Under normal circumstances, the standard precision of precision casting processing is affected by factors such as casting structure, casting material, mold, casing, baking, casting, etc. The setting and unreasonable operation of any link will shorten the angle of attack of the casting, and the precision Casting processing methods lead to standard accuracy and begging errors of castings. The following are elements that can form standard precision defects in precision casting:

(1) Influence of casting structure: a. Casting wall thickness, large reduction rate, thin casting wall, small reduction rate. B. The reduction rate is high, and the reduction rate is prevented from being small.

(2) Influence of casting materials: The higher the carbon content of the material, the smaller the shortening rate of the wire, and the lower the carbon content, the greater the shortening rate of the wire. b. The casting shortening rate of the material is as follows: The shortening rate of the casting is k = (lm-LJ) / ljx100%, lm is the cavity standard, and LJ is the casting standard. K is affected by the following factors: wax mold K1, casting structure K2, alloy type K3, casting temperature K4.

(3) The influence of mold making on the linear shortening rate of precision casting castings: The most obvious influence of wax temperature, wax pressure and holding time on the investment standard is the temperature of the wax, followed by the spraying of the wax. The pressure guarantees the time after the investment is formed, ensuring all the influences, and the standard is very small. The wire shortening rate of the wax (mold) material is about 0.9-1.1%. c. Melt mode storage, which will be further reduced, reduces the total value by approximately 10%, but when stored for 12 hours, the standard of the fusion model is stable. d. The radial shortening rate of the wax pattern is only the $number of the length shortening rate. The effect of the wax temperature on the leisure shortening rate is far greater than the blocking shortening rate (the optimum wax temperature is 57-59 ° C. The higher the temperature, the reduction amount The bigger.

(4) Influence of shell data: Zircon sand, zircon powder, sanding and paving are selected. Because of its small expansion coefficient, it can only be 4.6x10-6/°C, so it can be ignored.

(5) Effect of shell roasting: Since the expansion coefficient of the shell is small, when the shell temperature is 1150 ° C, it is only 0.053%, so it can be ignored.

(6) Effect of pouring temperature: The higher the pouring temperature, the higher the shortening rate, the lower the pouring temperature, the smaller the shortening rate, and the better the pouring temperature.

Investment casting is a fusible material made of specially designed refractory coatings. After drying and hardening to form a single-piece shell, the mold is melted from the shell by steam or hot water, and then the shell is placed in a sand box, filled with dry sand in the vicinity, and finally the mold is placed in a roaster. At high temperatures, the casting or casing is baked and the molten metal is poured into the casting.

Precision casting processing method

Investment in precision casting, fine, messy, close to the final shape of the parts, processing without direct processing or direct use is very small, is the leading skill of the near net form, the forging industry is a very good skill and skill, its use is very extensive. It is not only suitable for forging of various types and various alloys, but also for producing castings with high dimensional accuracy, higher surface quality than other forging methods, and even other forging methods that are difficult to cast, high temperature, and difficult to process castings. Selection in precision forging casting.

Nowadays, the world's investment precision forging technology is developing rapidly and has a wide range of applications. From the current situation, the development trend of this technology in the future is that the casting products are closer to the parts, and the traditional precision casting is processed into blanks, which are not adapted quickly. Market pressure. The level and quality of parts and components of goods are getting higher and higher, and development is becoming more and more powerful. Professional collaboration begins to flash, CAD, CAM, and CAE, and becomes a major component of product development.

From the current development situation analysis, investment casting technology has broad application prospects in use.