Processing of Low MFI plastic materials in injection molding

[manimaste]

Hi friends,

with our new project we have PP plastic material with low MFI values range from 1.95 to 5,is it possible to handle it by injection molding process,please give me some more ideas about this and also what are the accessoris required like accumulater or special machines to handle this material.please explain the details behind this low MFI....


Thanks,
Manikandan N

[Suhas]

Hi,
It is not impossible. it will depend on your part design and the flow length. If you are going to mold a 1 inch long 0.80 wall part, the answer is Yes. If you are going the mold a 20 long 0.060 wall part the answer is No. The answer is 'vague' - I agree, but I am sure you got the point.
Suhas

[rickbatey]

I have ran an extrusion grade PE in radiator bottle for automotive. We were down around MFI of 5 or so; we could mold the part because the wall stock was about 3 mm with two drops. So as Suhas pointed out, it all depends on wall stock and flow length. I doubt faster fill speeds and very high injection pressures will make this work.
Rick.

[johnnyplastic]

We've injection molded blow molding grade HDPE that had a 0.3 MFI so I'd say it is possible

[rickbatey]

Like Suhas stated it REALLY boils down to wall stock, flow length, and gating. Rick.

[manimaste]

If possible can you tell me the kind processing you are using to handle this low mfi material,it will help us on new project

[Team JAG]

If you have a flow analysis performed on the part, you should have an idea of the pressures needed to fill the part, where to place gates, and if the required pressures are feasible with your current molding machines. I think it is always a good idea to have an analysis done when the resin viscosity is low...

I will say, I am generally more concerned with a low viscosity engineering grade material like PC, PMMA, or POM as they can be much less forgiving than commodity resins in an unforgiving scenario. Just my 2 cents...