Machining ABS

[Guest]

I’m doing a 49 x 19 pocket ¼ deep in ABS. I might have to do 100-200 parts. Does anybody have any good information on machining this. I need a recommended tool type and speeds and feed for it. Thanks in advance.

[Keith Graydon]

Marc,

Use SHARP,SHARP tools.

Flood the cut with coolant.

Pocket "inside to outside" so that the material being cut is allways supoorted by the surrounding material. Sometimes this cant be done so make sure that any small projections that need to be removed dont get snapped of by the cutter. This will leave a small crater underneath the (former) projection.

Drilling might require a small peck size. DO NOT left stringy chips wrap up on the drill bit. They will ball-up and melt the area surrounding the hole.

Cut it as fast as you like if you can get the chips to eject.

HTH

-KLG

[Carl Vallance]

Use high speed tools 2 flute. For 1/2 inch dia I use speed of 425 fpm and chip load of .003. Listen to Keith this is good advice.

[Trevor Bailey]

Hey Marc,

My question is, how are you going to hold these parts? 49 x 19 is hughe. I cut a lot of ABS. One of our forum members gave me some good advice on holding parts like this. "Primer" the back of your part and then glue it to the holding surface. Amazing enough, there will be very little sanding where you put the glue and the primer comes off with a "cleaning" thinner. Or if you have a big vaccum plate, that would be the alternative. The point being here, you can drive the tools fast & hard, but watch out for small stems left behind or knocked off by the cutter as they will leave a crater. I use only a constant stream of high pressure air to blast the chips out and keep the part cool. The other thing to worry about, is do not let the chips wrap around any of your tools. As mentioned earlier, they will melt.

[ 10-24-2001: Message edited by: Trevor ]

[BernieT]

quote:

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One of our forum members gave me some good advice on holding parts like this.

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Also consider using 'double-back' tape to hold your parts to the table. We use a lot of 'double-back' tape here to hold aluminum blocks to the mill table. You can easily flycut .020 at a time off a 6" x6" block 1/2" to 2" thick that has been taped down with just two 3/4" strips.

[McRae]

How dimensionally stable is ABS? UHMW will creep over time and from this experience, I now let parts sit between roughing and finishing operations. If there are features that allow, I love to bolt parts thru themselves. This keeps any distortion from clamping to an absolute minimum.

MfgEng

[Scott Bond]

Hi Marc_Lindsey

When I cut a material that is not familiar to me ,I call the manufacture of that material and they always have a suggested speed, feed chart available,also (not related to machining but to the ABS) for molding plastics wall thickness min/max,drafts,pressures heating cooling, curing,and trouble shooting at the press booklets .and so on

[Trevor Bailey]

The only reason I did not suggest doubl-back tape, is that when cutting a lot, such as the pre-described pocket, the abs will heat up and move with the tape. The air line helps, but not a 100% all the time. Therefore using glue workd better. Also, with the tape, you will not be able to use coolant if you choose.

[bhyde]

I have in my experience use low spindle speeds and high feeds on drilling abs....That is mainly the material I am used to cutting for models. I do use double back tape and have also used an acid for plugging some of the inevitable "oops" factors for this material when needed.

[Guest]

Everybody:

Thanks for the information.