Relief Part Decoration via Selective Surface Adhesion
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Solution Overview
Problem
The existing methods for fabricating parts with relief decorations, such as timepiece dials, are costly due to the need for precise positioning and multiple steps like bonding and buffing, which increase with the thickness of the appliques, leading to excessive fabrication costs.
Innovation Solution
A method that involves forming a plastic part with relief by selectively modifying the surface state to control the adherence of a decorative layer, allowing for direct deposition and precise selection of adhesion areas, using techniques like laser radiation and vapour phase deposition, and removing non-adhered portions, thereby simplifying the decoration process and reducing material usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional bonding and masking steps are used to assemble appliques on the dial, then the decorations can be applied, but the fabrication cost increases excessively due to positioning precision requirements and multiple processing steps
Solution Approach 1:
The mould cavity is pre-structured with relief portions before injection molding, so that the relief decorations are formed directly during the molding process. This preliminary structuring eliminates the need for subsequent bonding and masking steps, reducing both positioning precision requirements and fabrication costs
Solution Approach 2:
The invention merges the decoration formation process with the base part manufacturing process. By integrating relief portion formation into the injection molding step, multiple operations (molding + decoration assembly) are combined into a single step, eliminating intermediate bonding and masking operations
2Shape
If the thickness of appliques is increased to improve decoration visibility, then the decorative effect is enhanced, but the positioning precision requirement increases leading to higher fabrication costs
Solution Approach 1:
The relief portions are pre-formed in the mould cavity with precise dimensions, ensuring that the thickness and shape of decorations are controlled during molding. This eliminates the need for thick appliques to achieve visibility, as the relief features are precisely formed from the start
3Reliability
If multiple bonding and masking steps are used to apply decorations, then the decorative layers can be applied, but the number of fabrication steps increases leading to excessive costs
Solution Approach 1:
The mould is pre-structured with relief portions that define where decorative material should adhere. This preliminary structuring allows decorative material to be applied in a single step without requiring multiple bonding and masking operations, maintaining decoration reliability while reducing step count
Solution Approach 2:
The mould cavity has different surface properties in different regions - relief portions that attract decorative material and flat portions that repel it. This local differentiation allows selective decoration without masking steps, as the surface structure itself guides material adhesion
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 reduces the number of steps and material required for decoration, enhances precision in positioning, and achieves a metallic appearance with fewer materials, resulting in lower fabrication costs and improved efficiency.
Implementation Method 1
Step b) is performed by laser type radiation
Implementation Method 2
Step c) is achieved by vapour phase deposition
Implementation Method 3
After step d), galvanoplasty is performed in order to thicken each portion including said decorative layer
Data Source
AI summary
A method for fabricating a part with relief, wherein portions in relief are at least partially coated with a decorative layer. The method a) forms the body of the part; b) selectively alters the surface state of the body of the part to change the adherence thereof locally relative to the decorative layer; c) directly deposits the decorative layer over the entire body; d) removes the portions of the deposited layer which have not adhered to the body of the part. The method can be utilized in decorating timepieces.