The processing method of the surface of CNC machined parts is first of all the technical standard of the machined surface. But we need to note that this technical standard is not necessarily the requirement of the part drawing, and sometimes it will be higher than the requirement of the part drawing to a certain extent due to processing technology. For example, because the standards do not overlap, the surface processing requirements of some CNC machined parts are improved. Or because it is used as an improved standard, it will clearly put forward higher processing specifications.
After the relevant technical standards are designed for the surface finishing of CNC machined parts, you can choose the final processing method that can ensure the regulations, and each step obviously requires multiple processes and processing methods. However, the selected CNC machined part surface finishing method should consider the quality of the parts, excellent processing rationality and high productivity. Therefore, the factors and points listed below should be considered when selecting the CNC machined part processing method.
Surface treatment process, key points and precautions for machined parts
With the development of modern industry, surface treatment technology has been widely used in all walks of life. Whether it is the anti-corrosion or performance treatment of metal CNC machined parts or the fine modification of plastic parts, surface treatment technology plays an important role. Elimold Company summarizes the relevant issues about the surface treatment of CNC machined parts.
Classification of surface treatment technology
Surface cleaning technology
Surface cleaning technology is an important part of surface treatment technology, and it is the basis of all surface treatment technologies. It includes grinding, polishing, cleaning and other methods to eliminate dirt, residues and other impurities on the surface of the workpiece, so that the surface can achieve the required cleanliness and appearance, and achieve the required cleanliness and appearance.
Surface heat treatment technology
Surface heat treatment technology is a technology that changes the surface temperature of the metal to change its mechanical structure and performance state, so as to reduce the surface residual stress, improve mechanical properties, improve surface hardness, wear resistance and other effects. These technologies include heat treatment, temperature tempering, surface quenching, bimetallic layer treatment, etc.
Surface coating technology
Coating technology is to improve the aesthetics or corrosion resistance of the surface, or increase the adhesion strength of the surface, or improve the lubricity of the surface, etc., and to coat the metal surface with suitable materials to change the appearance and performance of the surface. It includes electrostatic powder spraying, high-pressure spraying, sandblasting, etc.
Surface electroplating technology
Electroplating technology is a technology that puts electroplating solution or organic electroplating solution and electroplating anode of a certain shape into an electrolytic cell, adds electric power, and uses the metal extreme positive to remove the metal from the electroplating solution to form a uniform and delicate metal film on the surface of the workpiece.
Surface physical laser processing technology
Surface physical laser processing technology is a technology that uses laser energy to change the structure of the workpiece on the surface, change the scattering, chemical activity and other physical properties of the surface, and achieve the purpose of surface adjustment. It can achieve changes in the surface layer, such as marking, cleaning, refinement, etc., and increase the adhesion strength and wear resistance of the surface.
Surface treatment characteristics
- The surface treatment process technology is precise, the quality is reliable, the performance is predictable, and it has good functional effects and economic benefits;
- Surface treatment can achieve low-cost, non-destructive recycling, and has powerful functions, which plays an important role in production process technology;
- Surface treatment helps to improve the stability and reliability of product performance, reduce the number of defects, save raw materials, and save energy;
- The surface temperature of the workpiece changes little during the surface treatment process, and does not affect the surface material, thereby reducing thermal failure caused by surface treatment;
- Surface treatment can be completed in a short time, and the surface treatment process can be repeated, which greatly simplifies the surface process requirements of molded parts and saves costs and manpower;
- Surface treatment can adhere well to the surface, improve the surface finish and appearance, and help to ensure the surface quality of the workpiece;
- For multi-layer protective surface treatment, it can effectively prevent corrosion and oxidation in a humid environment and has good corrosion resistance.
Surface treatment process
- Cleaning: Before surface treatment, the surface needs to be cleaned to remove dirt, residues and other impurities to achieve a certain degree of cleanliness and roughness;
- Grinding: Grinding is an important part of surface treatment. Grinding can increase the surface roughness and make the surface smoother to meet the requirements of artistic processing;
- Polishing: Polishing is a way of surface treatment. It is a process of wiping with polishing agent or sandpaper to increase the gloss of the surface and further improve the surface accuracy;
- Spraying: Spraying is to use amide cleaning agent and water to mix into a spray flow to clean and remove pollutants if there are carbon, welding slag, oxides, oil stains and other pollutants on the surface of the workpiece. When the pollutants are hydrolyzed, they will gradually be washed away. ;
- Wire drawing: Wire drawing is a surface treatment that scratches the surface of a metal material with sufficient hardness to draw out bright parallel lines;
- Galvanizing: Galvanizing is the most commonly used surface treatment technology, which can increase the corrosion resistance of parts. The galvanizing method can be electroplating, cold plating, hot plating, etc.;
- Oxidation treatment: Oxidation treatment refers to the use of electrolysis, high-temperature heat treatment and other methods on the surface to form a protective film and a beautiful film by combining oxides with the metal surface, which is used to protect and decorate the metal surface;
- Assembly: Assembly is the last step in the surface treatment process, which assembles all parts into a complete product for use or shipment.
Finished product quality requirements
- Surface treatment requirements must meet the requirements of surface roughness, surface cleanliness and surface gloss, as well as surface forming requirements;
- Surface treatment is mainly to improve product quality, surface gloss, and increase product appearance;
- During the surface treatment process, the thickness and precision of the surface are strictly controlled to avoid product defects;
- After surface treatment, testing should be carried out to ensure the quality of the treated product and to ensure that the product can achieve the expected use effect.
