Ever wondered how those small precision bearings found in cars, machinery, and even simple skateboards are made? The answer involves cutting-edge technology, complex processes, and a high level of quality control.
The Beginning: Special Steel
It all starts with something seemingly simple: steel. But it's not just any steel. It's bearing steel, chosen for its extreme hardness, high wear resistance, and ability to withstand great stress.
This material is heated to approximately 1,100°C, until it becomes incandescent. Then, it is cut into small, thick cylinders, called blanks.
Forming and Preparation
These cylinders pass through a gigantic hydraulic press, which flattens them into a disc-like shape. Then, a hole is drilled in the center.
From there, ring rolling and hole expansion processes adjust the dimensions, approximating the desired bearing shape.
Before high-precision machining, the rings are softened and relieved of internal stresses. This occurs in a process called annealing, in which they are slowly heated to between 780°C and 810°C, held for a few hours, and gradually cooled—which improves the metal's structure.
Machining and Heat Treatment
In the next step, the rings undergo rough machining, where the inside and outside diameters are cut close to the final measurement, but still with a small margin for a perfect finish.
Next comes heat treatment: heating between 830°C and 860°C, followed by rapid cooling, forming a super-hard metallic structure called martensite.
To prevent the material from becoming brittle, tempering is performed, heating the rings between 150°C and 200°C for a few hours. The result is increased hardness, but with reduced internal stresses.
Precision at the Microscopic Level
In the precision grinding phase, automated machines work to achieve micrometer-level accuracy. The goal is to ensure smooth, perfectly aligned surfaces on the inner and outer diameters, as well as on the flat faces.
Before assembly, each component undergoes ultrasonic cleaning, which removes oil, dust, and even microscopic metal particles.
Assembly and Final Testing
High-quality steel balls are then positioned between the inner and outer rings. A cage is installed to maintain regular spacing between them, allowing for smooth rotation.
With the clearance precisely adjusted, the bearing is cleaned again, dried in rotation, and lubricated with grease—essential for reducing friction and increasing service life.
Finally, each bearing undergoes a high-speed vibration test. Low vibration means high manufacturing precision.
Only after passing this stage is the bearing ready to operate in everything from massive industrial machines to the smallest electronic devices—always quietly and efficiently.
