In order to ensure the dimension accuracy of castings. We should try to reduce the deformation of the casting of pattern material as the following requirements.
- high heat resistance: the investment under a certain temperature will soften deformation, so the mold material’s thermal stability is good. Usually, heat temperature should be higher than the workplace above 10 ℃.
- The little shrinkage, and expansion rate, due to uneven thickness of casting parts, after a first cooling and contraction, mold will cause distortion, the greater the shrinkage, deformation, therefore requires smaller shrinkage pattern material. In addition, in order to prevent casting off the shell burst pattern material, therefore, requires little inflation rate.
- Mechanics performance is good: after solidification pattern material request has a certain strength, hardness, and toughness, in order to make the investment in the whole process of (operating, storage, handling) is not easy to damage. In addition, in order to ensure the smooth surface of the casting and the following requirements.
- Mold material with good thermal stability, chemical liquid, smearing; Less ash, shell in the basic no residue after roasting.
(5) melting point must be moderate, with good welding performance.
- The source is adequate, cheap, can use repeatedly, and harmless to the human body.
In actual production application at home and abroad and are working on has a variety of pattern material, its composition is also each is not identical.
There are two kinds of currently recognized classification methods.
The first kind is according to the high and low melting point pattern material.
We can divide it into a low melting point in the mold material, melting point, and high melting point dies material types. Also known as the low temperature in the mold material, WenMo materials, and high temperature die materials.
The second is the main composition and performance. We can divide it into pattern material (wax pattern material, rosin base mold, and other mold material).