Multifunctional Material Application in Ultra High Precision Machine Tools Design

This paper aims to investigate a possible application of multifunction materials in realisation of structure components for Machine Tools (MT) in UHP (Ultra High Precision) machining. The proposed solutions offer a fundamental impact on functionality and reliability of a manufacturing system in terms of final machining. There are many aspects that affect the machining accuracy and the cutting conditions of a high performance MT. The most important issues are related to the dynamic and thermal behavior of the machines. In particular, a strict requirement that a machine tool has to fulfill in order to drastically reduce operating time while improving the final accuracy is the thermal stability. Changes of few degrees in the machine structure temperatures can cause machining errors that drastically compromise the work piece final precision. They are caused by geometrical distortions imputable to thermal fields generated from internal heat sources (e.g. the machine mechanical or electrical members). The dynamic behaviour of the machine also affects the precision of machining. High weight moving parts tend to decrease the "natural" vibration frequencies of the machines, causing instability problems (and then inaccuracy,) due to the mechanical resonance, and affecting definitely the final precision and quality of the machined work piece. This paper shows a structured study on a set of prototypes of UHP MT structures based on sandwiches with core made of metal foam and corrugate-core sandwich panels impregnated by a PCM (Phase Material Change) wax.