A True Powerhouse in Cutting: SCBN TOOLS CBN Inserts Unlock New Heights in Bearing Steel Machining

Bearing steels (GCr15, SUJ2, 100Cr6, etc.) are considered “hard currency” in the machinery manufacturing industry. After quenching, their hardness can reach HRC60-65. They have both high wear resistance and fatigue strength and are widely used in key components such as automotive wheel bearings, wind power bearings, and precision machine tool spindles.

Perfect Match Between CBN Inserts and Bearing Steel Properties

1. Superior Performance Compared to Traditional Cutting Tools: Hardness reaches HV3000-5000, heat resistance temperature reaches 1300℃, strong chemical stability, no chemical reaction with ferrous materials, cutting life is 10-30 times that of carbide inserts, and machining efficiency is 2-5 times higher than grinding.

2. Optimized Structure: The insert adopts a negative rake angle (-5°~-10°) + 0.15-0.25mm reinforced chamfer design, doubling the cutting edge strength and resisting cutting impacts during bearing steel machining; for complex curved surfaces such as bearing inner and outer ring grooves and raceways, custom-formed CBN inserts are used for one-time cutting, avoiding accuracy deviations caused by multiple dressings.

Core Application Scenarios and Advantages of CBN Inserts for Machining Bearing Steel

1. Rough Machining: Efficient Material Removal and Reduced Energy Consumption 

CBN inserts excel in rough turning of bearing steel forgings and after quenching:

a. Supports large depth of cut (ap≤8mm) and high feed (f=0.2-0.4mm/r), increasing material removal rate by over 50%;

b. High impact resistance, capable of handling complex conditions such as oxide scale and discontinuous grooves on the surface of bearing steel billets, avoiding tool breakage and downtime;

c. Adaptable to dry or high-pressure cooling cutting, reducing coolant consumption and lowering environmental treatment costs.

2. Finishing: Ultimate Precision, Replacing Grinding

a. After cutting, the workpiece surface roughness is consistently Ra0.1-0.3μm, and the dimensional accuracy is controlled within ±0.002mm, meeting the precision requirements of P4 grade and above bearings;

b. For large-sized parts such as wind turbine bearings and large slewing bearings, ultra-long-distance continuous cutting can be achieved, with a single-edge machining life of 50-100 pieces;

c. Directly replaces the traditional "rough grinding + fine grinding" process, reducing processing steps by 40%, shortening the production cycle, and reducing equipment investment costs.

3. Special Working Conditions: Overcoming Machining Challenges for Complex Structures

For complex structural components such as bearing rings with keyways and oil holes, and eccentric bearings:

a. Utilizes specialized edge treatment technology to prevent chipping caused by stress concentration during cutting; 

b. Optimized chip removal groove design ensures smooth chip removal and prevents built-up edge from affecting machining quality;

c. Compatible with milling and turning machines, enabling integrated multi-process machining, improving production efficiency and dimensional consistency.

Practical Application Case Study 

A carbide bearing manufacturer, machining the outer ring of a GCr15 bearing (HRC62-64 after quenching), previously used a rough turning process with carbide inserts followed by grinding with a grinding wheel. The machining time per part was 28 minutes, requiring frequent tool changes and incurring high grinding wheel wear costs.

By adopting SCBN TOOLS CBN inserts, direct hard turning and finishing with CBN inserts reduces the machining time per piece to 10 minutes, increasing efficiency by 180%. The single-edge life of the insert reaches 85 pieces, and the overall tooling cost is reduced by 55%, while also reducing equipment occupancy and labor costs. The surface roughness Ra of the machined insert is stabilized at 0.2μm, the dimensional tolerance is controlled within ±0.0015mm, and the product qualification rate increases from 96% to 99.8%.

Whether for mass production of automotive bearings or custom machining of large wind turbine bearings, SCBN TOOLS, with its core advantages of  "high-efficiency cutting, ultra-long life, and ultra-high precision," helps companies reduce costs, increase efficiency, and enhance market competitiveness.