The chip formation process is highly complex and is governed by mechanisms which are not yet fully understood. Material is not really cut away from a workpiece in the way that cloth is cut with scissors or meat is cut with a knife. It is deformed plastically and sheared away from the remaining metal. As metal approaches the rake face of the tool, it passes through a primary deformation zone which can be modeled as a plane. It is in this region that it changes direction, and undergoes adiabatic shearing. That is, although the region is of an extremely elevated temperature, it is transferring little (or no) heat to or from its surroundings while the material deforms in shear parallel to the shear plane angle. Machining parameters which affect chip morphology include the speed, feed, depth of cut, tool nose radius, edge radius, rake angle, tool and work materials, ambient temperature, cutting fluid, generated vibration in the machine tool and others. This makes predicting the chip morphology extremely difficult.
As a waste stream, chips are a prime candidate for recycling. They can often be melted down and reused. They can be a hazardous waste, in special situations. Grinding dust can be inhaled and cause lung disorders. The machining of exotic materials such as depleted uranium in the defense industry can be highly toxic. The volume of the chips will always be higher than the volume of the removed material. This is because the relative density of the chips is less than the workpiece. The chips will not pack as densely as unmachined metal.