On Saturday 05 September 2009, Youda He wrote: >Thanks, I am planning to cut aluminum, not the hard type, I can take when >cutting, so maybe I'll cut slowly, what stepper is recommended? How big >should it be? > >-- Youda
Be aware that _any_ alu will have a coat of alu oxide on it, thickness dependent on how long exposed to the air, and 1/1000 of a second is sufficient to form a 50 volt thick film. alu is a _very_ reactive element in the presence of the oxygen in the air. Generally for a machining operation, this coating is responsible for 99% of the wear & dulling, even on carbide tooling since alu oxide is the 2nd hardest substance in nature. There are some harder formulations between there and diamond, but neither of us can afford them, too new. You can't do anything about the surface of the raw material, but when machining, the surface should be well flooded by some relatively oxygen free fluid which will cover the cutting edge, and the freshly cut surface as quickly as possible. 2 schools of thought here, compete for how you do it. Either assumes the cut will be as deep as the spindle has power to do as that removes the unwanted material with fewer miles on the cutting edge. One is to cut an oil flooded surface very slowly so that the turning bit can remain wetted immediately behind the cutting edge, slowing the formation of the oxide. Water is comparatively useless for this as its 1/3rd oxygen. How fast you can turn the bit depends on how deep the flooding is. The other, and more commonly used method is to flood the area with a high pressure mist of oil, so everything is wet and cut as quickly as the machine has the power to do it. Again the idea is to get the job done with the least wear on the cutting edge as it plows through this rapidly forming coat of alu oxide. This will often give a better final finish as the high pressure blows away the chips so they won't get trapped by the next cutting edge and mark the surface as the chip then skids a bit before its recut again. All this needs to be taken into consideration when planning an alu machining operation. Dry, with high pressure air to clear the chips can work quite well, but its also pretty hard on the tooling, so you'll need to almost start each such part with a fresh cutting tool in the spindle. Not conducive to high profit margins. And since when am I the resident metallurgist here? I'm just an old (75 a month from now) retired television engineer. :) This gentleman Youda is obviously just getting his feet wet with this stuff, and there is a veritable encyclopedia of knowledge available on this list. In this crowd, I am _not_ a guru. So pipe right up with the stuff I'm missing guys. >On Fri, Sep 4, 2009 at 11:19 PM, Gene Heskett <gene.hesk...@gmail.com>wrote: [...] -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) The NRA is offering FREE Associate memberships to anyone who wants them. <https://www.nrahq.org/nrabonus/accept-membership.asp> petribar: Any sun-bleached prehistoric candy that has been sitting in the window of a vending machine too long. -- Rich Hall, "Sniglets" ------------------------------------------------------------------------------ Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
