Six Sigma is an overall strategy to accelerate improvements in its processes , products and services . It is basically a statistical tool that advocates to design , operate and control every process in such a way that none of them yields more than 3.40 defects out of every million units of output . It tells the firms in very clear , accurate and precise ( mathematical ) terms as to how ‘ good ‘ or ‘ bad ‘ the quality levels are and how much improvement is needed .
Its philosophy is the same as that of TQM – that is , reducing the defects . However six sigma adds octane to TQM fuel . The difference between S – Sigma and the other quality approaches is that other quality approaches measure the abilities of the firm to meet some quality . Six – sigma is more than a quantitative statistical measure of processes because , it embraces every aspect of work , using a disciplined , fact based approach to problem solving .
It is a new way of thinking about work and customer value . It is also a powerful force to create one corporate culture . Six – sigma actually measures the output of the processes . That is , it is less theoretical and more real world . It is more rigorous and robust than TQM which is conventional . The heart of six – sigma is the measurement . If the firm ‘ s metrics are ambiguous , you wont be able to control your defects which means that you will not be able to control your processes .
In other words , six – sigma makes the users to know what they are chasing and can measure their progress in objective terms . If TQM is to do with reducing the defects , the six – sigma adds octane to TQM fuel . The difference between six – sigma and other quality approaches measure the abilities of the firm to meet same quality . It measures the output of the processes .
In conceptual terms , the primary aim is to identify , within each sub process , the opportunities for defects which can be arrived at through the use of different statistical tools such as regression analysis , design of experiments , and chi – square testing . Whatever form a quality problem takes – say wrongly marked invoice , a defective spare , abnormally high warranty costs – the six – sigma strategy translates it into a metric named defect per opportunity ( DPO ) . This is further scaled down to defect per million opportunities ( DPMO ) reducing which becomes the aim of the six Sigma samurai .
The Six Sigma Process
(1) Measurement – The starting point is the establishment of the metrics that will be improved using six sigma . First , the CTQ characteristics of the process have to be identified in order to focus six sigma on areas that will have the greatest impact on consumer satisfaction . The output of the process , measured as multiples of its sigma under each CTQ , has to be recorded so that the DPO and DPMO can then be calculated .
(2) Analysis – This is the stage at which new goals are set , and the route maps created for the gap between current and target performance levels . Analysis is a key component of any defect – reduction program . It is only when you have understood why and where you are going wrong you can rectify your mistakes . The aim is to identify what causes the defects in each sub – process so that they can be rectified either by redesigning the product or reengineering the process .
(3) Improvement – The objective of this phase is to confirm the key process variables , and quantify their effect on the CTQs . This is the stage where the ground – work is translated into action .
(4) Control – In the fourth and final stage of six sigma implementation , the new process – conditions are documented , and frozen into systems so that the gains are permanent . The process is assessed once more after the setting in period in order to check , whether the improvements are being sustained or not
To speak of the successful companies by use of six – sigma strategy are : Godrej – GE reduced defects to 1000 per million parts as against 3 , 00 , 000 in assembly lines at Vikhroli , Mohali and Pune and first defect free consignment was shipped in 1998 . The other companies that gained cost reduction are Allied Signal , Bajaj Auto , General Motors , Hero Motors , Modi Xerox and Maruti Udyog .
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