From Raw Part to Finish: How Automated Grinding Lines Make a Bearing Every 15 Seconds

Automatic bearing grinding isn't just a single machine tool; it's an unmanned grinding line seamlessly integrated with CNC grinders, measuring instruments, robotic arms, and logistics systems. It integrates rough grinding, fine grinding, online inspection, dimensional compensation, grinding wheel dressing, workpiece cleaning, and marking processes under a single control system, enabling a single-flow production process from rough to finished product. The cycle time is typically ≤15 seconds per piece, and a single line can produce 6,000-8,000 units per shift.

I. Typical Process Chain
① Loading: A gantry manipulator or six-axis robot grabs the ferrule from the material storage → scans the code to confirm the model → places it in the electromagnetic centerless clamp;
② Rough Grinding: Dual grinding wheels cut in at high speed, leaving an allowance of 0.15-0.25 mm. An adaptive controller eliminates backlash in real time to prevent tool collisions;
③ Online Measurement: A pneumatic measuring instrument or contact probe performs spot checks every 10 pieces, with data fed back to the CNC for automatic tool offset adjustment;
④ Fine Grinding: The grinding wheel uses a 30,000 rpm electric spindle with a feed resolution of 0.1 µm, ensuring roundness ≤1.5 µm and Ra ≤0.2 µm;
⑤ Superfinishing/Polishing: Directly docked to the superfinishing machine within the same cycle, the oilstone oscillates and draws the wire to a Ra of 0.04 µm;
⑥ Unloading: The robot places the finished product in a cleaning process → air-drying → laser marking → anti-rust bagging → AGV delivery to the assembly line.

II. Core Technologies
1. Electromagnetic Centerless Support: Remote magnetic adjustment enables loading and unloading in 0.3 seconds, preventing pinching and deformation.
2. SBS Adaptive Control: Automatically advances and retracts the tool based on changes in grinding force, reducing backlash by 35%.
3. Single-Point Diamond Pen + Servo Interpolation Dressing: Grinds the grinding wheel online every 30 parts, maintaining surface accuracy ≤ 2 µm.
4. Digital Twin: 1:1 modeling of the entire production line, with real-time mapping of temperature, current, and dimensions. Predictive maintenance reduces downtime by 20%.
5. Green Grinding: MQL (Minimal Quantity Lubrication) + oil mist recovery reduces cutting fluid consumption by 80%, enabling near-dry machining.

III. Quantifying Advantages
Compared to the traditional "single machine + manual" approach:
- Operator requirements reduced from 12 to 2, while OEE increased from 65% to 90%;
- Dimensional dispersion reduced by 40%, with a Cpk ≥ 1.67;
- Batch scrap rate reduced from 0.8% to 0.1%;
- Changeover time is < 15 minutes, making even small batches of 500 pieces economical.

In summary: Automatic bearing grinding, combining CNC, robotics, and online measurement, is a common approach for reducing costs in low- and mid-end bearings and improving the quality of high-end bearings.