An asphalt milling machine is a type of grinder specifically made to grind and chew up asphalt of many sizes. The purpose of an asphalt milling machine is that, by reducing large pieces of asphalt to a coarse powder, asphalt can easily be recycled. Two people typically are needed to use a large asphalt miller, because one does the cutting and the other functions as a lookout to ensure the milling machine is picking up the correct asphalt from the street. While there are smaller units for consumer or small-construction needs, this term often is used to reference much larger machines.
The main task of an asphalt milling machine is to grind and chew up asphalt. It starts with loading the asphalt, which is done through an internal conveyor belt that brings collected asphalt farther into the machine. Once in the milling machine, large teeth and grinders take large chunks of asphalt and greatly reduce their consistency to a powder. The teeth and grinders normally are made from a strong material, such as dense steel or diamond.
Turning large chunks of asphalt into powder with an asphalt milling machine often is considered important for several reasons. This asphalt commonly is collected from streets when construction is being performed to ensure that the street level does not get too high from successive levels piling up. In the past, new asphalt was laid on top of old and broken asphalt to fix it, but this caused the streets to be too high, causing functionality issues. Turning the asphalt into powder also means it can easily be recycled and used again for streets or other asphalt applications.
Its large size means two people are often needed to work the asphalt milling machine. One person is responsible for ensuring the milling machine is only tearing up the correct section of the street, because hitting valves or manholes can damage both the milling machine and the street. The second person runs the milling machine, operating the conveyor belt, the grinders and moving the machine itself.
Smaller asphalt milling machines generally range from around 10 to 15 inches (25.4 to 38.1 centimeters) wide. While this performs a similar task, this smaller machine often is not referred to as such because it mostly is meant for consumer and small construction needs. When an asphalt milling machine is mentioned, it is more commonly referring to the larger units that dig up asphalt from the street.