PURPOSE: To improve adhesive strength through increasing coefficient of friction and to enable a machinery device to be light weight and compact or the like by placing fine powder having hardness which is equal to or more than the hardness of a pair of metallic bodies between the frictional surfaces of the pair of metallic bodies which transmit adhesive strength to each other through the frictional surfaces.

CONSTITUTION: When an iron column B is placed on an iron plate A and a plurality of loads C are operated on the upper portion of the iron column B, force W is applied at right angles on a contact surface between the iron plate A and the iron column B, and force F which slides the iron column B parallel to the contact surface is applied on the column B. And iron dust, sand or the like are placed on the contact surface between the iron plate A and the iron column B. And when coefficient of friction is calculated by measuring each force of W and F, the coefficient of friction is greatly stabilized and increased by placing appropriate quantity of iron dust on the frictional surface. Thus, the adhesive performance can be improved in a machinery device in which adhesive force is transmitted through the frictional surface of metals in a direction of the surface, for example, a railway vehicle, and the machinery device can be made light weight and compact or the like.