Non-metallic materials

1. Rubber

Rubber is rich in elasticity and can absorb more impact energy. Ebony can be used to make bearing bushings lubricated with water.

2. Plastic

The specific gravity of plastic is small, and it is easy to make parts with complex shapes, and various plastics have different characteristics, such as corrosion resistance, heat insulation, insulation, friction reduction, and large friction coefficient. Its application in machinery manufacturing is increasingly widespread. The plastic made of wood chips, asbestos fibers, etc. as fillers and pressed with thermosetting resin is called combined plastic, which can be used to make instrument brackets, handles and other parts with little force. The layered fillers such as cloth, asbestos and veneer are used as the matrix, and the plastics formed by pressing thermosetting resins are called laminated plastics, which can be used to make silent gears, bearing villages and friction plates. When designing mechanical parts, choosing the right material is a complex technical and economical issue. The designer should make comprehensive consideration according to the use of the part, the working conditions and the physical, chemical, mechanical and technological properties of the material, as well as economic factors. This requires designers to have extensive knowledge and practical experience in materials and processes. The foregoing is only a rough description. The chemical composition and mechanical properties of various materials can be found in relevant national standards, industry standards and mechanical design manuals.

Craftsmanship and Standardization

Craftsmanship

When designing mechanical parts, it should not only meet the requirements of use, that is, have the required working ability, but also meet the production requirements, otherwise it may not be manufactured, or although it can be manufactured, the labor and materials are very uneconomical . Under specific production conditions, if the designed mechanical parts are easy to process and the processing cost is low, such parts are said to have good manufacturability. The basic requirements for manufacturability are: (1) Rational selection of blanks The methods of blank preparation in mechanical manufacturing include: direct use of profiles, casting, forging, stamping and welding. The selection of the blank is related to the specific production technical conditions, and generally depends on the production batch, material properties and processing possibilities. (2) When designing the structural shape of the part with a simple and reasonable structure, it is advisable to use the simplest surface (such as plane, cylindrical surface, helical surface) and its combination, and at the same time, try to minimize the number of machined surfaces and the minimum machining area. (3) Specifying appropriate manufacturing accuracy and surface roughness The processing cost of parts increases with the increase in accuracy, especially in the case of high accuracy, this increase is extremely significant. Therefore, high precision should not be pursued without sufficient grounds. In the same way, the surface roughness of the parts should also be properly specified according to the actual needs of the mating surface. To design a well-crafted part, the designer must engage with and learn from process technicians. In addition, some basic knowledge about craftsmanship is also provided in metal craftsmanship courses and manuals for reference.