custom rod seal

Custom Rod Seals for Hydraulic and Pneumatic Cylinders

Quick Answer: A custom rod seal is a hydraulic or pneumatic sealing element matched to a specific rod diameter, groove dimensions, fluid, pressure, speed, and temperature. The seal stops oil leakage at the rod side and blocks external contamination. CORASEALS can supply a custom rod seal after receiving the rod diameter, bore diameter, groove dimensions, pressure, speed, hydraulic fluid, and seal profile.

A custom rod seal is needed when a standard seal does not match the cylinder rod diameter, groove geometry, or operating conditions. Rod seals work in hydraulic cylinders, pneumatic cylinders, mobile equipment, agricultural machinery, and industrial presses. The rod seal sits in the cylinder head or gland and seals the moving rod surface.

Rod seals differ from piston seals and wiper seals. A piston seal seals the cylinder bore and moves with the piston. A rod seal seals the rod surface and retains oil inside the cylinder. A wiper seal cleans the rod surface at the outside of the cylinder. A complete cylinder head often uses a wiper, a main rod seal, and a buffer seal in series.

Common Custom Rod Seal Profiles

CORASEALS can source different rod seal profiles. The profile must be selected with the groove drawing and operating conditions. Common profiles include:

U-cup rod seals for general hydraulic cylinders
Polyurethane rod seals for high wear resistance
PTFE step seals with an elastomer energizer for low friction
Compact rod seals for short gland designs
V-packing sets for adjustable sealing force
Buffer seals to protect the main rod seal from pressure spikes

Profile codes such as UN, UHS, HBY, and other designations can vary by catalog. CORASEALS checks the cross section, material, and dimensions before quoting a replacement. Do not rely only on a part number or model code.

Material Selection for Custom Rod Seals

The rod seal material must match the hydraulic fluid, temperature, pressure, and rod speed. Common rod seal material options include:

NBR for general mineral oil service
HNBR for higher wear and temperature resistance than NBR
FKM for high-temperature hydraulic oil and synthetic fluid resistance
Polyurethane for high wear resistance and extrusion resistance
Filled PTFE for low friction and high-temperature service

EPDM is not normally used for mineral oil hydraulic systems. The final material grade and Shore A hardness depend on the fluid chemistry, temperature range, and duty cycle. CORASEALS reviews the operating data with the material supplier before quoting.

Dimensions and Gland Data Needed

Custom rod seal dimensions usually include the rod diameter, groove diameter, groove width, and gland bore. Some suppliers also require the seal outer diameter and seal height. Both metric and inch measurements are used in hydraulic cylinders. The dimension order must always be confirmed with the drawing.

The rod surface finish, rod hardness, runout, and stroke speed are also important. A rod seal can leak if the rod surface is scored, pitted, or polished incorrectly. The groove clearance must also be checked because a large extrusion gap can damage the seal under pressure.

Common Rod Seal Failure Causes

If a rod seal leaks after installation, the cause may come from the seal, the groove, or the cylinder system. Common failure causes include:

Incorrect rod diameter or groove clearance
Rod surface scratches, corrosion, or excessive runout
Wrong material for the fluid or temperature
Pressure spikes that extrude the seal lip
Contaminated hydraulic oil with particles or water
Installation cuts from sharp threads or missing assembly tools

A replacement custom rod seal should not be selected without checking these points. The new seal must match both the original profile and the actual measured groove.

Custom Rod Seal Inquiry Checklist

Send the following information to CORASEALS for a custom rod seal quote:

Rod diameter
Groove diameter and groove width
Gland bore or housing bore
Seal profile or cross section drawing
Operating pressure in bar or MPa
Hydraulic fluid type
Operating temperature
Stroke speed in m/s or cycle rate
Required quantity
Existing drawing, sample, or part number if available

Use both metric and inch values where available. The data helps check extrusion gaps, material compatibility, and seal height.

FAQ

What is a custom rod seal?

A custom rod seal is a sealing element built or selected to fit a specific rod diameter, groove size, fluid, pressure, and temperature. The seal is used in the cylinder head or gland to seal the moving rod surface.

What dimensions are required for a custom rod seal quote?

The main dimensions are rod diameter, groove diameter, groove width, and gland bore. A drawing or sample helps confirm the cross section and lip geometry.

Can CORASEALS match a sample or existing rod seal?

Yes. CORASEALS can compare the sample, measurements, fluid, and operating data against available rod seal profiles and materials. A photo and a full set of groove measurements help avoid errors.

What materials are available for custom rod seals?

Common materials are NBR, HNBR, FKM, polyurethane, and filled PTFE. The correct material depends on the fluid, temperature, wear, and pressure conditions.

How should a custom rod seal be installed?

Clean the rod surface and groove before installation. Cover sharp threads, use assembly tools that do not cut the seal lip, and lubricate the seal with clean system fluid. Check the rod surface for scratches, rust, and runout before fitting the seal.

Request a Custom Rod Seal Quote

Send us the rod diameter, bore diameter, groove dimensions, pressure in bar or MPa, speed, hydraulic fluid, and seal profile. Include a drawing, sample photo, and required quantity if available. CORASEALS will check the dimensions and material options before quoting a custom rod seal. You can also review our hydraulic cylinder seal kits and wiper seals when you send the cylinder details.