On Thu, Feb 13, 2003 at 10:37:24AM -0800, [EMAIL PROTECTED] wrote: Hi Chris,
> I have little experience in 3D machining, so I would like to tap into > the knowledge base here. Though I am using Mastercam (gasp!) for this > 3D work, I still use Smartcam for most of our 2-1/2 axis work. I have little experience using Mastercam (zero, actually) so I can't help you there. > I roughed it out with an inserted end mill using planar cuts, > semi-finished it with a coated 1/2 ball end mill using a parallel > zig-zag tool path, and I am finishing it with an SGS Zcarb Tialn > coated 5mm ball em, also running a parallel zig-zag tool path, at a 45 > deg toolpath angle. > > The roughing and semi-finishing ops left about .020" stock. That's alot, in my experience. > I am running the SGS ball end mill at 6000 rpm and 20.0" feed for the > finishing passes, with the maximum step over set at .005" (slightly > less than .0002" maximum scallop height). That seems pretty slow, are you taking into account the effective cutting diameter when calculating your rates? > The finish is not bad, but I'm always on the look out for possible > improvements, both in cycle time and in finish. Polishers need to eat too, don't get carried away. <g> > -- How about using an inserted bull mill to make the finish passes > (can run much higher feed rate; about 75 to 100 IPM because of the > shallow finishing cuts -- only .020")? > > -- Do you have any suggestions as to which strategies are best for > "fine-finish" finishing? How much stock should be left in the roughing > passes? Which size and type end mills work best? Depending on the part geometry I'd most likely Semi to +0.007 with the 1/2 ball cutter, Finish with a 1/2 ball cutter, then finish pick corners with the 5mm ball cutter (perhaps Semi pick first, depending on how much material is left). I'm at home and don't have any formulae at hand, but Tialn coated solid carbide (the way to go) could probably be pushed to triple or quadruple your present rates (depending on your machine capabilities). Do you have HSM capabilities? You may be wasting money on the good tooling if you can't push it fast enough (Tialn needs to run hot). You want as smooth a motion as possible, eliminate engage / retract motions (stay in the cut as much as possible), insert radii to reduce rapid directional changes, use balanced tooling... -- Kelly D. Grills [EMAIL PROTECTED]
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