Detailed explanation of key points for attention in stamping of electronic product parts

Stamping processing of electronic product parts is one of the core links in the field of precision manufacturing, and its processing quality directly affects the performance stability, reliability and service life of electronic products. Due to the characteristics of small size, high precision, diverse materials (such as copper, aluminum, stainless steel, precision alloy, etc.) and complex structure, the stamping process needs to take into account the requirements of technological rationality, quality control, cost control and safety production. The key points for attention in stamping of electronic product parts are described in detail from the core dimensions such as technical parameters, material adaptation, process optimization, quality control, equipment maintenance and safety specifications.

First, the preparatory stage: accurately control the basic elements

The sufficiency of preliminary preparation is the premise to ensure the smooth stamping process, and it is necessary to focus on three core links: product design, material selection and die development. On the product design level, it is necessary to optimize the structure of the parts according to the characteristics of stamping process, so as to avoid designing too complicated special-shaped structures, too narrow groove width or too thin wall thickness, and reduce the risk of deformation and cracking in the stamping process. For example, for precision electronic connector parts, the fillet radius should be set reasonably (it is recommended not to be less than 0.5 times of the material thickness) to avoid stress concentration caused by sharp edges and corners; At the same time, it is necessary to define the key dimensional tolerance (such as precision tolerance requirement of 0.01 mm ~ 0.05 mm), surface roughness (usually reaching Ra0.8~Ra3.2μm) and form and position tolerance (such as flatness and verticality) of the parts to ensure that the design requirements match the stamping process capacity.

The material selection should be comprehensively judged according to the usage scene, performance requirements and stamping process characteristics of electronic products. The stamping formability of different materials is significantly different: copper materials (such as copper and brass) have good conductivity and ductility, and are suitable for stamping electronic contacts, wiring terminals and other parts, but it is necessary to control the stamping speed to avoid material oxidation caused by high temperature; Aluminum materials (such as 6061 and 5052) are light and corrosion-resistant, and are often used in mobile phone housings, heat sinks and other parts, but their hardness is low, so it is necessary to choose a sharp die cutting edge to prevent the material from sticking; Stainless steel (such as 304 and 316) has high strength and wear resistance, and is suitable for high-precision structural parts, but its stamping resistance is high. Therefore, it is necessary to select high-strength die materials (such as SKD11 and DC53) and set a reasonable gap (usually 8%~12% of the material thickness) to avoid burrs or cracks in the parts. In addition, it is necessary to strictly control the quality of raw materials, and require suppliers to provide material certificates and mechanical performance test reports to ensure that the tensile strength, yield strength and elongation of raw materials meet the stamping requirements, and at the same time avoid using raw materials with defects such as scratches, scales and impurities.

Mold development is the core guarantee of precision stamping, which needs to meet the requirements of high precision, long life and high stability. In the mold design stage, it is necessary to optimize the layout scheme according to the structure of the parts to improve the material utilization rate (for small precision parts, the material utilization rate needs to reach more than 70%); Reasonably design the cutting edge shape of punch and die, and for complex curved parts, we can adopt precision machining techniques such as wire cutting and EDM to ensure the cutting edge accuracy within ±0.005mm; Set a reasonable guide mechanism (such as ball guide post guide sleeve) to ensure the coaxiality and verticality of die movement and reduce the offset error in stamping process; For thin material stamping, it is necessary to design a pressing device (such as an elastic pressing plate) to prevent the material from warping and displacement in the stamping process. After the die is manufactured, it is necessary to carry out die trial debugging, focusing on the dimensional accuracy, surface quality and burr size of the parts (the height of burr should not exceed 0.01mm), and adjust the die gap, pressing force, stamping speed and other parameters according to the die trial results to ensure that the die meets the requirements of mass production.

Second, the processing process control: optimize the process parameters to ensure the processing quality.

