Quick-change chuck speeds changeovers

Capable of fast changeovers, a collet chuck has a runout accuracy of only five microns and is a replacement for other styles of collet chucks in bar-fed turning applications.

The speed of changeover, and accuracy and reliability, of the Hainbuch Lexon collet chuck from Leader Chuck Systems were the prime reasons why ATC specified the chuck when it invested in a Nakamura-Tome WT150 seven-axis turning centre as part of its continual investment programme.

Capable of fast changeovers, Lexon has a runout accuracy of only five microns and is designed as an economical replacement for multi-bore and other styles of collet chucks in bar-fed turning applications.

It boasts 30 per cent more gripping power than multi-bore systems, so allows faster machining speeds and feeds and therefore generates reduced cycle times.

In addition, its extra rigidity promotes increased tool life and improved surface finishes compared with other bar-fed lathe chucks.

As a specialist producer of components in medical grade stainless, titanium and cobalt chrome, for example, primarily to the medical and aerospace sectors, ATC's 5,750 (metres squared) site at Redhill, Surrey, houses an impressive portfolio of high-tech production equipment.

"We always like to keep up-to-date with the latest machining technology," explained sales director William Sanders.

"That way we stay ahead of the competition in terms of our ability to consistently produce cost-effective and high-quality parts.

In addition to sliding head lathes incorporating thread whirling and milling, as well as gun drilling, the company's turning section also features fixed head lathes, and it was to maintain the highest performance standards in this section - "And particularly our ability to produce complex turn-mill components in a single setting from multi-spindle, twin turret machines" commented Sanders - that the Nakamura-Tome was installed.

Capable of handling bar of 51mm, the Nakamura-Tome WT150 supplied by Mills Manufacturing Technology boasts main and sub-spindle speeds both of 5,000 rev/min (15kW on main spindle; 11kW on sub-spindle), and two by 12-station tool turrets.

It is a seven-axis machine, with C-axis on both spindles and y axis on the top turret.

Maximum turning diameter is 190mm and maximum turning length is 400mm.

A 65mm Lexon chuck was specified for the machine, said Sanders, primarily because of the fast changeovers possible with the system - in some cases just 6s compared with the traditional 15 minutes.

"In addition to acknowledging that the reliability and accuracy of Hainbuch collet chucks are essential to our business, the fact that we have other Hainbuch systems in use on our fixed-head lathes also means that we want to standardise on our chucking as much as possible," he added.

In addition to their accuracy and quick-change features Hainbuch collet chucks, which will accommodate workpieces up to 500mm diameter, also differ from standard chucks in being able to securely hold short component lengths due to the positive pull-back and clamping action - the clamping head being pulled into a perfectly mating taper.

Established in 1951 initially designing and manufacturing tooling packages for the business machine market, ATC gradually began supplying components to the aerospace/defence and general industrial sectors.

During the early 1990s it moved into the medical/orthopaedic sector which today accounts for 80 per cent of turnover.

ATC produces a wide range of components, from facial cheek bone screws a few millimetres long, to spinal/bone screws and large femur bone plates, all machined to micron accuracies and surface finishes.

The majority of this work is exported.

Supplying the major medical OEMs, William Sanders says that apart from price, the successful supply of medical components depends on consistent high-quality parts delivered on time, every time.

In addition to a plethora of bar feeds and round-the-clock working, ATC's policy of staying ahead of the game also naturally focuses on its machining capabilities.

"That's why we continually review our processes and are always looking to install the best equipment available," he concluded.

"We invest to stay the best.

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