Opinion: Top two most important Scientific Molding Studies?

[Suhas]

Of the 6-Steps of Scientific Molding - Viscosity Curve, Cavity Balance, Pressure Drop Study, Process Window, Gate Seal and Cooling Study, what are the top two that you think are the most important?

[Mauricio]

I think it depends of the requirements of the part being moulded (cost/process optimization, quaility, dimensional stability..)

[injector]

It would also depend on the part applications, mold cavitation (single cavity tool, mold balance n/a), etc. I prefer a pressure loss study before the mold leaves the mold builders shop. That way they can make the necessary adjustments before we get the mold in-house for further validations. Gate seal is critical to virtually every tool.

[Danny R]

Of course it would be dependant on different applications, resins, mold cavitation. But without properly setting the fill time (viscosity curve) everything else is pretty much useless.

[Adolfo]

process window and viscosity curve

[Suhas]

Most of you say Viscosity, but I beg to differ. When I worked in the insert molding industry for about 10 years, I rarely used it! But I had the most robust processes. To me the one that is HUGE is the process window. More soon after some more replies.

[ProcessEval]

We use a decoupled technique and then gate seal.

[RAF68]

as people said, it would be dependant on different applications, but to me the best two is the pressure drop and viscosity study.

[Suhas]

Good mix of answers here. I think there is some product dependency but I still say process window. Thanks all. New members, please keep posting and answering.
Thanks,
Suhas

[Timj40]

What is the proper way to perform the pressure drop study?

[Suhas]

Hi Timj40,
On this website, if you go to the home page, you should see all the procedures and even worksheets to do the study. Just remember, you do not have to get stuck doing 'all' the sections of the pressure drops. At the injection speed you have selected, the nozzle and the end of fill are most important two sections for finding the pressure drops. If you are pressure limited or close to being pressure limited, you must do the sections in between to find the section where most of the pressure drop is occurring. Any questions, let us know.
Suhas

[brentb]

As far as dimensional stability is concerned; Cavity Balance Study and Process Window.
I would substitute Gate Freeze for the 1st choice if the mold is a single cavity and cold runner. Now if the mold is single cavity hot sprue, I would sub Cooling Study. This effects economy and in many cases, dimensions (SC Resins).

Keep on Molding!

brent

[NATHAN]

Identify the Melt temperature range,mold temperature range,Injection speed range,flow balance variation,process window range,Holding time and Cooling time.

Perform DOE with respect to Mold temperature,Melt temperature ,cooling time and process window will provide the clear view of the Molding process on the
specified product.

[1Aahz]

There are four plastics variables that we need to control to assure quality and consistency. Fill rate, Melt Temp, Cooling rate and pressure (hold/pack). Of the 6 studies mentioned Cavity balance and gate freeze would be my top two. I am going to fill teh mold as fast as the mold, machine and material combination will let me anyway to save time if for no other reason.... process window will be a net result of optimizing the process in the first place.

GBYA

Aahz