Molded Plastic Part Positioning Relief for Shrinkage Compensation
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Solution Overview
Problem
Molded plastic parts often experience unpredictable shrinkage during cooling, making it difficult to achieve the required dimensions, and existing dimensional control methods are expensive, cumbersome, and time-consuming.
Innovation Solution
A molded plastic part design featuring surface positioning relief portions with measurement and supporting protrusions allows for accurate and repeatable dimensional control using a vernier caliper, enabling reliable measurement of distance between these protrusions to account for shrinkage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a metrological instrument specifically developed for the molded part is used to measure predefined dimensions repeatedly and accurately, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the measurement function from complex metrological instruments and implements it through simple positioning relief portions with protrusions that can be measured using basic tools like vernier calipers. The positioning relief portions are specifically designed to provide reference points for measurement, separating the measurement reference function from the complex measurement device.
Solution Approach 2:
The patent uses simple, inexpensive positioning relief portions with protrusions that can be easily molded into the plastic part. These positioning features serve as disposable reference elements that enable accurate measurement without requiring expensive, complex metrological instruments, thereby reducing both device complexity and cost.
2Measurement precision
If a metrological instrument specifically developed for the molded part is used to measure predefined dimensions repeatedly and accurately, then measurement precision is improved, but the instrument becomes cumbersome and time-consuming for application
Solution Approach 1:
The patent extracts the measurement reference function from complex metrological instruments and implements it through simple positioning relief portions with protrusions. These positioning features allow measurement using basic tools like vernier calipers, making the measurement process simpler and more accessible while maintaining precision.
Solution Approach 2:
The positioning relief portions with their protrusions are self-positioning features that automatically provide reference points for measurement. The design allows the molded part itself to serve as the measurement reference system, eliminating the need for complex external metrological instruments and simplifying the measurement operation.
3Manufacturing precision
If the mold is dimensioned according to expected shrinkage to achieve required dimensions, then manufacturing precision is improved, but shrinkage is difficult to anticipate and control
Solution Approach 1:
The patent incorporates positioning relief portions with protrusions during the molding process as preliminary reference features. These features are built into the molded part itself before measurement, allowing shrinkage compensation to be systematically accounted for in the design phase and enabling more reliable dimensional control.
Solution Approach 2:
The positioning relief portions with protrusions create a feedback mechanism where the actual measured distance between protrusions can be compared against target dimensions. This allows for systematic shrinkage compensation and process control, improving both precision and reliability by enabling continuous monitoring and adjustment of molding parameters.
Data Source
AI summary
A molded part made in plastic material that includes a body having a surface and two positioning relief portions formed on the surface while being spaced apart from each other along a measurement direction, each positioning relief portion having a positioning protrusion defining a measurement surface allowing the positioning of a sensor member of a distance measurement instrument along the measurement direction bearing against the measurement surface, in order to measure the distance between the positioning relief portions along the measurement direction.