Model Car Body Insert Molding for Shrinkage Control
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Solution Overview
Problem
Conventional plastic model car manufacturing methods face challenges in achieving a smooth outer surface while ensuring easy release from the mold, particularly when thicker plastic parts are required for features like openable doors, as uneven shrinkage during solidification can lead to an uneven outer surface.
Innovation Solution
The method involves using pre-fabricated plastic blocks attached to the inner core of the mold via insert-molding, ensuring a uniform cavity thickness to minimize shrinkage and maintain a smooth outer surface, while allowing for increased wall thickness at specific areas through integration of these blocks with the model car body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the plastic model car body is configured to have a draft angle at its interior to enable easy release from the inner core, then the ease of manufacture is improved, but the outer surface becomes uneven due to different rates of shrinkage during solidification
Solution Approach 1:
The invention divides the wall thickness into two segments: the main body panel thickness and the additional plastic block thickness. This segmentation allows the draft angle to be provided by the plastic block rather than the entire wall thickness, preventing shrinkage-induced surface unevenness while maintaining ease of release.
Solution Approach 2:
The invention applies different wall thicknesses at different locations of the car body. Thicker walls are provided at specific areas (using plastic blocks) where draft angle is needed for easy release, while other areas maintain minimal thickness to avoid shrinkage and maintain smooth outer surfaces.
2Strength
If thicker plastic parts are used to accommodate features like openable doors, then the structural strength is improved, but the shrinkage during solidification increases causing uneven outer surface
Solution Approach 1:
The wall thickness is segmented into the base panel thickness and the additional plastic block thickness. This allows structural strength to be enhanced locally at door frames through plastic blocks while the main body panels maintain minimal thickness to prevent shrinkage-related surface unevenness.
Solution Approach 2:
Different wall thicknesses are applied locally: thicker walls with plastic blocks at door frames for structural strength, and thinner walls at body panels to minimize shrinkage and maintain smooth outer surfaces.
3Manufacturing precision
If the wall thickness is kept minimal to avoid shrinkage, then the manufacturing precision of outer surface is improved, but the ease of release from the inner core deteriorates
Solution Approach 1:
The draft angle requirement is segmented from the main body wall thickness and transferred to the attached plastic blocks. This allows the body panels to maintain minimal thickness for smooth outer surfaces while the plastic blocks provide the necessary draft angle for easy release.
Solution Approach 2:
The plastic blocks act as intermediaries between the inner core and the main body panel. They provide the draft angle needed for release while being separate from the main panel thickness, thus not causing shrinkage-induced surface unevenness.
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 allows for a smooth outer surface and easy release of the model car body from the mold, as the pre-fabricated blocks provide additional thickness without causing uneven shrinkage, ensuring a high-quality, collectable model car body with enhanced structural features.
Implementation Method 1
solidifying the melted plastic so as to form the model car body
Data Source
AI summary
The present disclosure relates to a method of manufacturing a model car body, including preparing a steel mold comprising a core plate with an inner core, a top plate and at least two side plates; attaching at least one pre-fabricated plastic block to a side of the inner core of the core plate; combining the core plate, the top plate and the at least two side plates with each other, wherein a cavity is formed among the top plate, the side plates, the inner core of the core plate and the at least one pre-fabricated plastic block; injecting melted plastic material into the cavity, wherein the melted plastic material is filled with the cavity and the at least one pre-fabricated plastic block is encased by the melted plastic material; solidifying the melted plastic so as to form the model car body, wherein the at least one pre-fabricated plastic block is integrated with the plastic model car body; separating the core plate, the top plate and the at least two side plates from each other; and releasing the model car body with the at least one pre-fabricated plastic block from the mold.