Custom Radial Shaft Seal: Sizing, Materials, Profiles and Quote Requirements

Quick Answer: A custom radial shaft seal is specified by shaft diameter, housing bore, width, lip profile, material, fluid, temperature, speed and pressure. CORASEALS supplies custom radial shaft seals in NBR, HNBR, FKM, EPDM, silicone, PTFE and other materials. Send the shaft diameter, housing bore, width, fluid, temperature, speed, pressure, drawing and required quantity to receive a custom quote.

Procurement and maintenance teams look for a custom radial shaft seal when a standard rotary shaft seal does not match a worn shaft, an oversize bore, a discontinued size or a difficult operating condition. CORASEALS quotes custom radial shaft seals from dimensional data, operating data and the existing seal condition. A custom seal can be a modified TC, SC or TB profile, or a different lip and case construction entirely.

Do not send only a part number for a custom radial shaft seal. Different manufacturers use different code systems for oil seal profiles. A code such as TC can change in lip layout, case material, spring type and dust lip configuration depending on the catalog. The safest request for quotation includes measured dimensions, the old seal photo and the actual service conditions.

For standard radial shaft seal sizes, view the CORASEALS radial shaft seal category on coraseals.com. For custom dimensions, use the RFQ data in the sections below.

Custom Radial Shaft Seal Dimensions and Measuring Data

The main size format for a custom radial shaft seal is inside diameter × outside diameter × width. In many rotary shaft seal drawings, the inside diameter equals the shaft sealing diameter and the outside diameter equals the housing bore. CORASEALS confirms the dimension order before quoting because some users write shaft diameter × housing bore × width instead. Metric and inch units are both accepted. The unit must be marked on the drawing or in the inquiry.

For standard metric seals, ISO 6194 and DIN 3760 commonly define size ranges and tolerances. A custom radial shaft seal may be required when the shaft or housing falls outside those standard ranges, or when the old seal has nonstandard lips, case dimensions or spring loading.

• Shaft diameter at the lip contact area
• Housing bore diameter and bore depth
• Seal width or axial space available
• Shaft surface finish and hardness, if available
• Housing surface finish and chamfer or lead in
• Old seal dimensions, marking, front view, side view and back view

Measure the shaft on the sealing path, not on a corroded step or a heavily worn zone. If the housing bore is out of round, measure in two or more positions and report the largest and smallest values. A custom radial shaft seal can compensate for some dimensional variation, but excessive runout or an out of round condition will still reduce lip life.

Custom Radial Shaft Seal Material Options

Material selection depends on the fluid, peak temperature, shaft speed and contamination. A material that performs well in mineral oil may not perform well in steam, water emulsions, acids or fuels. The table below is a basic selection reference for custom radial shaft seals. The final material must be confirmed by CORASEALS against the full fluid and temperature condition.

Material	Typical Fluid Exposure	Common Application	Main Limitation
NBR	Mineral oil, grease, water, many hydrocarbons	General rotary shaft sealing	Limited high heat and strong solvent resistance
HNBR	Hot oil, R134a, HFC, abrasive oil	Automotive and mobile hydraulic rotary components	Not suitable for strong polar solvents
FKM	Mineral oil, fuels, acids, many chemicals	Chemical pumps, gearboxes, fuel systems	Not all grades suit steam, amines or low temperatures
EPDM	Water, steam, brake fluids, phosphate esters	Water pumps and steam services	Not suitable for mineral oil or most fuels
Silicone	Water, dry heat, some low temperature gases	Dust and low load sealing	Low tear strength and low wear resistance
PTFE	Chemicals, solvents, dry running conditions	Chemical pumps and low friction rotary sealing	Less elastic than rubber, needs controlled hardware

For rubber lip seals, hardness is usually specified in Shore A. A higher hardness can help with extrusion resistance, while a lower hardness can follow a shaft with minor misalignment. For PTFE lip seals, the lip geometry, spring load and shaft finish matter more than elastomer hardness. Always provide the actual medium and peak temperature. Do not select a custom radial shaft seal material from a brand statement alone. Some customer drawings call for brand name materials. CORASEALS can quote equivalent FKM, FFKM or PTFE compounds, but the actual temperature and chemical resistance must be verified against the specific compound and application.

