Basic Principles of the MD Process The Mechanical Descaling process is based on the principle that steel wire rod is ductile and hot-rolled scale is brittle. When the rod is deformed, the steel bends, but the hotrolled scale breaks and, provided the scale is there in sufficient quantity and provided the deformation is sufficient, the scale will release from the surface of the rod and fall away. The deformation mode is principally bending, but may also, importantly, include stretching deformation. What makes Mechanical Descaling a production process is the availability of equipment that will use the foregoing principle in a controlled manner to get consistent results of scale removal without unduly affecting the properties of the wire rod being descaled.
If the wire product is to have a clean, bright surface without any red rust staining, then a more aggressive descaler, for example a brushing-type unit would need to be used. Under any event, deep pitting-type rust should be avoided since rods with this condition are not capable of complete clean-up during descaling—in fact, even acid pickling would not be able to deal with that kind of rod surface.