With a 59 sq m footprint, the machine 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 worldwide.
The DMU 340G linear is capable of providing significant improvements in composite machining, ranging from high-end luxury vehicle monocells to next-generation aero engine fan blades. In addition, the machine is capable of titanium drilling and finishing operations, and working with materials of the future, such as glass-fibre reinforced aluminium, glass fibre in resin laminate interspersed with sheets of aluminium, and an array of high-temperature composites.
Further features of the machine include 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, as well as enhanced connectivity and plug-in technologies to interface with the AMRC’s data analytics suite.
Project proposals are already in the pipeline, and the machine will have applications for companies like McLaren, Rolls-Royce, Boeing, BAE Systems and Airbus. The machine also opens up opportunities in the renewables, medical and construction sectors.
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 chip formation and heat control within the system. The result is less damage, less waste and a better finish, which is why the technology is suited to machining hard, abrasive, brittle materials like carbon fibre composites, alloys and CMCs.
“The ultrasonic-assisted machining process is basically the same as a standard rotary cutting tool operation, but with an added highly tuneable, micro-scale, axial motion of the cutter providing a secondary motion during machining,” says Kerrigan. “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.
“The incoming machine also has linear drives that create better acceleration and change of acceleration, to push the machine really fast during 5-axis operations, which helps when producing complex shapes at high rates while retaining geometric accuracy of the part,” he continues. “With this linear drive system, the machine can achieve feed rates of 90 m/min. Current feed rates, between 1 and 4 m/min, are mostly limited by the fact that the forces generated during cutting, even with speeds 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.”
The machine is digital ready – kitted out with an intelligent, customisable controller that allows it to integrate process-monitoring techniques, providing data that can not only measure performance but help improve tool life.
“The usefulness of this is really on the process monitoring side of things,” says Kerrigan. “The 840D controller is considered state-of-the-art for enabling the extraction of process information, facilitating machine health monitoring, shop-floor connectivity and closed-loop adaptive control. It can also link to additional live retrofit process measurements.”
A fundamental part of the Composites Centre’s work into machining research is measuring cutting forces and temperature, as these provide a wealth of information about process health, such as whether a process is dynamically stable, if there is any chatter or forced vibration, the rate of tool wear, and whether a machine is being driven beyond its capabilities or experiencing mechanical/bearing wear.
“For carbon fibre-based composite materials, because it’s a highly abrasive process – even with diamond as the cutting tool – you have to replace the tool very regularly to the point where between 50 and 60% of the whole process cost comes from cutting tools,” explains Kerrigan. “The proposed data that will be extracted from this machine can be used by AI platforms, such as IBM Watson, to learn how to stretch the life of a tool without interrupting the process.”
Truly ‘composites capable’, the machine can operate in both dry and wet machining configurations – without harm to the machine’s moving parts, electronics or operator – and work on a range of materials from titanium to polymer composite. Further features include a particle-controlled door opening, an infrared measuring probe and a tool changer that introduces DMG’s novel modular carousel design.
The DMU 340G linear is due to arrive at the AMRC in late December and is likely going to be sited in the original AMRC 1 building.
