Automotive Trim Panel Over-Molding for Seamless Edge Wrapping
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Solution Overview
Problem
Conventional methods for manufacturing automotive interior trim panels are time-consuming, expensive, and result in unsightly edges and wrinkles due to manual skin folding and adhesive issues, requiring multiple molding tools and processes.
Innovation Solution
A single-cycle over-molding process that integrates injecting a liquid substrate polymer and a liquid urethane polymer directly against the substrate, wrapping the urethane polymer around the peripheral edges, and extending it onto the backside, eliminating the need for separate foaming and manual skin wrapping, while using a dam to control the flow and achieve a seamless, resilient skin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional slush molding and foaming processes are used to manufacture trim panels, then the substrate and skin can be formed, but the manufacturing process becomes time-consuming and expensive requiring multiple molding tools
Solution Approach 1:
The patent combines multiple separate manufacturing processes (substrate molding, skin formation, edge wrapping, and foaming) into a single integrated injection molding cycle. The substrate and skin are co-injected in one operation, eliminating the need for separate slush molding and foaming steps, thereby reducing manufacturing time while maintaining quality
Solution Approach 2:
The patent segments the trim panel into distinct functional zones with different material properties - a rigid substrate for structural support and a softer skin for aesthetic and tactile qualities. This segmentation is achieved through multi-material injection molding, allowing each zone to be optimized independently while being manufactured in a single cycle
2Manufacturing precision
If thermoforming and vacuum forming are used to create the skin, then the skin can be formed, but the process requires separate machines and multiple time-consuming steps including edge folding and cutting
Solution Approach 1:
The patent merges skin formation and edge wrapping into a single injection molding operation. The skin is injected directly onto the substrate and automatically wraps around the edges in one continuous process, eliminating the need for separate vacuum forming machines and manual edge folding operations
Solution Approach 2:
The injected skin material self-wraps around the substrate edges through the injection pressure and material flow characteristics. The process is self-contained within the mold cavity, with the skin automatically conforming to the substrate geometry without requiring external manipulation or separate equipment
3Manufacturing precision
If manual skin folding and adhesive application are used to wrap edges, then the skin can be attached, but the process is time-consuming and results in unsightly wrinkles and adhesive issues
Solution Approach 1:
The patent replaces manual mechanical operations (folding and adhesive application) with an automated injection molding process. The skin is injected as a liquid or semi-liquid material that flows and wraps around edges under pressure, then cures in place, eliminating the need for manual manipulation and adhesive materials
Solution Approach 2:
The patent changes the physical state of the skin material from solid (requiring manual folding) to liquid/semi-liquid during injection, allowing it to flow and conform to edge geometries. The material then transitions to a solid state through curing, creating a seamless wrap without wrinkles or adhesive residues
4Manufacturing precision
If traditional two-shot molding is used to create multilayer trim panels, then the substrate and skin can be formed, but the process results in unsightly raw peripheral edges and requires manual folding and gluing
Solution Approach 1:
The patent combines substrate molding and skin formation into a single integrated injection process where both materials are injected and formed simultaneously in one mold cycle. This eliminates the sequential two-shot process and its associated edge problems, creating clean peripheral edges as part of the unified molding operation
Solution Approach 2:
The patent applies different material properties to different regions of the trim panel - the substrate provides structural rigidity while the skin provides aesthetic surface quality and edge wrapping. This local differentiation of material properties is achieved through controlled material injection and distribution within the single molding cycle
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
The process significantly reduces manufacturing time to 2-6 minutes, improves manufacturing tolerances and accuracy, eliminates wrinkles, and achieves a seamless, soft-feel skin without adhesives, resulting in a cost-effective and aesthetically pleasing trim panel.
Implementation Method 1
injecting a liquid substrate polymer between molds to create a substrate
Implementation Method 2
injecting a liquid urethane polymer into a cavity directly against the substrate to create a skin or cover
Implementation Method 3
flowing or wrapping in a mold the urethane polymer around at least one peripheral edge of the substrate
Implementation Method 4
extending the urethane polymer onto a backside of the substrate
Implementation Method 5
damming a flow of an encapsulating urethane skin within the cavity by the liquid urethane abutting against a wall surface upstanding from the backside of the substrate
Implementation Method 6
these conventional skins are made by slush rotational molding or thermoforming
Data Source
AI summary
An over-molded interior trim method and system are provided. In another aspect, a method of manufacturing a trim panel includes: injecting a liquid substrate polymer between molds to create a substrate, injecting a liquid urethane polymer into a cavity directly against the substrate to create a skin or cover, flowing or wrapping in a mold the urethane polymer around at least one peripheral edge of the substrate, and extending the urethane polymer onto a backside of the substrate.