Abstract
The thermal inertia of a machine tool bed made from concrete material is generally much larger than that of conventional ones such as cast iron or steel. Hence, it is considered that the thermal response of a concrete bed depends strongly on the period of fluctuation of the ambient temperature. In this paper, the thermal behaviour of a concrete bed in fluctuating ambient temperature is discussed, comparing it with that of a conventional cast-iron bed. It is verified that a concrete bed has a great advantage from the viewpoint of thermal deformation when the period of ambient temperature fluctuation is relatively short.