Hammer wear represents a substantial operating element and expense of size reduction of solid waste. Wear of other parts, such as the rotor and wear plates, also represents a cost, but to a somewhat lesser degree than that associated with hammer wear. However, wear and its associated costs can be controlled if the properties of the waste, operating characteristics of the sizereduction device, and metallurgy of the hammers and other wearing surfaces are taken into consideration.
Selection of the base (parent) metal for the hammer and hardfacing metallurgy based on the properties of the feedstock and on operating conditions can minimise hammer wear. As illustrated in Figures VI-8 and VI-9, for the size reduction of mixed waste using vertical and horizontal hammermills, relatively hard surface materials have been shown to exhibit substantially less wear than softer (and often standardly supplied) commercial metallurgical formulations for base hammer material and for hardfacings.