cutters not lasting when cutting mdf

[edmond]

Hi All

I am cutting a lot of these dinosaur skeleton models out of 3mm MDF using a 3mm Belin upspiral 1 flute O flute cutter on my Lionclaw LC50 cnc router but the cutters dont seem to last.

I am using a feedrate of about 47ipm and rpm around 15000 but the cutters only are good for cutting about 8 models per cutter before the cutter starts turning black on the bottom and leaving a horrible fuzzy burr on the top surface of the mdf this happens gradually with the edge finish slowly getting worse until the cutter starts leaving burn marks on the edge

These cutters are expensive equal to about $40 here in South Africa I have tried using normal 2 flute 3mm straight router bits with a 1/4" shank but they break although they leave a decent finish with no big fuzzy burr

Any help guys?

Thanks in advance

[Geof]

Are the cutters HSS or carbide. MDF can be very abrasive so HSS cutters may not last long.

This could be exacerbated because you are spinning fast and feeding relatively slowly, your cutter is doing a lot of rubbing.

Even though it seems counter-intuitive you may get better cutter life and higher output by dropping the speed and at the same time boosting the feed.

[edmond]

Geof the cutters are solid carbide been done the HSS route already
The reason I spin at 15000 rpm is to keep the ryobi router that I am using as a spindle cool I think its lowest rpm is 10000 rpm
I probably cant increase the feed much more maybe to about 60 ipm.
If I go with 60 ipm what rpm would be suitable could i stick with the 15000rpm

Thanks

[Geof]

I cannot recommend specific speeds and feeds. Try dropping the speed to 10,000 and boosting the speed to your maximum and see if you get better tool life.

[edmond]

thanks will try that when i cut again

[ger21]

I cut at 125ipm and 10,000 rpm. Your going to slow.

[Pplug]

Hey ger,
How deep are you cutting with this speed and feed?

Originally Posted by ger21 I cut at 125ipm and 10,000 rpm. Your going to slow.

[ger21]

You should be able to cut the full 3mm depth with no problems. I misread your first post, I thought you were using a 6mm cutter. You should still cut at 125ipm, but you might want to up the rpm a little.

[edmond]

I cant go that fast the machine has some serious X leadscrew whip so I limit the max rapid and feed to about 70 ipm I dont think it would be rigid enough to cut that fast anyway only using 3mm pitch leadscrews because its all I could find here in SA
When I cut again(only on the weekend) im gonna try up the feed to about 60 -65ipm I know its still slow but thats about all I can get and drop the rpm to the min setting on the router

Would 2 flute slot drill work better with the slower feed?

Thanks for the advice guys

[jsheerin]

No, for more flutes you need a faster feed.

I have the same issue - MDF dulls my carbide bits somewhat quickly, but I get decent life out of them and can get them resharpened for $8 each (as opposed to ~$40 for a new bit). I currently cut at 120ipm, ~16.5k rpm because of router limitations with a 2 flute 1/2" bit at 1/8" depth of cut. I should be going faster, but this setup is all I can do for the moment, and my cutter is staying much cooler than it was before when I was feeding slower and cutting deeper.

[wildwestpat]

Hi

Also keep the cutter on the move if engaged with the MDF or send clear of the work. MDF has a fluffy surface and burns easily.

Regards

Pat

[underthetire]

Try Ti-Ni coating on the cutters. A place in Florida used to do them cheap. Increased our tool life by 80%.