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 1-2×107 N/mm/mm2 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.