Common Raw Materials of Wax at Medium Temperature and Their Performance Differences

2022-07-27 15:14:39 442

Medium temperature wax is the key material for parison production in melt casting production, and its related properties have a great impact on the subsequent shell and molten metal products. The following are some relevant knowledge about China's medium temperature wax products:

There are three common raw materials for medium temperature wax: wax materials, resin materials and polymer polymers

I,

Wax material: it is opaque or translucent solid under normal temperature, with fixed melting point or narrow solidification temperature range, and low viscosity after melting. It can be divided into:

Mineral wax (such as paraffin wax, microcrystalline wax, paraffin wax, lignite wax, etc.).

Animal and vegetable wax (such as beeswax, insect wax, palm wax, etc.).

Artificial wax (such as stearic acid)

II,

Resin: refers to amorphous organic matter, which is a transparent brittle solid at room temperature, has no fixed melting point, and has high viscosity after melting. Rosin and its derivatives and other natural or artificial resins (such as petroleum resin, terpene resin, etc.) are commonly used.

III,

Polymer polymer (polymer): refers to a polymer with a molecular weight of more than 10000. Polyolefin is often used in investment casting, such as polyethylene, EVA, polystyrene, etc. Its mechanical properties are much stronger than wax, and its viscosity after melting is large.

Wax and resin are the basic components of the three ordinary materials, and polymer is the additive.

An investment casting mold is usually a mixture of two or more of the above raw materials in a certain proportion. The final goal of preparing die materials is to integrate the advantages of various raw materials and realize complementary advantages to meet the requirements of investment casting. It is worth emphasizing that the liquid without sediment should be the basic sign of qualified mold composition.

Appearance wax: appearance wax (wax pattern) wax, which can also be divided into wax based pattern material, resin based pattern material and filler pattern material

Wax based mold materials: represented by paraffin stearic acid and paraffin polyolefin. This kind of mold material has relatively simple composition and low cost. Generally, the liquid viscosity is small and easy to dewax and recycle. Wax paste is a multiphase system with good fluidity, but the quality and dimensional stability of wax pattern are poor. It is combined with sodium silicate shell process to produce products with low quality requirements.

Resin based mold material: This mold material is generally complex in composition and high in cost. Generally, the liquid viscosity is high, which is not conducive to dewaxing and recycling. The wax paste belongs to a uniform system with poor fluidity, but the wax pattern has good quality and dimensional stability. It is mainly used in conjunction with the silica sol or ethyl silicate shell process to produce military or commercial precision castings with high quality requirements. Most foreign molds belong to this type.

Filler molding material: a certain amount (20%)~40%) of insoluble solid powder or water is evenly mixed into the body of the above two types of molding materials as the filler to reduce the shrinkage and contraction of the wax mold, improve the strength, and improve the waxing process. However, the cost is high, the liquid viscosity is high, the dewaxing is difficult, and the recovery/regeneration is inconvenient. Usually, it can only be used once, and is mainly used for high-end products.

Water soluble mold materials: mold materials made of water soluble or dispersed materials, mainly used to make wax cores and form the inner cavities and holes of wax molds. There are two kinds of urea based and polyethylene glycol based. The former is cheap, usually free pouring molding, low efficiency, poor effect, mainly used for production with low requirements and simple shape; The latter is expensive and can be pressed into shape with high efficiency and good effect. It is mainly used to produce wax cores with high requirements and complex shapes.


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