At sintering plants which process fused sinter, the l imestone is ground in hammer mills. The coarse l i m e stone entering the mil l is reduced by fr ict ion with the beater (hammers) and the fine fraction passes through the grate into a special bunker. The mater ia l is then screened, the 0-3 mm fraction going to the charge and the remainder being returned to the mil l . During operation, the beaters are subjected to abrasive act ion from contact with the l imestone, and dynamic stresses from impacts with pieces of mater ia l . In most plants, the beaters are buil t up manual ly using T590 and T-620 electrodes, or electrodes with a coat ing of stal ini te. This bui lding-up is very difficult and t imeconsuming. With manual building-up i t is diff icult to arrange that the weight of the restored components is the same, and the difference in the weight of the hammers leads to considerable imba lance in the rotor. Furthermore, manual bui lding-up does not provide sufficient durabi l i ty of the beaters. The bui l t -up layer often becomes pit ted during operation. In recent years, the Paton Zlectrowelding Insti tute of the Academy of Sciences of the Ukrainian SSR has developed a method for the automat ic bui lding-up of beaters in an annosphere of carbon dioxide, using direct current of reverse polar i ty with the A-537M automat ic machine, by the method of forced forming of the new metal . The section which is to be built up is surrounded on four sides by a copper form a mold, cooled by water. The mater ia l used was PP-U45Kh23G6T powder wire, fusing with the base meta l of steel 40-45 to give the following chemica l composit ion of the bui l t -up layer, %: C Cr Mn Ti 4.2 -4.7 21-28 3.5 -5.0 0.4-0.6 Before bui lding-up, each blank was heated to 550600 ~ The bui l t -up beaters were cooled slowly in the furnace. After building-up, the hardness was 84757 R c. The results of the Electrowelding Institute show that the l i fe of exper imental beaters buil t up by the gase lec t r ica l method is several t imes higher when grinding coal (compared with beaters buil t up manual ly by e l ec trodes with a s tal ini te coating). Owing to the fact that this method has not yet been extended to steel plants, i t is not yet possible to judge the durabi l i ty of beaters used for grinding flux. In steel plants, extensive use is made of heat t rea t ment to strengthen the beaters. Thus, at the Magnitogorsk t00-110 295