Injection Mouldng Number Of Gates

[toyman3]

Hi , All

Designing a part in PP which is much larger than I normally work on. Upshot is I am not sure how many feed points I need to include on the part. The part is 490mm long , with a main wall thickness of 4mm , width is about 80mm , depth is circa 30mm. Part will be subjected to some static loading so I am keen to make sure that the part is filled correctly and that I have no weld lines or weak areas where we can't fill the mould properly. I don't have access to any mouldflow programes , normally I just use my experience , but like I say the parts are normally mcuh smaller. So anyone got an advice , free programes / spreadsheets or rules of thumb they could point me to.?. Any pointers appreciated.

 

[Pud]

Where/how do intend to feed the part?

Centre fed I would be certain that it would easily fill, and more than likely with a tab gate at one end.

4mm is pretty thick.

You can get flow/pressure charts from material suppliers.

Cheers

Harry

http://www.tynevalleyplastics.co.uk

 

[patprimmer]

Your material supplier should supply flow path to thickness ratio charts.

These are produced from ideal conditions so subtract 30% for commercial moulding conditions unless you are prepared to pay a substantial premium for the need to use a big press and a slow cycling hot mould.

Also, it depends a heck of a lot on individual grades, so make sure the data is applicable to your grade.

A std medium high MFI PP should do it easily but may warp with a centre gate. A mineral filled grade won't warp as much but won't flow so well either.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

http://eng-tips.com/market.cfm

for site rules