Force-Limiting Step Chuck

Hardinge Inc. (Elmira, NY) has engineered force control into 16C and 20C step chucks to prevent crushing or distorting thin-wall parts during turning and grinding operations.

Hardinge Inc. (Elmira, NY) has engineered force control into 16C and 20C step chucks to prevent crushing or distorting thin-wall parts during turning and grinding operations. The concept incorporates a unique spring-loaded design as the primary closing mechanism. The lathe closer will bottom out before the spring system reaches its solid height.

The chuck’s features and benefits make it an ideal replacement for the standard power chuck when turning large or small diameter, delicate or thin-wall parts. The lathe operator will have better control over the cutting process while reducing scrap and maintaining part specifications. Excessive grip force on a delicate or thin-wall part can easily distort or crush a part so that when it is released it will not hold the concentricity.

Similarly, an out of round shape cannot be held and the shape maintained when an excessive gripping force is applied. The force-limiting step chuck assembly adjusts the grip while eliminating the nuisance of manually tweaking the draw bar force.

The actuation of the system is force independent from the machine draw bar. It can be operated at normal pressure—eliminating any loss of closing cycle time associated with a low pressure setting.

The chuck can be used for small diameter parts, such as a connector, to avoid crushing and distortion. Custom shapes can be engineered for holding non-round parts. Chucks are hardened and ground and ordered to size according to each individual application. Threads are heat-treated and the body is spring-tempered to assure accuracy and durability for long life. Applications include gripping thin-wall tubing, pipe, castings, housings, and soft or delicate materials that cannot withstand standard chucking methods.