Resin Molded Product Gate Mark Step Design
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Solution Overview
Problem
Resin molded products produced by injection molding often exhibit appearance deterioration due to silver streaks caused by air escaping from unfilled portions, especially in thin components where the cooling rate is high and the resin material cannot follow the mold's inner surface unevenness.
Innovation Solution
A resin molded product with a gate mark on a non-design surface and a step that intersects with the resin flow, featuring a tangential angle of 5° to 30° and a curvature radius of 0.2 mm or more, allowing the resin to fill smoothly and reduce appearance deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If the resin molded product is thinned to reduce weight and material cost, then the cooling rate increases, but the resin material cannot follow the mold's inner surface unevenness, causing unfilled portions and silver streaks
Solution Approach 1:
The invention applies local quality by creating a specific uneven shape only in the gate mark region rather than modifying the entire mold surface. The gate mark region is given a curved bottom with specific radius and tangential angle to locally improve resin flow and filling characteristics, while the rest of the mold maintains its original design surface quality.
Solution Approach 2:
The invention implements preliminary action by pre-forming an uneven shape in the gate mark region before resin injection. This pre-formed curvature with controlled radius and angle prepares the mold surface to guide resin flow properly from the beginning of injection, preventing unfilled portions and silver streaks before they occur.
2Productivity
If the resin is filled at high speed to compensate for high cooling rate in thinned components, then productivity increases, but the resin may not follow the unevenness of the inner surface, forming unfilled portions
Solution Approach 1:
The uneven shape is pre-formed in the gate mark region to create a favorable flow path before resin injection begins. This preliminary geometric configuration ensures that even at high injection speeds, the resin naturally follows the curved surface and fills all areas including previously problematic unfilled portions.
Solution Approach 2:
The invention applies curvature by forming the bottom of the gate mark uneven shape with a specific radius (0.1-1.0 mm). This spherical/curved geometry helps the resin flow smoothly along the contour without abrupt changes, enabling complete filling even at high injection speeds used for thinned components.
3Manufacturing precision
If a front surface cover with gate mark is used to suppress streaks, then appearance quality improves, but the uneven shape on the surface affects the occurrence of streaks
Solution Approach 1:
The invention resolves this by confining the uneven shape modification strictly to the gate mark region, which is a non-design surface. The design surface maintains its original smooth appearance, while only the localized gate mark area has the controlled unevenness needed to prevent streaks, thus improving appearance without excessive complexity.
Solution Approach 2:
The uneven shape in the gate mark region is created as a copy or replica of a specific geometric form (curved bottom with controlled radius and angle). This standardized geometric copying allows systematic control of the unevenness to suppress streaks while maintaining reproducibility and manageable complexity.
Data Source
AI summary
A resin molded product produced by injection molding includes: a gate mark formed on a non-design surface; and a step provided so as to intersect with a flow of a resin injected from a gate. When a flow distance of the resin from the gate mark to an end portion of the resin molded product is L [mm], and a thickness of the resin molded product is t [mm], the resin molded product is configured to have L/t of 185 or more, and a tangential angle of the step is 5° to 30°.