mold modification

[Kman007]

Can anyone please tell me if I can shoot an existing tool with nylon, that has been running and built to run polypropylene. What I'm looking for is to be able to offer customers more material options. Cosmetics are not an issue. I am not concerned about the processing side, I am concerned only with the tooling side. I'm wondering if it's possible without having to make major tooling modifications. Any suggestions would be appreciated... Thank you....

 

[patprimmer]

Generaly Nylon runs OK in a mould made for PP, but it depends on a number of factors.

Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
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[onyx01]

Nylon should run just fine. The only area of concern would be if the nylon has fillers. I have had a tool run ABS, PC-ABS, ASA, Nylon, Acetyl, PP and Styrene, just to evaluate materials for a customers needs.

Regards,


Brandon Jacobsen
Product Design Engineer - Catia

 

[sean01]

Hi Kman007,

I agree with Brandon - you shouldn't have any trouble if the nylon doesn't have any fillers - and then your problems will be more related to wear of the mould tool, filling and filler distribution throughout the final product.

Sean

 

[injunneer]

TO kman007

I just found this web-site and am having fun exploring forums and reading posts. I hope I am not insulting anyones intelligence with this reply. The primary issue I see with using a mold designed for PP to run nylon (assuming the nylon is unfilled)is dependant on the design and quality of the nylon part to be molded. PP will normally tolerate a gap clearance of .002-.003 before the material will flash. Nylon will sometimes flash at .0005 or less. If the part can tolerate some flash, and the mold is quality built and in good condition, you should not have a problem. Another issue is the size and tolerance of the part. PP and Nylon can have large differences in the shrink rate. The best thing to do is try it, you shouldn't hurt anything. (assuming the nylon doesn't flash down some knock-out pins and hang up in the tool) Hope this helps

 

[davidinindy]

The only other issue I see is possibly different shrinkage rates. Depending on the size and tolerances of your part, it might not be a problem.

 

[patprimmer]

Shrinkage is one of the many variables I eluded to in my original post.

PP is generally higher, but PP varies more with direction of flow. Nylon 66 will shrink more than some PP co-polymers, but nylon 6 will be much less than PP homo polymer.

Also, nylon is more susceptible to flash, but will fill a mould more easily.

PP is much more responsive to shear and likes small gates. To get best results and minimal shrinkage with nylon, you need bigger gates.

Filled nylon will mostly work in a mould designed for filled PP, but filled PP or filled nylon might not work in a mould that is marginal for unfilled PP.

The original question is way to vague for anything but the most general answer or wild speculation.

Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[patprimmer]

kman007 has not logged on since he posted his original question.

Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.