Overgrip collets, which are also referred to as over-the-shoulder collets, are used on a pick-off spindle when it is required to clear a shoulder and grip on a smaller diameter beyond. (A screw is a good example of this type of part.) In collaboration with Citizen Machinery Tech Center, managed by Bob Meunier, Hardinge has developed and now manufactures standard TF-25 OG overgrip collets for Cincom M20 and L20 lathes. Extra spread is required to open the collet wide enough to go over the screw head or larger diameter. Hardinge's collet design incorporates teardrop slots and reduced wall thickness for maximum flexibility for the overgrip pick-off process. A double-angle taper reduces the contact surface, which provides for quick opening of the collet.
Hardinge hardened and ground collets provide high accuracy and repeatability with precision in the collet back bearing and concentricity at the gripping area. Order holes are finish-ground on a high-precision Tripet internal grinding machine. A semi-finished stock program is in place at Hardinge to provide a quick turnaround from time of order.
Marubeni Citizen-Cincom is a leading manufacturer of Swiss-type turning centers. These machines are used extensively to manufacture an array of products, including medical instruments, electronics, fiber optics, automobiles, business machines, aerospace, defense, firearms, tools, valves, fasteners, and many others. Citizen Machinery America has partnered with Hardinge in their quest to develop solutions that will increase productivity and throughput in the Swiss turning industry.
"Our mission is to provide innovative tooling ideas and creative machining solutions to existing Citizen machine owners as well as new machine buyers", states Jim Cepican, General Manager of Citizen's Tooling and Accessories Division. Citizen Machinery America offers Cool Blaster high-pressure coolant systems, custom tool holders, thread whirling attachments and adaptive guide bushing spindles designed to provide reduced cycle time, improved tool life and increase throughput.
"We leave the collets and guide bushings to the experts. Hardinge has been in the business for over one hundred years and they have a proven reputation for long-lasting, high quality products that the medical and aerospace demands," says Jim. "The overgrip pickoff collet is one way of expanding or enhancing our machine's capability. We are extremely pleased with the quick turnaround on the prototype that totally met our specs the first time out the door. The Hardinge workholding group is highly-tuned to the industry and very attentive to our needs."
The Cincom M20 and L20 Swiss Turning Centers have extra stroke built into their sub-spindle to accommodate an over grip collet with a maximum recessed part diameter (extra spread requirements) of up to 3mm. Hardinge manufactures headstock collets, pickoff collets and carbide guide bushings for all Citizen machines.
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