Workholding product review: 5-Axis Machining

Euro-style collets for U.S. market

HARDINGE GROUP, Elmira, N.Y., (www.hardinge.com) manufactures solid collets, master collets and pads, solid feed fingers and master feed fingers and pads for Euroturn, Gildemeister, INDEX and Schütte multispindle machines, with 24-hour shipping of standard fractional and whole metric sizes. Decimal metric sizes and products for other machine builders are available for 5- to 7-day delivery. Hardinge has a semifinished blank program for pickoff burring collets and special-shape collets.

According to Hardinge, shops should match the collet size (order hole) exactly to the workpiece or bar stock diameter. “If you use inch bar stock, you should use fractional collets—not metric,” said Rick Schonher, Hardinge workholding product manager. Few metric sizes have a direct fractional equivalent. Metric collets for metric bar stock, fractional collets for inch bar stock and decimal collets for decimal bar stock will provide the best results, according to Schonher.

If the shop is using a ¼” bar stock with a 6mm collet, it could experience push-back, chatter or poor concentricity because the collet is smaller than the bar stock.

“Most operators don’t realize the ramifications of such a small variance in diameter,” Schonher said. “If the collet order hole is larger than the workpiece or bar stock, the part may pivot at the line of contact at the face of the collet. If the collet order hole is smaller than the workpiece or bar stock, the edges of the slots will bite into the workpiece and may damage the bar. When the collet is the proper size for the workpiece or bar stock, there is a full bearing along the angle and the circumference of each segment of the collet where they mate with the spindle angle (seat).”

Tilting rotary table works with multiple workholders

KOMA PRECISION INC., East Windsor, Conn., (www.komaprecision.com) distributes Tsudakoma’s RTT-111, CA, a high-speed, drop-trunnion, tilting rotary table that can use multiple workholding systems. The table is now equipped to utilize more systems, including system 3R and Erowa chuck and pallet systems, Northfield’s 5C collet closer and 2-jaw and 3-jaw chucks, and Hirschmann’s chuck and pallet system. The RTT-111, CA can also be used with a standard faceplate. The rotary table, with its pallet system, allows for five-sided access to the part when 5-axis machining. Vises, chucks and clamps limit access to the part, thus decreasing process efficiency, according to the company. Because the table rotates on center, shorter tools and less spindle travel are required. The pallet system creates a lower profile than parts held with conventional workholding, thus increasing rigidity.