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14th September 2018, Sheffield

AMRC prepares to go ultrasonic

The world’s largest ultrasonic assisted machine tool is coming to the University of Sheffield Advanced Manufacturing Research Centre (AMRC), cementing the centre’s reputation for world-leading research capabilities in composite machining.

The £1.8 million DMU 340 G linear machine tool arrives at the AMRC at the end of the year and will be the first of its size to be fitted with an ultrasonic-capable spindle for use in five-axis machining applications.

DMG Mori is currently developing advanced digital strategies to extract strategic information from next generation machine tools. © DMG Mori

The specification for the machine – which has a 59 sqm footprint - has been tailored and developed with the input of Dr Kevin Kerrigan, the lead for the Composites Machining Group at the AMRC Composites Centre, helping DMG Mori create a product it is able to market to the world. “This machine is the first of the DMU 340 G product range to have the ultrasonic assisted machining kit. It cements the AMRC’s reputation for world-leading research for capabilities in composite machining,” he said.

Improvements in composite machining

The DMU 340 G can provide significant improvements in composite machining, ranging from high-end luxury vehicle monocells to next-generation aeroengine lightweight fan blades. It is also capable of titanium drilling and finishing operations and working with materials of the future such as glass fibre reinforced aluminium, a glass fibre in a resin laminate interspersed with sheets of aluminium and an array of high-temperature composite materials, the institution explains.

The machine boasts many other features including linear motors for high accuracy and rapid motion, novel dust extraction technology, high pressure cutting fluid delivery systems, on machine inspection technology, and a multitude of industry 4.0 capabilities including wireless in-process monitoring and control technologies, enhanced connectivity and plug-in technologies to interface with the AMRC’s vast data analytics suite.

The second generation ultrasonic-assisted machining option enables this machine tool to undertake advanced machining operations, challenging the conventional CNC productivity and quality constraints. © DMG Mori

Project proposals are already in the pipeline and the machine will have applications for companies like McLaren, Roll-Royce, The Boeing Company, BAE Systems and Airbus. It also opens opportunities in the renewables, medical and construction sectors.

Higher degree of control

The advantage of the machine’s ultrasonic capabilities is that the high frequency movements – 40,000 micro-movements per second – bring a higher degree of control of chip formation and heat within the system. The result is said to be less damage, less waste and a better finish – which is why the technology is suited to machining hard, abrasive, brittle material like carbon fibre composites, alloys and CMCs.

“The ultrasonic assisted machining process is basically the same as a standard rotatory cutting tool operation, but with an added highly tuneable, micro-scale, axial motion of the cutting tool providing a secondary motion during cutting,” said Kevin. “It is the additional movement that has the ability to control the amount of energy supplied into the cutting interface affecting the amount of thermal energy and fracture energy associated with the process.”

DMG Mori’s new DMU 340 G Linear 5-axis machining platform with its 12m3 work area volume was particularly developed for large component machining, in the aerospace industry, tool and mould making and general mechanical engineering. © DMG Mori

“The incoming machine also has linear drives which create better acceleration and change of acceleration, i.e. jerk, to push the machine really fast during 5-axis tool paths which helps when producing complex shapes at high rate whilst retaining part geometric accuracy. With this linear drive system, the machine can get up to feed rates of 90 m/min. Current feed rates, between 1 and 4 m/min, are mostly driven by the fact that the forces generated during cutting, even with rpms of over 20,000 rpm, would snap the tools if feed rates got any faster. That is a massive difference and a huge benefit to productivity.”

Digital ready

The machine is digital ready – kitted out with an intelligent, customisable controller that allows the machine to integrate process-monitoring techniques, providing data that can not only measure performance but also help to improve tool life.

“The usefulness of this is really on the process monitoring side of things. The 840D controller is considered state-of-the-art for enabling the extraction of process information, enabling machine health monitoring, shop floor connectivity and closed-loop adaptive control. It can also link to additional live retrofit process measurements that are linked to things like tool wear, damage defects on a part,” added Kevin.

“That’s useful information that gives us greater insight into the machining operations being undertaken on complex materials.”

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