Mechanical parts mainly include metal parts materials and non-metal materials:
1. Metal materials
1. Cast iron
Cast iron and steel are both iron-carbon alloys. The main difference between them lies in the carbon content. Iron-carbon alloys with a carbon content of less than 2% are called steel, and those with a carbon content of more than 2% are called cast iron.
Compared with cast iron, steel has high strength, toughness and plasticity, and heat treatment can be used to improve its mechanical properties and processing properties. The blank of steel parts can be obtained by forging, stamping, welding or casting, so its application is extremely wide. According to the purpose, steel can be divided into structural steel, tool steel and special steel.
1) The carbon content of such steels as carbon structural steels generally does not exceed 0.7%. Low carbon steel with a carbon content of less than 0.25% has low strength limit and yield limit, high plasticity, and good weldability. It is suitable for stamping and welding. It is commonly used to make screws, nuts, washers, shafts, Valve guide rods and welding components, etc.
2) Alloy structural steel
The effect of adding alloying elements to steel is to improve the performance of steel.
3) Cast steel
The liquid fluidity of cast steel is worse than that of cast iron, so when ordinary sand casting is used, the wall thickness is often not less than 10mm. The shrinkage rate of steel castings is larger than that of iron castings, so the fillet of steel castings and transition parts of different wall thicknesses should be larger than iron castings.
3. Copper alloy
Copper alloys are divided into bronze and brass. Brass is an alloy of copper and zinc, and contains a small amount of manganese, aluminum, nickel, etc. It has good plasticity and fluidity, so it can be rolled and cast.
2. Non-metallic materials
Rubber is rich in elasticity and can absorb more impact energy. It is often used as an elastic element of a coupling or a shock absorber, and a belt drive belt. Hard rubber can be used to make bearing linings lubricated with water.
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, anti-friction, and large friction coefficient. Therefore, in recent years, they have been used in machine manufacturing. Its application is increasingly widespread.