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Geometric precisions are incorporated into a relational database from the perspective of geometric parameter precision design of the new generation of GPS and using the database technology. The processes can be simulated of their reasoning and decision-making in solving mechanical problems combining the theoretical knowledge, factual data and heuristic knowledge from the experience of specialists. An algorithm is designed and developed a system which provides query service on dimensional precision, form and position precision and surface roughness. This system can deduce a series of fit both automatically according to the form-position tolerance grades and the existing processing conditions, which can deduce the microscopic feature of surface and economic processing method. An application platform is also provided for the digitized realization of the new generation of GPS standards, the establishment of a traceability system and for the global integration.

Operation and operator technologies used in new generation Geometrical Product Specifications (GPS) provide the necessary knowledge basis for digitization and standardization in verification process of geometrical products. This paper presents a framework of predicate-based operations which obtain features or values of characteristics, their nominal values and their limits. The knowledge about operations, constraints, objective and result is represented using predicate calculus, and it forms the basis of formalizing operator. Conditions give an equality or inequality to be respected by the specified characteristic. With a simple example, the geometrical expression specifications for the functions, design, manufacture and verification of a product are illustrated. The case of perpendicularity tolerance indicates that the proposed method is efficient and feasible.