Machining Phenolic

[noel]

Hi, does anyone have any tips on machining Phenolic.  We are using a CNC thermwood machine.

My main question is what tooling and techniques is best thru HSM.  Right now I am cutting the parts at 200 in/min 1200 Spindle Speed.

I am cutting 5/16, 3/8 and 1/2" thick.  

My results are:  Finish on the material is ok, on the 1/2", I did a multi cut, twice with a speed of 100, this came out best.

I am not really familiar with tool, so if you have any suggestion on the I would greatly appreciate it.

My parts are also coming out fat, I know I can change the stock to leave, but without me making the model smaller, what suggestion do you have to have the items come out correctly.

thanks

[tperson56]

You don't really give enough information with what you are using for tooling and what you are trying to achieve; with that said...

Phenolic is nasty abrasive stuff, you need to use very sharp positive rake tooling, DO NOT use coolant as it turns the dust into an abrasive paste. Once your tool begins to get dull you will have to replace it, a good indicator of a dull tool is heat in part/tool or puffs of smoke when cutting material. You will go through multiple tools if your doing anything of quantity. You need to be fairly aggressive with your step overs or it won't cut...just rub. I would say never take less than 0.007" stepover even on a finish pass. 

Is it actually Phenolic or is it G10/FR4 material? Phenolic isn't widely used these days. For G10/FR4 material I have had good luck using a fish scale cutter for finishing passes...even then the material is very burry and you will spend a good deal of time cleaning it up.

Post up more about what your setup is and what tooling you are using and we might be able to help more