Power Workholding Product Design Information

Learn the ins-and-outs of Carr Lane Roemheld Power Workholding Products within this technical information section. Learn about Roemheld operating pressure, machining operations & fixture layout, making proper clamping force calculations, estimating clamping time, work supporting, manifold mounting, plumbing options, when to use a single-acting or double-acting clamp & more. It’s all below in our Power Workholding Technical Information section.

Although most Roemheld Power Workholding components operate comfortably and safely at up to 7500 psi, we recommend selecting a standard "design pressure" of 5000-6000 psi for workholding fixtures.

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Single-acting clamps are ideal for many clamping systems. Single-acting components are simpler and slightly less expensive to install, because they require fewer fluid lines and have simpler controls. In addition, Roemheld clamps are designed with faster, more-reliable spring returns than those of any other manufacturer, so the need for double-acting clamps is not very obvious. Beginning users can usually get excellent results using only single-acting clamps.

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To increase the effectiveness and efficiency of a workholder, use locators to resist most machining forces, rather than relying only on clamping force. Using smaller, less-expensive clamps is usually possible if the workpiece is correctly located and the locators properly designed.

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Clamping-force calculations can be quite complicated. Sometimes an approximate method is good enough. See table below for how much clamping force is available from manual clamp straps of various sizes (with a 2-to-1 clamping-force ratio) to compare with power-clamp forces.

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Work supports, unlike clamps, do not actually exert force on a workpiece. Instead, after adjusting to the location of the workpiece, work supports lock in place and essentially become fixed supports, or rests.

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Clamps with locking support plungers exert relatively little clamping force, but provide a high support force in the opposite direction. They are particularly suitable for clamping thin-walled workpieces with minimum deformation, as well as for floating clamping. Applying fluid pressure advances the piston, which simultaneously expands like a work support to lock inside the cylinder body.

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Supplying fluid to hydraulic fixtures is not merely an afterthought. Fluid supply is an integral part of fixture design. The following Swing Clamp fixtures illustrate four distinct plumbing concepts.

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Many Roemheld Power Workholding components can be manifold mounted ... powered directly through fluid passages drilled in a fixture. This unique mounting capability eliminates tubing and hoses in the working area, for clean fixtures without chip traps. Even fluid passages longer than your drilling capacity are possible by drilling shorter passages in separate blocks, then connecting them using connecting inserts.

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Due to increased use of coolants and cutting fluids in metal-cutting machining, there is also an increased danger that some very aggressive fluids penetrate into the spring areas of single-acting clamping elements and work supports, causing malfunctions.

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Hydraulic clamping is usually fast, but not instantaneous. To estimate clamping time, consider the two phases of clamping: Extending time, under low-pressure free flow, and Pressure-building time.

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The basis of hydraulic clamping systems is "Pascal's Law", which says that if pressure is applied to a static fluid that is completely enclosed, that pressure is transmitted equally in all directions.

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