Wednesday, 30 January 2013

Aerospace Manufacturing’s John Helm looks at how one company is responding to the composite CNC machine tool challenges of an ever-changing world.

The extraordinary growth in the demand for composite materials has forced CNC machine makers to adapt and devise new solutions to keep pace with ever changing market conditions.

Breton is one such company: It was established by Marcello Toncelli in 1963, and still remains a family controlled concern. Its original remit was to manufacture processing machines for the stone industry, but the company diversified during the 1990s and began designing and manufacturing CNC machines. Of these, the Matrix and Eagle are probably being the best known. They are quite flexible and can be used - if suitably modified first - for either composite or metallic work.

UK sales manager, Enrico Bragagnolo reckons the main customer concern with composite materials is dust.

“The dry machining involved requires an efficient dust extraction plant,” he begins. “Ideally, this should be directly placed on the spindle front in order not to impair machine capability - as done in our ‘rollover dust collector’ solution. Almost all latest company developments combine air filtration with special coolants round and through the tool .This increases cutter life and avoids heat transfer to the workpiece.

“CFRP machining centres need to be completely enclosed in an envelope, along with dust extraction and dedicated coolant filtration plants. Good lubrication techniques are essential for long life, and the oils and lubricants for machine drives must avoid leakage to prevent contamination getting to the composite parts. All covers need sealing and excess oil has to be extracted.

“The abrasive qualities of composite material generate excessive wear. So it is crucial that motors, direct drives, ball screws, racks, guideways and bearings are both accurate and durable.”

Breton machines can be customised to meet specific requirements. The Matrix 800 is a vertical 5-axis machine ideally suited to medium-sized milling, with 50kW electro-spindles and rotational speeds of up to 40,000rpm. For larger tasks, the Matrix 1000-1300 is more suitable. It has a gantry structure and moving crossbeam, but is slower (up to 40kW spindles and up to 28,000rpm). Breton's Eagle series is ideal for high-speed production requirements.

Bragagnolo maintains that one of the company’s biggest challenges is meeting ever-increasing demands for greater accuracy.

“Both civil and military aircraft parts require tighter tolerances,” he declares. “Machines need to be faster and more reliable. Downtime has to be minimised. We can guarantee 94% uptime availability spread over three working shifts.

“There is also increasing customer demand for greater automation. We provide automatic pallet changes, integrated in-process inspections, automated reading of parts codes, machining parameters, as well as cleaning and parts storage. Breton has also developed a ‘self-calibrating’ machine. This operates over a wide temperature range and maintains accuracy for longer periods, all of which goes towards reducing downtime.”

As for research & development, Breton  uns its own chemical laboratory. The company also employs a dedicated team of seven engineers and recently installed a third machine centre in the internal workshop.

“They are dedicated to cutting trials on composite materials,” he notes. “We are also working with developers to improve our CNC software and we have an agreement with a major global tool producer.”

Breton has co-operated with several leading European universities and has collaborated with some of the top names in motorsport, including F1 Red Bull Racing and Formula 3.

“We get positive feedback from our customers, many of whom place repeat orders” concludes Bragagnolo. “Our precision machines have saved many companies from the need to invest in expensive new equipment. Their confidence in our products encourages greater utilisation, and this enhances productivity.”
(Thanks to Aerospace Manufacturing)


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