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Originally Posted by Gary Dillard
I didn't see it specifically addressed anywhere in this thread (except in the Andy Baker "blue" index), but all polycarbonate is not the same. We have found a huge difference in Lexan brand versus other generic polycarbonates and the name brand is worth the price difference in terms of machinability and strength.
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So true. Here is how I *believe* things work in the thermoplastic world:
a. There are only a handful of places where polycarbonate resin is made. This is done in chemical plants, with huge capital costs and very big environmental considerations. Polycarbonate resin looks somewhat like white grape nuts, but a bit smaller.
b. Resin is sold to extruders or compounders. Some extruders make sheet, some make plastic pellets. Sheet is cut and sold to end users. Plastic pellets are sold to molders. Compounders mix other things with resin to make co-polymers or other special applications. They may mix in other materials (fiberglass, micah, other plastics, etc.) or they may filter it to make specialty grade products.
Like anything else, resins are tested and graded. The best resin sells for a higher price. Lower grade resin sells to lower prices, of course. Some companies focus on the high grade stuff while others sell cheaper grade material. These companies usually list the mechanical properties of their materials,
like this for LEXAN 101R. You can compare other polycarbonates by looking at elongation, hardness, fatigue, and other ratings.
Andy B.