Why choose resin sand in sand casting molding?

Resin sand is molding sand prepared with resin as a binding agent. The use of resin as a binder for molding sand is a major change in the sand casting process. Since its inception, this method has attracted the attention of the foundry industry and has developed rapidly. As a binder for casting sand, the variety and quality of resins are increasing to meet the requirements of various casting alloys. Due to the use of resin sand, many new molding processes have emerged, such as shell core, hot core box, cold core box, self-hardening sand core, etc. The production of resin sand has become one of the basic conditions for mass production of high-quality castings. In single-piece and mass-production sand casting workshops, the use of resin sand to make sand cores and sand molds is a common technology, which has developed particularly rapidly in recent years.

The main advantages of resin sand compared to other molding sands are:

1. The castings have good surface quality and high dimensional accuracy;

2. No need for drying, shortening the production cycle,

3. Save energy; The resin sand mold (core) has high strength, good air permeability, few casting defects, and low scrap rate;

4. Resin sand has good fluidity and is easy to compact;

5. It has good disintegration properties and is easy to shake off and clean, greatly reducing labor intensity.

But the main disadvantages of resin sand are:

1. Since the size, shape, sulfur dioxide content and alkaline compounds of raw sand have a greater impact on the performance of resin sand, the requirements for raw sand are higher;

2. The temperature and humidity of the working environment have a great influence on the hardening speed and hardening strength of resin sand;

3. Compared with inorganic binders, resin sand has a larger gas generation capacity;

4. Resins and catalysts have pungent odors and require good ventilation in the workshop;

5. Resin prices are higher.

The most widely used resin sand is furan resin self-hardening sand. Furan resin is based on furfuryl alcohol and is named after its unique furan ring in its structure. Judging from its basic structure, there are furfuryl alcohol furan resin, urea-formaldehyde furan resin, phenolic furan resin and formaldehyde furan resin. Furan resin is often used as a binder when preparing resin self-hardening sand in production. Furan resin for self-hardening sand has a higher furfuryl alcohol content, improved resin storage performance and high thermal strength, but the cost increases.

Furan resin self-hardening sand refers to molding sand in which the furan resin binder undergoes a chemical reaction under the action of a catalyst and solidifies at room temperature. Furan resin sand is generally composed of raw sand, furan resin, catalysts, additives, etc. The quality and performance of various raw materials will have a great impact on the performance of resin sand and the quality of castings. Therefore, it is necessary to correctly select the various raw materials of resin sand. .