How CBN Cutting Tools Solve the Machining Problems of Brake Drums

        Brake drums are the core safety component of automotive braking systems. These components are mostly made of wear-resistant gray cast iron. During the machining process, they face technical challenges such as high hardness, high cutting resistance, and easy formation of built-up edge and work hardening. CBN inserts, with their ultra-hard material properties and optimized design, have become a revolutionary solution for brake drum machining.

Core Technical Requirements for Brake Drum Machining

1. Stringent Precision Requirements: The roundness of the brake drum's inner bore must be controlled within 0.01mm, end face runout ≤0.02mm, and surface roughness Ra≤1.6μm. Otherwise, it can easily lead to safety hazards such as uneven brake wear and abnormal noise.

2.High-Efficiency Mass Production: The automotive parts industry often uses assembly line operations, requiring cutting tools with high cutting speeds and long lifespans to reduce tool change downtime and ensure continuous production line operation.

3. Stable Impact Resistance: The brake drum blank contains casting defects (such as sand holes and hard spots), which easily generate impact loads during cutting, requiring the cutting tool to have excellent anti-chipping performance.

4. Controllable Cost: Traditional cutting tools have short lifespans and require frequent replacements, resulting in high tool consumption costs. Improving the cost-effectiveness of cutting tools is necessary to reduce overall machining costs.

Typical Applications of CBN Inserts in Brake Drum Machining

1. Machining of External Diameters and End Faces: CNGN1207 series CBN inserts are recommended. Their 80° principal cutting edge angle design provides high cutting edge strength, allowing simultaneous machining of external diameters, end faces, and stepped surfaces, reducing process changes and improving machining efficiency. 

2. Machining of Internal Holes and Complex Curved Surfaces: WNGN0804 series CBN inserts are preferred. They offer low cutting resistance, smooth chip removal, and are precisely suited for high-precision machining of brake drum internal holes, preventing chip adhesion that could affect surface quality.

3. Integrated Roughing and Finishing: For mass production needs, CBN tipped inserts, combining wear resistance and sharpness, can be used to achieve integrated roughing for material removal and finishing for ensuring precision, thus shortening the production cycle.

        As the automotive industry’s requirements for braking system safety and production efficiency continue to increase, CBN inserts have become the core tooling choice for brake drum machining.