Feeds and Speeds for cutting Polycarbonate

[Rob B]

Can someone give me some starting points for SFM and chip per tooth when cutting polycarbonate's. I using a face cutter to cut face, then al other tools will be coated carbide endmills.

Thanks

Rob

[Guest SAIPEM]

Safe starting Point:

 

500 FPM Cutting Speed For Carbide Tooling

 

850-875 FPM for Indexable Insert Tooling

 

0.006 Chip Load per Tooth for Rough and Facing Ops

0.003 Chip Load per Tooth for Finishing

 

Use Water Soluable Coolant

 

Flame Polish for clear finish

[Rob B]

Saipem

Thanks,

Don't understand the flame polish????

Can you explain a little futher.

[bogusmill]

Yes, please explain. I've tried it before and couldn't get a good result. Melted corners, wavy part surface, etc. I also heard of vapor polish, but vapor of what? MEK?

[Jedi Lone Star X]

cool! i have also heard of this but never tried it. i am wondering how to apply this "flame polish".

 

-R.

[camgeneration]

just a note of caution against coolant, one coolant at a place i used to work hurt the polycarbonite. we did not notice at first, but problems latter with cracking and loss of strength made us investigate. we soaked some pieces in pure coolant of 2 different types, one did nothing to it, the other came out totally spider web cracking and brittle. might want to check with your coolant manufacturer about compability.

[MACHINEMASTERG]

i like sharp hss tool for polycarbs you can wipe pvc/abs cleaner on the edge to polish it

[Keith Graydon]

Really SHARP tool. Dont let chips pack, ever.

We use Blazocut soluble oil for coolant. No problems.

Fire polishing is a method used to smooth machined edges of acrylic and polycarbonate. Use a torch, Bernzomatic propane type is fine. Use a soft flame and play it aginst the machined edge. It will melt the surface of the material and leave a very smooth and shiny finish.

 

You will also ruin many parts untill you master the technique.

-Keith

 

most often i just use a soft cotton buffing wheel with Tripoli compound.

[Bruce Kanzelmeyer]

You can also put Weldon 3 or 4 or MEK on a clean white shop towel or cotton cloth and wipe the edges of machined polycarb for polished edge (slightly easier on the lungs than vapor polishing). Keep the cloth pretty wet. I've never had good success flame polishing polycarb myself.

[#Rekd™]

Hi,

 

Sharp HSS tools, single point flycutters, with wd40 or light oil and polish with brasso!

 

John

[New Job]

+1 on SHARP HSS!

[LaszloK]

We do a lot of flame polishing on molded polycarbonate. We use a hand help propane torch and just pass the flame over the area to polish. It will melt and soften if you do not move the flame around. We use it to eliminate "hit" marks that result from match molding the polycarbonate. We never use coolant of any kind since the polycarbonate will absorb moisture.

[bhyde]

I have, in my distant past, used methylene chloride to vapor polish polycarb. Boil it and hold the part over it. It works pretty well...The room has to be well ventilated and also, we did this in a box similar to a sand blast cabinet. Toxic to be sure. I would probably not do this again. Young and dumb.- go figure.

Also, I have had success in conventional milling the last profile passes (finish). Drilling...Ah...Slow spindle and high feedrates,..Plenty of chip clearance once retracting from the hole. I have heard of, but not tried to use Ronson lighter fluid? I think that is the stuff...I won't actually vouch for it...But have read that somewhere before..

 

 

Bill

[Guest SAIPEM]

Laslok -

 

Moisture is an issue in the MANUFACTURING of polycarbonate, not the machining of it.

 

Moisture introduced during the manufacture of polycarbonate will result in fractured material

 

Molding polycarb is using a semi-raw material.

The heat of molding and the catalysts for curing create the "finished" state material.

 

Introducing moisture during this process will produce defective material.

 

Machining polycarb is using a finished piece of material that has already been normalized.

 

You can not damage the molecular structure of polycarbonate by machining it with a water-soluable coolant.