Surrogate Parameter : Sigmaguru@gmail.com Surrogate Parameter A new Quality Improvement Tool
Surrogate Parameter is A New Tool for Quality Improvement : Sigmaguru@gmail.com Surrogate Parameter is A New Tool for Quality Improvement
Surrogate means Substitute Surrogate parameter is one which substitutes another which is of real interest to us : Sigmaguru@gmail.com Surrogate means Substitute Surrogate parameter is one which substitutes another which is of real interest to us
Surrogate Parameter Tool is used when - there is no simple / clear clue - there is no known cause and effect : Sigmaguru@gmail.com Surrogate Parameter Tool is used when - there is no simple / clear clue - there is no known cause and effect
Surrogate Parameter Tool is used when - it is very expensive or dangerous or time consuming or very inconvenient to work or experiment with the original parameter : Sigmaguru@gmail.com Surrogate Parameter Tool is used when - it is very expensive or dangerous or time consuming or very inconvenient to work or experiment with the original parameter
In such case, choose a closely related parameter with which it is easy to experiment The new parameter is called Surrogate Parameter : Sigmaguru@gmail.com In such case, choose a closely related parameter with which it is easy to experiment The new parameter is called Surrogate Parameter
Surrogate Parameter should be closely related to the one we are interested in but it need not be necessarily be specified or defined by the customer for example – weight of a product : Sigmaguru@gmail.com Surrogate Parameter should be closely related to the one we are interested in but it need not be necessarily be specified or defined by the customer for example – weight of a product
Customer may not be interested in weight as a parameter to be measured, but it is very useful to us as it can be easily measured. Change in material , dimension, process results into change in weight and it can give us the vital clue in problem solving. : Sigmaguru@gmail.com Customer may not be interested in weight as a parameter to be measured, but it is very useful to us as it can be easily measured . Change in material , dimension, process results into change in weight and it can give us the vital clue in problem solving.
The choice of the second Surrogate Parameter is of course very critical and one should be very careful in choosing it. : Sigmaguru@gmail.com The choice of the second Surrogate Parameter is of course very critical and one should be very careful in choosing it.
Let us consider a case to understand The Case of Plastic Moulder Project is To deliver zero defect products to customer : Sigmaguru@gmail.com Let us consider a case to understand The Case of Plastic Moulder Project is To deliver zero defect products to customer
Background Subsidiary of European Multinational Had Modern machines They had Zero Defect Policy But One customer was reporting sporadic failures at 2500 ppm level This is simply not acceptable. : Sigmaguru@gmail.com Background Subsidiary of European Multinational Had Modern machines They had Z ero Defect Policy But One customer was reporting sporadic failures at 2500 ppm level This is simply not acceptable .
In spite of attention of entire organization, defects persisted. Ultimately services of SigmaGuru were called in. : Sigmaguru@gmail.com In spite of attention of entire organization, defects persisted. Ultimately services of SigmaGuru were called in.
About the problem The problem was about a weld line around a hole splitting open when under pressure during assembly. : Sigmaguru@gmail.com About the problem The problem was about a weld line around a hole splitting open when under pressure during assembly.
PowerPoint Presentation : Sigmaguru@gmail.com About the process Moulding conditions were not precisely defined. Operating personnel free to twiddle the knobs.
PowerPoint Presentation : Sigmaguru@gmail.com A lot of trials made with no demonstrable results. Thousands of units were required per trial.
They had even posted one person at client location to monitor and report failures as they happen ! No efforts were spared!! : Sigmaguru@gmail.com They had even posted o ne person at client location to monitor and report failures as they happen ! No efforts were spared!!
At one stage, even Raw material quality ( melt flow index) was suspect and a narrow range of properties were demanded. But this too did not result in any improvement. : Sigmaguru@gmail.com At one stage, even Raw material quality ( melt flow index) was suspect and a narrow range of properties were demanded. But this too did not result in any improvement.
Due to all these difficulties it was decided to use Surrogate Parameter Tool. : Sigmaguru@gmail.com Due to all these difficulties it was decided to use Surrogate Parameter Tool .
