Any reference(s) about how to find out correct plastic injection parameters

I am an industrial engineer trainee. I am required to find out how to setup an injection machine with correct parameters. The technicians
in my working place they all operate the machines with their experience or trial-and-error methods. Workers need to monitor the quality of the molded parts regularly to see if any changes. If there is, the technician will then adjust the parameters. That's why my boss ask me to find out the correct parameters scientifically. Is there any reference about how to setup the parameters step by step? Appreciate for your help!
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I doubt that there exists something like "scientific moulding parameters", because in most cases you will always have a plastic, a tool and a molding machine with lots of unknown variables, which require non-scientific adjustments i.e. an experienced operator. Injection moulding isn't scientific! This is why most resin suppliers employ zillions of so-called "molding experts" who assist moulders in setting up molding machines or in trying to resolve molding issues with their resins. Also, in the end what counts is the quality of the part in its enduse environment and often you find out only later in enduse tests that something is wrong with the part, which can be related to the (poor or wrong) resin, the design of the part or to incorrect molding conditions. This is why you may have to go thru this molding-testing-cycle several times, before you can be certain everything is fine or that something has to be adjusted (e.g.tool or part design) or changed (e.g. wrong resin). And when you think you have set up everything correctly to start up commercial production of your parts, you may find out that your resin supplier has changed the quality of his resin. Having said that, of course you can get all sorts of molding parameters from your resin supplier, your tool maker and your moulding machine supplier and there exist lots of step-by-step references in form of books and software to collect all these data and feed them into a molding machine, but what gets fed into a molding machine has always to be decided and done by an operator who knows what he or she is doing ...

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I doubt that there exists something like "scientific moulding parameters", because in most cases you will always have a plastic, a tool and a molding machine with lots of unknown variables, which require non-scientific adjustments i.e. an experienced operator. Injection moulding isn't scientific! This is why most resin suppliers employ zillions of so-called "molding experts" who assist moulders in setting up molding machines or in trying to resolve molding issues with their resins. Also, in the end what counts is the quality of the part in its enduse environment and often you find out only later in enduse tests that something is wrong with the part, which can be related to the (poor or wrong) resin, the design of the part or to incorrect molding conditions. This is why you may have to go thru this molding-testing-cycle several times, before you can be certain everything is fine or that something has to be adjusted (e.g.tool or part design) or changed (e.g. wrong resin). And when you think you have set up everything correctly to start up commercial production of your parts, you may find out that your resin supplier has changed the quality of his resin. Having said that, of course you can get all sorts of molding parameters from your resin supplier, your tool maker and your moulding machine supplier and there exist lots of step-by-step references in form of books and software to collect all these data and feed them into a molding machine, but what gets fed into a molding machine has always to be decided and done by an operator who knows what he or she is doing ... --------------
I would have to disagree with your assumtion that molding (as well as extrusion) are such a "black box". I have worked in the medical device industry for almost 25 years in extrusion, and there are ways to set up "cause and effect" through proper experimentation/testing/DOE models. There is also flow modeling software (more so for molding, but extrusion flow modeling has come a long way).
We validate resin inputs to process outputs all the time. The key is material testing methodology and cross referencing the proper resin properties with the right process parameters. Of course, good well trained technicians are needed to minimize problems.
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... "proper experimentation/testing/DOE models" is what I indicated as the most common way for setting up a new tools with new materials, sometimes more experimentation sometimes less testing etc. ...
However, back to the original question: there isn't a possibility "to find out the correct molding parameters scientifically", without actually "operating the machines with the technicians experience or trial-and-error methods"! After all the "scientific" work you have done, you always have to get the tool onto the molding machine, throw the pellets in the hopper and get the molding machine started in order to find out whether all your modelling was on target or not, and if not to start wondering why not.

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how to

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step?
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