Tech Talk
How do you dress "Resin and Metal-bonded CBN Wheels"?
The first step in dressing a resin or metal CBN wheel is to true it. This process leaves the working surface of the wheel smooth, with little or no abrasive crystal protrusion. An important fact to remember is that truing closes the periphery of the wheel, and as a result it is no longer suitable for grinding. A wheel used in this condition will not be free cutting, removing little or no work material and burning the workpiece. Once the wheel has been trued, the dressing process itself is performed to prepare the wheel for grinding. Dressing opens the wheel's surface by lowering the bond level between the crystals. After sufficient dressing the wheel will have a rough, aggressive texture, indicating that the cutting edges of the crystals are exposed and that the dressing operation has been successful.
Today, the most common method of dressing resin and metal CBN wheels is the use of an aluminum oxide dressing stick. The popularity of this method is due to two factors: First, it creates an optimal level of crystal protrusion and, second, it provides good bond tail development. This dressing operation consists of bringing a soft, fine grit aluminum oxide stick into contact with the surface of the wheel while it rotates, thereby exposing the abrasive crystals. The stick should be 220-grit or finer, generally one or two grit sizes finer than the wheel itself.
