What is a casting mold - the types of casting molds and the differences between them

Casting mold - definition

Casting mold is a chamber that is embedded in materials such as sand, plaster, metal and , so that the melt after filling this chamber and freezing in it, takes the shape of the chamber. The mold is so important in casting that it can be said that it is possible to make a healthy casting piece with the desired specifications by using a suitable mold. In general, from a metallurgical and economic point of view, the molds are divided into permanent and temporary categories.

Permanent templates

Molds that are frequently used in the manufacture of castings are called permanent molds. The material of these molds is metal and is usually made of cast iron, steel and bronze. The choice of mold material is based on such things as the high melting point of the mold material compared to metal or cast alloy, having the least dimensional changes and the desired abrasion resistance. Permanent molds may be made by casting and then machined and polished to achieve the final dimensions. These molds are commonly used to make parts from metals and non-ferrous alloys such as aluminum, magnesium, zinc, lead, copper and their alloys, as well as to make parts from cast iron.

Advantages:

High production speed, dimensional accuracy and also creating desirable metallurgical specifications.

Limitations: Limitations of using permanent molds include high molding costs, unsuitable for casting metals with high melting points, such as steels, uneconomical production of large and small parts, and complex shapes.

Permanent molds are divided into three categories in terms of filling with melt: gravel, gravity or weight, under pressure and centrifugal pressure.

Temporary templates

Molds that break down after each casting as the piece is removed are called temporary molds. These molds, whose constituents are generally in the form of a mixture of refractory sand particles; Adhesives and other materials can be made in three ways:

By pounding and compacting a wet mixture around the model; By applying a free-flowing mixture to the dry around the shell molding model; By freely releasing the mixture as a liquid slurry around the precision molding model.

In general, the method of making the mold and the equipment required for this work were determined according to the molding materials. For example, in wet sand molding, which is one of the oldest molding methods, a mixture of sand molding including sand, glue, water and additives is used to prepare the mold.