Two mill/turn centres have been installed at a UK subcontractor, for 'round-the-clock' complete machining of high quality hose and pipe fittings' components from bar in 'one hit'.

Two Traub mill-turning centres from Geo Kingsbury have been installed at the Totnes works of subcontractor, Vire Engineering, for round-the-clock machining of components from bar in a single visit to the machine. Work is regularly carried out for the defence and security industries, but a majority of production is high quality hose and pipe fittings for brake, fuel, oil and coolant assemblies used in motorsport, from Clubman up to Formula One. There are around 2,500 different fittings produced in batches of between 50- and 2,000-off from stainless steel, mild steel, titanium and aluminium, most having a hose attachment at one end and a coupling or banjo union at the other.

Large stocks of standard parts are held to provide the next-day delivery that customers demand.

Explained Vire's owner and managing director, Jan Vincent: 'In early 2001 we decided to take cost out of manufacturing these parts, many of which are price sensitive, by supplementing plugboard automatics on the shop floor with a suitably equipped CNC lathe for 'lights-out' production.

Although it proved successful, the machine did not have driven tooling or a sub spindle and so components still needed to undergo second and sometimes third operations.

'So two years later we opted to cut production costs further by choosing a Traub TNK36 mill-turn centre fitted with an Iemca bar magazine for single-hit production of parts up to 36mm diameter, 24 hours a day.' Impressed by the performance of the twin-spindle TNK machine and with business growing rapidly, Vire went back to Geo Kingsbury for a smaller Traub TNL12K with FMB Minimag bar magazine, which was installed at the end of 2004.

Most components of 16mm diameter and under were transferred to this machine, which is also well equipped with driven tooling and a counter spindle and has the added capability of a head that travels 50mm into and out of the cutting zone.

This endows the lathe with some of the advantages of a sliding-headstock design, but without the guide bush.

Indeed, both Traub lathes look like sliders at first glance, with their mix of platen and turret tooling.

Vire wanted to avoid sliding-headstock lathes, however, as the company felt that they would not be able to machine bright drawn hexagonal bar efficiently, which is essential for the production of motorsport components.

Turning supervisor at the Totnes works, Tim Woodward, commented, 'Most lathes with similar capacities and capabilities to the Traub TNK and TNL models are physically larger, which means they have heavier machine elements and slower movements, resulting in longer chip-to-chip times and hence lower productivity.

Despite their compact size, the German-built machines are nevertheless solidly constructed.

This translates into higher accuracy machining, which in any case is helped greatly by not having to reclamp components on the Traubs.

One-hit machining also reduces handling damage, helps to keep track of jobs more effectively and allows us to confirm faster deliveries of non-stock items with greater precision.' Woodward went on to describe some of the savings being made.

One 316 stainless steel part previously produced in 7.5 minutes on two machines, including handling, now takes 1.5 minutes on the TNL12K, for example.

On the same machine a mild steel banjo bolt is produced complete in 33 seconds, whereas before it took 50 seconds just to turn it, followed by 90 seconds for manual facing on a capstan lathe, cross hole drilling on a mill and duburring.

A banjo union previously required 90 seconds on a CNC lathe followed by 55 seconds on a plugboard lathe.

By contrast, the finished component now comes off the TNK 36 in the same time that the second op used to take.

Almost all parts put on the Traubs need back end working, even if it is just a simple facing-off operation, and the driven tool capability is used in about 50 per cent of cases.

Rigid machine build allows efficient milling of flats from round bar using carbide cutters.

In one case, Woodward stretches the capabilities of the TNL12K by machining a 9/16in AF nut from 16.25mm round bar, a facility that is very useful as it is a popular size.

The TNK36 benefits additionally from 40 bar through tool coolant, allowing tools up to 10 times diameter to be used.

Whereas deep hole drilling on another lathe used to take 3.5 minutes per hole and the high speed steel drill lasted for only 35 components, a carbide twist drill on the TNK36 recently completed the job in 6.5 seconds and the cutter was still sharp after the batch of 200-off was complete.

Both Traub lathes operate 24/7 except Christmas day and New Year's day and were producing components for 80.69% of the time during 2004, although machine availability was much higher.

Shorter components and those that do not need tip changes or where sister tooling is available are reserved for night and weekend work, minimising 'out-of-hours' visits for retooling and bar replenishment.

An auto dialler has been fitted to both lathes, wired into the flashing light circuit, so that the operator on call is alerted immediately by mobile telephone if either machine stops.

Concluded Vincent, 'UK manufacturing is under threat as never before from overseas subcontractors in low wage countries, but installing automated, highly capable machines like the Traubs is one way to fight back.

If a machine works unattended for a large proportion of the time, it does not matter so much whether it is in India, China or the UK, as the labour cost differential is much smaller.

UK manufacturing has a bright future if it takes advantage of automation and plays to its strengths, which include a base of highly skilled engineers - rather more difficult to find in Totnes than elsewhere, unfortunately - and well developed logistics for quick and reliable deliveries, without customers having to wait six weeks for goods to be shipped half way around the world.'