Watch Dial Overmolding Coating for Assembly Damage Protection

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Solution Overview

Problem

Watch dials in the watchmaking, fashion, and jewelry sectors are fragile and prone to damage during manufacturing and assembly, necessitating effective mechanical protection.

Innovation Solution

A coating process involving overmolding with a plastic polymer material to create a protective and decorative overmolding layer, which can be applied through spraying or injection molding, replicating patterns using laser beam devices, and utilizing molds made of silicone, metallic, or ceramic materials.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If watch dials are handled and assembled during manufacturing, then the watch components can be assembled into functional timepieces, but the fragile dials are prone to damage and may need to be discarded

Engineering Contradiction:
Improveassembly processVSAvoiddamage risk to dials
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent applies a protective coating to the watch dial before assembly operations. This coating acts as a cushioning layer that absorbs mechanical stresses and prevents damage to the fragile dial during handling and assembly processes, thereby reducing discard rates while maintaining ease of manufacture

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The protective coating serves as an intermediary layer between the fragile dial and the external mechanical stresses during assembly. This intermediate layer absorbs the impact and prevents direct contact between damaging forces and the dial surface, resolving the contradiction between assembly ease and damage risk

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If a protective coating is applied to watch dials, then mechanical protection is provided during assembly, but the coating process adds manufacturing steps and complexity

Engineering Contradiction:
Improvemechanical protectionVSAvoidcoating process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent utilizes changes in material parameters (applying a coating with specific physical and chemical properties) to provide protection. By selecting appropriate coating materials and adjusting their properties, mechanical protection is achieved without requiring complex multi-step coating processes, thus resolving the contradiction between protection reliability and process complexity

Inventive Principle:
Principle #35Parameter changes

3Loss of substance

If expensive watch dials are protected against damage, then economic losses from discard are reduced, but the protection method must be effective enough to prevent even minor scratches and damages

Engineering Contradiction:
Improveeconomic loss from discardVSAvoidmechanical stresses during production
Core Design Contradiction:
Loss of substanceVSObject-affected harmful factors

Solution Approach 1:

The patent employs composite material structures for the protective coating, combining materials with complementary properties to achieve enhanced protection. This composite approach provides robust protection against various mechanical stresses during production, effectively preventing damage to expensive dials and reducing economic losses from discard

Inventive Principle:
Principle #40Composite materials

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 overmolding layer provides mechanical protection and decoration, reducing damage risks during production and assembly while enhancing the visual appeal of components.

Implementation Method 1

coating the covering piece with an overmolding layer formed by spraying this covering piece with the plastic polymer material

Methodology Applied
Scientific EffectSpray deposition: Fluid Spray

Implementation Method 2

hot replicating the pattern in the overmolding layer by means of a tool made using a laser beam device which carries in negative the pattern to be replicated in the overmolding layer

Methodology Applied
Scientific EffectLaser heating: Laser

Implementation Method 3

the pattern contained in this metallic or ceramic mold and intended to be replicated in the overmolding layer is made using a laser beam device by means of which the pattern intended to be replicated in the overmolding layer is made in negative in the metallic or ceramic mold

Methodology Applied
Scientific EffectLaser ablation: Laser Ablation

Implementation Method 4

inject the plastic polymer material into the mold so that it forms the overmolding layer which at least partially overmold the trim piece

Methodology Applied
Scientific EffectInjection molding: Injector

Implementation Method 5

hot replicating the pattern in the overmolding layer

Methodology Applied
Scientific EffectThermal replication: Heat Treatment

Data Source

PatentEP4390559B1Method for coating a covering part, in particular in the timepiece area, and coated covering part
Publication Date: 2026.04.15 THE SWATCH GRP RES & DEVELONMENT LTD
  • EP4390559B1 patent drawingFigure 1~3
  • EP4390559B1 patent drawingFigure 4
  • EP4390559B1 patent drawingFigure 5

AI summary

The invention relates to a method of coating a case part (1) in the field of watchmaking, fashion articles, jewelry and fine jewelry, this coating method comprising the steps of: - overmolding at least in part the case part (1) by means of an overmolding layer (4) formed of a plastic polymer material chosen from the group formed by thermoplastic polymers of the polyurethane family and thermosetting polymers of the epoxy polymer family, or from the group formed by thermoplastic acrylic resins.The invention also relates to a component for the watchmaking, fashion, jewelry and fine jewelry sectors, this component being at least partly coated with an overmolding layer made of a plastic polymer material chosen from the group formed by thermoplastic polymers of the polyurethane family and thermosetting polymers of the epoxy polymer family, or from the group formed by thermoplastic acrylic resins.