Evaluation of surfaces complementarity based on high definition metrology

The gap between two mating surfaces has a direct influence on sealing performance. However, traditional surface metrology rarely characterizes the gap between two mating surfaces. To solve this problem, a novel concept of surfaces complementarity is proposed in this paper. Surfaces complementarity measures how well two rough surfaces fit into each other. To make this concept applicable in engineering practices, a virtual assembly algorithm is developed. The automatic virtual assembly algorithm aligns the mating surfaces by maximizing the overlap ratio of the surface masks. Then, a sum surface which is complementary to the surface gap is constructed to represent the mating states. The top surface of a cylinder block and corresponding cylinder head surface measured by high definition metrology is mated by the virtual assembly algorithm. The differences of functional parameters between the mating surfaces and the sum surface are discussed thoroughly. Due to surfaces complementarity, parameters of the sum surface has a certain deviation from expected combined parameters from two individual surfaces. A case of square surface shows the practical application potential of the virtual assembly algorithm to optimize the sealing performance of the mating surfaces.