A UK sliding headstock turning specialist has replaced its last operating cam automatic lathe with a CNC sliding headstock machine - bought straight from the catalogue.
Sliding headstock turning specialist, Auto Screw Products, doubled its shop floor area in April 2005 by expanding into an adjacent unit on the East Gillibrands Industrial Estate in Skelmersdale, UK. It was the latest initiative by the new owner, Mike Worsley, who bought the 35 year old company in April 2003. Since buying the company, he has been replacing the company's single-spindle cam automatics with CNC sliding headstock lathes from Star Micronics GB, of which there are currently eight on site working unmanned 24h a day, seven days a week.

The last cam auto was replaced by the latest Star, an SR-32J, which was bought 'sight-unseen' from the catalogue, such is the subcontractor's confidence in this supplier.

The first Star machine the company purchased was an SH-12 - an early model that was relatively simple to operate.

To extract maximum benefit from the seven subsequent CNC lathes, which have a sub-spindle and a large number of tools, many driven, for in-cycle front-, cross- and back-working, the company was heavily dependent on help and advice from the supplier, especially at the outset.

Assistance with applications engineering and programming has been readily available from the Star team in Melbourne, Derbyshire, according to Worsley, who also confirms that after-sales service is prompt and the few problems that have arisen have been solved quickly.

He says that the supplier's positive approach and overall willingness to 'hand-hold' have been key to Auto Screw's continuing purchase of Star machines.

Worsley cited an instance of a drawing that he faxed over to Star, whose engineers responded within 30 minutes with the advice that an extended nose collet would allow the awkward part to be turned.

The relevant collet was supplied straight away from stock to allow production to start the following day.

Components are machined in mild and stainless steels, titanium, brass and aluminium, batch size normally being in the range 200,000 down to 100-off.

Most parts need back endworking and/or driven tool operations and none requires manual handling onto another machine for one or more subsequent operations.

A big advantage with modern CNC sliders such as the Stars when dealing with smaller runs is the ability to reset the lathes in less than an hour if it is a repeat job, or a little longer for a new component.

A cam auto takes up to a day to reset, resulting in much lower machine availability and consequently higher unit production costs, which are in any case elevated by the frequent need for second operations.

Auto Screw regularly achieves 150h production time per week from its Star lathes out of a total of 168h, equating to 89% availability.

Worsley suggests that cam auto shops in the UK are in decline, as long runs are needed to make them economical, but these have mostly gone overseas.

However, if UK subcontractors invest in CNC lathes, fixed- or sliding-head, their greater reliability coupled with better component consistency and accuracy resulting from one-hit machining can win even long runs back.

He mentioned a contract for 350,000-off gearbox parts that was recently awarded to Auto Screw by a German car manufacturer owing to poor component quality and long lead times from a Malaysian subcontractor.

The arguments for replacing cam autos with CNC sliders are compelling, says Worsley.

In his own subcontract business, elimination of second operations and introduction of long periods of unattended running on the Stars have allowed the headcount to be cut from 17 to seven in two years.

At the same time, turnover has risen 50% due to increased output and higher added-value production.

These factors have improved profitability.

People that talk of the demise of UK manufacturing may take heart from Auto Screw's experience.

In Spring 2005, there was enough work to occupy all eight Star lathes and the volume of enquiries was rising rapidly.