Application of a Composite Hot Shearing Tool Manufactured by Co-Spray Forming

In modern manufacture, like in automotive industry, high quality products and high output rates as well as low costs are achieved by highly efficient processes. Optimized tool design represents a key factor for such processes, leading to long tool life and hence to low tooling costs. Early in the industrial manufacturing chain of roller bearings for example, hot bars are sheared into billets, which are subsequently transported automatically to the first forming stage of a press. The shear blades should have a high wear resistance at high temperatures. In this study the first bi-metal composite shear blade made by spray-forming has been developed and tested in industrial environment. The composite tool has been deposited in a co-spray forming process to directly combine a hard-facing alloy layer with a hot working steel body in order to take advantage of the high microstructural homogeneity and the low segregation generated in spray forming. After machining, heat treating and quality inspection of the new material composite, the hot working tool was used in manufacture to prove its wear resistance and durability. The results show that the interface properties of the composite are of high quality and the material has a lower vulnerability to cracks after use in production than the conventional tool, respectively material. Only the porous zone near the interface leads to fissures which are partially going deep into the tool. Hence the parameters of the co-spray forming process need to be improved.