Crosslinked UHMWPE Sliding Layer for Wear Resistance

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Solution Overview

Problem

Conventional sliding members with crosslinked ultra high molecular weight polyethylene as a solid lubricant often exhibit reduced heat resistance and deteriorated lubrication characteristics due to brittleness, leading to insufficient seizure and wear resistance.

Innovation Solution

A manufacturing method involving the sealed irradiation of ultra high molecular weight polyethylene with electron beams at specific absorbed doses to ensure proper crosslinking, maintaining the material's integrity and enhancing its melting point and gel fraction, thereby forming a sliding layer with improved seizure, wear, and heat resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If crosslinked ultra high molecular weight polyethylene is simply irradiated with radiation rays, then crosslinking is achieved, but the material becomes brittle and heat resistance deteriorates

Engineering Contradiction:
Improvecrosslinking degreeVSAvoidheat resistance and lubrication characteristics
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent applies inert atmosphere by conducting electron beam irradiation in a sealed state (vacuum or inert gas atmosphere) to prevent oxidation of ultra high molecular weight polyethylene during crosslinking. This resolves the contradiction by enabling proper crosslinking while preventing the material from becoming brittle, thereby maintaining heat resistance and lubrication characteristics.

Inventive Principle:
Principle #39Inert atmosphere (Inert environment)

Solution Approach 2:

The patent applies parameter changes by controlling the absorbed dose of electron beams within a specific range (60-500 kGy) to achieve optimal crosslinking. This resolves the contradiction by finding the right parameter window where sufficient crosslinking occurs without excessive brittleness, maintaining both strength and reliability.

Inventive Principle:
Principle #35Parameter changes

2Strength

If the absorbed dose of electron beams is increased to improve crosslinking, then wear resistance improves, but the crosslinked polyethylene becomes brittle and wear resistance deteriorates

Engineering Contradiction:
Improvewear resistanceVSAvoidbrittleness control
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The patent applies parameter changes by establishing an optimal absorbed dose range (60-500 kGy) for electron beam irradiation. This resolves the contradiction by identifying the precise parameter window where sufficient crosslinking achieves wear resistance without excessive brittleness that would deteriorate performance.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies feedback by measuring the gel fraction of crosslinked ultra high molecular weight polyethylene to control the crosslinking process. This resolves the contradiction by using gel fraction as a feedback parameter to monitor and adjust crosslinking degree, ensuring optimal wear resistance while preventing excessive brittleness.

Inventive Principle:
Principle #23Feedback

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The method results in a sliding layer with enhanced friction coefficient, reduced wear, and improved heat resistance, ensuring excellent sliding characteristics under various environmental conditions.

Implementation Method 1

the particulate ultra high molecular weight polyethylene is irradiated with radiation rays in the sealed state in the crosslinking step

Methodology Applied
Scientific EffectElectron beam irradiation: Electron Beam

Implementation Method 2

the ultra high molecular weight polyethylene is properly crosslinked

Methodology Applied
Scientific EffectCrosslinking: Chemical Bonding

Implementation Method 3

enhancing its melting point and gel fraction

Methodology Applied
Scientific EffectMelting point elevation: Melting

Implementation Method 4

enhancing its melting point and gel fraction

Methodology Applied
Scientific EffectGel formation: Gel

Data Source

PatentEP3712234B1Sliding member and method for manufacturing same
Publication Date: 2022.10.05 TOYOTA INDUSTRIES CORP
  • EP3712234B1 patent drawingFigure 1~2
  • EP3712234B1 patent drawingFigure 3~5
  • EP3712234B1 patent drawingFigure 6~8

AI summary

A sliding member in which a sliding layer is capable of exhibiting excellent sliding characteristics in terms of seizure resistance, wear resistance and heat resistance. A method for manufacturing the sliding member of the present invention is a method for manufacturing a sliding member to manufacture a sliding member sliding with a mating material. The manufacturing method includes a crosslinking step of irradiating particulate ultra high molecular weight polyethylene with radiation rays in a sealed state, and crosslinking the ultra high molecular weight polyethylene, a composition preparing step of preparing a composition for a sliding layer containing a solid lubricant and a binder resin, and a sliding layer forming step of forming a sliding layer sliding with the mating material by providing the composition for a sliding layer on a base material, and obtaining the sliding member. The solid lubricant includes the ultra high molecular weight polyethylene crosslinked in the crosslinking step.