What is ester hardened alkaline phenolic resin self-hardening sand?
Ester hardening alkaline phenolic resin self-hardening sand is a kind of self-hardening sand process developed by British Burton company in the 1980s.
Advantages of ester hardened alkaline phenolic resin self-hardening sand
The alkali phenolic resin self-hardening sand has the following characteristics besides the good collapsibility, fast hardening speed and adjustable service time in a large range of common resin self-hardening sand:
1. There are few defects of sulphuration and needle like pores in the surface layer of steel castings.
2. Toxic and pungent gases are rarely released during production.
3. It has obvious secondary hardening process and significantly reduces the hot cracking tendency.
Defects of ester hardened alkaline phenolic resin self-hardening sand
Of course, this process also has some problems:
1. The specific strength of alkaline phenolic resin is relatively low, and the amount of resin added in molding sand is large, which leads to high production cost. Especially when silica sand is used, the resin addition is sometimes as high as 1.8%.
2. The regeneration performance of used sand is poor. When using general mechanical regeneration equipment, the regeneration rate of furan resin used sand can generally reach more than 96%, while the regeneration rate of alkaline phenolic resin used sand can only reach about 70 ~ 80%, which increases the amount of new sand, increases the discharge of old sand, increases the cost and pollutes the environment.
3. Silica sand has high crushing rate, and its dust is harmful, which is easy to cause workers to suffer from silicosis.
4. The silica sand has low fire resistance, the casting is easy to stick to sand, and the surface quality of the casting is poor, which increases the cleaning workload.
Technological advantages of Fused ceramic sand alkali phenolic resin self-hardening sand
For a period of time, some foundry enterprises need to use a large amount of chromite sand as surface sand due to the increasingly high price of sand for cast steel and the difficulty in purchasing. At the same time, the discharge of used sand is subject to increasingly stringent restrictions, and new process methods are needed to solve the rising cost of castings and the increasing pressure of environmental protection. Fused ceramic sand alkali phenolic resin self -hardening sand has become a useful choice.
In order to give full play to the advantages of the alkaline phenolic resin self-hardening sand process and overcome its shortcomings, foundry workers have made remarkable achievements in the modification of resin/curing agent system, the use of special sand (such as Fused ceramic sand), and the improvement of the old sand recycling process and equipment over the years, so that this process can significantly reduce the production cost at the same time, Reliable steel castings can be produced in an environmentally friendly manner.
The practice in recent years shows that compared with silica sand, fused ceramic sand alkaline phenolic resin sand has achieved the following remarkable results:
1. Reduce the amount of resin added by 30 ~ 50%, and reduce the material cost.
2. With powerful mechanical regeneration, the regeneration rate can reach more than 97%, reducing the discharge of old sand, realizing green casting, and reducing the purchase of new sand.
3. The use of Fused ceramic sand for molding and core making has greatly improved the dimensional accuracy of the core, the dimensional accuracy of the casting and the utilization rate of metal materials;
4. The sand sticking of castings is reduced and the surface quality of castings is improved.
5. Single sand production improves production efficiency and reduces material costs.
6. Significantly reduce the workload and costs of sand falling, cleaning and grinding, improve labor efficiency and reduce labor costs (some customers use fused ceramic sand to reduce the cleaning workload by 60%).