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Views: 0 Author: Site Editor Publish Time: 2026-10-09 Origin: Site
Lead When seals leak, wear or crack early, it is rarely a size problem — it is usually the wrong material. In the hydraulic systems of excavators and loaders, three materials dominate: NBR (nitrile rubber), PU (polyurethane) and PTFE. There is no "best" one — only the right one for the job. Here is how they compare.
1. NBR (Nitrile Rubber) — the general-purpose, oil-resistant workhorse
Good oil resistance, moderate cost, widely used for O-rings and standard oil seals;
Service temperature roughly -40°C to +120°C;
Moderate wear and extrusion resistance — not ideal for heavy load or extreme heat;
Typical use: O-rings, static seals, standard oil seals, and the energizer in Glyd/Step seals.
2. PU (Polyurethane, AU/EU) — the wear and load champion
Excellent tensile strength, abrasion and extrusion resistance, ideal for reciprocating rods;
Service temperature roughly -40°C to +80°C (lower heat limit than NBR);
Typical use: rod seals, wiper seals and buffer seals — common on excavator boom/arm cylinders.
3. PTFE — low friction and high temperature
Extremely low friction, non-stick, chemically resistant, wide temperature range (about -200°C to +260°C);
Little elasticity on its own, so it needs an NBR or FKM energizer to keep the lip loaded;
Typical use: Glyd Rings, Step Seals, wear/guide rings, high-speed low-friction applications.
Quick comparison
Material | Oil resistance | Temperature | Wear resistance | Friction | Best for |
NBR | Good | -40~+120°C | Moderate | Medium | O-rings, static seals, standard oil seals |
PU | Good | -40~+80°C | Excellent | Medium-high | Rod seals, wipers, buffer seals |
PTFE | Excellent | -200~+260°C | Good | Very low | Glyd/Step seals, guide rings, high speed |
One-line rule for maintenance & purchasing
O-rings / static seals → NBR;
Rod, wiper, high-frequency reciprocating (high wear) → PU;
Piston seals, low friction, high temperature / high speed → PTFE + NBR/FKM energizer.
Discuss your selection on site Choosing the right material can double or triple your overhaul interval. Bring your machine model and conditions (pressure, temperature, fluid) and meet us at bauma CHINA 2026 · Shanghai New International Expo Centre (SNIEC) · Hall W2 · Stand W2.530 (24–27 November 2026). 【Insert here: booking link / contact email】
