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• Time of issue:2023-01-04 15:01
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(Summary description)At present, the global investment casting forming process is developing rapidly and widely used. From the current situation, the future development trend of this process is that casting products are increasingly close to component products, and traditional precision castings are only used as blanks, which is no longer suitable for the rapid changes in the market. The complexity and quality level of component products are increasing, and research and development methods are becoming stronger. Professional collaboration is beginning to emerge, and the application of CAD, CAM, and CAE has become the main technology for component product development. From the current development situation analysis, the application of casting technology is very extensive, and its future development prospects are quite broad. Today, foundry Dongrong Machinery will have a detailed discussion with you about the factors that affect the accuracy of castings: In general, the dimensional accuracy of precision castings is influenced by various factors such as casting structure, casting material, mold making, shell making, roasting, pouring, etc. Any unreasonable setting or operation of any link can cause changes in the shrinkage rate of the castings, leading to deviations from the requirements for dimensional accuracy of the castings. The following are the factors that can cause dimensional accuracy defects in precision castings: (1) The impact of precision casting structure: a. Casting wall thickness, high shrinkage rate, thin casting wall, low shrinkage rate. b. The free shrinkage rate is high, while the hindrance shrinkage rate is low. (2) The impact of precision casting materials: a. The higher the carbon content in the material, the smaller the linear shrinkage rate. The lower the carbon content, the greater the linear shrinkage rate. b. The casting shrinkage rate of common materials is as follows: casting shrinkage rate K=(LM LJ)/LJ × 99.9%, LM is the cavity size, and LJ is the casting size. K is influenced by the following factors: wax mold K1, casting structure K2, alloy type K3, and pouring temperature K4. (3) The influence of mold making on the linear shrinkage rate of precision castings: a. The influence of wax injection temperature, wax injection pressure, and pressure holding time on the size of the investment mold is obvious in wax injection temperature, followed by wax injection pressure. The pressure holding time has little effect on the final size of the investment mold Z after ensuring investment molding. b. The linear shrinkage rate of wax (mold) material is about 0.9-1.1%. c. When the mold is stored, further shrinkage will occur, with a shrinkage value of about 10% of the total shrinkage. However, after 12 hours of storage, the size of the mold is basically stable. d. The radial shrinkage rate of wax molds is only 30-40% of the shrinkage rate in the length direction, and the influence of wax injection temperature on the free shrinkage rate is much greater than that on the hindered shrinkage rate (the optimal wax injection temperature is 57-59 ℃, and the higher the temperature, the greater the shrinkage).