FAQ about bearings

Installation

Q1: I stripped the cross recess when assembling a plastic bearing with screw shaft (DR-B type). How can I take countermeasures?

A1: The cross-holes for fastening screws are size No. 2 in JIS B 1012, so please use a screwdriver with a No. 2 bit (Nominal No. 2) and ensure proper engagement between the bit and the screw head during fastening. If you are concerned about the strength of cross recess, we also offer hex socket head screws (bearings with “-JH” at the end of the product name).

Q2: What is the recommended fastening torque when fastening bearings with screws, and what is the strength of the screw parts?

A2: The recommended fastening torque varies depending on the hardness and material of the object to be fastened. Please set the proper fastening torque according to the typical fastening torque specified for each screw size.

Q3: When mounting a plastic bearing with riveting shaft (DR-A type) on a steel plate, are there any specifications for the shape of the mating hole, dimensional tolerances, or plate thickness? Also, what precautions should be taken when riveting shaft on a steel plate?

A3: We do not provide recommended dimensions. Please install the bearings so that they meet your usage conditions. The mating hole should have minimal clearance with the bearing’s riveting shaft for easy riveting. The minimum clearance that allows easy manual insertion of the shaft is about 0.03 mm. The 3.5 mm riveting length of the plastic bearings assumes riveting on a steel plate with a thickness of 2.3 mm to 2.6 mm.

As a precaution when riveting bearings on a steel plate, we recommend that the edge face of the inner race be used as a bearing to prevent the impact of riveting from being applied to the outer race. This is because a shock to the outer race may cause ball indentation inside the bearing and affect its rotational performance. In addition, in case of riveting, the applied shaft may crack after the riveting process, so we would recommend *spin riveting.
*Spin riveting: it forms the rivet by pressing and rotating the shaft at an offset angle.

This information is provided for general reference based on typical usage conditions. Please verify according to the actual operating environment and intended application when designing or machining.

Specification

Q4: The outer race of D series bearings are made of POM, which typically has a heat resistance above 100°C. Why is the operating temperature range limited to only 40°C?

A4: Each of the materials offers a heat resistance of over 100°C. However, each material has a different coefficient of thermal expansion. Furthermore, the retainer molded from PP resin is designed to be assembled by hooking it onto a ball rolling groove of the inner race. Therefore, in a high-temperature environment, the retainer expands more than the inner race, causing it to come off more easily. For this reason, the upper limit of the operating temperature range is set at 40°C.

Q5: Do you have bearings that can be used in high-humidity environment?

A5: We recommend S series and DR-S series (with plastic outer races) made of corrosion-resistant stainless steel, PE series and PK series made entirely of resin, or C series, which incorporates ceramics.

Q6: I can’t find the right size in the product catalog list. Is it possible to produce customized products?

A6: Yes, we can handle custom orders. Prototypes can be produced starting from just 1 piece. If the desired size can be achieved by combining existing parts, we can provide a relatively cost-effective solution. However, if existing parts cannot be used, machining will be required, which may result in higher costs. For custom products that require new design work, it typically takes about 1 month to provide a quotation, followed by approximately 45 to 75 days for production.

Q7: Is it possible to place a custom order only some parts such as outer race and inner race? Or, is it possible to manufacture bearings with the desired shape?

A7: Design confirmation is required in advance, but we can handle customization ranging from individual components to full customized products. For fully customized designs, we kindly request a minimum order quantity of 1,000 pieces. We can also accommodate small-lot production, but please note that the cost may be higher.

Q8: Is it possible to design and assemble units with bearings mounted?

A8: By involving us from the design stage, we can not only provide design proposals but also handle everything from material procurement, component sourcing, machining, and assembly in a one-stop process.
This approach significantly reduces your management workload and procurement efforts, while enabling shorter lead times and optimized costs. Ultimately, we deliver the bearing units you require smoothly and efficiently.

Product name and markings

Q9: Is the 6-digit number “287839” emboss marked on the side of the outer race a product code?

A9: “287839” is an intellectual property registration number and is not related to the product name or code.

Q10: Is a product marked “DR-24 PAT” a TOK product?

A10: Yes, it is a TOK product. “PAT” indicates patent and is not part of the product name.

Q11: How can I identify the product name?

A11: Detailed information is available in the catalog or on our website under the “How to identify D-series plastic bearings” page.

Others

Q12: Are CAD data available?

A12: Yes. CAD data can be downloaded from our website.

Q13: Can a bearing parameter sheet be issued?

A13: Yes. Please contact us via the inquiry page on our website, or reach out to your sales representative or distributor.

Q14: What are the dimensions and weight of the small shipping box?

A14: Width: 260 mm, Depth: 190 mm, Height: 160 mm, Weight: approximately 200 g.

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