There’s good reason why subspindle-equipped turning centers, particularly Swiss-type lathes, are so popular for small, complex parts produced in high volumes. However, there’s also good reason for the prefix “sub.” Automatic part hand-off for backworking operations isn’t viable without secure gripping, and the smaller, already-machined portion of the work presented to the subspindle tends to create more challenges than the raw barstock gripped in the main spindle. As a result, subspindles can be limited when it comes to blind-hole broaching, heavy peck drilling and other processes that risk pushing a part off-kilter or damaging it.
However, the right workholding can break down these barriers, says Matt Saccomanno, CEO of Masa Tool (Oceanside, California). Founded in the wake of Mr. Saccomanno’s own frustration with secondary operations and underutilization of subpsindles, Masa Tool offers the Microconic system, an alternative to traditional, extended-nose collet designs that applies force closer to the part for greater rigidity and concentricity—advantages that extend to main-spindle operations as well. Another benefit is the ability to adjust clamping pressure at the spindle nose to grip securely without damaging small, fragile workpieces. On the efficiency front, a collet in one size can be swapped for another without reaching anywhere beyond the spindle nose, and any collet can fit multiple draw-type or push-type machine collet closers. This saves time and eliminates the need for different collet series for different machines. Finally, overgrip models that expand 0.157 inch (4 mm) beyond the clamping diameter enable reaching over and gripping the part behind large-diameter areas.
In some cases, yes. Like many machine shops, Beistel Machining of Donora, Pennsylvania, tries to overcome the difficulty with finding experienced machining employees by hiring promising inexperienced candidates who can learn on the job. In addition, shop owner Brent Beistel tries to go even farther than this, engineering systems that allow for the job shop’s high variety of work while still enabling inexperienced employees to carry out critical steps effectively and on their own.
The photos above show an example. Mr. Beistel developed a work positioning device for CMM inspection that is quickly and easily adaptable to different part numbers. As the photos show, a single fixture includes holes for the locating stops for various part numbers. The user simply has to place pegs in all of the holes corresponding to the part in need of inspection—information engraved into the fixture itself. With these pegs in place, the part will be positioned correctly for the inspection routine for that particular part. Thus, the same work positioning device can remain in place on the CMM table as various different part numbers are being run, and an inexperienced operator can effectively “set up” the CMM for inspecting a new part. He or she simply inserts the pegs, positions the work using those pegs, and calls up the CMM program for that part.
Time’s almost up. Modern Machine Shop’s seventh-annual Top Shops benchmarking survey is still open, but only through the end of this month. You have until February 28 to complete the survey, which identifies optimal shopfloor practices as well as operational and business metrics that define world-class machine shop competitiveness.
Posted by: Derek Korn 15. February 2017
Posted by: Stephanie Hendrixson 14. February 2017
The Additive Manufacturing Conference returns to Knoxville, Tennessee, for its 2017 edition, happening October 10-12. This annual event focuses on industrial applications of additive technologies for making function components and end-use production parts.
Past presentation topics have included application success stories, materials, design, postprocessing, production via AM and much more. (For highlights from the most recent conference, see this series of articles and our interview series on YouTube.)