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!
Reply to
Chris
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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 ...
"Chris" schrieb im Newsbeitrag = news: snipped-for-privacy@posting.google.com...
Reply to
Rolf Wissmann
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.
Reply to
Larry Alpert
... "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.
"Larry Alpert" schrieb im Newsbeitrag = news:aMWfb.222337$ snipped-for-privacy@rwcrnsc51.ops.asp.att.net...
Reply to
Rolf Wissmann
as the most common way for setting >up a new tools with new materials, sometimes more experimentation sometimes less testing etc. ...
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.
Yes, you still need to prototype your part. In these days of more complex parts for both processes (molding and extrusion) and the competitive nature ofthe business, the scientific method will get you much closer to what you want and even show you things you might not have realized until parts are in the field (stress points, etc.).
Being closer means: Less machine time and design changes to bring the part design to fruition (fewer iterations of tools, less machine time, overall lower cost to develop), less time overall to put a part in your customers hands, either internal or external, which means the product time to market is reduced.
It can also be instrumental in understanding problems that come up with processes already in place. I'm sure that most everyone, if in this business long enough, has had a process in place that has run forever with no trouble that all of a sudden "doesn't run" at one point.
Is it necessary in all cases? Maybe not. Can it save time and money? Yes.
"Larry Alpert" schrieb im Newsbeitrag news:aMWfb.222337$ snipped-for-privacy@rwcrnsc51.ops.asp.att.net...
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Reply to
Larry Alpert

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