The present surface roughness research is based on machine parts surface cross section profile analysis. But in practical applications machine parts surface roughness behaves as a 3D object. Therefore it is necessary to create a new theoretical and practical basis for machine parts surface assessment as a 3D quantity. The results of investigation of surfaces of iron-copper details after compacting, sintering and infiltration are offered. The influence of the technological process on the surface conditions was evaluated and analyzed by comparison of the average 3D roughness parameters of iron-copper detail. Based on the obtained surface roughness parameters and physical-mechanical properties the wear intensity of powder details surfaces was calculated using new approach offered by authors. New approach is based on the application of original contact criteria and probability theory. Calculation of wear was executed using stray field to roughness evaluation of friction surfaces. Analytical values show well accordance with practical values.