Precision die casting
Precision die casting is an advanced die-casting process that combines high precision, high speed, and high density. Its core goal is to achieve near-net-shape die-cast parts by precisely controlling injection parameters, mold temperature, and molten metal conditions, significantly reducing subsequent processing costs. This process, based on traditional die casting, incorporates a real-time monitoring and adaptive adjustment system that dynamically optimizes process parameters for die-cast parts of varying structures. It is particularly suitable for the production of precision parts with stringent requirements for dimensional accuracy and surface quality.
The key technology behind precision die-casting lies in the precise control of the injection system, which directly determines the stability of the filling process. The injection system utilizes a servo motor drive, coupled with high-precision pressure sensors (±0.1 MPa accuracy) and displacement sensors (±0.01 mm accuracy), enabling stepless adjustment of injection speed and pressure. The filling phase is divided into three intervals: low-speed advance (0.2-0.5 m/s) to prevent molten metal splashing; medium-speed transition (1-3 m/s) to prevent air entrapment; and high-speed filling (5-20 m/s) to ensure full filling of complex cavities. The entire process has a response time of ≤0.01 seconds, and the speed can be adjusted in real time based on changes in cavity pressure. For example, if a sudden increase in localized pressure is detected, the filling speed in that area is automatically reduced to reduce stress concentration. This dynamic adjustment capability enables die-cast parts to maintain dimensional tolerances within IT5-IT7, far exceeding the IT8-IT10 of conventional die-casting.
Mold design and temperature control systems are another core element of precision die-casting. The mold adopts a modular structure, and the cavity surface is ultra-finely ground (Ra ≤ 0.4μm) and nitrided (hardness ≥ 65HRC) to improve wear resistance and surface accuracy. The cooling system uses independent zone control, with each zone equipped with a flow sensor and temperature probe. The coolant flow rate is adjusted using a PID algorithm (accuracy ±1L/h), keeping the temperature difference between different parts of the mold within ±5°C. For thin-walled complex parts (wall thickness 0.5-2mm), a high-frequency induction heating coil is embedded in the mold to instantly raise the local temperature by 30-50°C before filling to prevent the molten metal from quenching. In addition, the mold’s guiding accuracy reaches 0.005mm/m, and with precision locating pins (clearance ≤ 0.003mm), the cavity misalignment during mold closing is ensured to be ≤ 0.01mm, avoiding the formation of flash.
The quality advantages of precision die-casting are reflected in many aspects. Due to smooth filling and precise temperature control, the density of die-castings can reach over 99.8%, and the internal porosity is ≤0.1%, fully meeting the airtightness requirements of hydraulic components (no leakage under a pressure of 10MPa). In terms of mechanical properties , through grain refinement (average particle size 5-10μm), the tensile strength of aluminum alloy die-castings is increased to 350-400MPa, and the elongation reaches 12%-18%, which can be directly used in structural parts bearing dynamic loads. In terms of surface quality, the flatness of die-castings is ≤0.02mm/m, and they can be electroplated or anodized without polishing, and the bonding strength of the coating is increased by more than 30%. In terms of dimensional stability, the aging deformation of precision die-castings is ≤0.01mm/m, which is far lower than the 0.05mm/m of traditional die-castings, making them suitable for precision assembly scenarios.
The application areas of precision die-casting are concentrated in high-end manufacturing. In the automotive industry, it is used to produce transmission valve bodies and core components of EPS steering gears, with dimensional accuracy reaching ±0.02mm and assembly clearance controlled at 0.05-0.1mm, significantly reducing noise and wear. In the 3C industry, the filter housings of 5G base stations are precision die-cast. The complex internal cavity structure and flange surface are molded in one step, with a flatness of ≤0.03mm, ensuring signal transmission efficiency. In the medical device field, precision interlocking components of surgical instruments are produced using this process, with dimensional tolerances of ±0.01mm and a surface roughness of Ra0.2μm, meeting sterility and wear resistance requirements. With the development of new energy vehicles, precision die-casting is being used for high-precision parts such as motor end covers and battery terminals. Through integrated molding, the number of parts is reduced and system reliability is improved. In the future, with the introduction of intelligent algorithms, precision die-casting will achieve full-process adaptive control, further expanding its application in cutting-edge fields such as aerospace.
