TOPIC
APPROACHES TO SUSTAINABLE OPTIMIZATION OF HIGH SPEED CUTTING TECHNOLOGIES
The projects presented in this “Forschungsforum” have been realized within the “Factory of Tomorrow” subprogram. In 1999, the Austrian Federal Ministry of Transport, Innovation and Technology (bmvit) launched the “Sustainable Development” research and technology program, which aimed to effectively support a sustainable economy through research. Various research and development projects as well as demonstration and diffusion measures, which give new impetus to innovation in Austria’s economy have since been supported within the scope of a number of subprograms. The “Factory of Tomorrow” subprogram aims to encourage trend-setting pilot projects in the field of sustainable technology development. Model examples include innovative manufacturing processes, future-oriented products or exemplary enterprises.
Abbildung 1: Profactor Produktionsforschungs GmbH
High-speed cutting (HSC) is an innovative machining process used in the metal working industries today. In this process, cutting speeds and feed rates are much higher than in conventional processes. On account of the high cutting speed, the forces acting in HSC processes are reduced by up to 30%.
In addition to a longer tool life, the process also has advantages in the machining of complicated work pieces. Environmental benefits result from an improved surface quality, which in many cases makes additional stages of surface treatment unnecessary. Processes using the HSC technology almost attain the quality of finely ground surfaces.
As in conventional machining, cutting by means of HSC technology also requires cooling lubricants. Estimates suggest that in Austria some 7,000 tons of oils and emulsion concentrates per year are being consumed in metal cutting processes. The overwhelming part of the cooling lubricants is petroleum-derived; renewable raw materials are hardly used. A considerable proportion of the lubricant is misted in the process and, on account of the heat generated in the cutting process, evaporates and is thus discharged into the ambient air. On account of their complex composition, cooling lubricants are classified as hazardous substances. In 2001, threshold limit values for cooling lubricant mist at the workplace were first introduced in Austria. Reducing environmental problems and the burden on employees through cooling lubricants, requires expensive investment in filtering and ventilation equipment at workplaces and causes high operating costs.
The only sustainable approach to solving these problems consists in avoiding as far as possible the formation of lubricant mist in the cutting process. One method, which has already been successfully used in practice, consists in minimum cooling lubrication (MCL); compared to conventional flood lubrication the quantities of lubricant needed is considerably reduced here. The amount of lubricant applied to the tool-work piece interface is reduced to such an extent that it is consumed in the process and recovery of excess lubricant can be omitted. This also avoids the necessity of cleaning, pumps, and maintenance work. A new approach (hardly tested, so far) to minimum cooling lubrication uses an oil-in-water emulsion made from renewable raw materials.
The innovative technologies – HSC and minimum cooling lubrication – are still at an early stage of practical application in industry. At present, appropriate machining strategies in HSC processes still have to be developed experimentally for each individual work piece. The diffusion of this ecologically sound technology requires further experience from practice as well as model processes that make systematic use of this experience gained in experiments.
Two research projects within the “Factory of Tomorrow” subprogram aimed to optimize these technologies. In line with sustainable development the projects considered not only the requirements of the production process, but also focused on environmental and occupational safety.
While the first project developed a process model, demonstrating the manifold interrelations between technological requirements and the impacts on humans and the environment, the follow-up project further advanced optimization and tested the process in practice using real-life applications in various enterprises.
PROJECT 1
Holistic model for the design of hsc processes
Profactor Produktionsforschungs GmbH, Steyr 2002
PROJECT 2
Bio-Minimum-Lubrication
Profactor Produktionsforschungs GmbH, Agatex Feinchemie GmbH, Steyr 2005
