Metal-Resin Composite Joining via Roughened Surface Anchoring

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Solution Overview

Problem

Existing methods for joining metal and resin members often result in unsatisfactory joining strength and hot-cold shock resistance.

Innovation Solution

A method involving the formation of a roughened surface on the metal member with a developed area ratio (Sdr) of 5 or more, followed by joining with a resin member using frictional heat generated during friction stir welding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional joining methods (screws, adhesives, or simple friction stir welding) are used to join metal and resin members, then the joining process is simple, but the joining strength and hot-cold shock resistance are unsatisfactory

Engineering Contradiction:
Improvejoining strengthVSAvoidprocess complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The metal member surface is pre-roughened before joining to create an anchor structure. This preliminary surface treatment enables the melted resin to penetrate deeply and form strong mechanical interlocking, significantly improving joining strength and hot-cold shock resistance without complicating the overall joining process

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The surface roughness parameters of the metal member are specifically controlled (Sdr ≥ 5%) to optimize the anchor effect. By adjusting the roughened surface parameters, the joining strength is enhanced while maintaining process simplicity through friction stir welding

Inventive Principle:
Principle #35Parameter changes

2Strength

If the metal member surface is made smooth for easy manufacturing, then the manufacturing process is simple, but the resin member cannot penetrate deeply enough to achieve strong joining

Engineering Contradiction:
Improvejoining strengthVSAvoidsurface preparation complexity
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The metal member surface is pre-roughened before joining to create an anchor structure. This preliminary surface treatment enables the melted resin to penetrate deeply and form strong mechanical interlocking, significantly improving joining strength and hot-cold shock resistance without complicating the overall joining process

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The roughened surface mechanism replaces the need for complex mechanical anchoring systems. By creating surface roughness, the mechanical interlocking is achieved passively through the resin penetration into surface irregularities, simplifying the overall joining system while enhancing strength

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 significantly improves the joining strength between the metal and resin members by creating a strong anchor effect due to the deep penetration of the melted resin into the roughened metal surface.

Implementation Method 1

joining together the resin member and the metal member by melting the resin member with the frictional heat generated in the surface of the metal member

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 2

joining together a metal member and a resin member by using FSW (friction stir welding)

Methodology Applied
Scientific EffectFriction stir welding: Friction Welding

Implementation Method 3

forming a roughened surface in at least a portion of the surface of the metal member

Methodology Applied
Scientific EffectSurface roughening: Abrasion

Data Source

PatentEP3865284B1Metal/resin composite and production method therefor
Publication Date: 2025.05.21 DIC CORP
  • EP3865284B1 patent drawingFigure 1~2
  • EP3865284B1 patent drawingFigure 3
  • EP3865284B1 patent drawingFigure 4a~4e

AI summary

There is provided a method for producing a metal-resin composite which includes a resin member and a metal member having a roughened surface in at least a portion of the surface thereof, the resin member being joined so as to be in contact with at least a portion of the roughened surface. The method includes a step of joining the resin member and the metal member by melting the resin member with the frictional heat generated in the surface of the metal member on its side opposite to the resin member in a state where the metal member and the resin member are superposed. The method includes making adjustment so that when the roughened surface is measured at arbitrary five points by using a confocal microscope according to ISO 25178, the developed area ratio (Sdr) is 5 or more in terms of number-average value.