The control of process parameters in stamping process directly affects the quality and production efficiency of parts, and it needs to be accurately regulated according to the material, structure and precision requirements of parts. In terms of stamping speed, it is necessary to set it reasonably in combination with material characteristics and die strength: for copper, aluminum and other materials with good ductility, the stamping speed can be appropriately increased (for example, 100~200 times/minute) to improve production efficiency; For stainless steel with high hardness and high stamping resistance, it is necessary to reduce the stamping speed (such as 50~100 times/minute) to avoid the overload damage of the mold and reduce the deformation of the material due to high temperature. The control of stamping pressure should follow the principle of "sufficient and not overloaded". If the pressure is too small, the part will be incomplete and the edge burr will be too large. If the pressure is too high, the die will be damaged and the part will be excessively deformed. The best pressure value should be determined through die trial, and it is usually appropriate that the part can be completely formed, the surface has no indentation and the dimensional accuracy reaches the standard.

Gap control is one of the key technologies in stamping, and the gap between punch and die directly affects the quality of shear surface, dimensional accuracy and die life. When the gap is too large, the material will be stretched excessively in the stamping process, which will lead to the increase of the burr on the edge of the part and the decrease of the dimensional accuracy. When the gap is too small, the shear resistance of the material will increase, the cutting edge of the die will be easily worn, and the parts may have defects such as springback and warping. For precision parts of electronic products, it is necessary to accurately set the gap according to the material thickness and material characteristics: the gap of ordinary steel is usually 5%~10% of the material thickness, stainless steel is 8%~12%, and non-ferrous metals such as copper and aluminum are 3%~8%. In the process of mass production, it is necessary to check the gap of the mold regularly. If problems such as burr increase and out-of-tolerance are found, the mold should be ground or adjusted in time to ensure that the gap is always within a reasonable range.

Temperature control is particularly important in precision stamping, especially for thin materials and high-precision parts, temperature changes will lead to material thermal expansion and cold contraction, which will affect the dimensional accuracy. In the stamping process, the friction between the die and the material will generate heat. If the temperature is too high, it may lead to material softening, increased wear of the die edge, and even die sticking. Therefore, effective cooling measures should be taken: for high-speed stamping production line, an oil injection cooling system can be set up to lower the temperature of dies and materials by spraying special stamping oil (such as precision stamping oil containing extreme pressure additives), and at the same time, it can play a role in lubrication and reduce friction loss; For small precision parts stamping, air cooling can be used to avoid oil pollution to the parts. In addition, it is necessary to control the ambient temperature of the workshop (it is recommended to keep it at 20 5℃) to reduce the influence of environmental temperature change on the dimensional accuracy of parts.

Surface quality control of parts is one of the core requirements of electronic product parts stamping, and it is necessary to avoid scratches, indentation, oxidation, deformation and other defects. During the stamping process, it is necessary to ensure that the surfaces of the die cutting edge and the pressing device are smooth and free of impurities, and regularly clean up the oil stains, iron filings and other impurities on the die surface; Select stamping oil that meets the requirements to avoid oil residue or corrosion on the surface of parts caused by poor quality lubricating oil; For parts with extremely high surface requirements (such as the frame of electronic display screen), protective film can be used to cover the surface of the material during stamping to prevent scratches. At the same time, it is necessary to establish an online quality inspection mechanism. Through visual inspection equipment, micrometer, projector and other inspection tools, 100% full inspection or sampling inspection is carried out on the stamped parts, focusing on key dimensions, shape and position tolerances, surface defects and other indicators, and the unqualified products are found, and the reasons are promptly investigated and the process parameters are adjusted.

Third, mold maintenance: extend the life of the mold and ensure the stability of production.

