Design for machining is an essential part of design for manufacturability (DFM). This paper presents a fuzzy logic expert system, SMARTDFM, to help designers obtaining technical information about design for machining. It can help design engineers to consider various machining aspects in the early stage of product design. A hierarchical structure has been established for the knowledge base. This expert system can classify all the components into different component shapes. The design guidelines and their justifications have been built into the expert system. This system also offers graphic display for visualization of the product design. Backward chaining is used in the inference engine. This system solves the uncertainty of the classification of component shapes using fuzzy reasoning. The design engineers can obtain very specialized guidelines and explanations about design for machining, such as component shapes, accuracy and surface finish, work material and standardization, kinematic design, component assembly, etc. Furthermore, SMARTDFM offers the shortest path for all the questions so that design engineers can get the information about design for machining very quickly. In simple words, SMARTDFM can be used by design engineers to apply design for machining principles efficiently and effectively.