Validating multiple injection molding machines efficiently



I have a question on common practices for validating injection molding processes across several molding machines. It is viable to perform an OQ study to define a process window on one machine, then move to PQ and apply the nominal setting to multiple identical machines to check for conformance to CpK requirements?

I have been informed by a purported expert that the best molders in the world typically use multiple similar (not identical- may have slightly different screw, barrel, etc.) machines without specifically running parts in them provided the OQ and PQ has been completed on a single machine. This seems somewhat unlikely for sensitive parts used in medical and pharma applications, so I am looking for confirmation of the general practices in use. Is requiring separate PQ runs on multiple machines common to approve those machines for production?

How do you typically go about qualifying multiple presses?



Involved In Discussions
That is only applicable if you have same make and model of machine and same auxiliaries (same capacity chiller or water thermolator) and same screw size. Our common practice is run the whole IOP validation in one machine and run only PQ on multiple machines with same make and model and same screw size.



Involved In Discussions
I currently work for a supplier of components of medical devices - we do full validation for each pair of mould/production cell. From experience - the same mould on 2 IMMs of the same make and type can have slightly different process window. I think this is caused by technical state of the IMMs - they are long-living machinery and although going through authorized testing, they actually work in slightly different manner.

Bev D

Heretical Statistician
Super Moderator
agree with previous poster. even 'identical' equipment bought and installed at the same time will not be the same. They have different components made at different locations within their tolerances; they will age/wear differently based on dimensions and material properties and usage; they will have different voltages, current, pressures, etc. remember nothing is ever exactly the same as another 'identical' thing.

In my experience PQ is almost useless in qualifying parts or equipment. real ife rarely stays at the Nominal...

Michael Malis

Quite Involved in Discussions
I would also recommend to obtained from OEM statement that all original equipment was installed and validated by the molding company. This will help to avoid questions about original vs. modified software...



To Validate multiple injection molding machines efficiently ...
IQ: Every machine. Learning from the first helps in the rest to a great extent
OQ: Learning from OQ / PQ from the first helps in the rest to a great extent
PQ: Logically follows OQ
Aim for the machine & mold combination effectively
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