Annular Insert Molding With Local Adhesive Placement
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Solution Overview
Problem
The manufacturing method of annular insert molded articles, such as magnetic encoders, faces issues with adhesive contamination, adhesion to metal molds, reduced binding force, and increased material costs due to excessive adhesive application and the need for a primary heating step to achieve cross-linking, which complicates the process and reduces productivity.
Innovation Solution
Applying a thermoset resin adhesive only within a specific range not exceeding 3 mm beyond the boundary with the annular plastic, avoiding unnecessary portions, and omitting the primary heating step to maintain adhesive reactivity, allowing for precise adhesion and reduced waste, thereby improving separation from molds and attachment to rotating bodies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the insert is soaked in liquid adhesive to apply adhesive to the entire insert, then a large number of inserts can be processed simultaneously, but the adhesive is applied to unnecessary portions including surfaces to be contacted with the metal mold
Solution Approach 1:
The patent applies adhesive only to specific local areas of the insert surface that require bonding, rather than coating the entire surface. This is achieved through controlled application methods that limit adhesive placement to predetermined zones, preventing contamination of areas that contact the metal mold or transfer jig while maintaining batch processing efficiency.
2Stability of the object's composition
If the adhesive is applied to the entire insert including surfaces to be contacted with the metal mold, then complete coverage is achieved, but the insert and metal mold adhere firmly making separation difficult and stopping the molding step
Solution Approach 1:
The patent selectively applies adhesive only to specific regions of the insert where bonding is required, deliberately excluding areas that will contact the metal mold during injection molding. This localized application ensures complete adhesive coverage where needed while preventing unwanted adhesion to mold surfaces, allowing easy separation after molding.
Solution Approach 2:
The insert surface is divided into functional zones: areas requiring adhesive application for bonding and areas requiring no adhesive for mold contact. This segmentation allows differential treatment of surface regions, applying adhesive only where beneficial while avoiding areas where it would cause manufacturing problems.
3Object-generated harmful factors
If the adhesive is dried to drive off solvent and then heated and baked into a semi-cured state, then contamination of transfer jig and metal mold is prevented, but the reactive groups in the adhesive decrease reducing binding force between insert and plastic
Solution Approach 1:
The patent performs preliminary drying to remove solvent and prevent contamination, but delays the cross-linking curing reaction (baking into semi-cured state) until after injection molding. This sequencing preserves reactive groups in the adhesive during molding, maintaining strong binding force between the insert and plastic while still preventing contamination during transfer operations.
Solution Approach 2:
The adhesive processing is divided into distinct periodic stages: first drying to remove solvent, then injection molding while adhesive remains reactive, and finally cross-linking curing after molding. This periodic action allows each stage to serve its specific function without interfering with subsequent stages.
4Ease of manufacture
If the insert is soaked in liquid adhesive, then adhesive application is simple, but excessive adhesive material is used increasing material costs
Solution Approach 1:
The patent uses controlled application methods to place adhesive only in specific local areas where bonding is required, rather than soaking the entire insert. This precision application maintains simplicity of the adhesive application process while dramatically reducing the total amount of adhesive material used, eliminating waste on unnecessary portions.
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 minimizes contamination, maintains high adhesion strength, reduces material waste, and enhances productivity by ensuring effective adhesion without excessive heating, thus improving the overall manufacturing efficiency and product quality.
Implementation Method 1
heat and bake the adhesive into a semi-cured state, that is, perform the primary heating step involving a cross-linking curing reaction
Data Source
AI summary
A method of manufacturing an annular insert molded article that suppresses contamination of a metal mold and generation of foreign matter without increase in material costs for an adhesive or contamination of a transfer jig, and has a high adhesion strength so that, when the annular insert molded article is attached to a rotating body, the adhesive does not peel off from the insert or remain as foreign matter in the rotating body.An annular insert molded article 1 is manufactured by injection molding in a state where a thermoset resin adhesive A is applied to a joining surface of an annular insert 2 attachable to a rotating body to an annular plastic 3 and then the annular insert 2 and the annular plastic 3 are placed in a metal mold.