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Manual clamping comes of age

Supplier: Romheld Automation
02 May, 2006

Manual clamping technologies now bridge the gap between powered and traditional manual workholding fixtures meaning that more shops can benefit from reduced set-up times and increased productivity.

Typically, powered workholding fixtures are used only in shops with very high production volumes, in other words, those where the job can justify it.   Everyone else then had to settle for manual clamping which relies heavily on the operator to put all the clamp components into position and secure them with a wrench or other special tools.

Not only is this inefficient, but also prone to operator error which can lead to expensive damage to machines, fixtures and workpieces, not to mention the lost time in recovery.

Recent manual clamping developments and product releases have vastly improved flexibility, performance and payback for the machine shops looking to stay one step ahead of the competition.

One-Touch Clamps

With the recent release of a new clamping system from Imao of Japan, a high-tech clamping solution to manually operated fixtures is now possible. So called "One-Touch" clamps because they incorporate a clamp handle that requires only a partial turn to operate due to the clever internal design.

Fixtures built with One-Touch clamps are about one third the price of hydraulically powered fixtures, whereas they will be approximately 3 times faster to set-up than conventional manually clamped fixture. One-Touch clamps are available in both standard and heavy duty types, standard for light machining of alloy components and heavy duty for heavy cutting of cast iron and steel workpieces. 

The range includes push and pull clamps, swing clamps and side clamps all with the option of a low-cost adjustable torque handle to provide consistent clamp force up to 8 kN.

Computer Aided Fixturing (CAF)

And Imao has taken things even one step further with the release of computer aided fixturing (CAF) software which was developed in conjunction with leading machine tool makers. CAF and CAM add-in software programs are available which allow inexperienced machinists to create accurate NC programs. Set-up times are reduced through the combined use of standard fixture components and CAF/CAM programs.

Simple and Ingenious Devices

Another development in manual fixture location and clamping is the use of simple, yet ingenious devices which are purpose designed for their task. For instance, OK-Vise produces a range of wedge type manual clamps which are operated with a hex-key to secure single or multiple parts and produce clamping forces up to 60 kN. They can easily be designed into purpose built workholding fixtures and tombstones etc for a reliable and low cost clamping solution (see photo).

Lateral spring pins from WPR System act as locators and/or clamping devices. Typically just a few dollars each, these clever devices incorporate a spring loaded contact pin which generates a lateral force to effectively pre-locate heavy or difficult parts prior to clamping. In some light machining operations (drilling, tapping etc) the spring pin itself can provide enough clamping force and no tools are required as the workpiece is simply ‘snapped’ into position.

Chucks and Vices

'Manok' is a flexible, manual chucking system from Hainbuch of Germany which incorporates a quick change system to convert from a collet chuck into a jaw chuck, or even into an expanding mandrel. Combined with its high precision, extremely high clamping force and anti-vibration features this chuck can be permanently mounted on the machine table and actuation is via an integrated hand lever. The Manok system provides extreme flexibility and short set-up times for shops where workholding requirements constantly change from internal (mandrel) to external (collet or jaws) clamping.

The ‘MultiChuck’ from Leader Chucks offers a manual concentric clamping system for horizontal and vertical machining that incorporates rapid clamping and short set-up times. A simple top face operation enables more chucks, and therefore workpieces, to be banked close together in either 2-jaw or 3-jaw configurations and combines a fast initial jaw travel with controlled second stage clamping to provide a large jaw opening with high clamping force. The low profile design maximizes the machine z-axis and reduces the potential for tool interference.

Precision machine vices have long been a mainstay for manual clamping of prismatic parts and these days, machine vices are available in a variety of types to meet the most demanding clamping requirements. For instance, Hilma GmbH produces both mechanical and hydro-vices for single parts or multiple parts, via floating central jaws. The tower clamping system incorporates a number of vices arranged on tombstones to provide long unmanned operation where multiple parts are being processed. Clamping is fast and accurate and a quick jaw change option can further reduce set-up times.

Standard and Modular Clamping Components

Completing the transformation of manual clamping techniques is the availability of standard and modular, off-the-shelf, fixture components which offer a quick and economical workholding solution, plus the added benefit that components can be re-cycled and re-used once the job is complete. Manual work supports provide a counter to vibration and enable bigger cuts during the machining process. Virtually all the parts required to manufacture a fixture, including risers, supports, contact bolts, jacks, stops and clamps can be selected from standard products.

A Profitable Investment

Today's machine shops are increasingly deploying the highest technology CNCs available to provide that much needed competitive edge. This usually means a very high capital investment in the machine and cutting tools, however the critical aspect of workholding is often overlooked.

It is now possible to match workholding technology with the machine technology to provide fast, reliable and economical manual clamping solutions that ensure maximum return from the investment.

Romheld Australia is a specialist distributor of precision workholding, clamping and tooling equipment for CNCs throughout Australia and New Zealand.