Multi-purpose machines ensure enhanced independence

By: Nikolaus Fecht

The crisis is over, but selling machinery remains a tough business. Machine tools nowadays have to be veritable “jack of all trades, ” able to handle all kinds of materials, to manage without any process materials as far as possible, and be capable of adapting to new job profiles with maximised flexibility. Two highly respected experts on machining and forming from Dortmund and Chemnitz report on what’s in store for machine tool manufacturers and users.

“In most sectors, batch sizes are decreasing,” observes Prof. Dr.-Ing. Dirk Biermann, who heads the Institute for Machining Technology (ISF) at Dortmund University of Applied Science. “The demand is for machines suitable for handling small batch sizes, coping with several different processes, and ideally providing options for complete machining.” In some cases, they are intended to replace highly elaborate specialised machines: as an example, the ISF’s director cites a machining centre that thanks to collaboration between a machinery manufacturer and a tool producer now enables gear wheels to be produced efficiently as well.

Multi-purpose machines are a declaration of independence

The trend towards the kind of multi-purpose machining centres that is able to cost-efficiently handle a broad portfolio of products with small batch sizes accelerated significantly during the crisis. “With a multi-purpose machine, you’re less dependent on particular products and sectors, ” explains Biermann. “But there are still going to be specialised machines for large batch numbers.” However even when it comes to the classical representatives for large-series production, there is definitely an incipient trend reversal: in the automotive industry, for example, the multiplicity of different variants and drive concepts is increasing, as they arrive on the market in ever-shorter cycles. “Here, too, the requirement is for machines that are able to cope effortlessly with rapid changes in the components being manufactured,” says the scientist.

Energy-efficiency, too, is meanwhile playing a prominent role. Purchasers should consider not only the equipment capabilities themselves, such as using efficient drives, avoiding unnecessary load pick-up and minimising power consumption in stand-by mode. They should also think in terms of the process as a whole.

Sometimes it’s worth changing tools

As an example from the field, Biermann cites deep drilling. “When the user does not have very exacting requirements for the surface quality of the drill-hole, he can use twist deep drills instead of a single-lip tool, ” he explains. “They’re on offer as standard with a length-to-diameter ratio of 40.” The benefit, says Biermann, is that the twist deep drills can machine workpieces at a much higher feed rate (for example: 0.2 instead of 0.02mm) - at a significantly lower cooling lubricant operating pressure (for example: 25 instead of the previous 80 bar). Changing a tool type not only cuts the cooling lubricant pump’s energy consumption and the machining time involved. “For deep drilling, in particular the enormous time savings achieved can lead to entire machine systems being rendered superfluous,” says Biermann.

With a view to sustainability, he recommends adopting a holistic approach, placing the process concerned in its wider context: for example, the hardness and mechanical strength of bainitic steels can be increased without any significant losses in toughness. Purposeful development of the alloy and the process involved, moreover, ensure that the costly and energy-intensive thermal treatment otherwise customary for tempering can be dispensed with. “The requisiteNIKE