six Sigma, Six sigma and TQM.

OBJECTIVE

To understand the meaning, applications and Importance of:

Introduction to Six Sigma

Historical developments, statistical framework for six sigma, DPU and DPMO concepts, DMAIC methodology,

Training for Six Sigma, Benefits of Six Sigma, Six sigma and TQM.

INTRODUCTION TO SIX SIGMA HISTORICAL DEVELOPMENTS

Six Sigma at many organizations simply means a measure of quality that strives for near perfection. Six Sigma is a disciplined, data-driven approach and methodology for eliminating defects (driving toward six standard deviations between the mean and the nearest specification limit) in any process – from manufacturing to transactional and from product to service.

The statistical representation of Six Sigma describes quantitatively how a process is performing. To achieve Six Sigma, a process must not produce more than 3.4 defects per million opportunities. A Six Sigma defect is defined as anything outside of customer specifications. A Six Sigma opportunity is then the total quantity of chances for a defect. Process sigma can easily be calculated using a Six Sigma calculator.

The fundamental objective of the Six Sigma methodology is the implementation of a measurement-based strategy that focuses on process improvement and variation reduction through the application of Six Sigma improvement projects. This is accomplished through the use of two Six Sigma sub-methodologies: DMAIC and DMADV. The Six Sigma DMAIC process (define, measure, analyze, improve, control) is an improvement system for existing processes falling below specification and looking for incremental improvement. The Six Sigma DMADV process (define, measure, analyze, design, verify) is an improvement system used to develop new processes or products at Six Sigma quality levels. It can also be employed if a current process requires more than just incremental improvement. Both Six Sigma processes are executed by Six Sigma Green Belts and Six Sigma Black Belts, and are overseen by Six Sigma Master Black Belts.

Dept of MBA, SJBIT Page 104 According to the Six Sigma Academy, Black Belts save companies approximately $230,000 per project and can complete four to 6 projects per year. (Given that the average Black Belt salary is $80,000 in the United States, that is a fantastic return on investment.) General Electric, one of the most successful companies implementing Six Sigma, has estimated benefits on the order of

$10 billion during the first five years of implementation. GE first began Six Sigma in 1995 after Motorola and Allied Signal blazed the Six Sigma trail. Since then, thousands of companies around the world have discovered the far reaching benefits of Six Sigma.

Many frameworks exist for implementing the Six Sigma methodology. Six Sigma Consultants all over the world have developed proprietary methodologies for implementing Six Sigma quality, based on the similar change management philosophies and applications of tools.

STATISTICAL FRAMEWORK FOR SIX SIGMA

Six Sigma is a business strategy and a systematic methodology, use of which leads to breakthrough in profitability through quantum gains in service quality, product performance, productivity and customer satisfaction.Today SixSigma has been considered as a strategic approach to achieve excellence in operations and service performance through the effective utilization of statistical and non-statistical tools and techniques .Like other programs emerging under the TQM umbrella,Six Sigma requires a transformational change in an organization’s culture, structure, and processes. The emergence of Six Sigma as a distinct approach to TQM occurred in 1987 at Motorola ,Six Sigma is a disciplined approach to define, measure, analyze, improve and control processes that result in variability and defect reduction. Six Sigma is a business improvement strategy that seeks to find and eliminate causes of defects or mistakes in business processes by focusing on outputs that are of critical importance to customers. It is a powerful approach to process improvement, reduced costsand increased business profitability and revenue growth. Six Sigma originated at Motorola in the early 1980s in response to a challenge to achieve ten-fold reduction in product failure levels in five years. Six Sigma has both management and technical components. The focus of management component is to select the right people for Six Sigma projects, select the right process metrics, provide resources for Six Sigma training, provide clear direction and guidance with regard to project selection, etc. The focus of technical component is on process improvement by reducing variation, creating data which explains process variation, using statistical tools and techniques for problem solving, etc.

Dept of MBA, SJBIT Page 105 In statistical terms, Six Sigma means 3.4 defects per million opportunities (DPMO), where sigma is a term used to represent the variation around the average of a process. Today, Six Sigma is exploited by many organisations such as GE, Honeywell, Sony, Caterpillar, J P Morgan, American Express, Common Wealth Health Corporation, Lloyds TSB, City Bank, Jaguar, Kodak, Ford and Starwood Hotel Group . These contrast results make Six Sigma implementation a complex and central process, where the CSFs in its implementation must be recognised.

Although different resources are now available on Six Sigma subjects, it seems there are only a few, in which CSFs are addressed. In the following, the efforts made in the literature are reviewed in case of CSFs for successful implementation of Six Sigma projects; then, a case study is presented in which a set of CSFs are analyzed in major car maker companies in Iran..

DPU AND DPMO CONCEPTS Defects Per Unit - DPU

Total Number of Defects DPU = ---

Total number of Product Units

The probability of getting 'r' defects in a sample having a given dpu rate can be predicted with the Poisson Distribution.

Total Opportunities - TO

TO = Total number of Product Units x Opportunities Defects Per Opportunity - DPO

Total Number of Defects DPO = --- Total Opportunity

Defects Per Million Opportunities - DPMO DPMO = DPO x 1,000,000

Defects Per Million Opportunities or DPMO can be then converted to sigma values using Yield to Sigma Conversion Table given in Six Sigma - Measure Phase.

Dept of MBA, SJBIT Page 106 DMAIC METHODOLOGY

Dept of MBA, SJBIT Page 107 TRAINING FOR SIX SIGMA

Six Sigma Business Improvement training, Lean, FMEA, SPC

Six Sigma gives your company a global competitive edge and with a certified quality framework in place, you can be confident in

 Cutting costs,

 Improving efficiency and

 Meeting your business targets

Six Sigma training courses

Lean Six Sigma Transactional Black Belt Lean Six Sigma Transactional Green Belt Six Sigma Green Belt Certificate

Six Sigma Yellow Belt Lean Practitioner

Failure Mode and Effect Analysis Statistical Process Control

BENEFITS OF SIX SIGMA, LIMITATIONS , SIX SIGMA AND TQM.

Cost reduction

Productivity improvement

Market share growth

Cycle time reduction

Defect reduction

Culture change

Product / service development

Dept of MBA, SJBIT Page 108