投资铸造过程的步骤|的优点和缺点
Investment Casting Process
The investment casting process, which is commonly referred to as the “lost wax method”, originated in and around the fourth millennium B.C. It is evidenced through the architectural works found in the form of idols, pectorals and jewelry in remains of the ancient Egypt and Mesopotamia. The investment casting process initiates with the production of wax replicas or patterns of the required shape of castings. Each and every casting requires a pattern to be produced. Wax or polystyrene is made used as the injecting material. The assembly of large number of patterns are made and attached to a wax sprue centrally. Metallic dies are used to prepare the patterns. The pattern is immersed in refractory slurry which completely surrounds it and gets set at room temperature forming the mold.
The mold is further heated, so that the pattern melts and flows out, leaving the required cavity behind. After heating, the mold gets further hardened and molten metal is poured while it is still hot. After the casting gets solidified, the mold is broken and it is taken out.
Step Involved In Investment Casting :
投资铸造过程的基本步骤如图所示：
1. Preparing the heat-disposable wax, plastic or polystyrene patterns in a die.
2. Assembly of the prepared patterns onto a gating system
3. “Investing,” (covering) the pattern assembly with a refractory slurry which builds the shell.
4. Melting the pattern assembly (burning out the wax) by firing, for removing the traces of the pattern material
5. The metal in molten state is poured into the formed mold.
6. Once the metal solidifies, the shell is removed (knocked out).
7. Fettling (cutting off) of the pouring basin and gates followed by finishing operations to get the desired dimensional tolerances and finish.
投资铸造的优势
1. Many Intricate forms with undercuts can be cast.
2. A very smooth surface is obtained with no parting line.
3. Dimensional accuracy is good.
4.某些无法切换的零件可以施放以预先计划的形状。
5. It may be used to replace die casting where short runs are involved.
6.出色的表面饰面
7.Almost any metal can be cast
Disadvantages of investment casting
1. This process is expensive, is usually limited to small casting, and presents some difficulties where cores are involved.
2.孔不能小于1/16英寸（1.6毫米），并且不应深入直径的1.5倍。
3. investment castings require very long production cycle times versus other casting processes.
4. This process is practically infeasible for high volume manufacturing, due to its high cost and long cycle times.
5.如果适当地应用了不涉及投资铸件的缺点的现有过程，则可以通过其他铸造技术实现投资铸造过程的许多优势。
6.可能很难施放需要内核的物体。
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早上好。我有一个查询。为什么不能完成投资铸造的孔比2次更深的洞？
sorry dia not dai