Evaluation of hardness and abrasion properties of grain mill blades

The mill is one of the equipments which used in agricultural products processing. Impact or hammer mills are used for crushing grain, animal feed and spices due to their simplicity and ease of operation. In these mills, the crushing operation is done by impacts from the blades to the grains. The movement of the blade in the grain, after a relatively short period of time, leads to wear and erosion on the impacting edge of the blade. Frequent replacement of blades requires cost and time, which reduces the efficiency of the device and increases the cost of the product. Therefore, in this study, the evaluation of mechanical properties of steels with different alloys is considered as a suitable alternative to existing hammer mill blades. For this purpose, the effect of blade material on four levels and the effect of heat treatment in two different cycles for each sample on the hardness and abrasion resistance indices were investigated by laboratory test and practical test. Hardness test and abrasion test were performed using a hardness tester and pin on disk method in the metallurgical laboratory of the Islamic Azad University of Majlesi branch. The practical test of the blades was performed by installing the blades on the rotor of the milling machine and measuring their amount of wear in terms of mass losses, after grinding 1800 tons of grain. The results showed that DIN X 210Cr12 steel with SPK brand after quenching heat treatment cycle in oil, has more hardness and higher abrasion resistance than other samples. Appearance examination of the blades in the practical test showed that the DIN X 210Cr12 steel blades with different heat treatment cycles has the least erosion at the impact edge of the blade and is recommended as a suitable replacement for current blades.