Study Of Fine Blanking Die Life Under The Influence Of Tool Steel And Surface Coatings

Fine Blanking is a high-efficiency, high-quality and high value-added precisionplastic forming process, which could obtain high-quality parts. However, with thedevelopment of the fine blanking, the die life becomes an obstacle to the developmentof fine blanking industry. Therefore, it is very significant to comprehensively analyze themain factors affecting the die life for resolving the problem of low die life. Meanwhile,ANSYS Workbench was used to make a structure analysis of mold, and the results showedthere was stress concentration, which caused die failure, due to the irrational structure.Firstly, based on Pallet mold, SKD11, QHZ and S790were used to produce thepunchs with same size. With the comparison of material properties and actual punching,the impacts of tool steels on the die life were comprehensively analyzed. The resultsshowed that the hardness and toughness of tool steels determined the die life, when thecompressive strength met the requirements.Secondly, some test equipments were used to analyze the impacts of coatingthickness on the properties of TiN and TiAlN coatings, such as hardness, texture andresidual stress. Meanwhile, the impacts of coatings on substrate were comprehensivelyanalyzed. The hardness of both TiN and TiAlN coatings increased with the film thickness.The residual stress of TiN coatings was ranging from-2347MPa to-1920MPa, and thestress of substrates was ranging from-154.9MPa to-69.21MPa, which both increasedwith the film thickness. As to the TiAlN coatings, the residual stress of the substrates wasbetween-123.7MPa and469MPa. Majority of the stress were tensile stress, which impacton the life of dies, increasing with the film thickness. Additionally, TiNand TiAlN coatings improved the surface friction coefficient of the sample surface,but had no significant effect on surface roughness.Finally, the Pallet mold was used to carry on punching test, in order to analyze theimpacts of TiAlN coatings on the die life. In the test, except the life and wear volume of the die, the quality of stamping parts were measured and recorded. However, because ofthe low guiding precision of the test press, the TiAlN coating peeled off early and did notplay advanced performance.