Polymer Thickened Grease Low Friction via Composite Structure

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Solution Overview

Problem

Conventional polymer thickened lubricating greases do not effectively reduce friction in bearing applications, leaving room for improvement.

Innovation Solution

A grease composition comprising a lubricating base oil, a polymeric thickener with a mixture of high and low molecular weight propylene polymers, and a polar wax, along with a metal salt, which is specifically designed to enhance friction reduction by forming a sponge-like structure that retains lubricant oil and lowers friction characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If conventional polymer thickened grease compositions are used, then the grease provides basic lubrication, but the friction reduction in bearing applications is insufficient

Engineering Contradiction:
ImprovefrictionVSAvoidlow friction behavior
Core Design Contradiction:
Loss of energyVSReliability

Solution Approach 1:

The grease composition combines a polymeric thickener (mixture of high and low molecular weight propylene polymers) with a polar wax additive to create a composite lubricating material. This composite structure provides both the thickening function and the low friction properties through the synergistic interaction between the polymer matrix and polar wax components, resolving the contradiction between basic lubrication and insufficient friction reduction.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The invention changes the molecular weight parameters of the polymeric thickener by using a mixture of high molecular weight (>200,000) and low molecular weight (<200,000) propylene polymers. This parameter variation optimizes both the structural integrity and friction reduction capabilities of the grease, enabling improved low friction behavior while maintaining reliable lubrication.

Inventive Principle:
Principle #35Parameter changes

2Stability of the object's composition

If a polymeric thickener with high molecular weight is used, then the grease structure is stable, but the friction reduction capability is limited

Engineering Contradiction:
Improvegrease structure stabilityVSAvoidfriction
Core Design Contradiction:
Stability of the object's compositionVSLoss of energy

Solution Approach 1:

The polymeric thickener is segmented into two distinct molecular weight components: high molecular weight propylene polymer for structural stability and low molecular weight propylene polymer for friction reduction. This segmentation allows each component to fulfill its specific function, with the high molecular weight portion providing grease structure stability and the low molecular weight portion enhancing friction reduction capability.

Inventive Principle:
Principle #1Segmentation

3Loss of energy

If polar wax is added to the grease composition, then friction is reduced, but the complexity of the grease formulation increases

Engineering Contradiction:
ImprovefrictionVSAvoidgrease formulation complexity
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The polar wax component serves multiple functions simultaneously: it acts as a friction modifier to reduce friction, works synergistically with the polymeric thickener to enhance lubrication, and contributes to the overall stability of the grease composition. This multi-functionality reduces the need for additional separate additives, thereby limiting the increase in formulation complexity while achieving superior friction reduction.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 grease composition exhibits excellent low friction behavior, providing improved mechanical stability and consistency, as demonstrated by reduced coefficients of friction in various bearing tests compared to conventional greases.

Implementation Method 1

a polar wax, which is specifically designed to enhance friction reduction by forming a sponge-like structure that retains lubricant oil and lowers friction characteristics

Methodology Applied
Scientific EffectAbsorption: Absorption (physical)

Implementation Method 2

a polymeric thickener comprising a mixture of (1) a (co- or homo)polymer of propylene with a weight average molecular weight of more than 200.000 and (2) a (co- or homo)polymer of propylene with a weight average molecular weight of less than 200.000

Methodology Applied
Scientific EffectViscometer effect: Viscometer

Data Source

PatentEP2649169B1Polymer thickened grease compositions with improved low friction properties
Publication Date: 2018.04.04 AB SKF SKF PATENT DEPARTMENT

AI summary

An angle encoder (10) is provided for determining a rotation angle of a rotating part (11) relative to a static part (12). The angle encoder (10) comprises a magnetic ring (11) having at least two magnetic poles and being attached to the rotating part (11) and, attached to the static part (12), means for measuring a magnetic field. The means for measuring the magnetic field comprise an optical fiber (13) with a fiber Bragg grating (14) coated with a magnetostrictive material. The means for measuring the magnetic field further comprise a light source (15) and an optical sensor (16), both being optically coupled to the optical fiber (13) and electronically coupled to an electronic circuit (17). The electronic circuit (17) is arranged to determine the rotation angle based on measured signals from the optical sensor (16).