Sure-Grip Expanding Collet

Expanding collets and between center arbors (mandrels) grip the internal diameter of a part for turning, milling, grinding, assembly, inspection and automation applications. Hardinge Workholding Div.'s Sure-Grip Expanding Collet Systems have design features that provide durability for long production runs with superior surface finishes and fast collet changeover from the front.

Hardinge patented Sure-Grip Expanding Collet Systems are a one-piece body design that use exact-size, through-hardened collet heads that will interchange with all assembly sizes from machine to machine. The collet heads have an under-over capacity of -.001" to .015" (-.025mm to .38mm) from its specified size to accommodate a range of part diameters. Other brands of expanding collet systems use soft, machineable collet heads that require extra time to machine to size, are not durable for long production runs and are not keyed for repeatability. Hardinge through-hardened collets are keyed for accurate part positioning for repeatable performance.

The Hardinge double-angle design offers parallel gripping. Parallel gripping means that the collet expands equally the entire length of the collet rather than just at one end of the collet, providing maximum bearing contact against the part. This results in greater stability and better part accuracy. Parts are instantly centered and located without adjustment. Higher rpm and greater feed rates provide the ability to produce more parts-per-hour. The Hardinge Sure-Grip Collet System also features a built-in safety stop to prevent the collet from over-expanding.

During chucking operations, parts can be located against the face of the arbor or against a machineable workstop. This provides exact part-length control as well as improved part consistency. The expanding collet draws the part firmly against the stop, producing an extremely stable part location. Longer parts can be easily machined due to this added stability. The results are heavier cuts, better surface finishes and closer tolerances when using a workstop. Short grip lengths can be firmly held when the part is pulled back against a workstop. When machining just the OD of the part, workstops may not be necessary.

Machines or devices with ANSI type-A spindles and machines with collet-ready spindles or collet adapters can use the Hardinge system. 5C, 16C and 3J collet-style expanding collet systems mount directly into the collet angle of the spindle or in fixtures (collet blocks) with instant centering. There are no spindle adapters required. A2-5, A2-6 and A2-8 expanding collet systems will mount directly on the spindle. Hardinge also manufactures center arbors that use Sure-Grip Expanding Collets for grinding machines, lathes and other applications that can be held between centers, or chucked on one end and supported by a center on the other end.

There are several instances where an expanding collet can shorten cycle time, reduce waste, or simply hold a hard-to-grip part. An expanding collet may eliminate the expense of manufacturing a custom fixture or collet, or eliminate secondary machining. An expanding collet will grip a thin-wall part without crushing or distortion and prevent damage to threaded outside diameters. The patented design of the Hardinge Sure-Grip Expanding Collet System with thru-hardened collet heads outperforms others on the market in terms of durability, functionality and value. Custom-manufactured solutions are available.