Roger Innes of Inro says that he has based his company's rapid growth over the last three years mainly on the purchase of Japanese-built Star CNC lathes through A and S Precision

In 1988, six years after it started life in a proverbial garden shed in East London, subcontractor INRO moved to a factory unit producing stainless steel fasteners for such prestigious projects as the QE2, Channel Tunnel and Canary Wharf. Today it operates from 12,000 sq ft premises in Chingford and uses, amongst other plant, seven Star sliding-headstock lathes for producing not only specialist fixings and fasteners for the construction industry, but also precision turned parts for the leisure, defence, ironmongery and safety equipment industries. Founder and senior partner, Roger Innes, says that he has based his company's rapid growth over the last three years mainly on the purchase of these Japanese-built Star CNC lathes through A and S Precision, Melbourne, Derbyshire.

He says that he now benefits from second operations 'for free', and whilst strictly speaking there is no such thing as a free machining cycle, it is certainly true that he has limited the number of additional staff recruited and gained an edge over his conventionally-equipped competitors.

'We bought the first machine, an SR-20, in 1997 and found that its round-the-clock productivity allowed us to replace four Petermann cam automatics, which were operated over a single, 8-hour shift.

Moreover it still left one week's spare capacity every month,' says Roger.

'If they were operated for a single shift on weekdays only, the Star machines would pay for themselves over a three-year finance period.

But we run them 24 hours a day, five, six or even seven days a week according to workload, so even while we're paying for the machines, everything over 40 hours is profit.' Taking out four cam-type machines freed up space in the factory for two more Star lathes.

It is not difficult to see from these space and productivity figures that output per square metre of shop floor is increased approximately four fold, so a company in INRO's position can quadruple the size of its business before having to move to larger premises.

The other main benefit of Star lathes is the plethora of tools which they can deploy to turn and prismatically machine both the front and reverse end of even very complicated components in one set-up, a significant proportion of the respective cycles being performed simultaneously.

A massive 95 per cent of INRO's work needs backworking so the benefits are clear.

Further analysis of the company's production reveals that up to 30 per cent of parts require milling and significantly more need drilling.

The second set-up and extra handling which is invariably needed with parts produced on cam auto's translates into higher manufacturing cost per part, whereas these operations are incorporated into the Star cycles.

Within the first three months of operating the Star SR-20, Roger Innes and his production team recognised the sea change that modern CNC sliding-head technology could make to a turned parts manufacturing organisation.

So at the MACH 98 exhibition a year later it was not a question of whether to invest in more machines, but which make of machine to choose.

Patently it was beneficial to opt again for Star, but INRO was such a short way into its investment programme that a change of vendor would have been easy.

Continued Roger, 'We spent the whole of the show researching all the major sliding-head lathe suppliers in detail.

The prime reason for selecting Star machines was the high build quality.

In our experience, if a machine looks as though it will do the job, it normally does.

'When we walked around to the back of some lathes, it was amazing how many had cables and hoses hanging out.

Even cleaning round machines like that can be hazardous.

The Star lathes on the other hand were well finished.

If they pay attention to detail in this area, it is a good indication that they do so in other areas as well.

We are also impressed with the performance of FMB full length bar magazines and have had them fitted by A and S to all our machines.' Roger left it until the very end of the show to order the 8-axis CNC Star SV-20 and 6-axis SR-20R which were on the A and S Precision stand, taking delivery of them directly from Birmingham.

INRO has since installed a further SV-20, an SR-32 for producing components from 32 mm diameter bar, and most recently (June 2000) two SA-16s fed by FMB Minimags with bar up to 16 mm diameter.

Whilst Star machines are operated unattended for long periods by many users, INRO has now adopted a policy of running its machines over two manned, 12-hour shifts.

Two operators supervise all seven machines and reset them when necessary during the day or night, giving more flexibility for the production of smaller batch sizes.

Furthermore, a machine can be restarted straight away at any time should there be a stoppage.

Customers order anything from 500- to 20,000-off per month from INRO, so these are the spread of batch sizes produced at the Chingford factory.

Bar diameters down to 3 mm are fed into the 20 mm capacity lathes from the FMB Turbo 3-20 magazines, the wide range of material sizes which may be handled being a particular benefit of this German equipment.

Stainless steel still accounts for 80 per cent of throughput, the majority of the remainder being steel, brass and aluminium.

General tolerance is ñ 0.05 mm although the tightest held is 0.02 mm total.

(Some Star users report holding 6 microns).

Programming is said to be straightforward.

Roger's son Nigel, for example, was originally trained at Chingford on a Star SR-20 for three days by an A and S engineer.

Nigel never looked back, despite having had no programming experience on any CNC machine tool before.

When the more complex SV-20 was installed, it was no problem for him or the other operators.

Most programs are currently prepared on the Fanuc 16-T control at the machines although an off-line programming facility is currently being set up.

Cycle times currently vary from three minutes for an interpolated stainless steel component to around 12 seconds for simpler parts.