LMT TeraSpeed sets new speed record for machining cast material

The demands that are being made on machining tools are steadily increasing all the time: on one hand, new, challenging materials are being introduced and, on the other, there is a trend toward minimal lubrication or dry machining, both of which result in higher tool temperatures than wet processing. Toolmakers are responding to this development with new high-performance coatings optimized to withstand the resulting high levels of stress. Above all, coating systems based on AlTiN (aluminium titanium nitride) have proved to have ideal characteristics for machining steel and cast iron. However, it is normally produced using a PVD process, which is precisely the problem when it comes to dry machining: the thermal resistance of this system is limited to 900 degrees.

Horizontal machining of cast housing plates.

Tool withstands significantly higher temperatures

Using a new kind of CVD technology, the coatings experts at LMT alliance partner Boehlerit have succeeded in significantly raising this limit for the first time. The result is a CVD-AlTiN coating called TERAspeed, which, for example, demonstrates far higher resilience during uninterrupted cutting. TERAspeed is exceptional because of its hardness of roughly 3,500 HV. Furthermore, an aluminium content of over 90% guarantees a high thermal resistance of up to 1,100 degrees Celsius working temperature. “The combination of coating system and CVD technology is decisive for performance. AlTiN provides toughness and temperature stability, while CVD provides extremely high adhesion and a uniform distribution of coating thickness on cutting and open areas. We are simultaneously using the advantages of both technologies with the new coating,” explains Reinhard Pitonak, coatings expert and project manager at Boehlerit.

The difference is clearly visible: wear is significantly reduced with the new LCK10M grade.

Up to 200% performance increases

The advantages for customers are obvious: the hardness and thermal resistance allow the use of significantly higher cutting parameters than would be possible with the PVD-AlTiN coatings currently available on the market. Workpieces can be processed much faster without any negative impact on process reliability. Production costs are dramatically reduced. Trial applications have resulted in huge performance hikes: in face milling, for example, material removal is increased by 100% compared to using other grades; removal rates are even increased by 200% in step milling applications. “You could say that the cutting speed achieved using indexable inserts with the new coating reaches the ‘tera scale’, which is where the name TERAspeed came from,” explains Jana Siouzou, product manager at LMT Fette.

Optimum solution for post-cast machining

It is particularly in post-cast machining that the TERAspeed coating reveals its full potential. This material is increasingly being used in the automotive industry – for good reasons: compared to steel, it offers higher tensile strength and lower weight. Nevertheless, the efficient and cost-effective machining of cast materials presents a real challenge. “In the case of ductile cast iron, for example, the carbon is present in spherical form. This structure improves its mechanical properties compared to lamellar graphite. However, tensile strengths up to 1,000 N/mm2 make machining more difficult. With TERAspeed we are now offering a high-efficiency solution that guarantees exceptional performance especially in the field of post-cast machining. Higher cutting speeds enable users to make considerable cost savings,” explains Siouzou.

The product launch for indexable inserts with the TERAspeed coating is currently being prepared and this innovative new product will become available to all customers from July.