It is the ability of the Volvo disc brake rotors to have friction applied to them that will bring your vehicle to a stop in a safe and orderly manner. The friction is made on the flat disc sections of the brake rotor by the disc brake pads. They are mounted on both sides of the rotor and have pressure applied to them by the brake calipers that are part of the braking system on your Volvo. The Volvo brake rotors have the wheels and wheel hubs bolted directly to them. This is how it is guaranteed if the rotors have friction applied to them that the wheels' rotation will be slowed down. These braking components can last for just as long as the Volvo is being driven on the roads if the brake system is maintained properly. This has to include the changing of the disc brake pads before they are totally worn out. If the brake pads are totally worn out, the metal backing plate they are mounted to will come in contact with the flat surfaces of the brake discs. When metal to metal contact is made, there is always excessive wear on both components causing damage to both metal parts. A Volvo owner will be fully aware of this situation when they apply pressure to the brake pedal and they hear the notorious grinding sound of metal to metal contact coming from the wheel assembly on their vehicle. This sound is an indication that the disc brake rotors are being damaged. If this is the present situation on your vehicle, when the brake job is being done, expect that the brake rotors and discs will have to be turned on a lathe so the surfaces can be flat again or they might have to be replaced.