The Benefits of Resin Coated Sand in Foundry Applications

 

Resin coated sand is an excellent choice for foundry applications. The high performance and durability of this product is made possible by adding an environmentally friendly hardener, Hexamethylenetetramine (HMETM), along with a lubricant such as Calcium stearate. It is also available in various coating systems and can be custom mixed to meet specific specifications. HA-International provides customized resin coated sand formulations.

Using a special resin composition, sand particles are coated with a phenol formaldehyde-based polymer. The sand is heated and a foaming agent is added to the mixture. When this happens, the sand particles will expand. When the sand is cooled, these resin coated sand particles are then charged into a metal mold and heated at 250degC for 60 seconds. This process produces a 10mm x 60mm test piece with a bending strength between 70 and 75 Kg/cm2.

Among the benefits of resin coated sand is its durability and high strength. It is highly resistant to rust and is ideal for small and medium steel castings. The resin-coated sand particles are significantly stronger than the ordinary ones and their break-down strength is much higher than ordinary sand. In addition, they produce a lower amount of ammonia and formaldehyde than ordinary sand.

Western Foundry Products, a subsidiary of Western Minerals & Mill Stores, manufactures RESIN COATED SAND with an excellent performance track record. The material is an accurate and effective method for foundry practices. The shell molding process is the most precise way to obtain a smooth surface and free of blow holes and casting defects. When using this product in your foundry, it is vital to understand the underlying science behind this innovative and sustainable technology.

The process of generating resin coated sand has two main advantages. The first one is the low gassing sand. This type is made from sand with a high strength low gassing. The second type of resin coated sand is the high strength low gassing version. This is mainly used in middle and small-sized steel castings. However, if you are concerned about the environmental impact, you can choose the low gassing version.

This method is based on two different types of resin. A foaming agent is applied to sand particles. A sand particle coated with foaming agent is significantly stronger than a sand without foaming agent. The resin is mixed with the sand and heated to a temperature higher than the melting point of the resin. The resin coating will form a layer on the sand particles. The sand is then heated to a temperature higher than the resin melting point.

In a preferred embodiment of this invention, a resol resin composition was prepared by the condensation reaction of phenol and formaldehyde. This resin composition was then added to sand particles that were heated to a melting point of about 150 degrees Celsius. The resulting sand was coated with a thin layer of resin. These layers will provide the sand with a high level of durability and corrosion resistance.