UHMWPE inclusion/subsurface defect detection
UHMWPE inclusion/subsurface defect detection
(OP)
I have recently been tasked with scrap reduction in my manufacturing cell. The reason for most our scrap is through vendors, and we are currently working with them to reduce the levels. In any event, one main scrap contributer in our plastics division is inclusions/subsurface defects (voids, burnt resin ,etc...). Any visual defect is immediately scrapped if on a bearing surface. The problem is, a lot of these defects are not visually noticeable until the device is milled. Does anyone know of any processes that could identify the location of these defects? I would like to be able to scrap these components prior to accumulating the value associated with machining.
Thanks
Thanks





RE: UHMWPE inclusion/subsurface defect detection
http:
http://www.olympusndt.com/en/index.html
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http://www.scanmaster-irt.com/
Regards,
Cory
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RE: UHMWPE inclusion/subsurface defect detection
Regards
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.
RE: UHMWPE inclusion/subsurface defect detection
Back to the problem.......
Not sure if it's your vendors giving you the problem, but if it is, my approach would be to get them to to do the corrective action. All you will be doing is their final/inprocess quality checks!!
Voids/burns/ are usually process errors - very occasionally part or tool design.
Not very cost-effective all round!
Cheers
Harry
RE: UHMWPE inclusion/subsurface defect detection
Sometimes linear polyolefins (HMWPE, LLDPE, UHMWPE, etc) will crosslink from the heat associated with shearing (machining)the part.
RE: UHMWPE inclusion/subsurface defect detection
From the insufficient evidence provided I would guess the voids and burns are gas traps.
These can be controlled by moulding conditions, but this is a poor remedy.
Best remedy is to position the gate(s) correctly and have sufficient vents correctly placed and designed.
The concept that for plastic to fill a mould, it must also expel the air is sometimes lost. The fact that air compresses allows people to forget its there, but at high compression, it gets very hot and burns parts.
Regards
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.
RE: UHMWPE inclusion/subsurface defect detection
http://
Some really interesting stuff at that site.
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