Comparative Analysis of the Wear of NC11LV and Hardox 600 Steel Used in Tools for Extrusion of Clay Strands in the Process of Producing Ceramic Roof Tiles

This article presents the results of a comparative analysis performed with respect to the wear of tools used for the extrusion of a clay strand (for ceramic roof tile) made from two materials: steel NC11LV and steel Hardox 600. The aim of the studies was to determine the causes and mechanisms of wear as well as to evaluate the possibility of choosing the optimal material, mostly in respect to its resistance to intensive wear as well as an increase in the operation time. The results of the conducted investigations included: an analysis of the technology, thermovision measurements of the forming process, a macroscopic analysis combined with 3D scanning of the worn tools, ball-on-disc tests of the sliding wear resistance and hardness measurements. The obtained results demonstrated that the tools made of steel NC11LV were much less worn than those made of steel Hardox 600, as the operation time for the NC11LV steel tools was almost three times longer. The results of the ball-on-disc tests showed a similar manner of wear for both materials (with the working temperature of about 50 °C). The higher durability of the tools made from steel NC11LV can be an effect of a slightly lower coefficient of friction in the initial period of operation as well as the presence of hard carbides, which means increased hardness and thus also higher wear resistance at working temperatures.