Composite Washer With Visual Tightening Indication and Anti-Loosening

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Solution Overview

Problem

Existing fasteners face challenges in maintaining the correct tightening force and preventing loosening due to vibrations or excessive force, which can lead to damage or failure, and current tools are cumbersome, expensive, or unsafe for difficult-to-reach locations.

Innovation Solution

A composite washer with a top part, elastic part, and base part that visually indicates when the correct tightening force is applied by changing from a primary to a secondary state, where the elastic part is concealed, and includes features to enhance friction and resistance against rotation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a torque wrench or screwdriver with a pre-set torque meter is used to control tightening force, then the tightening force can be controlled accurately, but the process becomes tedious and the tools are heavy and expensive

Engineering Contradiction:
Improvetightening force controlVSAvoidtool complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts the force measurement function from complex torque wrenches and screwdrivers, integrating it into a simple washer component. The elastic part deforms under compression to provide visual feedback about applied force, eliminating the need for expensive torque meters while maintaining force control capability

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The washer performs self-measurement of applied force through the deformation of its elastic part. The visual indication system automatically shows whether sufficient tightening force has been applied without requiring external measurement devices or complex tooling

Inventive Principle:
Principle #25Self-service

2Measurement precision

If handheld automated tools are used for fastening fasteners in unreachable places, then tightening force can be controlled, but it becomes dangerous or impossible due to lack of space

Engineering Contradiction:
Improvetightening force controlVSAvoidaccessibility
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The washer provides self-indication of proper tightening through visual feedback from the elastic part deformation. This eliminates the need for operators to use complex handheld tools in difficult-to-reach locations, as the force control function is built into the washer itself

Inventive Principle:
Principle #25Self-service

3Reliability

If metallic washers are used to prevent loss of tightening force, then fastening stability is improved, but there is no visual indication of tightening force status

Engineering Contradiction:
Improvefastening stabilityVSAvoidtightening force status
Core Design Contradiction:
ReliabilityVSLoss of information

Solution Approach 1:

The patent uses color changes in the elastic part to provide visual information about tightening force status. The elastic part is colored differently from the metallic parts, and its deformation (compression or expansion) changes the visible color pattern, indicating whether sufficient tightening force has been applied or if the fastener has loosened

Inventive Principle:
Principle #32Color changes

Solution Approach 2:

The patent combines metallic parts (top part, base part) with an elastic non-metallic part to create a composite washer. This composite structure provides both the mechanical stability of metal and the visual indication capability of elastic materials, simultaneously achieving fastening stability and information provision

Inventive Principle:
Principle #40Composite materials

4Strength

If excessive tightening force is applied, then fastening strength is improved, but damage may occur to the object or fastener

Engineering Contradiction:
Improvefastening strengthVSAvoiddamage risk
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The elastic part provides immediate visual feedback when the correct tightening force is applied through its deformation. This feedback mechanism prevents operators from applying excessive force by clearly indicating when sufficient tightening has been achieved, thereby avoiding damage to the object or fastener

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

Enables quick and safe application of the correct tightening force without additional tools, reduces the risk of loosening, and ensures secure fastening by providing a visual indication and increased friction, thus extending the lifespan of the fastener.

Implementation Method 1

an elastic part (130) which has a circumferential extension around the axis A... the elastic part is arranged to be in a primary state where the elastic part is visible at a lateral surface thereof, and wherein the composite washer is arranged to be in a secondary state where the elastic part is compressed by the top part and base part

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 2

the elastic material is, as a reaction when being compressed, pressing against the top part and the base part. Thus, the composite washer is applying an expansive force towards the fastener and the object the fasteners is fastened towards. From this, the friction between the fastening element and the object it is fastened against is increased, which is advantageous for improving the fastening element's resistance against rotation

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP4562311B1A composite washer for force indication and loosening prevention
Publication Date: 2026.04.01 WORXSAFE AB
  • EP4562311B1 patent drawingFigure 1~2b
  • EP4562311B1 patent drawingFigure 3~5
  • EP4562311B1 patent drawingFigure 6~8

AI summary

The invention relates to a composite washer (100) for force indication and preventing a fastener from loosening. The composite washer comprising a top part (120) which has a circumferential extension around an axis, an elastic part (130) which has a circumferential extension around the axis a base part (140) which has a circumferential extension around the axis, wherein the top part, the elastic part and the base part are connected to each other, wherein the elastic part is arranged in-between the top part and the base part, wherein there is a central opening (102) which has an extension along the axis throughout the top part, the elastic part and the base part. Further, the composite washer is arranged to be in a primary state where the elastic part is visible at a lateral surface thereof, and wherein the composite washer is arranged to be in a secondary state where the elastic part is compressed by the top part and base part such that the elastic part is hidden by at least one of the top part and the base part, at the lateral surface (104) thereof. There is thus provided a composite washer which is indicating the tightening force on a fastener and counteracting loosening of the fastener.