K
Hello,
I work at a small medical device company where we produce a bunch of low-volume devices with a lot of operator-dependent processes, and I would appreciate input on some SPC related questions. Mainly, what is the most appropriate method for a) verifying that the design is acceptable and b) validating processes which have critical impact on the product.
As mentioned, since this is a small company, the production is mostly manual labour with processes such as UV gluing.
Our production quantities for a typical product might be 50 pieces a month, so right away there are limited product available for testing.
We control the material that comes in fairly well as we have good specifications, and the equipment is properly maintained and calibrated. Most of the specs are 100% verified, but some cannot be since they are destructive.
With that background, here is a specific example:
A product (say a needle) is designed. The needle's dimensions and performance requirements are pre-determined. Samples are built with R&D techniques using representative processes and materials for design verification, usually 10 samples. Sticking to the UV example, a performance requirement might be tensile strength of X Newtons.
To transfer the product to production, processes are fine-tunes (as much as we can) and a process validation is done (or at least we try to).
The UV process might look like:
1. Spread UV glue around shaft of needle at about 10mm from the end.
2. Attach hub to needle
3. UV glue hub using UV wand for 45s to 60s.
4. Verify under a microscope that there are no gaps in the UV.
That's it!
So, my specific questions are:
1. What is an appropriate method to analyze results from design verification? For example, should we do a 95/95 test? A t-test? Mean - 3 standard dev > minimum? Or just make sure all test pieces pass the criteria? Or something else? Keeping in mind we have limited quantities to spare due to cost constraints.
2. For transferring product to production, our process validation requires at least 3 lots be validated. We perform an IQ, OQ, PQ, but the processes are extremely dependent on the operator. So I don't know how to analyze the test results, or whether the validation is meaningful. Should we do a Cpk analysis of 1.33? Or some other way to ensure the processes are capable for production in the long-run?
Thanks, any advice is kindly appreciated.
I work at a small medical device company where we produce a bunch of low-volume devices with a lot of operator-dependent processes, and I would appreciate input on some SPC related questions. Mainly, what is the most appropriate method for a) verifying that the design is acceptable and b) validating processes which have critical impact on the product.
As mentioned, since this is a small company, the production is mostly manual labour with processes such as UV gluing.
Our production quantities for a typical product might be 50 pieces a month, so right away there are limited product available for testing.
We control the material that comes in fairly well as we have good specifications, and the equipment is properly maintained and calibrated. Most of the specs are 100% verified, but some cannot be since they are destructive.
With that background, here is a specific example:
A product (say a needle) is designed. The needle's dimensions and performance requirements are pre-determined. Samples are built with R&D techniques using representative processes and materials for design verification, usually 10 samples. Sticking to the UV example, a performance requirement might be tensile strength of X Newtons.
To transfer the product to production, processes are fine-tunes (as much as we can) and a process validation is done (or at least we try to).
The UV process might look like:
1. Spread UV glue around shaft of needle at about 10mm from the end.
2. Attach hub to needle
3. UV glue hub using UV wand for 45s to 60s.
4. Verify under a microscope that there are no gaps in the UV.
That's it!
So, my specific questions are:
1. What is an appropriate method to analyze results from design verification? For example, should we do a 95/95 test? A t-test? Mean - 3 standard dev > minimum? Or just make sure all test pieces pass the criteria? Or something else? Keeping in mind we have limited quantities to spare due to cost constraints.
2. For transferring product to production, our process validation requires at least 3 lots be validated. We perform an IQ, OQ, PQ, but the processes are extremely dependent on the operator. So I don't know how to analyze the test results, or whether the validation is meaningful. Should we do a Cpk analysis of 1.33? Or some other way to ensure the processes are capable for production in the long-run?
Thanks, any advice is kindly appreciated.
