In order to reduce the production cost of small to medium steel castings in automatic production line of ester hardened sodium silicate and eliminate the series quality problems of traditional sand casting products, a general lean casting method for small to medium steel castings was proposed, which can be used to produce high quality castings with multiple types and small batch. Production results show that this method can effectively reduce costs foundry tooling, pattern management site and transportation, reduce the risk of pattern transportation and handling safety, and satisfy the customers’ requirement of short leading time