Secrets of Molded Shell Roasting

Secrets of Molded Shell Roasting

Original He Weifeng Precision casting everyone talk April 03, 2019 20:29

Mold shell is of course silica sol mold shell, then what is the secret that, listen to me slowly. 1, the thickness of the mold shell. This is the most critical factor in mold shell roasting. Mold shell roasting two major factors: roasting temperature and roasting time. Who decides, is the thickness of the mold shell. The greater the thickness, the longer the roasting time and the higher the roasting temperature. Of course, everything has to be within reasonable limits. Generally speaking, silica gel mold shells are roasted at a temperature of about 900 - 1050 degrees Celsius. Then in the case of thicker mold shells, the temperature has to go to the upper limit, and the time may be around 1.5 - 2 hours. So where is the thin mold shell? Roasting temperature is also related to the structure of the product, thin-walled parts of the roasting temperature should be high, especially out of the temperature should be high, so as not to casting under injection, pouring not. Then the general wall thickness that, but also concerned about the structure of the product, in order to determine a reasonable mold shell roasting temperature. 2, mold shell refractory materials used. Refractory material is good or bad, also determines the baking temperature. To give a practical example: I used to be in charge of a foreign company dry golf head, is 17 - 4 material, wall thickness of 0.6-0.8mm, it is difficult to mold. The original use of Taiwan's mullite, roasting temperature can reach 1100 degrees Celsius. However, after changing to another material, the mold shell broke directly from the gate. 3、The difference between the baking temperature of the mold shell and the discharge temperature. Generally enterprises set these two temperatures as one temperature. Employees can operate well, and records can also be made. But in practice I found that this should actually be two temperatures, the former should be greater than or equal to the latter. The former to ensure that the shell of the baking results, is not the mold shell burned, burned through; the latter determines the molding of the product as well as the quality of the product. In practice, I thought the roasting curve is like the heat treatment curve of the two platforms. 4, the surface condition of the mold shell. In addition to the thickness of the mold shell, the surface condition of the mold shell is also very important. Sometimes there are shrinkage holes, shrinkage loosening, air holes on the casting, and you can't find the reason. Please take a close look at the surface of your mold shell. There is no mold shell gap blocked case; there is no pulp after the mold shell surface can not see sand, all powder, these are very dangerous signals, if the mold shell roasting temperature, time is not appropriate, the casting will certainly appear you unexpected problems. 5, the purpose of the mold shell roasting. The purpose of the mold shell roasting is to burn off the free water and combined water in the mold shell, so that the mold shell has a high temperature strength, remember that there is one more thing, that is, to make the mold shell air permeability becomes good. As in the case of Article 4, the solution is to raise the roasting temperature and increase the roasting time. So after saying so much, do you think there is a secret inside the mold shell roasting? I hope you can decipher the secrets of the casting sea through practice.