Process and control today | Magnifying miniature engineering practices: how are miniature bearings made?


Walk over the Millennium Bridge and you’ll have a view of the Tate Modern and St. Paul’s Cathedral. Look down another side and you’ll see the miniature world of Ben Wilson, an artist who has spent decades turning hundreds of chewing gum pieces into tiny works of art. These works of art often take hours or days to create – it’s safe to say that miniature art is a precise craft. In this article, Chris Johnson General Manager of Miniature Bearings SMB Bearings specialist explains the rigorous processes behind the creation of miniature bearings.

Sometimes called instrument bearings or micro bearings, miniature bearings – components with a bore typically under 10mm – are used in a wide range of specialist applications. These applications include anemometers, miniature gearboxes and radio controlled models. Despite the varied nature of these applications, they all have one thing in common: the bearing must be manufactured correctly and with ultimate precision to ensure a high quality component. Here are the five essential steps in making miniature bearings.

Select material

The accuracy of a miniature ball bearing is determined by several factors, including the roundness of the inner and outer ring raceways, the sphericity and quality of the balls, and the quality of the raw materials used in each of the bearing parts. The first step in the manufacturing process of any bearing is to select the material. This material must be perfectly matched to the application to ensure its suitability. The majority of bearings are made of chrome steel, but other materials are sometimes considered to optimize bearing performance and life.


Using an automatic machine, the inner and outer rings of the bearings will be cut from steel tubing to the recommended size, leaving some extra material to accommodate warping that occurs during the cutting step. heat treatment. In the hardening stage, the races go through a heating process to ensure the components are hard and tough. The races are then quenched in oil and quenched. A grinding operation using specialized grinders coupled with an abrasive machining process, known as honing, will ensure precise geometry, radius and surface finish.


Ball bearings begin life as a thread or rod. These ingots then undergo cold heading fabrication – a multi-step process used to form metal parts at room temperature. The balls are then filed down to remove burrs and burrs before using a soft grind to ensure uniformity. A hardening process is also an essential part of the ball manufacturing process and is followed by a honing process to achieve final surface finish requirements and tolerances.


Bearing supports are manufactured using a number of different processes. Depending on the material and size, this includes stamping and forming, casting, forging and machining. Standard steel roll cages or retainers are stamped from thin sheet metal using a die – a specialized machine tool for cutting material into the desired shape or profile. Plastic cages, on the other hand, are usually made by injection molding. This process produces parts by injecting molten material into a mold.

Assembly and quality control

After this step, all components are measured, matched and assembled to create a finished bearing. Testing will have been carried out throughout the manufacturing process including at the heat treatment stage to ensure proper hardness as well as testing to ensure correct sizing and shapes and a final noise test to ensure a silent operation.

One of the essential steps in quality control is to stamp the bearing with the correct manufacturing information and bearing number. The stamp usually appears on the outer faces of the ring and is essential for tracking product authenticity, although many EZO bearings are too small to be marked with a part number, so the outer packaging is marked . Reputable manufacturers such as EZO brand miniature bearings are known for their consistent quality and reliability through continuous improvement in manufacturing and quality control.

Miniature bearings may not be physically impactful at first glance, but delve into the precise manufacturing process and you’ll discover that these components are quite a feat of engineering.

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