Pragmatism and attention to detail when devising methods for workpiece clamping have boosted production efficiency at International Safety Components (ISC) to the point where manufacturing costs at the Bangor factory are comparable with those in the Far East.
Applications engineer Regan Irwin, who is responsible for the work-holding arrangements for the company’s lathes and machining centres, said: “The 1st Machine Tool Accessories Web site is one of the first I visit when buying new vices and other clamping equipment. In the last couple of years, we have invested in 10 of their Chick System 5 Qwik-Lok work-holding systems. They are used on our machining centres — alongside 15 Qwik-Loks of an earlier design — to secure complex parts in soft jaws machined for specific applications. This avoids having to use costly bespoke fixtures.
“Earlier this year, we bought a Chick One-Lok from 1st MTA for our tool-room. This lighter work-holding device is easier to move on and off a machining-centre table — and it is much quicker to adjust than our conventional vices. We also make good use of other 1st MTA products, including Mitee Bite knife edge clamps for gripping plate to allow skimming during the machining process. We also use the same manufacturer’s Pitbull fixture clamps, which can grip firmly on just 3mm of material, reducing the billet size and saving money for any given job. Indeed, they allow us to use a 16mm-diameter tipped end mill to take cuts up to 7mm wide and 9mm deep from the edge of a 7075 aluminium block.”
Expansion collets and ID expansion clamps for work holding in vices and fixture plates, plus Kitagawa 6in and 8in three-jaw chucks for turning centres, are among other products from Salisbury-based 1st MTA
(www.1mta.com) that are in regular use in the Bangor factory.
Safety first
ISC is the leading UK manufacturer and exporter of industrial ‘working at height’ safety products used in climbing, rigging and rescue in over 25 countries. The company manufactures more than 250,000 karabiners a year, as well as pulleys, harness buckles, rope back-up devices and many other complex products that are characterised by a wide variety of sizes and materials used. The latter include 7075-T6 and 6082-T6 aluminium, EN1A-L, EN8-DN, EN19T and Hitenspeed steels, stainless steels (303, 304, 316, 17-4PH and Duplex) and 10% aluminium-bronze.
It is the combination of complexity and tough materials that has resulted in the wide adoption of US-made Chick clamping systems across the shopfloor at ISC. Indeed, Mr Irwin says the latest Qwik-Lok System 5 incorporates design changes that improve the rigidity, speed and repeatability of clamping. Stainless-steel anvils rather than aluminium ones secure quick-release jaws, which no long-er need a dowel to be tapped through to complete the process. Jaw change is many times faster than was previously possible, thereby shortening set-up time, minimising machine idle time and maximising production output.
A pull-down action as the jaws are wound shut ensures security of work holding. Moreover, the dual-station clamping units squeeze the two moveable jaws from either end against a central fixed jaw to cancel the opposing forces, resulting in even pressure and repeatable work holding.
Either one clamping station or both can be used to secure components. ISC machines aluminium jaws to match the often complex shapes of components, several of which can be held simultaneously in each vice. Multiple workpiece clamping shortens floor-to-floor time per component and minimises tool changes during a batch run.
Heavy operations
The rigidity with which parts are secured allows heavier cuts to be taken than would normally be possible using conventional work-holding practices. Cycle times are therefore shorter, and productivity is raised. Furthermore, the high accuracy that is achievable allows ISC to easily hold the tolerances — 20µm on hole diameters and 0.1mm for position — specified on most of its drawings.
For some applications requiring longer production runs, Mr Irwin has made special sizes of zero-point steel fixture plates that clamp over both anvils on a Chick Qwik-Lok, in place of the jaws. A high degree of repeatability is achieved; and by having two plates — one on the machine and one being set up — large batches are completed with little spindle down-time (1st MTA supplies standard sizes of foundation plates to provide similar pallet-style quick-change flexibility).
ISC’s tool-room at Bangor is where jigs and fixtures are produced for presses and metal-cutting machines on site, as well as for product assembly. Metals from aluminium to tool steel are routinely machined. In this department, which doubles as a prototyping facility for new-product development, the Chick One-Lok from 1st MTA provides the work-holding capability for a Haas vertical machining centre.
Unlike traditional machine vices that require dozens of turns of the operating handle between fully opened and closed, One-Lok features a fast-acting adjustment mechanism that allows the moveable jaw to be unlocked and slid quickly close to the component, after which a few turns of the handle secure it.
Ken Williams, one of ISC’s tool makers, says: “The problem with our older vices is that the moveable jaw tends to lift when clamping a part. In contrast, the One-Lok’s pull-down action holds the component firmly, allowing me to take heavier cuts without risk of the part moving in the jaws.
“Another benefit is the hinged handle, which allows me to open and close the jaws faster during the non-clamping part of the traverse when the One-Lok is mounted across the machine table, rather than from front to back. A handle fixed at 90deg would interfere with the table and would need to be adjusted on each turn.”