To identify the correct grease seal, record three primary dimensions in millimeters: shaft diameter, housing bore diameter, and seal width. These dimensions are commonly written as inside diameter × outside diameter × width, such as 35 × 52 × 7 mm. I recommend measuring the shaft and housing directly whenever possible, then confirming the seal material, lip design, operating temperature, speed, and grease compatibility before placing an order.
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I prepared this guide for maintenance teams, mechanical engineers, purchasing specialists, distributors, and equipment manufacturers who need to replace or source a grease seal. It is suitable for applications such as wheel hubs, agricultural machinery, gearboxes, electric motors, construction equipment, pumps, and industrial rotating assemblies. The guide is also useful when an old seal is damaged, unreadable, or unavailable for reference.
A size chart can narrow the search, but it should not replace dimensional verification. A seal that appears close in size may leak, loosen in the housing, create excessive shaft friction, or become damaged during installation. For reliable selection, I use the dimensional size as the starting point and then review the operating conditions around the seal.
The following chart shows common example dimensions and typical application considerations. It is a reference for product searching rather than a universal list of interchangeable seals. Actual availability depends on the seal profile, material, spring arrangement, dust lip, pressure capability, and manufacturer design.
| Example Size (ID × OD × Width) | Typical Use Consideration | Common Material Starting Point |
|---|---|---|
| 20 × 35 × 7 mm | Compact shafts and light-duty rotating equipment | NBR for moderate oil and grease service |
| 25 × 40 × 7 mm | Small motors, gear drives, and general machinery | NBR or FKM according to temperature and fluid |
| 35 × 52 × 7 mm | General industrial shafts and bearing housings | NBR for standard conditions |
| 40 × 62 × 8 mm | Medium-duty hubs and mechanical assemblies | NBR, FKM, or reinforced design as required |
| 50 × 72 × 10 mm | Larger rotating shafts and higher-load equipment | Material selected by temperature, grease, and contamination |
For example, a seal marked 35 × 52 × 7 mm normally has a nominal 35 mm inside diameter, a 52 mm outside diameter, and a 7 mm axial width. The first dimension must fit the shaft, while the second must fit the housing bore. The width should match the available recess unless the equipment drawing specifically permits an alternative.
I recommend removing the old seal carefully so the shaft and housing are not scratched. Clean away grease, dirt, rust, and adhesive residue before measuring, because contamination can alter caliper readings. If the old seal is distorted, measure several locations and compare the results rather than relying on one compressed edge.
Measure the shaft diameter at the actual running track where the sealing lip contacts the shaft. Use a calibrated vernier caliper or micrometer and take readings at more than one position to identify wear or out-of-roundness. If the shaft is worn, the original seal size may still be correct, but a new sealing lip alone may not resolve the leakage problem.
Measure the housing bore diameter after cleaning the recess. Take readings at different angles because damage, corrosion, or an oval bore can affect retention. The seal outside diameter must provide the intended interference fit for the housing design; I do not recommend forcing a seal into a bore simply because the dimensions appear similar.
Measure the depth and usable width of the seal cavity. A seal that is wider than the available recess may bottom out before it is fully seated, while a substantially narrower seal may sit incorrectly or leave insufficient support. Record the result in millimeters and compare it with the original seal marking, equipment drawing, or replacement specification.
Two seals with the same nominal dimensions may have different profiles. Check whether the replacement has a single lip, a double lip, a dust lip, a metal outer case, a rubber-covered outside diameter, or a pressure-resistant configuration. I also check the direction of any hydrodynamic grooves because some designs are intended for a particular shaft rotation direction.
Size determines physical fit, but it does not fully determine service performance. I review shaft speed, temperature, grease type, contamination level, pressure, vibration, and expected service life before recommending a design. For example, a standard NBR seal may be a practical choice for general mineral-oil-based grease, while FKM may be considered when higher temperature or chemical resistance is required.
