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 The two Star CNC sliding-headstock lathes operated by Reading-based contract machinist, Rodmatic, are able to mill-turn components of medium to high complexity as quickly as any of the 42 cam-type, six-spindle automatics on site, according to owner and managing director, Brian Steatham.
He also points out that the turned finish achieved using the Stars, mainly on stainless steel and steel components, is so good that subsequent grinding is frequently eliminated, lowering unit production cost significantly.
A multi-spindle auto takes around two days to reset, so batch sizes above 30,000-off are needed to justify the time investment. By contrast, sliding-head lathes can be set in a couple of hours, so much smaller runs are economic. Rodmatic has produced batches as low as 7-off on the Stars, although runs can be up to 5,000-off.
In this connection, Mr Steatham has the following tip for precision turned parts manufacturers: when producing larger batches on CNC sliding-head lathes, think of using form tools alongside single-point cutting tools to reduce cycle times. Rodmatic often does just that, using its experience of wire-eroding and grinding form tools for the multi’s and transferring the technology to the sliding-head machines. Dramatic reductions in cycle times are achieved, typically of around 30 per cent.
 One component regularly produced, a profile-turned and bored steel shaft for a European customer in the fluid power sector, is machined in part by form tools in an overall cycle of 37 seconds. This is over 38 per cent faster than the 60 seconds it used to take by exclusively single-point cutting.
The competitive advantage this gives Rodmatic has resulted in considerable business success at a time when many subcontractors are struggling. Whereas order intake for the multi’s was down by 20 per cent during the last quarter of 2008, the sliding-head lathes continued to work flat out during that period, 24 hours a day.
Since 2006, when Mr Steatham formed the company’s CNC division, Rodmatic Hytek, he has invested £1.5 million in new plant for turning, prismatic machining, wire erosion, tool grinding and component washing. He plans to continue investing at the rate of three to four CNC machines per year, the latest having been installed at the end of January 2009.
 £1.5 million of new orders received from two UK companies since the beginning of 2009, spread across multi and CNC work, gives credibility to Rodmatic’s investment plans. Around half of turnover currently comes from European companies, mainly in Germany, and this proportion is likely to increase, helped by the continuing strength of the Euro against Sterling. Another area of recent success has been in the UK autosport sector, with three new customers won in 2008.
Many of the new components are being put onto the Star sliding-head lathes, which are also regularly taking work from the multi’s as batch sizes fall. Tolerances of ± 2.5 microns are routinely held on the sliding-head machines, which would be very difficult to achieve on the multi’s.
Equipped with a four-metre bar magazine and high-pressure coolant to allow long periods of unattended running, the first Star was a 9-axis SV-32 of 32 mm bar capacity, installed mid 2007. It was followed in 2008 by a similarly equipped, 7-axis SR-20RIII for mill-turning parts up to 20 mm diameter. They joined three multi-axis CNC fixed-head lathes for producing larger components.
When asked why he did not continue down the route of fixed-head lathes to satisfy the market’s increasing demand for smaller size, high accuracy mill-turned parts in lower volumes, Mr Steatham says that in his opinion, a sliding-head lathe is twice as fast as an ‘equivalent’ fixed-head lathe, ie one with a counter spindle and two turrets containing driven tooling.
 “Major factors slowing fixed-head lathes are their inability to cut with more than two tools simultaneously, and long turret indexing times compared with the rapid infeed of gang and crossworking tools on sliding-head machines,” he suggests. He also likes the advanced mill-turning and simultaneous end-working capabilities of modern sliding-headstock lathes, as well as their traditional strength – that of producing shaft components accurately due to the support given by the guide bush at the point of cutting.
During machining trials against competitive sliding-head lathes, the Star machines were inherently faster. In addition, Mr Steatham felt that their extra weight and rigidity would allow the production of more accurate components. Rodmatic considers Star GB’s service to be good and is comfortable dealing with the supplier’s staff, both of which are regarded as important issues.
In a prediction that will encourage all involved with manufacturing in the UK, Mr Steatham thinks that it will start to emerge from recession before the end of 2009, ahead of the rest of the economy. Moreover, he believes that manufacturing has a brighter future now that the country is in need of value-added industries to replace the wealth formerly created by the banks.
He concluded, “The Pound has been artificially high against the Euro for a long time due to the apparent strength of the financial sector in the UK, but that is no longer the case.
“In fact it wasn’t for most of 2008, which is why we and many other UK-based suppliers have been winning business from Continental Europe and I expect the trend to continue. We are still seeing a lot of interest from the Eurozone.”
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