From all the machines produced, machine tools are the most significant homogeneous group, in terms of value it could be up to 20%. The predictive strategies developed for machine tools are applicable for most of the sub-categories, including machining centers and lathes. This gives a global market size of 60% of the machine-tools produced.
Both machine tool and machine tool processes has received extensive research in the area of process improvement, with little been done on machine condition monitoring to predict malfunction and less on energy optimization. Most of the research has been based around known applications in temperature and vibrations. The use of these technologies has been limited to use during the engineering phase, testing and final machine assembly.
Currently condition monitoring has to be done selectively and the potential economic savings have to be analyzed carefully. The two main factors that have to be considered: the reduction in production losses due to breakdowns and the maintenance costs (replacement parts and labour). Under these criteria there are two critical elements in a machine tool: the spindle and the linear guides.