A disk brake rotor is what you find in a car in order to slow down or stop the rotation of a wheel when it is moving. This brake rotor is connected to the wheel or even the axle. What happens when you want to slow down a car is that a disk brake rotor will come into contact with friction material called brake pads via either a hydraulic, pneumatic or electromagnetic system. The resultant high amount of friction will cause the disk rotation and therefore the wheel rotation to slow or stop completely. As such a disk brake rotor needs to be made from very durable materials. A disk brake rotor is most commonly made from cast iron, but with the emergence of new metallurgical technologies and more demanding vehicles, a disk brake rotor can be even made of composite materials like carbon-fiber or even something like a ceramic matrix composite material.


The design of a disk brake rotor varies according to the type of vehicle that it is being used on. Sometimes a disk brake rotor can have the two contact surfaces and a hollow inside. This is primarily done to reduce the massive amount of heat that is created during normal use. Another way a disk brake rotor is molded for heat dissipation is having holes drilled in them although this method was only widely used in the 1960s. A disk brake rotor can also be slotted in order to aid in the removal of dust and gas that gathers. Since the slotting can greatly reduce the lifespan of a rotor, this is generally used only on the racing circuit even thought it helps a lot on wet surfaces.


A disk brake rotor can be damaged in a few ways. One way this can happen is called warping. Warping is caused by excessive heat on a disk brake rotor. When the contact points on the rotor have a significantly higher temperature compared to the inner layers the temperature difference can cause a major uneven expansion which can ruin a disk brake rotor. Another way is scoring. Scoring is simply when the friction material on the brake pads is worn away and their steel plates and screws do damage to a brake rotor. While minimal scoring can be rectified by machining off a slim top layer off a disk brake rotor it is best that regular checking be done for prevention. The third method that a disk brake rotor can get damaged is by cracking. Cracking is affected mostly to drilled disk brake rotors. Severe stresses on these rotors can cause them to make small cracks around the drilled parts of the disk brake rotor damaging the structural integrity. Lastly, cast iron disk brake rotors can rust. While regular use will keep a disk brake rotor clean of rust, when a vehicle is not used for some time, it can develop into serious issues.