Multi-Stage Injection Molding Positioning Accuracy
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Solution Overview
Problem
In injection molding, the accuracy of positioning portions in multi-stage molded products is compromised due to heat deformation caused by the liquid molding material, leading to misalignment and reduced precision.
Innovation Solution
The method involves molding the entire positioning portion in a single injection step, where a preformed product with a notch is used as an insert material in the mold cavity, allowing the notch to be filled with molding material to ensure accurate positioning and alignment by compressing the insert material against the mold walls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the positioning portion is molded in multiple stages like other parts, then the manufacturing process is simplified, but the positioning accuracy deteriorates due to heat deformation
Solution Approach 1:
The positioning portion is separated from the main body and molded independently as a separate component. This allows the positioning portion to be manufactured with dedicated precision molding processes while the main body can be molded separately, thus maintaining both manufacturing simplicity and positioning accuracy.
Solution Approach 2:
The positioning portion is pre-formed as a separate component before being integrated with the main body. This preliminary action enables precise control of the positioning portion's geometry without the interference of subsequent molding operations on the main body, preventing heat-induced deformation and ensuring high positioning accuracy.
2Manufacturing precision
If the insert material is compressed by mold clamping force to prevent misalignment, then positioning accuracy is improved, but the insert material deforms due to compression stress
Solution Approach 1:
The positioning portion is pre-formed with its final precise shape before being placed as an insert in the main body molding. This preliminary precision molding prevents subsequent deformation that would occur if the positioning portion were compressed during the main body molding process.
Solution Approach 2:
A dedicated positioning portion mold is used as an intermediary tool to create the precise positioning features separately. This intermediary molding process ensures the positioning portion achieves its target shape without being subjected to the compression stresses of the main body molding operation.
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 enables precise molding of positioning portions, preventing heat-induced deformation and ensuring accurate alignment, thereby improving the overall accuracy and precision of the finished product.
Implementation Method 1
The insert material receives heat from the liquid molding material inside the cavity space, and thus, is softened in the vicinity of a boundary between the insert material and the liquid molding material.
Implementation Method 2
In order to prevent misalignment inside the cavity space, the insert material has a contour slightly larger than that of the cavity space when viewed in mold opening and closing directions, is compressed by the mold clamping force, and is pressed against the wall surface of the cavity space.
Data Source
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AI summary
A positioning portion (44, 46, 48) of a finished product (40) manufactured by injection moldings a plurality of times is accurately molded. In an injection molding method of molding a finished product (40) by injection molding of a plurality of times, the finished product (40) includes a positioning portion (44, 46, 48) which is fitted to a convex portion or a concave portion of a mating part (81) on which the finished product (40) is to be mounted and determines a position between the finished product (40) and the mating part (81), and in one injection molding of the injection moldings of the plurality of times, the entire positioning portion (44, 46, 48) is molded.