Cutting models from 20mm thick Polypropylene problems - CNCzone.com-The Largest Machinist Community on the net!

blasttiod · #1 01-24-2010, 12:11 PM

Hi all to this great forums,
I am trying to cut 20mm thick Polypropylene on my CNC. I'm using a 2 fltued cutter running at about 28000rpm. The problem I'm is that the Polypropylene is melting and clogging the cutter as it cuts and the finished model is all rough and not smooth edges.

Where am I going wrong ?

Is it the cutter/ Speed ?

Regards
Kevin

student1616 · #2 01-30-2010, 08:17 AM

i did this before.
u need to work on speed and feed.its melting and sticking to tool means your feed is very low bcz of which tool is rubbing against the job and generating heat.
lower the spindle speed(15-18K) and increase the feed.
take a scrap sheet and do all the experiments on it.best way is trial and error.

ger21 · #3 01-30-2010, 08:19 AM

How big is the tool? And what feedrate are you using? More than likely, the 28,000 rpm is much too high.

blasttiod · #4 01-30-2010, 07:50 PM

Thanks for the suggestions so far.
I have since tried a single fluted upcut cutter and its working fine and leaving a good cut. The only thing is, because its single flute the finish isn't as smooth as I want. I am now looking for a twin fluted cutter to try. I am having problems locating a supplier here in New Zealand. Well one who is selling at a relistic price !!!!

Regards
Kevin

blasttiod · #5 02-08-2010, 03:57 AM

Cutting HDPE

Hi all,
Things have improved. I am now cutting at higher feed rates and its a lot better.
The only thing is now is the surface finish. Does anyone now how I can get a better finish. At the moment its quite ripply where the cutters been. I have tried doing the cutting then doing a final fine cut but this isnt making much difference.

Regards

jalessi · #6 02-08-2010, 04:39 AM

Blasttiod,

Have you tried a downcut end mill?

Jeff...

blasttiod · #7 02-08-2010, 06:23 PM

Hi Jeff,

A downcut endmill won't be any good. I doing 2 x cuts to get through the 20mm HDPE.

Regards
Kevin

ger21 · #8 02-09-2010, 10:58 AM

Ripples are usually either due to spindle runout, or a lack of rigidity in the machine.

blasttiod · #9 02-09-2010, 07:10 PM

Hi All,

Just found out why I'm getting these issues.
I have the routers Gcode set to climb milling and not conventional !!!

Regards
Kevin

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