Workholders - Hydra-Grip Arbors and Chucks

EXPANSION LIMITS Expanding or compressing metals under hydraulic pressure is accomplished by working within the tested elastic limits of the metals being used. The general rule for expansion is .003 for the first full inch of chucking diameter and .001 for each additional inch of diameter. The following table lists typical expansion limits but these may vary somewhat due to the many variable factors for each specific application.

Chucking Diameter Normal Expansion Limit Special Maximum Expansion Limit .250 .00075 .002 .500 .0015 .005 .750 .0022 .007 1,000 .003 .010 2,000 .004 .015 3,000 .005 .020

WORK HOLDING FORCE A.G. Davis - AA Gage hydraulically expanded arbors and chucks are custom engineered to embody the correct gripping force for each application. The gripping power may range from only a few pounds to several thousand pounds per square inch. They withstand rugged production operations--turning, hobbing, boring, grinding or "you name it"--and handle the most delicate inspection operations over long periods. NEED FOR GREATER ACCURACY Manufacturing tolerances throughout industry have been greatly reduced in recent years. In many instances conventional work holding devices are no longer capable of functioning within required production limits. In the manufacturing of precision parts the work or tool holding device must locate the part with consistent extreme accuracy so that the machine tools have the full benefit of the part tolerance. This must be accomplished without complicating the processing of machining operations whereby many non-critical part dimensions must be held to closer than necessary limits. It is illustrated in this web site how Davis hydraulic expanding arbors and chucks compensate for "intolerance" piece part variations such as size, taper, "bell-mouth", "out-of-round", etc. It is explained how concentricity, squareness, and parallelism tolerances are easily held even when chucking from surfaces whose allowable tolerance limits would make it impossible using conventional taper arbors, selective fit arbors or mechanical chucking devices.