TPE Material
IMM 08/02

We currently process several lenses out of acrylic resin. Lately, there seems to be a recurring theme with swirly, milky contamination. These particular tools and processes are not new to us. We've had some of the jobs for about four years now, but the problem is fairly new. This is getting to be quite costly. Has anyone else experienced this frustration with acrylic or any other clear lenses and is there a solution?

I experienced the same problems when I was molding polycarbonate lenses. Our problem was caused by our loading system - we loaded out of Super Sacks and gaylords. If either material handling personnel or the supplier was not careful, then some of the plastic liner bag would get sucked into the material handling lines and end up in the lenses looking like a swirly , milky contamination. Generally, the problem does not last very long, but it depends on shot size and amount of bag sucked into the system.

– J. VerMurlen, EcoWater Systems Inc., Woodbury, MN, (651) 738-5808, vermurlenj@ecowater.com.

If this is a problem that just cropped up, I suspect it's related to heat in specific areas of the mold. Check your waterlines for coating and contamination. If you haven't already done so, start a timed program of preventive maintenance that would include cleaning the waterlines with a chemical.

– B. Deimling, Deimling/Jeliho Plastics Inc., Amelia, OH, (513) 752-6652, billdeimling@deimling-jeliho.com