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HUALONG CASTING MATERIAL

Other Problems of Alkaline Phenolic Resin No-bake Sand Process

Release time:

2022-06-15 09:04

  In addition to the problems in the regeneration of used sand, the Alkaline phenolic resin no-bake sand process has some shortcomings. When this process is used, corresponding measures should be taken to obtain better results.

Alkaline phenolic resin

  1. The bonding strength of Alkaline phenolic resin no-bake sand is slightly lower

  Alkaline phenolic resin no-bake sand, the strength after hardening is slightly lower than that of furan resin no-bake sand, and the addition amount should be slightly more. The actual addition amount varies according to the requirements of the casting mold, generally between 1.3 and 1.8%.

  2. Residual resin film has certain hygroscopicity

  After the Alkaline phenolic resin self-hardening sand is regenerated, the residual resin film on the surface of the sand grains is hygroscopic. This feature has two functions: the advantage is that the bonding performance of the regenerated sand can be improved by adding water or other treatment agents; the disadvantage is that The reclaimed sand stored in the sand bucket in wet season is easy to adhere to the bucket wall.

  3. The alkalinity of reclaimed sand and the content of alkali metal salts in it should be strictly controlled

  The alkalinity of the reclaimed sand and the content of alkali metal salts in it are too high, which will affect the refractoriness of the molding sand and cause sand sticking defects on the surface of the casting.

  4. The cooling rate of the casting in the mold is low after the Alkaline phenolic resin self-hardening sand is poured

  The reasons for the low cooling rate of castings in the mold have been described. Therefore, the hot joints of steel castings are prone to defects such as shrinkage cavities and shrinkage porosity, which should be considered in the design of the process plan.

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