Multi-shot Moulding Joining Surface Ink Exclusion
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Solution Overview
Problem
In two-color injection processes using In-Mold Decoration by Roller (IMR), the transferred ink reduces the bonding strength between the first-shot and second-shot injection parts, leading to poor adhesion and easy separation, especially when soft polymer materials are used, and causes accumulation issues at the junctions.
Innovation Solution
A multi-shot moulding part structure design where the joining surface is not coated with an ink decoration layer, allowing the second structural part to directly touch the uncoated joining surface of the first structural part, thereby increasing the bonding strength between the two parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If IMR ink is transferred to the first-shot injection part, then the appearance effect is improved, but the bonding strength between the first-shot and second-shot injection parts is reduced
Solution Approach 1:
The patent applies local quality by creating a differentiated surface treatment on the first-shot injection part: the external surface receives IMR ink transfer for aesthetic appearance, while the joining surface remains ink-free to ensure optimal bonding strength. This is achieved through precise control of the IMR transfer process to exclude specific joining surfaces, allowing each surface to have the quality appropriate for its function.
2Manufacturing precision
If the printing area on the IMR transfer film is precisely aligned during the first shot, then the appearance precision is improved, but the transferred ink accumulates at the junction between the first-shot and second-shot injection parts
Solution Approach 1:
The patent implements local quality by applying IMR ink transfer selectively to specific areas of the first-shot injection part while deliberately excluding the joining surfaces. This precise spatial control allows high printing alignment precision on visible surfaces without causing ink accumulation at junctions, as the joining surfaces are specifically identified and protected from ink transfer.
Solution Approach 2:
The patent segments the surface of the first-shot injection part into functional zones: decorative surfaces that receive ink transfer and joining surfaces that remain ink-free. This segmentation is achieved through careful design of the IMR transfer process parameters and mold configuration, allowing independent control of ink transfer to different surface regions.
Data Source
AI summary
A multi-shot moulding part structure includes a first structural part, an ink decoration layer, and a second structural part. The first structural part has a first area surface, a second area surface, and a joining surface located on the second area surface. The joining surface is non-parallel to the second area surface. The ink decoration layer is spread on the first area surface and the second area surface, but not on the joining surface. The second structural part is combined with the first structural part and covers the second area surface. The second structural part touches the joining surface. By the second structural part touching the joining surface of the first structural part that is not coated with the ink decoration layer, the structural bonding strength between the first structural part and the second structural part is enhanced.