Hand Tool Handle Manufacturing via Inverted Two-Step Moulding
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Solution Overview
Problem
The existing manufacturing process for hand tool handles, which involves two or more materials, is cumbersome due to the need to transfer a large and heavy body portion between moulds, leading to unpredictable distortions and quality variations during the moulding of the surface portion.
Innovation Solution
Fabricate a smaller and lighter surface portion first, which is then placed in a mould where the body portion is moulded, allowing the melt mass to flow underneath and press the surface portion against the mould wall, eliminating the need to transfer the larger body portion and reducing distortion-related quality issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the body portion is transferred between moulds from first to second moulding, then the handle can be manufactured with multiple materials, but the transfer process becomes cumbersome due to size and weight, and quality variations increase
Solution Approach 1:
Instead of transferring the body portion from the first mould to the second mould as in conventional processes, the invention inverts the sequence by first forming the surface portion in the first mould, then transferring only this smaller component to the second mould where the body portion is formed around it. This inversion dramatically reduces transfer complexity while maintaining multi-material capability.
Solution Approach 2:
The handle manufacturing process is segmented into two distinct phases: first forming the surface portion separately, then forming the body portion around it. This segmentation allows each component to be optimized independently and eliminates the need to transfer the entire assembled handle or large body portion between moulds.
2Volume of moving object
If the body portion is large in size, then it can accommodate the shaft connection, but distortions during shrinkage and solidification increase, making it difficult to fit inside the second mould cavity
Solution Approach 1:
The surface portion is formed in advance in the first mould with precise geometric control before being transferred to the second mould. This preliminary action establishes a stable reference geometry that guides the subsequent body portion formation, compensating for shrinkage and solidification distortions that occur during the second moulding process.
Solution Approach 2:
The surface portion acts as an intermediary element between the two moulding processes. It is first formed with high precision in the first mould, then serves as a template or guide in the second mould, ensuring that the body portion is formed with accurate geometry despite the challenges of large-volume casting and material shrinkage.
3Manufacturing precision
If the mould cavity of the second mould follows the geometry of the body portion closely, then successful moulding of the surface portion is achieved, but the process becomes problematic due to unpredictable distortions
Solution Approach 1:
The invention inverts the conventional approach by making the surface portion the reference geometry rather than the body portion. The mould cavity of the second mould is designed to accommodate the pre-formed surface portion, not the other way around. This inversion makes the process more reliable because the surface portion, being smaller, experiences less distortion and can serve as a stable geometric reference.
Solution Approach 2:
The invention changes the critical parameter from body portion geometry to surface portion geometry. By focusing precision requirements on the smaller surface portion that experiences less thermal and shrinkage distortion, the process achieves both good fit and consistent quality. The mould cavity design adapts to this parameter change by being tailored to the surface portion's geometry.
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
Simplifies the transfer process and reduces quality variations by minimizing distortions, making it easier to match the surface portion's geometry with the mould cavity, resulting in a more consistent handle manufacturing process.
Implementation Method 1
melt mass, of which the body portion is formed, is cast into the cavity of the mould such that the melt mass flows under the surface portion pressing simultaneously the surface portion against the wall of the mould cavity
Data Source
AI summary
The present invention relates to a method for manufacturing a handle for a hand tool, the handle comprising a body portion and a gripping part that is provided at least partly on the body portion and intended for the user to grip when using the hand tool. In the method of the invention there is first fabricated the gripping part and it is set in a mould cavity, whereafter melt mass is cast into the mould cavity to provide the body portion such that the melt mass flows underneath the gripping part, whereby the gripping part is pressed against the wall of the mould cavity.