Keep the pressure on

Schunk says that any workholding devices deployed in 5-axis machining should be compact and sturdy, and yet allow plenty of room for the workpiece and for unimpeded access to the working spindles. The firm's compact centric-clamping device Kontec KSK meets all these criteria, having a large clamping range, and can be used for a rough part clamping and as precision toolholder – centering accuracy is 0.02 mm. Kontec KSK is claimed the world's first completely encapsulated centric clamping device. It offers a modular jaw change system, so that a variety of workpiece sizes and geometries can be clamped. Kontec KSC accommodates conventional clamping, small clamping depths, moulded parts, plates or workpieces with saw cuts. It has a construction that makes it possible to design high supporting jaws, allowing all sides of the workpiece to be reached – even with standard tools – at a clamping force of up to 35 kN. Another powerful all-rounder for 5-axis machining (of round workpieces) is the stationary manual Rota-S plus chuck from Schunk. Having reversing top jaws, the unit can be switched rapidly from OD to ID clamping, covering a wide clamping range with the same top jaws. The quick-change jaw system shortens the time for a complete jaw change to just one minute. Image: Schunk says that 5-axis clamping devices should be compact The Rota-S plus has high repeat accuracy of 0.02 mm, so that turned, soft jaw sets can be used over and over again. Like the Kontec clamping modules, the 3-jaw chuck Rota-S plus can be combined with the quick-change Unilock pallet system. Continuing the 5-axis theme is the new double-concentric Quadrok clamping vice from Hainbuch. The capacity of Quadrok is 250 by 250 mm, and users can choose between five different clamping functions: vice; concentric; double-vice; concentric and vice; or double-concentric clamping function. Image: Hainbuch's Quadrok supports five different clamping functions Kurt Manufacturing (Carillon Industrial Services) has introduced workholding kits for trunnion fixture rotary tables. With this, users can add clamping stations and increase vertical machining centre productivity. The kits include a four-sided column with eight clamping stations that provide repeatable clamping to 5 micron. Using this Kurt workholding system adds a fourth indexing axis to 3-axis vertical machining centres. Replicating the eight clamping stations of a vice tower system, this rotating workholding set-up is designed to reduce part set-up time, while increasing machining speeds. In terms of power-operated workholding vices, new to the market is the high capacity VE125LWN from Kitagawa that features a compact, low-profile design with three levels of clamping force, and a jaw stroke of up to 405 mm for production versatility. Close manufacturing tolerances ensure that individual vices in the range have a maximum height variation of 20 micron for consistent set-ups and manufacturing consistency. SMALL CLAMP OFFERS GOOD ACCESS Roemheld has introduced a mini hinge clamp that enables jig designers to incorporate hydraulic clamping into areas tight on space. This low-cost, compact, hydraulic-clamping element is suitable for thin-walled components that need to be clamped in areas of reduced space. The kinematics of the clamp's design enable clamping without side loads. As well as enabling a variety of mounting positions, this offers protection against deformation, and unimpeded loading and unloading of components. Moving to rotating workholding and Hainbuch's new Toplus chuck has a hexagonal core made of cast resin to make it lighter than steel chucks and thus offer a much lower inertia. The resin also has a positive dampening effect, which is useful when hard turning as it prevents component ringing. Instead of the supporting taper in a normal chuck body, the principle of Toplus is based on six angled steel plates that are cast in the resin to form the chuck taper. To match this, the clamping head also has six flat outer surfaces, which mate exactly with the surfaces of the chuck. It does not matter if the chuck is open or closed, the clamping taper is completely sealed. Because of the reduced surface pressure and the full surface contact of the clamping segments, the radial clamping force of Toplus is a full 25 per cent higher than other chucks, claims Hainbuch. Elsewhere, Kitagawa's new NV chuck range has been developed to meet the demand for large vertical lathe power chucks. Produced in eight models for components from 62 to 1,000 mm diameter, NV series units feature a protective jaw cover and scraper system that prevents the ingress of swarf or coolant into the chuck mechanism. In a concurrent development, the new Kitagawa BBT208 2-jaw chuck features a 66 mm through-hole and is suited to machining irregular shaped workpieces at up to 5,000 rpm, while the company has also released an updated version of the company's DL 200 chuck that features an innovative two-stage gripping action. In operation, the jaws initially clamp in a radial direction before pulling the workpiece back for seating confirmation. Another range of chucks new to the UK is the Bison range, available through agent 1st MTA. The Bison brand of units includes a variety of manual self-centring and power chucks, manufactured to ISO 9000-quality standards to ensure performance over extended production runs. Image: The Bison brand (1st MTA) includes a variety of manual self-centring and power chucks Box Item 70th anniversary celebrations Workholding and machining specialist Brown & Holmes is celebrating 70 years since its inception in 1939. "As a company, we have survived a world war and two recessions, and even in these challenging times, we are maintaining our workforce levels," says current co-director Kevin Ward, who started as an apprentice at the company in the 1970s. "We remain focused on offering our customers the right workholding solutions for their needs, on-time and within budget, whether they require an off-the-shelf product or a bespoke solution." Brown & Holmes was started by two draughtsmen from Coventry, Mr W Brown and Mr C Holmes. Today, the firm specialises in the supply of standard and semi-standard CNC cubes and tombstones, test rigs, jigs and fixtures, special machines and gauges. The company also offers precision machining and complex assembly work for the automotive, aerospace, oil and power generation industries, and is the UK agent for Forkardt workholding, standard and special rotary power chucks, expanding mandrels and steady rest packages. First published in Machinery, November 2009