Workholding for Fast Changeovers

Workholding for Fast Changeovers

Zero point clamping system on a vertical machining center shuttle. Photo courtesy of BIG Kaiser
Zero point clamping system on a vertical machining center shuttle. Photo courtesy of BIG Kaiser Precision Tooling Inc.

Effective management of a machine workspace and workholding devices goes a long way toward efficient production and fast changeovers. Gerhard Vacio, Workholding Product Manager at BIG Kaiser Precision Tooling explained, “If you need a large number of workholding devices to produce your products, you need either to swap out workholding devices or add machine tables.

“However, duplicating machine tables requires large amounts of floor space and usually is cost prohibitive; although pallet pools on horizontal machining centers are an exception to this rule. For companies that cannot duplicate machine tables, it is desirable to have a workpiece handling system positioned and clamped in a way that allows for fast, accurate changeovers.”

Most companies choose to retrofit a quick-change positioning and clamping system to their machine table to facilitate changeovers. These workholding systems need to provide fast, accurate and rigid positioning and clamping. The most common quick changeover machine table setup systems are:
• Grid plates
• Zero-point clamping systems
• Shuttle tables (for vertical machining centers).

Grid plates provide a repetitive series of accurate bushing locations that accept positioning pins to locate workholding devices or workpieces. These positioning locations are intermixed with threaded locations that provide a way to attach clamps to hold the workpiece or workholding device with sufficient rigidity for the production process.

Zero-point clamping systems combine positioning and clamping into a single process. A retention knob with a geometric reference datum is appended to the workholding device or workpiece. The clamping process draws the retention knob into a ground reference that allows for simultaneous positioning and clamping. For small workspaces, a single retention location works well. Larger components can be held with multiple clamping locations.

Shuttle tables consist of a track mechanism that connects the machine table through a rail system to a table storage position. One workholding table can be shuttled out of the machine and a second table can be shuttled into the machine.

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