Tricool TC1 and lexan

[ckhalford]

Hello everyone,

I hace a small cnc Lathe/Mill setup that I run flood cooling on. I am currently using a synthetic coolant made by Trico.

http://www.drillspot.com/products/27...ic-Coolant?s=1

I like the stuff for the following reasons.

(1) doesn't stink or make slime in the reservoir.

(2) does not rust my machines. When I am done I just hose the machines off with the stuff and all is well.

One thing that I have noticed, however, is that it seems to accelerate stress cracking in lexan. When I was putting my system together I made several parts from lexan and I noticed that in short order any place that there was a bend or a screw there was a crack. I have made things from lexan before and I have not seen this. Has anyone had a similar experience with this product or any others. Also can anyone reccomend a coolant which does not do this.

Thanks
Chris

[Geof]

Stress cracking in Lexan is unusual. Are you absolutely sure you have Lexan? If you are cold bending then it must be. Are you absolutely sure it is not the abrasion resistant coated Lexan? Once the protective film is peeled off it is almost impossible to differentitate between coated and uncoated; there is a small difference in the reflectivity when viewed obliquely and a slightly different sheen to the surface.

The coated Lexan will stress crack under conditions and treatment that will not cause stress cracking in uncoated. I think the cracks start in the coating which is harder and then propagate into the Lexan.

The only time I have seen stress cracking in uncoated Lexan was when it was exposed to the vapors from Loctite thread locking compound. This was accentuated around drilled holes which had been done with a dull drill or too fast without lubricant.

I have succesfully machined Lexan using only a soap solution as coolant, more of a lubricant really, or just by rubbing soap on the drill in the case of holes. I have also found that Shell Dromus water mix coolant is completely compatible with Lexan.

[ckhalford]

Geof
Thanks for the reply,

It was definitely lexan because I did cold bend it. I dont think that it was the abrasive resistant type. I have tried polycarbonate from a variety of manufacturers GE, Makrolon etc with the same result. One of the items that I made was a cover which goes over the lathe to keep the coolant in the pan. It is basically a piece of lexan with two 90 degree bends which fits over a steel tube frame. The plastic was attached with sheet metal screws. I thought maybe I would have better luck with nylon machine screws. The other things that I made were stepper motor covers. These did not have any screws. After about two weeks of use all of the ones which were exposed to the coolant had completely failed at the bends whereas the ones which were not exposed were OK.


Chris