Operating temperature should be checked against the actual compound data and equipment conditions rather than a generic range. As a conservative example, a seal exposed continuously near 120°C should not be selected solely because its dimensions match; the elastomer, spring, lubricant, and neighboring components must all be suitable. If the application involves water, abrasive dust, chemicals, or frequent washdown, I may recommend a different lip or material construction.
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The sealing lip runs directly against the shaft, so grooves, corrosion, burrs, and excessive roughness can accelerate wear. I inspect the contact track and check whether the new lip will run on the same damaged area as the old one. Depending on the equipment, corrective options may include relocating the seal, repairing the shaft, using a wear sleeve, or selecting a different sealing arrangement.
Grease seals are generally designed to retain lubricant and help exclude contaminants, but they are not automatically suitable for high pressure. Rotational speed, shaft runout, temperature rise, and grease volume can all influence lip performance. If the assembly experiences pressure pulses or high peripheral speed, I ask for the shaft speed in revolutions per minute and the pressure condition before confirming the design.
NBR is a common starting material for general-purpose grease seals because it offers practical resistance to many mineral oils and greases. FKM is often evaluated for higher-temperature or more chemically demanding conditions, although compatibility must still be confirmed for the specific lubricant. PTFE and other specialized materials may be considered where low friction, chemical resistance, or unusual temperature conditions are important.
Seal construction also affects selection. A metal-cased seal can provide a firm structure and compact design, while a rubber-covered outside diameter may help accommodate certain housing conditions and improve static sealing. A secondary dust lip can provide additional contamination protection, but it may also increase friction, so I match the profile to the environment rather than selecting the most complex option by default.
I also recommend confirming installation orientation before production release. The primary sealing lip normally faces the retained grease or lubricant, while the dust lip faces the contamination side, but the correct orientation depends on the seal design and equipment assembly. If the application has a specific manufacturer drawing, that document should take priority over a general size chart.
Grease seal pricing depends on dimensions, material, profile, tooling, spring and casing construction, order quantity, packaging, and inspection requirements. Standard sizes usually offer a simpler sourcing path than non-standard dimensions, but I still confirm the exact profile before quoting. A lower unit price may not represent better value if the seal requires special tooling, has a long replenishment cycle, or does not match the equipment condition.
Minimum order quantities vary by construction and production planning. For standard items, suppliers may be able to support smaller trial quantities, while customized profiles or special compounds may require a higher MOQ. Lead time also depends on raw material availability, tooling status, production capacity, and approval requirements, so I provide a confirmed schedule only after reviewing the complete specification.
At TEBIETE, I support buyers by organizing the required dimensions and operating data before recommending a grease seal. Our product and sourcing discussions can cover standard and custom sizes, NBR or FKM material options, casing and lip configurations, packaging, inspection points, and repeat-order requirements. When an old seal is unavailable, dimensional drawings, photographs with a scale, samples, and application information can help us evaluate a suitable replacement direction.
I encourage buyers to send the size in the format ID × OD × width, together with shaft speed, temperature, grease type, contamination, and estimated quantity. If the application includes pressure, water exposure, abrasive particles, or unusual rotation conditions, those details should be stated before quotation. This information helps reduce the risk of selecting a dimensionally correct seal with an unsuitable material or profile.
The correct grease seal size is normally identified by shaft diameter, housing bore diameter, and width, written as ID × OD × width. My recommended process is to measure the installed dimensions, inspect the shaft and housing, identify the seal profile, and then match the material to temperature, grease, speed, pressure, and contamination. A size chart is useful for narrowing options, but final approval should be based on the equipment conditions and the supplier’s confirmed specification.
For your next step, record the three dimensions in millimeters, photograph the old seal and housing, and provide the operating conditions to TEBIETE for review. I can then help evaluate a standard or customized grease seal solution, clarify material and profile options, and prepare a quotation based on quantity, packaging, and delivery requirements. This approach gives purchasing teams a clearer path from measurement to dependable supply.
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