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Machine tool supplier's applications engineers helped a subcontractor reduce aerospace component cycle times and tooling costs by identifying improvements to the cutting cycles

Having been used to 3- and 4-axis machining, Scottish subcontractor, Qualtronic had to move into 5-axis machining. It had the machining centre and rotary/tilt table to do so, but had had littl experience. The original machine tool supplier, Matsuura Machinery, sent in its application engineers to assist.

Some 80% of Qualitronics' turnover is involved in aerospace contracts.

Contracts include machining microwave transmission components, connector bodies, cable terminations and other instrumentation.

Historically, Qualitronics' Glenrothes factory's operations have involved 3- and 4-axis prismatic machining on Matsuura machining centres and multi-axis mill-turning on a variety of lathes.

At the UK's Southern Manufacturing show, in February 2004, Qualitronic attracted the attention of a global supplier of mechanical and control products.

Impressed with the sample components on display and with the knowledge of the engineers staffing the stand, the company placed a large order for stainless steel parts to go into a new passenger aircraft.

One of the components needed 5-axis machining to produce it economically.

In 2003, Qualitronic had bought a Nikken 2-axis rotary/tilting table for its Matsuura MC-510VG vertical 3-axis machining centre (VMC) to machine close-tolerance, 5-axis parts.

Said Qualtronic's managing director, Adrian Harper: 'Matsuura applications engineers helped us to reduce the cycle time and tooling costs when machining these components by identifying improvements to the cutting cycles'.

He said that was once carried out in simultaneous 4-axis mode is now machined by interpolating the other rotary axis on the Nikken table as well.

The component can be tilted to allow access for a different cutter to perform more aggressive roughing.

So the delicate milling is now required for only the finishing pass.

Production of the components at Qualitronics is expected to increase significantly in 2008.

So in December 2007, a full 5-axis Matsuura MAM72-25V twin-pallet VMC was installed to take over some of the machining.

* Full 5-axis brings advantages - significant advantages result from using the full 5-axis machine rather than the MC-510VG with add-on compound table, in spite of the remarkable accuracies obtained with the latter configuration.

The MC-510VG has enabled improved surface finish to be achieved on certain features of the aerospace components and reduced overall cycle time by 40%, said Qualitronics.

The greater rigidity of the more modern machine allows full use to be made of the higher power, 15,000 rev/min spindle and the faster feed rates while cutting, and also reducing 'air cutting' time when repositioning or changing tools.

At the same time, Matsuura applications engineers made a further improvement in the way that the five CNC axes are interpolated to allow a greater area of one of the cutters to contact the component.

In this way, the the life of the cutter is doubled.

Furthermore, the same cutter is now used to mill features that previously required a separate cutter, so one tool change has been eliminated from the cycle.

A machine-mounted probe checks critical features before it leaves the fixture and every second component undergoes a functional check.

* Attracting more work - now that the full 5-axis Matsuura VMC is installed, other components will be manufactured under contracts that the subcontractor would have had to turn away before.

One is the production of a surgical instrument for performing tracheostomies.

The 316 stainless steel assembly contains around 30 parts, including a complex camera head and another component that can only be produced in one hit by 5-axis interpolative machining.

Other jobs lined up for the new machine are destined for the offshore sector, which need relatively small parts machined from difficult materials.

Harper's philosophy is to invest in the best quality plant.

H said that he found that customers will pay a premium for the high precision components that can be machined.

'Many subcontractors walk away from such close tolerance work and that is when we step in,' he said.

'But if you win that type of contract, you don't want to be worrying about the repeatability of your machine tools - chasing microns is difficult enough - so we always buy the best equipment available,' he added.

Qualtronic now uses six Matsuura machining centres to the exclusion of all other makes.

The oldest, an MC500 VMC, was installed in 1985 and is still in full production, despite having been in continuous use, 18 h/day.

The machine has stopped for unscheduled maintenance only five times in 22 years.

'We would be very unlikely to go elsewhere for prismatic metalcutting machines,' continued Harper.

'Matsuura machining centres are in the top category for quality and accuracy, but just as important is the quality of back-up we receive'.

Harper said: 'The supplier is streets ahead of all other machine tool vendors we have dealt with over the last 20 years in terms of the service provided, be it routine maintenance, emergency call-out, training, applications or spares.

Even a replacement spindle for any of our machining centres is available ex-stock from Matsuura's Leicestershire headquarters and can be with us the same day'.

* 5-axis replaces 3-axis working - the trend over the coming years at the Glenrothes subcontractor will be to replace 3-axis with 5-axis machining centres.

The thinking is that a greater variety of higher-added-value work can be undertaken in fewer set-ups, which also improves component accuracy by reducing accumulated tolerance errors.

In addition, fewer spindles are needed overall, minimising manual intervention and lowering labour costs.

* About Qualitronic - co-founded by Harper in 1984, Qualtronic moved locally to its current premises in May 2007.

In so, it increased factory space by a third to 20,000ft2.

It has an enviable record for customer service, with 99.8% of its 25 monthly deliveries correct and on time.

It has the engineering expertise to help customers develop their designs to simplify manufacture, is strong in traditional shop floor skills and has a particularly stable workforce, three staff having been with the company for more than 20 years.