Stainless Steel Miniature Bearings for high precision

Stainless steel miniature bearings for shaft sizes from 0.6mm to 9mm

Stainless steel miniature ball bearings, also called instrument bearings or micro bearings, are crucial components in various applications.

They are used in:

• clocks
• wind speed measuring instruments
• medical instruments
• fishing reels,
• scanners
• encoders
• small drones

Materials and environments 

Many instrument bearings are made from 440 grade stainless steel because they can support the moderate load demands of instrument applications, like surgical robots.

• KS440 stainless steel — SMB Bearings’ EZO instrument bearings, are made from KS440 stainless steel, also known as ACD34 or X65Cr13, and provide superior performance. EZO instrument bearings have better low noise qualities than the regular AISI-440C grade and a higher load capacity.
• Stainless steel ball bearing materials excel in mildly corrosive environments because of the corrosion resistant properties of this material. However, it's important to note that exposure to seawater or strong acids and alkalis can still impact their performance.

That is why SMB Bearings recommends marine grade stainless steel bearings, plastic bearings, or full ceramic bearings for these demanding environments.

Other advantages of stainless steel bearings include:

• Their ability to function without preservative oil on the exterior surfaces, which allows then to be operated dry, without lubrication.
• They can be supplied with various sealing options to suit specific application needs. From AISI-304 stainless steel shields and rubber seals to Teflon contact seals, we offer a range of configurations to accommodate your operational requirements.

These bearings are durable, reliable and offer exceptional, high precision performance in diverse environments. They are also available with a flange on the outer ring.

• What are flanged bearings? Flanged stainless steel miniature bearings feature a steel flange machined on the outer ring. This allows the bearing to be more easily located in a housing. The flange also helps prevent axial movement of the bearing when it is subjected to thrust loads, which ensures greater stability.
• Where are flanged bearings used? They are used in applications where it may be difficult to locate a bearing with a tight housing fit. They are also used in high temperatures, where the bearing’s housing material expands more than its outer ring. This overcomes potential movement issues that may arise with non-flanged bearings, due to loose fits.

Scroll down to the bottom of this page to see more examples of SMB Bearing’s product variants.

Lubrication

In terms of lubrication, our bearings are highly adaptable. The open miniature bearings are normally oil lubricated. Shielded or sealed bearings are generally pre-lubricated with grease, but shielded bearings can also be supplied with instrument oil for low torque applications or completely dry for very low speed applications where very low rotational resistance is required.

In addition, our in-house lubrication facility enables us to custom relubricate bearings according to your specifications.

Applications and performance

For cage or retainer options, we offer flexibility to meet various design and performance criteria. The standard cage for our stainless steel miniature bearings is made from either AISI-304 or AISI-420 stainless steel. A one-piece crown cage is more common for the very small and the very thin section bearings due to space constraints. Larger sizes have a two-piece ribbon cage.

For higher speeds, a re-inforced nylon TW cage is recommended. However, it's important to note that this increased performance comes with a trade-off — the maximum operating temperature is reduced to 120 °C because of the limitations of the nylon material.

Temperature limitations 

Stainless steel bearings, with a stainless steel retainer and a suitable high-temperature lubricant, enable operation at temperatures ranging from a steady 250°C to intermittent peaks of 300°C.

However, it's worth noting that stainless steel's load capacity is reduced beyond these thresholds. That’s why, for temperatures exceeding 300°C, we suggest using full ceramic bearings that can be used up to 600°C or 1200°C depending on the material.

For comprehensive technical insights, click on ‘INFO’ in the provided rows below for detailed technical drawings showcasing load and speed data for the bearings. The load ratings shown are for AISI-440C stainless steel bearings. Load ratings are higher for EZO KS440 bearings.

Please note that we use the maximum loads and speeds in theoretical life calculations. We recommend using bearings at significantly less than the maximum load and speed ratings to ensure reasonable bearing life.

Get in touch with us 

Beyond providing quality products, we offer unparalleled technical support and expertise. Our team of engineers is available to assist customers with product selection, application engineering, and troubleshooting. Get in touch with our team today by emailing sales@smbbearings.com or fill in the contact form.

See product table below for dimensions and technical drawings

See Products Variants below for low noise options