Precision machining is a process in which processing machinery is used to change the shape or performance of a workpiece. According to the temperature state of the workpiece to be processed, it is divided into cold processing and hot processing. Generally processing at room temperature, and does not cause chemical or phase changes of the workpiece, it is called cold processing. Generally, processing at higher or lower than normal temperature will cause chemical or phase changes of the workpiece, which is called thermal processing. Cold processing can be divided into cutting processing and pressure processing according to the difference in processing methods. Thermal processing commonly includes heat treatment, forging, casting and welding.
Generally speaking, the commonly used materials for precision machining are divided into 2 categories:
Processing of metal materials. Processing of non-metallic materials (such as ceramics, plastics, etc.)
Hardness from high to low: stainless steel>cast iron>copper>aluminum
Let’s talk about several commonly used ones, I hope they are useful to you:
1. 45—High-quality carbon structural steel, commonly used medium-carbon quenched and tempered steel.
Main features: Commonly used medium-carbon quenched and tempered steel, with good comprehensive mechanical properties, low harden ability, and easy to crack during water quenching. Small parts should be quenched and tempered, and large parts should be normalized.
Application examples: Mainly used to manufacture high-strength moving parts, such as turbine impellers and compressor pistons. Shafts, gears, racks, worms, etc. Pay attention to preheating before welding and annealing for stress relief after welding.
2. Q235A (A3 steel)-commonly used carbon structural steel.
Main features: It has high plasticity, toughness, welding performance, cold stamping performance, as well as certain strength and good cold bending performance.
Application examples: Widely used in general requirements of parts and welding structures. Such as tie rods, connecting rods, pins, shafts, screws, nuts, ferrules, brackets, machine seats, building structures, bridges, etc. that are not under strong force.
3. 40Cr-one of the widely used steel grades, belongs to 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 harden ability, high fatigue strength when oil-cooled, and easy parts with complex shapes when water-cooled. Crack occurs, cold-formed plasticity is moderate, good machinability after tempering or quenching and tempering, but poor weld ability, easy to produce cracks, should be preheated to 100 ~ 150 ℃ before welding, generally used in quenched and tempered state, it is OK Carburize carbonitriding and high frequency surface hardening treatment.
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., after quenching and tempering, and high-frequency surface quenching, it is used to make the surface with high hardness and resistance. Grinding parts, such as gears, shafts, spindles, crankshafts, spindles, sleeves, pins, connecting rods, screws and nuts, intake valves, etc., after quenching and tempering at medium temperature, they are used to manufacturing heavy-duty, medium-speed impact 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 At the nit riding site, transmission parts with larger dimensions and higher low-temperature impact toughness, such as shafts, gears, etc., will be manufactured.
4. HT150-gray cast iron
Application examples: gear box body, machine bed, box body, hydraulic cylinder, pump body, valve body, flywheel, cylinder head, pulley, bearing cap, etc.
5.35-Common materials for various standard parts and fasteners
Main features: proper strength, good plasticity, high cold plasticity, acceptable weld ability. Partial upsetting and drawing can be done in cold conditions. Low harden ability, use after normalizing or quenching and tempering
Application examples: Suitable for manufacturing small cross-section parts, parts that can withstand larger loads: such as crankshafts, levers, connecting rods, hooks and loops, etc., various standard parts, fasteners
6, 65Mn-commonly used spring steel
Application examples: all kinds of small size flat springs, round springs, seat springs, spring springs, and can also be made into spring rings, valve springs, clutch springs, brake springs, cold rolled coil springs, circlips, etc.
7, 0Cr18Ni9-commonly used stainless steel
Features and applications: The most widely used as stainless heat-resistant steel, such as food equipment, general chemical equipment, and industrial equipment
8. Cr12-commonly used cold work die steel
Features and applications: Cr12 steel is a widely used cold work die steel, which is a high-carbon and high-chromium ledeburite steel. The steel has good harden ability and good wear resistance; because the carbon content of Cr12 steel is as high as 2.3%, it has poor impact toughness, easy brittleness, and easy formation of uneven eutectic carbides;
Because Cr12 steel has good wear resistance, it is mostly used to manufacture cold punches, punches, blanking dies, cold heading dies, punches and dies for cold extrusion dies, and drills that require high wear resistance and are subject to less impact load. Sets, gauges, drawing dies, stamping dies, thread rolling boards, deep drawing dies, and cold press dies for powder metallurgy, etc.
9. DC53-commonly used cold work die steel imported from Japan
Features and applications: High-strength and toughness cold-work die steel, Japanese Dating Special Steel Co., Ltd. steel grade. After high temperature tempering, it has high hardness, high toughness and good wire cutting performance. 9Used for precision cold stamping dies, drawing dies, thread rolling dies, cold blanking dies, punches, etc.
10. SM45-ordinary carbon plastic mold steel