Die is the core equipment of stamping process, and its maintenance directly affects the production efficiency and parts quality. In the process of mass production, it is necessary to establish a perfect mold maintenance system, and regularly check, clean, lubricate and repair the mold. Before daily production, it is necessary to check whether the key parts of the mold, such as the guide mechanism, punch and die, are worn, deformed and cracked. If the cutting edge of the mold is found to be worn, it is necessary to grind and repair it in time to ensure that the cutting edge is sharp; Clean the iron filings, oil stains and other sundries on the surface of the mold to avoid sundries affecting the movement of the mold or scratching the surface of the parts; Apply special grease (such as lithium grease) to the guide mechanism and sliding part of the mold to reduce friction loss and improve the flexibility of the mold movement.

In terms of regular maintenance, it is necessary to make a mold maintenance cycle according to the use frequency and production batch (usually a comprehensive maintenance is carried out every 10,000 to 50,000 pieces are produced). During the maintenance process, it is necessary to disassemble the mold, thoroughly clean the punch, die, guide post, guide sleeve and other parts, check the wear of each part, and replace the seriously worn parts in time; Re-adjust the mold gap to ensure uniform gap; Check whether the fastening bolts, springs and other parts of the mold are loose and tired, and tighten or replace them in time if problems are found; Rust-proof treatment is carried out on the mold, and it is properly stored after being coated with rust-proof oil to avoid rust and corrosion of the mold. In addition, it is necessary to establish a mold maintenance file to record the use time, maintenance content, replacement parts and other information of the mold, so as to provide reference for subsequent maintenance.

Iv. Safe production and environmental control: preventing risks and complying with production.

Stamping processing of electronic product parts involves high-speed equipment and precision molds, and safety production is the most important. It is necessary to establish and improve the safety production management system and provide professional training for operators to ensure that operators are familiar with equipment operation procedures, mold structure and safety precautions. Operators must wear labor protection articles (such as safety helmet, protective gloves, protective glasses, etc.) before taking up their posts, and it is forbidden to wear jewelry, watches and other items to avoid being involved in moving parts of equipment; In the process of operation, it should be carried out in strict accordance with the operating rules, and illegal operation (such as direct contact with the die cutting edge or parts conveying area by hand) is strictly prohibited. For the automatic stamping production line, safety protection devices (such as safety light curtain and protective fence) should be set up to prevent personnel from misoperation and causing safety accidents.

In terms of equipment safety, it is necessary to regularly maintain the stamping equipment, check whether the motor, hydraulic system, pneumatic system, control system and other components of the equipment are operating normally, and ensure that the parameters such as pressure, speed and stroke of the equipment are controlled accurately; Regularly calibrate the pressure gauge, counter and other instruments of the equipment to ensure the accuracy of the equipment operation data; Set up an emergency plan for equipment failure. If the equipment is abnormal (such as abnormal sound, vibration, unstable pressure, etc.), stop the machine immediately for inspection, and restart it after troubleshooting.

In terms of environmental control, it is necessary to keep the workshop environment clean and orderly, and clean up the iron filings, wastes and other sundries generated in the production process in time to avoid potential safety hazards caused by accumulation; Reasonably plan the production area to ensure that there is enough safe distance between equipment and between equipment and channels; Control the dust and noise pollution in the workshop. For high-speed stamping equipment, a sound insulation cover can be installed to reduce the noise (the noise should not exceed 85 dB); The oil pollution and waste water generated in the stamping process should be discharged after professional treatment, which meets the environmental protection standards.

5. Follow-up treatment and quality inspection: ensure that the products meet the standards and meet the use requirements.