Profile and Lip Options for Custom Radial Shaft Seals

A custom radial shaft seal can have different lip arrangements depending on the sealing direction and contamination:

• Single lip with garter spring for general rotating shafts
• Double lip with dust lip for dusty, wet or abrasive environments
• Springless lip for special media or low speed service
• PTFE lip for low friction, dry running and chemical services
• Metal case, rubber covered OD or cassette construction

The case style affects installation, bore retention and tolerance of the housing surface. A rubber OD can accommodate slight bore surface irregularity. A metal case can provide stronger retention in a machined housing. A cassette seal can protect the lip from heavy contamination, but the available axial space must be confirmed.

Operating Conditions That Change the Design

Standard radial lip seals are commonly used in low pressure rotary applications. If the seal must handle pressure, high speed, poor lubrication, abrasive particles or shaft runout, the seal design must change. Custom radial shaft seals can be produced with stiffer lips, special spring loads, different case designs or PTFE elements. The following information must be included in the RFQ:

• Rotational speed in rpm or m/s
• Pressure in bar or MPa
• Fluid type and additives, including water or cleaning agents
• Operating temperature and start up temperature
• Shaft runout, out of round condition and axial movement
• Contamination risk from sand, metal particles, ceramic dust or water spray

For custom radial shaft seals used in gearboxes, pumps, axles or bearing housings, the lip contact area must be free of spiral machining marks, nicks, pitting and corrosion. Shaft surface finish values such as Ra and Rz are often specified on original equipment drawings. CORASEALS can review these values during the quotation. For worn shafts, a shaft repair sleeve or remachined surface may be required instead of changing the seal alone.

Custom Radial Shaft Seal Quote Requirements

To receive a quote from CORASEALS, prepare the following data before sending an inquiry:

• Seal type or existing profile code, if known
• ID × OD × width or shaft diameter × housing bore × width
• Material preference, if known
• Fluid, pressure, temperature, speed and contamination
• Drawing, sample photo and required quantity

Send CORASEALS the seal type, material, ID × OD × width, operating temperature, pressure, medium, shaft speed, drawing, sample photo, and required quantity. CORASEALS will compare the old seal profile, material and dimensions with the application before returning a quotation.

Frequently Asked Questions

What information does CORASEALS need for a custom radial shaft seal quote?

Send the shaft diameter, housing bore, width, fluid, operating temperature, pressure, speed, lip type, material preference, drawing and required quantity. For replacement seals, send the old seal marking and a photo of the front, side and back views.

What does ID × OD × width mean for a radial shaft seal?

ID × OD × width normally means inside diameter × outside diameter × width. For rotary shaft seals, the inside diameter usually matches the shaft diameter and the outside diameter usually matches the housing bore. CORASEALS confirms the dimension order before production.

Can a TC oil seal be replaced by a custom radial shaft seal?

Yes, if the dimensions, profile, lip direction, material and operating conditions are confirmed. Do not replace a TC seal by code alone. Some TC seals have different case and lip constructions depending on the manufacturer. Compare the section drawing and old seal condition before changing material or profile.

What material should be selected for a custom radial shaft seal in mineral oil?

NBR and HNBR are common starting points for mineral oil. FKM may be selected when chemical or high temperature resistance is required. The final material depends on oil additives, peak temperature, shaft speed, and whether water or cleaning agents are present.

Does CORASEALS require an existing drawing for custom radial shaft seals?

No. CORASEALS can quote from measured dimensions and application data. A drawing, old sample, or photo helps reduce errors. Actual measurements are preferred because worn housings and remachined shafts can differ from the original drawing.