Common casting methods for investment casting
The investment casting production line produced by Qingdao Xinyuanzhu Machinery Co., Ltd. has the advantages of high dimensional accuracy and good surface quality. It is a widely used advanced technology with little and no cutting. The fusible model is made of fusible materials, and the investment casting method can save a lot of machine tools and processing man-hours, and also greatly save metal raw materials. Compared with Self-setting sand casting, this sand casting equipment method effectively reduces costs and improves the competitiveness of casting enterprises. The most important step in investment casting is pouring, so what are the common pouring methods for investment casting?
1. Crystallization under pressure
Place the shell in the pressure tank for pouring. After the completion, immediately close the pressure tank, and pass high-pressure air or inert gas into the tank to solidify the casting under pressure to increase the density of the casting.
2. Vacuum suction pouring
Put the mold shell in the vacuum casting box, suck the gas in the cavity through the tiny pores in the mold shell, so that the liquid metal can better fill the cavity, copy the shape of the cavity, improve the accuracy of the casting, and prevent air holes and pouring. Insufficient defects. This method is more common abroad.
3. Directional crystallization
Some investment castings, such as turbine blades, magnets, etc., if their crystal structure is columnar crystals arranged in a certain direction, their working performance can be improved a lot, so investment casting oriented crystallization technology is rapidly being developed.
4. Thermal gravity pouring
This is the most widely used form of casting, that is, after the shell is taken out of the baking furnace, it is poured at high temperature. At this time, the metal cools slowly in the mold shell, and the mold can be filled with high fluidity. Therefore, the casting can replicate the shape of the cavity well and improve the accuracy of the casting. However, the slow cooling of the casting in the hot mold will make the crystal grains coarse, which reduces the mechanical properties of the casting. When casting carbon steel castings, the surface of the castings with slow cooling is also easy to oxidize and decarburize, thereby reducing the surface hardness, smoothness and dimensional accuracy of the castings.
The pouring of investment casting is a strict step, and different pouring methods have different characteristics. Therefore, in the investment casting process, a suitable pouring method must be selected to cast a good melt.