Self-lubricating Thermoplastic Layers with Polymodal PTFE

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Solution Overview

Problem

Thermoplastic sliding materials face challenges in achieving low coefficients of friction during media lubrication without compromising wear resistance, as high PTFE content weakens the matrix and reduces wear resistance, while PTFE gradients improve friction but reduce wear resistance.

Innovation Solution

Incorporating a mixture of high molecular weight (HMW) and low molecular weight (LMW) PTFE additives within specific volume ratios into a thermoplastic matrix, along with additional components like high-temperature thermoplastics, solid lubricants, and fiber materials, to optimize both wear resistance and friction coefficients.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If high PTFE content is added to thermoplastic sliding materials, then the coefficient of friction is reduced, but wear resistance deteriorates

Engineering Contradiction:
Improvecoefficient of frictionVSAvoidwear resistance
Core Design Contradiction:
Object-affected harmful factorsVSStrength

Solution Approach 1:

The patent applies parameter changes by using PTFE with different molecular weights (low, medium, high) to alter the physical and mechanical properties of the sliding material. The low molecular weight PTFE reduces friction, while high molecular weight PTFE maintains wear resistance, achieving optimal performance through compositional parameter optimization.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite PTFE system by combining PTFE particles of different molecular weights in specific ratios within the thermoplastic matrix. This composite approach allows the material to simultaneously exhibit low friction characteristics from low molecular weight PTFE and high wear resistance from high molecular weight PTFE, resolving the contradiction between friction reduction and wear resistance maintenance.

Inventive Principle:
Principle #40Composite materials

2Object-affected harmful factors

If PTFE gradient is created by impregnating with PTFE dispersion, then the coefficient of friction is reduced in the outer area, but wear resistance deteriorates

Engineering Contradiction:
Improvecoefficient of frictionVSAvoidwear resistance
Core Design Contradiction:
Object-affected harmful factorsVSStrength

Solution Approach 1:

The patent applies local quality by creating a non-uniform distribution of PTFE particles with different molecular weights throughout the sliding material thickness. The outer regions contain higher concentrations of low molecular weight PTFE for low friction, while inner regions contain high molecular weight PTFE for wear resistance, optimizing both surface and bulk properties simultaneously.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent uses parameter changes by varying the molecular weight distribution of PTFE particles across different depths of the sliding material. This gradient in molecular weight parameters creates corresponding gradients in friction and wear properties, allowing the surface to have low friction while the bulk maintains high wear resistance.

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If PTFE additive is added to thermoplastic matrix, then sliding properties are improved, but the matrix is weakened

Engineering Contradiction:
Improvesliding propertiesVSAvoidmatrix strength
Core Design Contradiction:
Ease of operationVSStrength

Solution Approach 1:

The patent creates a composite structure where PTFE particles of different molecular weights are distributed within the thermoplastic matrix. The low molecular weight PTFE provides sliding properties, while the high molecular weight PTFE and thermoplastic matrix work together to maintain structural strength, preventing excessive matrix weakening.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent optimizes the molecular weight parameters of PTFE additives to balance sliding properties and matrix strength. By selecting specific molecular weight ranges and ratios, the material achieves improved sliding characteristics while the higher molecular weight components and matrix polymer maintain adequate mechanical strength.

Inventive Principle:
Principle #35Parameter changes

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 solution achieves a balance by significantly reducing wear and friction coefficients, ensuring the sliding material has the lowest friction and greatest resistance to wear, even under varying load conditions.

Implementation Method 1

the sliding material having a thermoplastic matrix material and a PTFE (polytetrafluoroethylene) additive

Methodology Applied
Scientific EffectBoundary lubrication: Lubrication

Implementation Method 2

A porous sinter layer is applied to a carrier medium

Methodology Applied
Scientific EffectCapillary action: Capillary Action

Data Source

PatentEP3087142B1Self-lubricating thermoplastic layers containing PTFE additive having a polymodal molecular weight
Publication Date: 2019.06.19 FEDERAL MOGUL WIESBADEN GMBH & CO KG
  • EP3087142B1 patent drawingFigure 1
  • EP3087142B1 patent drawingFigure 2
  • EP3087142B1 patent drawing

AI summary

The invention relates to a gliding material for gliding elements, said gliding material comprising a thermoplastic matrix material and a PTFE additive. The gliding material is characterized in that the PTFE additive includes at least two different types of PTFE having different molecular weights.