Multi-Material Toothbrush Grip Injection Molding
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Solution Overview
Problem
The existing methods for manufacturing grip bodies for body care and cosmetic products, such as toothbrushes, using injection molding with multiple thermoplastic materials are costly, inefficient, and limit design possibilities due to high tooling costs, low productivity, and the need to minimize injection points for aesthetic reasons.
Innovation Solution
A method where two or more thermoplastic material components are injected through a common injection point outside the mold partition line, with one component forming a jacket body and the other as a core, allowing for a simpler and more cost-effective manufacturing process with fewer tool cavities, enabling a high degree of automation and varied material combinations for different functional parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple tool cavities are used for injection molding different material components, then manufacturing precision and functional differentiation are improved, but tooling costs and device complexity increase
Solution Approach 1:
The patent merges multiple injection molding operations into a single tool cavity by using a movable partition wall that divides the cavity during injection. Different material components are injected sequentially into the same cavity space, eliminating the need for multiple separate cavities while maintaining functional differentiation. This reduces tooling costs and device complexity while preserving the ability to manufacture multi-material grip bodies with precise functional zones.
Solution Approach 2:
The tool cavity is segmented into different regions using a movable partition wall that can be positioned to create separate injection zones. This segmentation allows different material components to be injected into distinct areas of the same cavity, enabling functional differentiation without requiring multiple permanent cavities. The partition wall can be moved or removed after injection, facilitating the production of complex multi-material structures.
2Manufacturing precision
If multiple reapplication steps are used for different material components, then functional differentiation is improved, but productivity and manufacturing speed decrease
Solution Approach 1:
The patent enables continuous injection molding by using a movable partition wall that allows sequential injection of different material components into the same cavity without removing or repositioning the workpiece between steps. The first material component is injected, then the partition wall is moved or removed, and the second material component is injected continuously into the same cavity, eliminating idle reapplication steps and significantly improving manufacturing speed while maintaining functional differentiation.
3Manufacturing precision
If multiple injection points are used for different material components, then material distribution and functional zones are improved, but aesthetic appearance deteriorates due to visible injection points on surface
Solution Approach 1:
The patent extracts the injection points from the visible surface area by positioning them on the rear side or non-aesthetic portions of the grip body. The movable partition wall system allows injection points to be located at the rear injection zone, away from the front aesthetic surface. This extraction maintains effective material distribution and functional zoning while eliminating visible injection marks from the aesthetic surfaces, thus preserving product appearance.
4Manufacturing precision
If conventional injection molding with multiple cavities is used, then material component separation is improved, but design flexibility and interflowing possibilities are limited
Solution Approach 1:
The patent introduces dynamic elements to the injection molding system through a movable partition wall that can be repositioned or removed between injection steps. This dynamic approach allows the same tool cavity to accommodate various design configurations and material distributions, enabling interflowing effects and diverse aesthetic patterns that are impossible with static multi-cavity systems. The movable partition provides adaptability for different design requirements while maintaining clear material component separation through controlled injection sequencing.
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 approach reduces manufacturing complexity and costs, enhances design flexibility, and allows for the use of different materials for specific functional areas, improving the aesthetic and functional properties of the grip body while maintaining a minimal number of injection points.
Implementation Method 1
a first material component is injected into a first tool cavity of an injection moulding tool
Implementation Method 2
The injection moulding tool comprises a hot-runner system with a hot-runner nozzle
Data Source
AI summary
A grip body of a body care article, such as toothbrush, includes a grip part, a neck part, and a head part. The grip body includes a first and a second material component of a thermoplastic plastic. Manufacturing of the grip body is performed via an injection moulding tool with at least one tool cavity, and the grip body including a first, second, and third material component of a first, second, and third thermoplastic material, respectively.