Net/Gross yield optimization on high value-added steel casting

The manufacturing of cast steel components presents numerous improvement opportunities in a whole range of materials, from manganese steels to nickel based alloys, with a high level of complexity and a large amount of critical requirements. Among all the possible advances, this paper focuses exclusively on the optimization of the production yield, defined as the ratio between the weight of the cast part itself and the total amount of metal poured into the mold (net weight/gross weight ratio = yield).

Most of the companies belonging to the cast steel component manufacturing sector have utilized, in different degrees, casting process simulation tools that are currently available in the market. Jobbing shops, or producers of short production runs, make up a key segment of the steel casting industry. The aforementioned simulation software can be used by these metal casters as a tool to provide a low risk and a low cost review of the existing patterns, in such a way that the “traditional design criteria” of the feeding systems can be submitted to optimization strategies, focusing mainly on yield.

The work presented in this paper is based on an intensive review of the feeding systems that are currently employed in the manufacturing of cast steel components, where special attention is paid to yield optimization due to its direct and significant influence on the manufacturing costs.

This work has been developed from a complex variable matrix that takes into account the materials to be cast (liquid state metallurgy and solidification), the novel state-of-the-art feeding systems (core-sleeves, paddingsleeves and Exactcast™ mini-risers patented by ASK Chemicals) and some advanced feeding concepts (thermal modulus, volume minimization and feeding distance).

The industrialization stage has been performed together at the facilities of ASK Chemicals and in several foundries, particularly at FONDESAL, leading to yield levels over 60% in parts subjected to radiographic controls. The R&D Project named “SUPERALLOY” serves as basis for this paper, where the main achieved results are published, new feeder designs and compositions are proposed and the latest news regarding the feeding systems of the near future are presented.