After the stamping process is completed, it is necessary to carry out follow-up treatment and comprehensive quality inspection on the parts to ensure that the products meet customer requirements. Subsequent treatment mainly includes deburring, cleaning, rust prevention, surface treatment and other processes. Deburring is the key process of precision electronic parts after stamping, so it is necessary to choose the appropriate deburring method according to the structure and precision requirements of the parts: for small precision parts, ultrasonic deburring, electrochemical deburring and other precision deburring processes can be used to ensure that the deburring is completely removed without damaging the surface of the parts; For parts with simple structure, manual grinding and mechanical grinding can be used, but the grinding intensity should be controlled to avoid deformation of parts. In the cleaning process, impurities such as stamping oil, iron filings and dust on the surface of the parts need to be removed. An ultrasonic cleaning machine can be used in conjunction with a special cleaning agent (such as an environment-friendly neutral cleaning agent), and then it is rinsed with pure water to ensure that there is no residual oil on the surface of the parts. In terms of anti-rust treatment, for steel parts, electroplating, passivation and anti-rust oil can be used to prevent parts from rusting; For non-ferrous metal parts such as copper and aluminum, anodizing and passivation can be carried out to improve the corrosion resistance and surface hardness of the parts.

Quality inspection is the last line of defense to ensure qualified products, and it is necessary to establish a perfect inspection system, covering dimensions inspection, surface quality inspection, mechanical properties inspection and other dimensions. High-precision inspection equipment (such as three-coordinate measuring instrument, projector, micrometer, etc.) shall be used for dimensional inspection, and 100% full inspection or sampling inspection shall be conducted on the key dimensions and form and position tolerances of the parts (the sampling ratio shall be determined according to customer requirements and production batch, usually not less than 5%) to ensure that the dimensional accuracy meets the design requirements; Surface quality inspection can use visual inspection and magnifying glass observation to check whether there are scratches, indentations, oxidation, burrs and other defects on the surface of parts. For parts with extremely high requirements, optical microscope can be used for inspection. Mechanical properties inspection requires regular sampling inspection of tensile strength, yield strength, elongation and other indicators of parts to ensure that the mechanical properties of parts meet the requirements of use. At the same time, it is necessary to establish a quality traceability system, manage the number of each batch of parts, record the production batch, raw material batch, mold number, inspection results and other information, so as to facilitate the traceability and handling of subsequent quality problems.

VI. Cost Control and Efficiency Optimization: Balancing Quality and Benefit

On the premise of ensuring product quality, it is necessary to reduce production costs and improve production efficiency through process optimization and management improvement. In terms of process optimization, the cost of raw materials can be reduced by optimizing the layout scheme, improving the utilization rate of materials; Adopt automatic stamping production line (such as manipulator, automatic feeding device and automatic detection equipment) to reduce manual intervention and improve production efficiency (the production efficiency of automatic production line can be improved by 3~5 times compared with manual operation), and at the same time reduce quality fluctuation caused by human factors; Reasonably plan the production process, realize multi-process integration (for example, integrate stamping, bending, shaping and other processes into one production line), and shorten the production cycle.

In terms of management improvement, it is necessary to establish a lean production management system to reduce the waste in the production process (such as reducing the waste of scrap and reducing the rate of unqualified products); Strengthen supply chain management, establish long-term cooperative relations with high-quality raw material suppliers and mold suppliers, ensure the quality stability of raw materials and molds, and reduce procurement costs; Regularly train operators and technicians, improve employees' professional skills and quality awareness, and reduce production losses caused by operational errors. In addition, it is necessary to establish a cost accounting system, regularly analyze the unit cost of stamping processing (including raw material cost, die wear cost, equipment depreciation cost, labor cost, energy cost, etc.), identify the key points of cost control, and take targeted measures to reduce costs.

In a word, the stamping process of electronic product parts is a systematic project, which needs to be carefully managed from many links such as preliminary preparation, process control, mold maintenance, safe production and subsequent treatment. Only by strictly controlling every key node and balancing the relationship between quality, efficiency and cost can we produce parts that meet the requirements of high precision and high reliability of electronic products and win advantages for enterprises in the fierce market competition. With the continuous development of electronic technology, stamping technology is also developing in the direction of higher precision, higher efficiency and more environmental protection. Enterprises need to continue to pay attention to the technical trends of the industry, constantly optimize the process plan, upgrade equipment and facilities, and enhance their core competitiveness.