Multicolored Ceramic Watch Bezel With Laser-Ablated Decoration
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Solution Overview
Problem
Ceramic or cermet watch components with multi-color decorations face challenges due to significant shrinkage during sintering, leading to separation at material junctions and complex mechanical assembly for decoration attachment, and existing methods struggle to achieve uniform color and seamless integration.
Innovation Solution
A multi-material injection process using an insert with a raised or recessed structure to create a gripping surface between materials, followed by sintering and laser ablation machining to produce a seamless, uniformly colored article with distinct color decorations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If multiple materials of different colors are injected to create decorated components, then the decoration is integrated into the component, but shrinkage differences during sintering lead to separation at the junction between materials
Solution Approach 1:
The patent applies local quality by creating a gripping surface with a specific roughness profile (Ra 0.4-2.5 μm) at the junction zone between different materials. This localized surface treatment enhances mechanical interlocking and reduces shrinkage-induced separation at the critical interface, while maintaining smooth surfaces elsewhere for aesthetic purposes.
Solution Approach 2:
The patent implements preliminary action by pre-forming the gripping surface structure on the first injected material before the second material is injected. This pre-prepared surface with controlled roughness ensures optimal adhesion and minimizes separation during subsequent sintering, addressing the shrinkage issue before it occurs.
2Adaptability or versatility
If materials are injected to form decorated components, then color decoration is achieved, but significant shrinkage during sintering causes separation at material junctions
Solution Approach 1:
The patent creates a localized gripping surface with optimized roughness (Ra 0.4-2.5 μm) at the material junction zone. This local surface modification provides enhanced mechanical interlocking specifically where needed, maintaining junction integrity while preserving the aesthetic quality of the overall decorated surface.
Solution Approach 2:
The patent uses composite material structures by combining different ceramic or cermet materials with distinct color properties. The gripping surface acts as a transition zone that mechanically bonds these different materials, ensuring reliable junctions while maintaining the desired color decoration and material properties in each zone.
3Adaptability or versatility
If mechanical assembly is used to attach decorative elements to the component, then decoration is added to the component, but the process becomes costly and complicated
Solution Approach 1:
The patent merges the decoration creation process with the component manufacturing process itself. By injecting different colored materials directly into the mold cavity in a multi-material injection process, the decoration becomes an integral part of the component, eliminating the need for separate mechanical assembly steps and reducing overall process complexity.
Solution Approach 2:
The patent replaces mechanical assembly methods (such as gluing or brazing) with a material-based bonding approach. The gripping surface creates mechanical interlocking at the molecular level during injection, substituting complex post-manufacturing assembly operations with a streamlined injection process that achieves the same decorative effect more efficiently.
4Manufacturing precision
If uniform color is achieved in the mass of colored parts, then aesthetic quality is improved, but the injection and sintering process becomes more difficult to control
Solution Approach 1:
The patent applies local quality by concentrating the gripping surface treatment specifically at the junction zones where materials meet, rather than treating the entire surface. This localized approach with controlled roughness (Ra 0.4-2.5 μm) ensures proper adhesion and uniform color appearance without requiring complex adjustments to the overall injection and sintering parameters.
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 method reduces shrinkage differences and ensures a seamless, uniformly colored article with integrated decorations, eliminating the need for costly mechanical assembly and achieving a one-piece component without discontinuities.
Implementation Method 1
a significant shrinkage, which can amount to 30%, is observed during sintering
Implementation Method 2
Machining by laser ablation of at least the second material to produce the decoration in said second material
Implementation Method 3
Sintering of the green body to form a blank
Data Source
Figure 1~2
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Figure 6~7
AI summary
The invention relates to a multicoloured article made of cermet and/or ceramic, and in particular a bezel (1) of a watch part, made by an injection process of at least two materials (2,3) of distinct colours, said article comprising a relief decoration (11) of a colour different from the rest of the article, said decoration (11) being made by laser ablation after injection of the two materials.