Workholding: Secured by suction: General Industry Coverage

For those who’ve dismissed vacuum workholding as too inflexible or risky to securely grip workpieces that would otherwise be difficult to hold, it’s time to reconsider.

Lance Nelson, president of 2L Inc., Hudson, Mass., noted there are far more vacuum-workholding choices available than in recent years, largely because shops are trying to avoid using custom fixtures. The company has addressed this need with a series of replaceable top plates, which, according to Nelson, protect the surface of the vacuum chuck when machining through a workpiece. They cost about $200 each.

This also addresses one of the main criticisms of vacuum workholding: its inability to grip parts smaller than 3″ (76.2mm) on a side. Mounting edge clamps and similar tooling directly to an aluminum top plate, Nelson said, allows the plate to act as a quick-change fixture suitable for holding the smallest workpieces.

Vacuum chucks can be set up directly on the machine table or, as in this case, placed
in conventional vises for fast changeovers. Image courtesy of 2L.

Nelson added: “We recommend sharp, slow-helix cutters, preferably with a flute angle of 20° or less to reduce lifting and sideway forces. Lighter feed rates and depths of cut are best, especially with smaller parts, where the amount of gripping force is limited. Despite this, vacuum chucks remain an easy and affordable way to hold a variety of workpieces.”

IBAG North America, North Haven, Conn., also has its eye on small-part vacuum workholding. President Bill Popoli said the Witte small-parts chuck IBAG offers features a slotted aluminum plate and a mating plastic pad. Vacuum holes are cut in the pad to match the underside of part locations, which hold the workpieces in place while they are machined, usually from a sheet of workpiece material sitting on the pad.

Flip-Pods are another novel approach to vacuum workholding, although they’re generally not used for small parts. Originally made of plastic and designed for the furniture industry to grip components during routing, Flip-Pods have been redesigned for greater accuracy and load capability, and now consist of a round aluminum body surrounded by a suction cup.

By placing many of these devices on a modular vacuum plate, even large workpieces, such as aircraft wings, can be gripped securely without distortion.