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Precision collet halves changeover times

Edited by the Manufacturingtalk editorial team Jun 3, 2003

A precision collet chuck used on a multi-axis CNC lathe has halved changeover times and boosted overall machining efficiency at a manufacturer of precious metal findings, stampings and mounts.

A Hainbuch Lexon precision collet chuck used on a new multi-axis CNC lathe has halved changeover times and boosted overall machining efficiency at Slimbrand, one of the UK's leading manufacturers and stockists of precious metal findings, stampings, cast ring mounts and stone settings.

The purchase of the cost-competitive Lexon 52 mm collet chuck from award-winning workholding specialist Leader Chuck Systems has optimised workholding operations and reduced changeover times by more than 50 per cent on the Mazak Integrex 100Y CNC lathe installed at the company's Hockley (Birmingham) site.

As CNC technician Gary Law explains: "We selected the Lexon chuck since it was considered the best workholding system for our type of work.

Production on this machine is mainly centred on turning four main styles of wedding ring blanks from cast gold tube.

"The chuck's accuracy is superb, it provides excellent gripping rigidity and is very quick to change, particularly because of the Manu-Quick quick-change manual collet changing gun.

We may have to handle up to 12 different jobs in a day, so rapid changeover is a key issue - and with the Lexon this takes just seconds." Designed as an accurate and economical replacement for multi-bore and other styles of collet chuck in bar-fed turning applications, the Hainbuch Lexon chuck has radial serration grooves which provide 30 per cent more gripping power than other multi-bore systems.

Two chuck sizes are available from Leader Chuck Systems for maximum bar diameters of 52mm and 65mm and A5 and A6 spindle noses.

Slimbrand is using a range of collet clamping heads that will handle round bar from 4 mm up to 38mm outside diameter.

With its new found integrated milling capability, Slimbrand can now produce various types of wedding ring blanks in a one-hit cycle.

As well as turning ring profiles such as 'flat', 'D-shape', 'court' and 'comfort flat', the lathe is also used to mill small round or square pockets (from 1 mm to 6 mm) to locate gem stones.

Wedding ring blanks are produced from 9/18 ct yellow gold and 18 ct white or red in sizes from 'g' up to 'z' (around 14mm to 22mm ID).

These are machined from round gold tube in batches which can be as high as 3,000-5,000 off, although one-offs may also be required.

Some body-type jewellery products are also machined on the Integrex (like beads, spikes and cones) and this can involve drilling and tapping small holes down to around 1 mm diameter as well as turning.

"Tolerance is not the major issue on these gold components," adds Gary Law, "as surface finish and weight are the prime considerations.

However, some of the high carat golds we machine do not chip form that readily, so secure and rigid workholding is also a high priority.

"Whether we are turning and/or milling wedding ring blanks or elements for body jewellery, the Lexon chuck has more than met our requirements and has also enabled us to machine some jobs at higher speeds than previously possible.".