Stability and flatness of platic injection molding parts
Stability and flatness of platic injection molding parts
(OP)
We have a flat rectangle, 30mm W x 96mm L x 4 mm H that we need to manufacture in high production quantities, ~100k/year that needs to have a flatness on the 30x96 face of 0.005mm.
Chemical resistance is not a high requirement.
Operating temperatures are in the 25dC +/- 5dC range with a controlled temperature change of no more than 2dC/hour.
Non-flourescence is a high requirement.
Any recommendations on what plastics families we should be looking at are?
Chemical resistance is not a high requirement.
Operating temperatures are in the 25dC +/- 5dC range with a controlled temperature change of no more than 2dC/hour.
Non-flourescence is a high requirement.
Any recommendations on what plastics families we should be looking at are?





RE: Stability and flatness of platic injection molding parts
Otherwise, I would suggest a non-crystalline material - e.g. styrenics, acrylics etc. Not PP, PA, etc.
You might make them by casting PMMA onto an optically flat glass surface, but I have no idea of the feasibility of this
Incidentally, 100K per annum would be considered low volume for injection moulding...
Cheers
Harry
www.tynevalleyplastics.co.uk
RE: Stability and flatness of platic injection molding parts
I agree that the flatness requirement is extreme.
Instead of plastic try optical glass parts or metal gauge blocks.
RE: Stability and flatness of platic injection molding parts
I assume these are aluminium?
www.tynevalleyplastics.co.uk
RE: Stability and flatness of platic injection molding parts
100,000 parts per year is considered high volume but not very high volume here.
Noryl would be a good material choice to optimise flatness. Gate position and size and very uniform surface temperature of the mould also is essential.
Cast acrylic would certainly work. They make Perspex brand acrylic sheet by casting between glass plates. I am not aware of their normal flatness specs, but I expect it is quite tight, but then again 5 micron is also very tight. A few degrees temperature difference accross the part from body heat as you hold it in your hand could distortit that much
Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
http://eng-tips.com/market.cfm
for site rules