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Injection mold problems

Are you a mold flow analyst, have you run the new transient thermal analysis feature? Or if not, have you looked at using COMSOL or ANSYS-CFD to get a simulation look for comparison to what you are seeing? Moldflow does a moderate job with thermal because of its reliance on steady state thermal analysis techniques. Only now do they have a transient model but be careful because it appears that they still use steady state with a time "snapshot" so not as deep into the science as the above CFD approaches. Understand that, while simulation is always improving, you should trust it to be about 80% accurate. This goes across most all forms of simulation types not just mold flow. Therefore, physical instrumentation is highly useful.

I don't see a description of the plastic part, such as size and if you are dealing with asymmetrical features, also injection mold feed system description is missing. This could be issues with gate location, type, size, etc. and your thermal issue may not be your problem. Therefore, answers can only be given in a very general sense.

My assumption is that the design was not first well understood by simulation and the injection mold was designed and built without a deep vetting of the expected capability. I see this a lot in the industry, I take a position that injection molds need a lot more engineering than they get otherwise issues like this would not be so common. So, my advice in the future is to engineer the injection mold don't design the injection mold.

I don't think you will be very successful in making a good serial troubleshooting guide, however, I do recommend you develop some level of organized method, a DOE, to guide a resolution. Developing that is a job in itself.

When the injection mold was brought up was a complete decoupled (scientific) molding DOE performed? If so then this should have data defining the processing parameter relationships and, from there, you can see how moving settings will affect the plastic part. This also reveals injection mold performance issues as well as press issues. Not doing this often leads to discussions and answers like these, it's all over the place. The answers are not wrong but also are not aligned with the problem. Let's be honest with this, you can't solve a problem in a general sense only in a specific sense so tossing ideas around is interesting but let's not kid ourselves that this necessarily is helpful.

One thing I always do with my injection molds is provide for instrumentation. This means have thermocouples and pressure transducers in the first injection mold of any new design. While I don't always install the pressure transducers I always have locations ready for them. However, you can never have too much thermal information so I always have a lot of thermocouples where I feel I can get the most useful data from.

As mentioned above, the advice given is good and solid but only when there is a good understanding of the problem. Otherwise it's a fractured approach illustrating that the problem has not been defined and broken into a good DOE. Relay on solid engineering methods and practices, don't "design" but "engineer".

My advice is that you reach out to a quality consultant such as Aco Mold who can help define the issue in a face to face discussion.

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