Qingdao Hezhi Machinery Co.,Ltd
As a traditional casting process, clay sand casting is restricted by factors such as environmental pollution, waste of resources, quality defects of castings, and high production costs. Therefore, it has become the first choice for reform and change in the casting industry, so our Hezhi machinery company chose A new type of coated sand casting process has been developed to replace clay sand casting.
Coated sand casting is a casting process in which the core box surface is covered with a layer of coated sand mixed with phenolic resin during molding and core making, and is heated and hardened into a shell. This modeling process has the following advantages:
1. Small pollution: the work site environment has improved significantly. Because the addition of a large proportion of combustible coal powder to the clay sand is mainly used to increase the appearance quality and permeability of the workpiece, the coal powder cannot be reused in the sand, resulting in waste of resources. The ash content after burning has a great impact on the quality of our working environment. At the same time, the reducing gas and PM2.5 produced during combustion cause serious pollution to the atmosphere. Although the molding method mainly based on coated sand also has a certain impact on the environment, after all, it uses less sand, and at the same time, all the used sand is recycled. The work site is clean and free of dust pollution.
2. Thin sand coating layer and low dosage: low production cost and low waste. The used molding sand can be recycled. Due to the thin sand coating layer, the sand coating layer is usually designed to be 5-10㎜ according to the wall thickness of the workpiece, and the minimum sand coverage of clay sand modeling is also 30-50㎝. . Although the clay sand can also be recycled for a second time, the additional raw materials such as high-weight pulverized coal and bentonite have been basically consumed, and the quality of the sand has been greatly reduced, affecting the appearance quality of the product. After the high-temperature roasting of the molding sand with film-coated sand, the expansion volume is greatly reduced, and the process steps of pickling are reduced during the secondary use. At the same time, the addition of solid resin and curing agent is also greatly reduced, which reduces the production cost.
3. Change the appearance quality of the blank, reduce the chip residue, the process yield is high, and the quality is stable. Due to the low hardness and high yield of clay sand modeling sand, the casting defects such as cast box expansion, sand dropping, porosity and shrinkage are serious, which not only causes poor product appearance, but also has many internal casting defects, which seriously affect the product Long service life and high scrap rate. The aggregates in the coated sand modeling are pickled or roasted at high temperature, which reduces the expansion of the sand mold after combustion. After curing, the sand mold has high strength and small gas evolution. It has many advantages. The appearance quality, inherent casting defects, and accuracy to product size are far superior to those produced by clay sand modeling.
4. Improve the inherent quality of the product. Due to the fast cooling speed during the casting of the coated sand, the graphite form of the casting is greatly improved, the mechanical properties of the product are improved, and the service life of the product is increased. The products produced by coated sand molding, especially nodular cast iron, are far superior to the products produced by clay sand molding regardless of the spheroidization level, matrix structure, hardness, tensile strength, yield strength, etc. Implicitly improves the inherent quality of the product. The service life of the product is increased, which indirectly provides a strong guarantee to meet customer needs.
5. The shape of coated sand adopts automatic production line to improve the production efficiency, reduce the labor intensity of workers and shorten the labor time. The traditional clay sand modeling uses manual molding or molding machine molding, the labor intensity of workers is large, and the work efficiency is low, which is 1/3 to 1/4 of the molding efficiency of the production line.