Electropolishing Validation of Orthopedic Parts - What OQ parameter range


We’re a contract manufacturer and now we're doing a EP validation for different type of materials.
We have 440A, 420B, 17-4, 455, 304, 316.

We never get formal input from our customers. So my intension is to define two validation purpose, one is the surface roughness is reduced, and the other is corrosion resistance (ASTM F1089).

I understand some customer requires to test cytotoxicity. I don’t want do it, because I have a wash process to remove manufacturing material after EP. and cleaning process will be validated. Or is there any other purpose of cytotoxicity of EP that I did not see?

Also some customer will have dimension removal requirement, for example the dimension change is no more than 0.0006 inch. Don’t want to that either unless specifically required by customer. Because required dimensions on the print will be measured after EP and in final inspection. Although it will be an more solid evidence to show EP capability is stable…

As for parameter for OQ and PQ, I have time, temperature, and voltage.
My biggest question is how do you choose those parameters for different material and product.
I mean normally we have one validated range of above parameters for all material. Or is there someone using different parameter range for different materials or product size?

My problems is, during EP OQ challenge test, I found “time” varies a lot on different material and product (size of product).
For example, for a 5mm diameter drills made of 420B, it takes 20 seconds to remove deburrs and have corrosion resistance layer. But it takes about 1 minute for a 12mm diameter drill made of 420B. And for a 5mm diameter drills made of 17-4, it only needs 5 seconds, and it got burned if putting a 17-4 in EP solution for 1 minute.

Does anybody have any suggestion on what parameter range do you use for OQ?
Do you have a large range on those parameters?



I think for each material it needs to define OQ & PQ parameter range separately, that's why "change in material" is also a process re validation trigger.
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