The contraction of wear resistant steel castings by various obstacles.Some resistance from mold, core, some is due to the obstacles caused by the casting structure itself.Casting shrinkage with casting size, wall thickness and structure of the complex degree of different and different, in casting diverge in all directions.Wear-resistant steel hard processing, are not usually use processing or assembling.Casting size deviation, the error of the flatness influence assembly use.Just because of the size deviation, cast hole size deviation is likely to make the casting scrap, etc.So how to get in line with the size deviation of castings, accurately control the shrinkage of casting is an important issue.Therefore must study the law of size shrinkage, determine the necessary technical parameters as a basis for production technology.Wear resistant steel castings in sand mold casting under the condition of casting shrinkage rate of 2.6% 2.7%, but it varies with the different of casting size and thickness change.Wall thickness, metal stronger heat action of mold, casting mold material heated lose strength of casting shrinkage resistance decreased, casting in the cast have greater shrinkage, shrinkage rate is high.Vice shrinkage value is low.Casting size is larger, the contract is hampered by mold and casting itself is larger, less shrinkage.Whereas shape simple small shrinkage rate is high.