Key points of operation
- The surface treatment process must be carried out in accordance with strict procedures to ensure the quality of the entire process;
- The tools and equipment for surface treatment must be qualified to ensure that the surface of the product will not be defective;
- Before completing the surface treatment process, accurate dimensional measurements must be made to ensure the quality of the finished product;
- The construction site should be kept clean to reduce errors and avoid damage to the surface treatment process.
Precautions
- Before applying the surface treatment process, full preparation must be carried out in accordance with product requirements to ensure the quality of the workpiece surface;
- During the surface treatment process, the prescribed process sequence must be followed to avoid quality problems;
- The use of tools must be proficient so that the treatment is fast and accurate;
- After the surface treatment is completed, strict inspection must be carried out to ensure that the prescribed standards are met;
- Any conditions that may damage the surface treatment must be fully controlled;
- The operating procedures must be strictly followed in order to grasp the requirements of quality control and to fully protect the product surface;
- During the surface treatment process, attention must be paid to odor
Technical requirements for surface finishing of mechanical parts
All post-processing steps will increase component cost and extend production cycle, but choosing the right surface processing can turn your design concept into reality. The following are the relevant requirements for surface finishing technology of mechanical parts.
Part surface treatment
- There should be no scratches, abrasions or other defects that damage the surface of the parts on the processed surface.
- The processed thread surface is not allowed to have defects such as black skin, bumps, random buckles and burrs.
- All steel parts that need to be painted must be free of rust, scale, grease, dust, dirt, salt and dirt before painting.
- Before rust removal, use organic solvents, alkali solution, emulsifier, steam, etc. to remove grease and dirt on the surface of steel parts.
- The time interval between the surface to be painted after shot blasting or manual rust removal and the application of primer should not be more than 6 hours.
- The surfaces of the riveted parts that are in contact with each other must be coated with anti-rust paint with a thickness of 30 to 40μm before connection. The overlapping edges should be sealed with paint, putty or adhesive. Primer damaged by processing or welding should be repainted.
Heat treatment of parts
- After quenching and tempering, HRC50~55.
- Medium carbon steel: 45 or 40Cr parts are subjected to high frequency quenching, tempering at 350~370℃, HRC40~45.
- Carburizing depth 0.3mm.
- High temperature aging treatment is performed.
Technical requirements after finishing
- After finishing, the parts must not be placed directly on the ground, and necessary support and protection measures should be taken.
- The machined surface is not allowed to have rust and defects such as bumps and scratches that affect performance, life or appearance.
- The surface of the rolling finishing process should not have peeling after rolling.
- The surface of the parts after the final process heat treatment should not have oxide scale. The mating surface and tooth surface after finishing should not be annealed.
Sealing of parts
- If the seals are processed, then each seal must be soaked in oil before assembly.
- Before assembly, strictly check and remove the sharp corners, burrs and foreign matter left during the processing of the parts. Ensure that the seals are not scratched when installed.
- After bonding, the excess adhesive that flows out should be removed.
Gear technical requirements
- After the gear is assembled, the contact spots and side clearance of the tooth surface should comply with relevant regulations and design technical standards.
- The reference end face of the gear (worm gear) should fit the shaft shoulder (or the end face of the positioning sleeve), and a 0.05mm feeler gauge should be used to check if it does not penetrate. The verticality requirements of the reference end face of the gear and the axis should be ensured.
- The joint surface of the gear box and the cover should have good contact.
Technical requirements for forgings
- Each ingot should have sufficient cut-off amount for the nozzle and riser to ensure that the forging has no shrinkage holes and severe deflection.
- Forgings should be forged on a forging press with sufficient capacity to ensure that the forging is fully forged through.
- Forgings are not allowed to have visible cracks, folds and other appearance defects that affect use. Local defects can be removed, but the cleaning depth shall not exceed 75% of the machining allowance. Defects on the non-machined surface of the forging should be cleaned and smoothly transitioned.
- Forgings are not allowed to have white spots, internal cracks and residual shrinkage holes.
Precautions
- Safety: During the surface treatment process, it is possible to come into contact with some harmful substances, such as chemicals, organic solvents, etc. Therefore, operators should wear protective equipment to ensure their own safety. At the same time, the working environment should have good ventilation facilities to avoid the accumulation of harmful gases.
- Environmental protection: The wastewater and waste gas generated by the agents used in the surface treatment process and the wastes need to be properly handled to avoid pollution to the environment. Enterprises should operate in strict accordance with environmental protection laws and regulations and take effective governance measures to reduce the negative impact on the environment.
- Technology selection: Different materials and workpieces require different surface treatment technologies. Therefore, the correct technology selection is required when performing surface treatment. For example, for metal parts with high hardness requirements, electroplating or spray coating can be selected to increase their hardness. For soft materials, avoid using too strong treatment methods to avoid damage to the materials.
Conclusion
The application of surface treatment technology cannot be ignored in modern industry. It not only protects metal products from corrosion, but also improves the hardness, wear resistance and other characteristics of the material. However, when applying surface treatment technology, we must also pay attention to safety and environmental protection. Only when the technical effect and social benefits are balanced can the surface treatment technology really play its value. If you have custom parts to be processed, no matter the quantity or technical difficulty, Elimold can serve you.