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ABS Plastic?


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12 replies to this topic

#1
CNC PRO

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I am supposed to machine some 29"x17.25" x1"frames, using 1/4"Flat ABS plastic.
I am in the woodowrking industry, so I don't have a whole lot of experience with plastics, although I ran this job before, I didn't get very good results, so this time I figured I would ask the experts first.

I used a Down sprial 7/16" Solid Carbide Endmill, tried verying feeds and speeds...between 200-350 ipm, and 16000-18000rpm

Due to how narrow the parts are, one problem became apparent was material hold down at higher feeds, although I seemed to get better cuts.

Another problem was that the plastic that was already cut would melt right behind the cutter (could be due to the down spiral not cleaning out the chips enough...reason I used down spiral was to lessen the chance of material lift off -should note that I am using a flat bed Router with vacume for hold down on top of a MDF spoilboard)

Any knowledge shared on how to machine this would be greatly appreciated.

I Thank you in advance.

#2
Trevor Bailey

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you have to use some kind of air cooling. i would also suggest HSS end mills as they have a sharper edge than carbide.

the down cut should be OK. if perimeter or channel cutting, try a ramping type toolpath. you do not want to plunge that material, especially if you have no cooling element available.

other than that, pretty basic stuff to cut.

#3
KalCam

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You can also try cutting a deep channel at the trim edge to give those chips a place to go. I usually seal the mdf anywhere that is not needed to hold down the plastic. Also add o-rings, after that its almost impossible to lift the material off with the vacuum on.

#4
CNC PRO

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Thanks Trevor, I'll check into the endmill you suggested.
Air cooling...I hadn't thought of that.

Thank you

#5
CNC PRO

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Thanks KalCam

#6
Matthew Hajicekā„¢ -Midland Tech

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In my experience when using a router on ABS you need to turn the RPM down and/or the feedrate up. That will help reduce the melting. Getting the chips out efficiently will help too.

#7
JohnW@M.I.P.

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I cut .220 ABS using a single "O" flute 1/4" cutting tool. Ramp entry, and feeds are typically in the 150 - 200 ipm range, 12,000 - 15,000 RPM. We sometimes run one job behind another, so I'm holding the newer part over grooves cut by the previous part, which is ok most of the time if they're larger parts. If the parts start moving around on me, I'll resurface the spoil board. If your spoil board is clean and smooth and it still tries to move around, use tabs.

#8
Jay Kramer @ Precision Programming

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I usually cut between 200 and 300 with RPM around 7000 to 9000. I hold it down with 3M double sided tape after cooking for 10 hours then flatten the plastic with a shell mill or fly cutter.

#9
k turk

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a little late in the game, but john's single flute cutter is good advice. i've also used double sided tape to avoid tabs on small parts and it is very effective if you have the right tape.

k

#10
NEW2007

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One yr ago i did same job ,I took 3/8" finisher(slow spiral) 200ipm. Keep one side two pass(first pass 1/32 material remain).Sigle flute spiral bit is good ,but never good on that router(i dont know why).On my new company, it's very good.


Eric P

#11
NEW2007

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Down spiral bit is not good chice.Cut all outside and three inside (leave one inside, two pass)all through one pass.Cut slot along the norrow frame on spoil board,it will hold the piece.up-spirl bit will lift the piece,my experience is up-slow spiral bit.


Eric P

#12
LancoUSA

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Also Using MAsking to cut to on the router works well too. THat way it gives you .005" or so before you break into your MDF and start loosing Vacuum.

#13
JParis

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Posted 02 December 2008 - 04:35 PM



:geek:

lol