Common materials and instructions for precision machining?

Generally speaking, the commonly used materials for precision machining are divided into two categories:

Processing of metal materials. Processing of non-metallic materials (such as ceramics, plastics, etc.)

Hardness from large to small: stainless steel > cast iron > copper > aluminum

Let's talk about a few commonly used ones, I hope they are useful to you:

1. 45 - high-quality carbon structural steel, which is the most commonly used medium carbon quenched and tempered steel.

Main features: The most commonly used medium carbon quenched and tempered steel has good comprehensive mechanical properties, low hardenability, and is prone to cracks during water quenching. Small pieces should be quenched and tempered, and large pieces should be normalized.

Application example: Mainly used to manufacture high-strength moving parts, such as turbine impellers, compressor pistons. Shafts, gears, racks, worms, etc. Welded parts should be preheated before welding and annealed to relieve stress after welding.

2. Q235A (A3 steel) - the most commonly used carbon structural steel.

Main features: It has high plasticity, toughness and welding performance, cold stamping performance, as well as certain strength and good cold bending performance.

Application examples: Widely used for general requirements of parts and welded structures. Such as tie rods, connecting rods, pins, shafts, screws, nuts, ferrules, brackets, machine bases, building structures, bridges, etc.

3. 40Cr—one of the most widely used steel grades, is an alloy structural steel.

Main features: After quenching and tempering treatment, it has good comprehensive mechanical properties, low temperature impact toughness and low notch sensitivity, good hardenability, high fatigue strength can be obtained when oil cooling, and parts with complex shapes are easy to be obtained when water cooling. Cracks are generated, the cold bending plasticity is medium, the machinability after tempering or quenching and tempering is good, but the weldability is not good, and cracks are easy to occur. It should be preheated to 100 ~ 150 ℃ before welding. Carbonitriding and high frequency surface hardening are carried out.

Application example: After quenching and tempering, it is used to manufacture medium-speed and medium-load parts, such as machine tool gears, shafts, worms, spline shafts, thimble sleeves, etc. Grinding parts, such as gears, shafts, main shafts, crankshafts, mandrels, sleeves, pins, connecting rods, screws and nuts, intake valves, etc., are used to manufacture heavy-duty, medium-speed impact after quenching and medium-temperature tempering. Parts, such as oil pump rotors, sliders, gears, spindles, collars, etc., are used to manufacture heavy-duty, low-impact, wear-resistant parts after quenching and low-temperature tempering, such as worms, spindles, shafts, collars, etc., carbon The nitriding part is used to manufacture transmission parts with larger size and higher low temperature impact toughness, such as shafts and gears.