Polycarbonate And Oils

[hman]

Searching for a good way to peel the paper from some polycarbonate sheet (brand names like Lexan, Hyzod, Makrolon, Lupilon, Calibre, etc.), I ran across several posts (on other forums) that claimed that polycarbonate would be attacked/weakened/ruined by oils. Among the discussions was a caution about making machine guards of polycarbonate.

I decided to do a quick-and-dirty test. Took a 1/4" x ~3/8" strip of the material and applied dabs of WD-40, way oil, black (sulfur) cutting oil, and drug store mineral oil to various places along one side. Waited 24 hours. Then I cleaned the oil off and tried bending/breaking each of the oiled places. To do this, I held the strip in my vise and used a 7/16" box end wrench to give each point a ~45 degree kink. The oiled areas were on the outside of the bend, so they got get tensile stress. I also tested an un-oiled section of the bar.



Results - Each of the bends produced a flattened, stretched area on the outside (oiled face) of the bend, but there were no signs of any kind of failure at any of them. All the bends (oiled or not) seemed to take about the same amount of force.



Initial conclusion - oils don't seem to affect polycarbonate. I realize that 24 hours would not be long enough for oil to diffuse deeply into the plastic, but I would have expected some kind of change to show up in the bend test.

Does anybody have further information or direct experience?

 

[uncle harry]

Searching for a good way to peel the paper from some polycarbonate sheet (brand names like Lexan, Hyzod, Makrolon, Lupilon, Calibre, etc.), I ran across several posts (on other forums) that claimed that polycarbonate would be attacked/weakened/ruined by oils. Among the discussions was a caution about making machine guards of polycarbonate.

I decided to do a quick-and-dirty test. Took a 1/4" x ~3/8" strip of the material and applied dabs of WD-40, way oil, black (sulfur) cutting oil, and drug store mineral oil to various places along one side. Waited 24 hours. Then I cleaned the oil off and tried bending/breaking each of the oiled places. To do this, I held the strip in my vise and used a 7/16" box end wrench to give each point a ~45 degree kink. The oiled areas were on the outside of the bend, so they got get tensile stress. I also tested an un-oiled section of the bar.

View attachment 108499

Results - Each of the bends produced a flattened, stretched area on the outside (oiled face) of the bend, but there were no signs of any kind of failure at any of them. All the bends (oiled or not) seemed to take about the same amount of force.

View attachment 108500

Initial conclusion - oils don't seem to affect polycarbonate. I realize that 24 hours would not be long enough for oil to diffuse deeply into the plastic, but I would have expected some kind of change to show up in the bend test.

Does anybody have further information or direct experience?

My experience with Lexan polycarbonate is relative to large outdoor sign faces. These faces are routinely decorated by silk screening and/or spray painting with some fairly aggressive solvents. For this reason I don't think soaking the paper with a thin oil for a short duration will be harmful. You might try a vegetable type oil or go all out & use butter (lol). You could Google Lexan to find stats on chemical resistance.

 

[Ebel440]

The guards on my machines at work use polycarbonate and get sprayed with coolant and oil all day. Iv never seen polycarbonate affected by oils. Some solvents will cloud it and soften it. Iv left it in a container of water to soak the paper then it will peel off leaving some of the adhesive behind which I used alcohol to take off

 

[Wreck™Wreck]

UV light has a profound effect on polycarbonate as the sign maker that posted above will probably agree. more modern formulations with UV inhibitors are much less prone. In the late 70's early 80's I worked for a builder of sailboats, we built nearly 100 thirty foot boats using Lexan™ windows, by 1985 all of the windows looked like frosted Christmas decorated glass windows, it was interesting to see the slow failure over several years.

At the shop where I currently work we make laser printers for Pharma labeling lines, very powerful lasers printing sequentially numbered labels (with barcodes) up up 400 per minute, they use a formulation of what appears to be POM (delrin/polyacetal) which is black to guard the laser head.

 

[coolidge]

Weird, machine guards 'are' polycarbonate and get blasted with oil and coolant its tough stuff. The only issue I ever had with it is you need to use special tooling when drilling it or it will develop cracks like glass. UV is tough on just about everything.

 

[RJSakowski]

Initial conclusion - oils don't seem to affect polycarbonate. I realize that 24 hours would not be long enough for oil to diffuse deeply into the plastic, but I would have expected some kind of change to show up in the bend test.
to take about the same amount of force.

View attachment 108500


Does anybody have further information or direct experience?

Some years ago, I made a polycarbonate lens out of 1/2" plate for a custom LED work light on my Tormach CNC. The lens was exposed to flood coolant as it sat directly behind the spindle and about six inches above the cutting edge. The coolant was Premere 600 Synthetic Coolant from Reladyne.

Within a few weeks, it began to crack with the cracks eventually working their way across the lens and splitting it into multiple pieces. The main exposed surface of the lens was not machined although the edges were milled and four mounting holes were drilled and counterbored .

I suspect that the polycarbonate behaves much like acrylic when machined. There are micro-fissures created which provide an ingress for liquid which then swells the material and expands the crack. I am not sure that cold bending wouldn't produce a similar phenomenon.

I have since replace the lens with one made from PVC. It is not as clear as the polycarbonate so I had to thin the lens down to .030" for more light transmission and I still lost some intensity but it has so far held up with no problems.

Bob

 

[JimDawson]

Try drilling and tapping polycarbonate with some oil, that's where you see cracking. As long as the surface is intact, it's pretty solvent resistant.