Laser-Textured Interference-Fit Fasteners With Lower Insertion Force

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Solution Overview

Problem

Current interference fit fastening methods, such as press-fit and shrink-fit, face challenges including high insertion forces, excessive plastic deformation, and complex assembly processes, leading to premature joint failure and increased costs, particularly in industries like aerospace and automotive where precise tolerances and high frictional forces are required.

Innovation Solution

A novel laser micro-profiling technique is used to alter the surface texture of metal pins, creating a secure interference-fit by controlling laser parameters to achieve precise surface texturing, allowing for controlled bond strength and reduced plastic deformation, enabling easier assembly and disassembly with defined insertion forces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If traditional press-fit or shrink-fit methods are used to achieve interference fit fastening, then high frictional forces and secure bonding are obtained, but excessive plastic deformation and high insertion forces are required

Engineering Contradiction:

Improvebond strengthVSAvoidplastic deformation

Core Design Contradiction:

StrengthVSObject-generated harmful factors

Solution Approach 1:

The pin surface is pre-textured using laser processing before assembly to create micro-roughness features. This preliminary surface modification enables the pin to achieve secure bonding with reduced insertion forces and minimized plastic deformation during the interference fit assembly process

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The laser texturing creates localized surface roughness features at specific locations on the pin surface. These localized micro-features concentrate the bonding interaction at textured regions, allowing secure fastening while reducing overall plastic deformation of the pin material

Inventive Principle:

Principle #3Local quality

2Manufacturing precision

If tight tolerances are used in interference fit fastening to ensure precise coupling, then secure bonding is achieved, but very high insertion forces are required

Engineering Contradiction:

ImprovetoleranceVSAvoidinsertion force

Core Design Contradiction:

Manufacturing precisionVSForce

Solution Approach 1:

The surface roughness parameter is modified through laser texturing to create optimal micro-features. This parameter change in surface topology allows the interference fit to achieve secure bonding at reduced insertion forces by enhancing local mechanical interlocking without requiring tight dimensional tolerances

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If conventional interference fit methods are used for fastening, then simple design and ease of manufacture are maintained, but assembly and disassembly are difficult and time-consuming

Engineering Contradiction:

Improvedesign simplicityVSAvoidassembly ease

Core Design Contradiction:

Ease of manufactureVSEase of operation

Solution Approach 1:

The laser texturing process applies periodic pulsed laser energy to the pin surface to create the textured pattern. This periodic action enables precise surface modification with controlled material removal, facilitating easier assembly while maintaining design simplicity

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The mechanical laser texturing process replaces traditional mechanical surface preparation methods. This substitution enables precise surface texturing with reduced tooling complexity and improved assembly characteristics while maintaining ease of manufacture

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Strength

If high insertion forces are applied in interference fit fastening, then secure bonding is achieved, but physical damage and premature failure occur

Engineering Contradiction:

Improvebond strengthVSAvoidjoint life time

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The laser texturing creates a cushioning effect by distributing stress across textured surface regions. This beforehand surface preparation cushions against peak stresses during assembly, reducing the risk of physical damage and extending joint life time

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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

This method provides a rapid, cost-effective, and reliable solution for interference-fit joints with improved bond strength, reduced plastic deformation, and extended joint life times, facilitating user-friendly assembly and disassembly with controlled insertion and removal forces, and eliminating the need for additional equipment.

Implementation Method 1

a laser is used to melt and/or ablate a surface of the metal pin to create a textured profile

Methodology Applied

Scientific EffectLaser heating: Laser

Implementation Method 2

a laser is used to melt and/or ablate a surface of the metal pin to create a textured profile

Methodology Applied

Scientific EffectLaser ablation: Laser Ablation

Data Source

PatentUS11248636B2Interference fit fastener and method of fabricating same

Publication Date: 2022.02.15 DUBLIN CITY UNIVERSITY

AI summary

An interference fit fastener (FIG. 1) and method of fabricating same is described.