Plastic material in VMC windows??

[CNC Viking]

Hi,

Does anyone know the best transparant plastic material for windows for a VMC's protection cage. I have a Feeler FV-800 VMC that need a new window ( it is actually one of the side slide doors). They are made of 10 mm thick material that even withstand cellulose thinner.

[Geof]

I have only ever seen polycarbonate (Lexan or Tuffak) used for machine windows. It is resistant to methanol and regular oils and Varsol, but I do not know what you mean by cellulose thinner.

[One of Many]

Poly Carbonate? Likes of the brand names of Lexan or Hyzod.

DC

[CNC Viking]

I checked a little, and my machine was equipped with Acryl (Plexiglass) windows. The plastic type is PMMA. I believe that this type is more resistant to solvents than Polycarbonate (PC). The cast quality is supposed to be the best, but is maybe harder to come by than extruded.

[Geof]

Originally Posted by CNC Viking I checked a little, and my machine was equipped with Acryl (Plexiglass) windows. The plastic type is PMMA. I believe that this type is more resistant to solvents than Polycarbonate (PC). The cast quality is supposed to be the best, but is maybe harder to come by than extruded.

Check much deeper!!!!!!

Acrylic, Plexiglas, Perspex, PMMA (Polymethylmethacrylate if you want the tongue twisting name) Is in no way more resistant to various solvents than polycarbonate AND IS FAR LESS IMPACT RESISTANT than polycarbonate.

It is possible your source of information was wrong, I have found a great many people casually say that all clear plastics are acrylic.

You final sentence is accurate, cast acrylic is far better than extruded, it is less available and is more expensive.

[One of Many]

Originally Posted by Geof Check much deeper!!!!!! Acrylic, Plexiglas, Perspex, PMMA (Polymethylmethacrylate if you want the tongue twisting name) Is in no way more resistant to various solvents than polycarbonate AND IS FAR LESS IMPACT RESISTANT than polycarbonate. It is possible your source of information was wrong, I have found a great many people casually say that all clear plastics are acrylic. You final sentence is accurate, cast acrylic is far better than extruded, it is less available and is more expensive.

I placed the Polycarbonate as a question mark, since I don't really know what the OEM material actually is. Most guarding on industrial equipment specified by OSHA is PC. Although, the windows in our Bridgport. Milltronics and Okuma machines seem to be much harder than PC as far as scratch and chemical resistance. So, it wouldn't be any surprize to find it is some form of hard coated cast acrylic with a rubberizing component to increase its impact strength.

Something along the lines of Polycast SAR ?

DC

[Geof]

Originally Posted by One of Many ... the windows in our Bridgport. Milltronics and Okuma machines seem to be much harder than PC as far as scratch and chemical resistance...DC

I am not familiar with the SAR but I know it is possible to get polycarbonate with a very scratch resistant coating; to my knowledge it is used in glazing applications.

But I think this hard coating makes the polycarbonate more brittle. I have done a lot of forming of plain polycarbonate and it cold bends extremeley well, but the abrasion resistant stuff would often crack.

I was also thinking about the resistance to 'cellulose thinner'; the material in CNC Vikings machine could be laminated tempered glass, or even laminated plain glass.

[One of Many]

Originally Posted by Geof I am not familiar with the SAR but I know it is possible to get polycarbonate with a very scratch resistant coating; to my knowledge it is used in glazing applications. But I think this hard coating makes the polycarbonate more brittle. I have done a lot of forming of plain polycarbonate and it cold bends extremeley well, but the abrasion resistant stuff would often crack.

Just tapping on these windows gives a completely different sound than some of the panes we have replaced with PC. The OEM ones do seem harder and as a guess more brittle. The replacements were due to some previous coolant usage degrading their clarity.

My bad experience with PC was well after cold forming and machining pinch guards for tube stretching fixtures I designed. Upon finishing, I cleaned them of oils with some "convenient" brake cleaner I tested to make certain it wouldn't melt the material. I sprayed them down, whiped them clean ready to install. Within 10 minutes, they cracked like baked glass marbles and just fell apart. The replacement batch of 8 were cleaned with a water based cleaner.....lesson learned. Solvents and transparent, thermal formed plastics are a bad combination, not worth the risk, so I no longer take the chance!


DC

[Geof]

Originally Posted by One of Many ...I cleaned them of oils with some "convenient" brake cleaner...DC

Naughty, naughty as you found out.

I learnt a similar lesson. Unfortunately the cracking was delayed by several days during which time we shipped a lot of items to customers. That rresulted in a lot of phone calls, a lot of UPS call tags to pick up the packages and a lot of expense on overnight shipments for the replacements.

[cam1]

Our VMC has double pane tempered glass.....heavy, but resistant to most if not all common chemicals.

regards

[One of Many]

Originally Posted by cam1 Our VMC has double pane tempered glass.....heavy, but resistant to most if not all common chemicals. regards

I've seen SAE safety laminated glass in Sand Blaster windows. I am not certain what, if any local regulations allow for in chip producing type machine tools.

Probably best to be penny wise and not pound foolish on the usage and abusage. Environment dependant verse the risk over why it needs replaced this time.

DC

[Geof]

That is a good point about tempered glass where it can be hit by chips. I wonder if the chips would be enough to trigger it shattering?

You do the experiment and report back, okay.

Some crazy things I am willing to do but occasionally I find delegation a good approach.