Getting more work done in one setup is the goal of various capabilities for machining centers and lathes. Some machining centers, for example, permit high speed machining—taking fast, light cuts to bring the part closer to its final surface finish at the machine. And some CNC lathes offer live tooling capability to let the machine perform milling and drilling in addition to the turning operations. In both cases, the payoff for the higher-end capability comes from doing away with the handling necessary for some downstream operation to perform additional work on the part.
However, in some applications, that downstream operation may not be demanding enough to merit the added capability on the machine. Instead, enabling the machine to do just a little bit more would be enough to eliminate the extra stop. In place of higher-end capability, a lower-cost accessory may be able to do the job.
One such accessory is the "Mini-Mac" air-powered spindle from Macro Technologies, Inc. (Kirkland, Washington). Two different designs for the spindle allow it to be mounted on a lathe's turret or slide (like an add-on live-tool spindle) or mounted in a machining center's toolholder. In either case, the spindle is capable of 30,000 rpm. When driven by an 80-psig shop air supply, the spindle can deliver 75 W of cutting power.
What can you do with a 75 W spindle? Obviously, you can't take heavy cuts. Even so, Macro has seen the spindle applied effectively in a variety of applications. It can drill small holes, for example. It can be used for engraving. It can mill plastics, aluminum and brass. And a mold or die maker can use it on a machining center to perform CNC polishing. One way to accomplish this is to have the spindle rotate a polishing tool at high speed while the machining center drives it back along the tool paths used for finish milling.
The spindle costs about $600. It can hold tools up to 3/16 inch in diameter, but the company says the best results come from tools 1/8 inch or smaller. The spindle requires an air supply in the range of 40 to 80 psig. The unit features a single hose for both air inlet and outlet.
According to company vice president Ed Huncovsky, the next step in the development of this unit is to offer a version that's toolchanger-friendly. That product, which features a quick-disconnect link to the air supply, is being developed now, he says. When it becomes available, the product will make it possible to use the air-powered spindle in unattended machining applications.