Since the problem was with the finished product, weight of the finished product was chosen as Surrogate Parameter. : Sigmaguru@gmail.com Since the problem was with the finished product , weight of the finished product was chosen as Surrogate Parameter .
It is very easy to measure weight compared to predicting if a part will break or not at the client! : Sigmaguru@gmail.com It is very easy to measure weight compared to predicting if a part will break or not at the client!
PowerPoint Presentation : Sigmaguru@gmail.com Original Surrogate Parameter Strength at particular location Weight Method Destructive Non destructive Time to test 72 hours 1 minute Cost heavy negligible Size of trial 5000 30 Ease Difficult Very Easy Comparison of Original and Surrogate
Here is initial snap shot of quality in terms of surrogate parameter - weight : Sigmaguru@gmail.com Here is initial snap shot of quality in terms of surrogate parameter - weight
It is known that Variation in (inputs and outputs of) processes causes defects Six sigma movement was ignited in Motorola by this discovery. And it was also known that the process parameters ( machine settings parameters) were frequently changed. : Sigmaguru@gmail.com It is known that Variation in (inputs and outputs of) processes causes defects Six sigma movement was ignited in Motorola by this discovery. And it was also known that the process parameters ( machine settings parameters) were frequently changed.
Hence it was decided to check the weight again after keeping machine parameters constant at their known best level. : Sigmaguru@gmail.com Hence it was decided to check the weight again after keeping machine parameters constant at their known best level.
Now the variation looked like this. Quite an improvement over the initially observed. : Sigmaguru@gmail.com Now the variation looked like this. Quite an improvement over the initially observed.
The results are quite positive! At this point, a small meeting was convened with – Production Quality Process Personnel. : Sigmaguru@gmail.com The results are quite positive! At this point, a small meeting was convened with – Production Quality Process Personnel.
The 4 most critical parameters for the weld line problem were listed 1. Cycle time 2. Fill time 3. Mould temp 4. Hold time : Sigmaguru@gmail.com The 4 most critical parameters for the weld line problem were listed 1. Cycle time 2. Fill time 3. Mould temp 4. Hold time
The team also decided the best and the worst levels( values) for these parameters. Knowing these, a quick trial was made with only 30 units with all parameters at their worst and best levels. : Sigmaguru@gmail.com The team also decided the best and the worst levels( values) for these parameters. Knowing these, a quick trial was made with only 30 units with all parameters at their worst and best levels.
All parameters at their worst is called ( 0000) level All parameters at their best is called( 1111) level : Sigmaguru@gmail.com All parameters at their worst is called ( 0000) level All parameters at their best is called( 1111) level
All parameters at their worst level gave this weight variation : Sigmaguru@gmail.com All parameters at their worst level gave this weight variation
And All parameters at their best level …. : Sigmaguru@gmail.com And All parameters at their best level ….
Thus we found sigma dropping from 1.36 % to 0.12 % improvement by a factor 10, within a single working day! : Sigmaguru@gmail.com Thus we found sigma dropping from 1.36 % to 0.12 % improvement by a factor 10, within a single working day!
PowerPoint Presentation : Sigmaguru@gmail.com
PowerPoint Presentation : Sigmaguru@gmail.com
Going back from surrogate to original parameter, trials made with now best-known parameters gave no failures at the customer. Zero defect for the critical customer achieved within a week. : Sigmaguru@gmail.com Going back from surrogate to original parameter , trials made with n ow best-known parameters gave no failures at the customer. Zero defect for the critical customer achieved within a week.
Conclusion Wisely chosen Surrogate parameter yields wonderful results Zero defect is a reality and it can be achieved. : Sigmaguru@gmail.com Conclusion Wisely chosen Surrogate parameter yields wonderful results Zero defect is a reality and it can be achieved.
The problem which was evading solution for one year… Surrogate Parameter helped solve in just one week : Sigmaguru@gmail.com The problem which was evading solution for one year… Surrogate Parameter helped solve in just one week
PowerPoint Presentation : Sigmaguru@gmail.com Send your comments. Criticism, arguments Back to us to sharpen the tool. You are also welcome to share own case studies , experience. Send them to Sigmaguru@gmail.com Vidyut Bapat +91 94235 07631