Operational Qualification (OQ) Question

[chrisprocess]

In regards to IQ, OQ, PQ...

How do you guys execute OQ??

Historically, we've done "High and Low" runs to establish evidence our process limits result in parts that meets defined specification.

Generally,

High Process: + 10 melt temp, +10 mold temp, +500 pack psi +1s cooling time
Low Process: - 10 melt temp. - 10 mold temp, - 500 pack psi, -1s cooling time

It's not perfect, but it's stuck here for some time.. There is certainly a lot of discussion over it.
What other methods are there? Any ideas for improvement?

Thought is to be thorough, but in a timely manner. (mostly timely it seems lately) :confused:

Thanks,

Chris

[JayDub]

First question is why are you doing OQs? If you are a regulated facility, then you should have a procedure that tells you exactly how to do them. If not, it’s a customer requirement and you can do whatever the customer wants to pay for.

That said, in practice you should have done enough characterization prior to OQ that you know how the part behaves, so I would not advise pinning yourself down to fixed ranges ahead of time. Could be +/- 10 degrees for one part, +/- 20 for the next. (Although it should be at least the range of variation you will see from the heater thermocouples). If you have performed a window study and measured parts, you should have a good idea of where the process will produce good parts consistently. (Do this preliminary work thoroughly and you will not risk failing OQ and looking like a jackass).

Unless you know other factors have a substantial impact on the parts, I would restrict the challenge to temperature profile and hold pressure, leaving everything else constant. I have done high/nominal/low runs, but I prefer to do four corners (HI/Hi, Hi/Lo, Lo/Hi, Lo/Lo), because that establishes a window with known capability.

Just my opinion, but the best way to be both thorough and timely is to have a well-defined development procedure and good documentation (protocol/report forms).

[chrisprocess]

Thanks JayDub, good info. Current Mold Validation procedure leaves the OQ relatively open for the process designer..
And I haven't dealt with too many picky customers on how 'thorough' the OQ run needs to be. (Mostly they just want to see we have a procedure/plan and can execute to that plan).

Temp profile and hold pressure definitely seems achievable. -Mostly to convince our QE and new engineering manager (both have no inj. molding experience).

[Suhas]

Hi Chris,
What you mention above is good. What Jay mentions are also valid points. WHat my clients have been doing is a full DOE, find the process that makes you the parts you want WITH a robust and wide window process and then vary the process around that. I think a 10 deg melt is too small. Is the 500 psi plastic or hydraulic? I am assuming plastic which again is small. But it is a great start. I find very few companies doing this and so whatever you do is good.
You can try to widen the windows by doing a DOE.
Regards,
Suhas

[chrisprocess]

Thanks Suhas. +/- 10 melt & +/- 500 plastic pressure..

I'll need to explore this a little bit.
I've worked with Minitab here and there.. DOE can be a very powerful tool if done correctly!

Do your clients execute DOE prior to OQ run? Or is the DOE run itself considered the OQ run? (this to me seems justifiable)

[Suhas]

Everyone does it in their own way. Some do it part of the OQ - which is always my choice and make the most sense. You have explore the process and that is what is OQ. When you have a chance, read through my website and you will get an idea. I do things differently than others. I have done that for 25 years and have been VERY successful and the reason I have been able to sustain my consulting. It is a paradigm shift.
-Suhas

[chrisprocess]

Thanks Suhas.

I've read a lot of the FIMMTECH articles and am a very big fan of your app.

I work at a fortune 500 company and unfortunately it seems recent R&D effort is focused on "project tasks" and "checking boxes" more than digging into the science and understanding of injection molding.. We did consulting in the past (RJG) but it sort-of fell off the bandwagon because budget cuts blah blah (some operations guy lowering his financial costs for the quarter).

We tend to focus more on validation protocols/quality systems these days, which is great but it seems a little overboard - I write IQ/OQ/PQ protocols all week - these guys are more concerned about the formatting, revision control, and approvals more than what the protocols actually say!!

It wasn't always like this, it was founded by a gentlemen who built his own custom plunger molding machines, and bought out 4 - 5 times.
A lot of the early employees made it out quite well (a lot of them retired) but a few of the early tooling/molding guys are still around.

So building a justification for us to get consulting would be a daunting task.
To be honest if I wanted advanced consulting it would probably be on my own budget..

At least there's a great senior process guy and tooling manager to learn from for now.

[Suhas]

Hi Chris,

All seems familiar - unfortunately. I had to chuckle when I read 'these guys are more concerned about the formatting, revision control, and approvals more than what the protocols actually say' :) All I say is do your best, be a good molder, be a team player but do voice your concerns.

I have a passion for molding and teaching. Just let me know if I can help. Don't worry, no PO needed. :) :)

All the best formatting, sorry, molding :)

Suhas
P.S.: This calls for a new forum thread, may be I will start it.

[chrisprocess]

I have a passion for molding and teaching. Just let me know if I can help. Don't worry, no PO needed. :) :)

Thanks Suhas - careful though, I may take you up on that ;)


All seems familiar - unfortunately. I had to chuckle when I read 'these guys are more concerned about the formatting, revision control, and approvals more than what the protocols actually say' All I say is do your best, be a good molder, be a team player but do voice your concerns.

Great advice - 'gotta feed the dragon I suppose.


All the best formatting, sorry, molding

I'll do my best but apparently windows 95 is outdated.. hah just kidding.

[Jojo63]

Hi,

I want to share with you my experience.

Setting the parameters is often a problem.

At home, we have defined 3 parameters: the switching pressure, the holding pressure and the holding time. I know that many other parameters can have an impact on the results but we must limit ourselves otherwise it would be unmanageable.
To define the parameters and their tolerances, we look at several things:
- The dimensions of the product
- The injection of the product is correct (no incomplete)
The problem is, with time, it can evolve. For example, in early 2017, we had validated tooling on a new press (calibrated at the factory) and we did not manufacture this product any more during the year. At the beginning of this year, we had to manufacture again. When we loaded the validated program, the products were not compliant. We had to lower the switching pressure by 200 bar (900 => 700) and the holding pressure by 250 bar (700 => 450). So we conducted a new validation with new parameters. Between the 2 validations, the tooling has not been modified. The press has been calibrated. This is thought to explain these changes but we have not seen any evolution with other tools.

Jo.