Measurement of Contact Stiffness for Stiffness Estimation of Machine Tool Supports

The contact stiffness is measured at the interfaces of several materials that are often used for machine tool supports. Models of machine tool supports and the contact stiffness are described. Then, a measurement method of the contact stiffness is proposed according to the model and demonstrated. The unit normal contact stiffness is 1-2x10(7)N/mm/mm(2) for general steel and cast iron. The unit normal contact stiffness is positively correlated with the longitudinal elastic modulus. The unit tangential contact stiffness is 1/10-1/5 of the unit normal contact stiffness and is not correlated with the elastic shear modulus. The surface roughness of the specimen should be small to reduce the dispersion of the measured unit contact stiffness.