What is the primary purpose of drilling/slotting brake rotors?

The primary purpose of drilling or slotting brake rotors is to remove heat and gases between the pads and the rotors. During braking, heat is generated, and gases can form due to the high friction between the brake pad and rotor surfaces. If these gases are not dissipated, they can create a layer that reduces the effectiveness of the braking system, leading to brake fade. The holes drilled or the slots cut into the rotor surface help to vent these gases, allowing for better contact between the pads and rotors. This process not only enhances braking performance but also helps maintain a consistent and effective braking response by preventing overheating and ensuring that the friction materials can operate optimally.

While aesthetics and weight reduction may be considered secondary benefits of drilled or slotted rotors, they are not the primary reasons for their design. Additionally, while some may think that increasing braking pressure is a primary objective, it is more related to the overall physics of braking force rather than a specific function of drilling or slotting the rotors.