Need Help Fast!!! CNC machining PP/polypropylene

[Alicia]

I am trying to cut fairly complex parts out of polypropylene (PP) using a CNC machining center...I need to get this done ASAP, but I've never machined PP before. I have two main problems; if you can help answer either/both I would greatly appreciate it!!

1)
I know PP has a tendency to melt and gum up on cutting tools, so I need to figure out what cutting parameters to use in order to avoid this problem.

Specifically, I need to know:
spindle speed, feed rate, and maximum cutting depth

From reading previous posts, I've gathered that the spindle speed should be around 15k-18k rpm and that the feed rate should be set "high"...I'm looking for more specific values since I can't afford to waste material or break any tools.

2)
My intentions are to use the DeskProto 3D CAM software package to convert the CAD model of the part into G Code that can be uploaded into the CNC machining center. The CAD model was made using Pro/Engineer. The machine was manufactured in 1998 by Fadal Engineering (Model #914-15) and is old enough that it only accepts floppy disks.

I've heard that DeskProto does not have the capability of writing code that this specific machine can read (mainly for lines in the code specifying feed rates, tool changes, etc). Does anyone know a quick and easy way to convert the Pro/E file to G code that will work with this particular machine?

[genchopetkoff]

Dear Alicia,

Pro/E has a very good CAM part. It is in Pro/Manufacturing mode. There You can generate the NC code programme. The problem is, that if you have not used before it is a little "heavy".
But you can import the Pro/E solid model in any CAM package and to make the NC there. Try with the original ".prt" file first. If it does not work, use the old good ".igs" format.
About the cutting conditions:
The rule is: For soft materials as PP use only new sharp tools and depends of your machine, high "RPM" and high "F".
I do not recomend 12k-15k, because the material will become melted and possible burned. Use not more than 4k-5k with a proper feedrate

[DareBee]

I agree.

The last PVC parts I ran - I did at 1500 SFM and .006 chipload, in my Fadal