LWRT Panel Fabric Overmolding for Complex Feature Integration
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Solution Overview
Problem
Current methods for constructing vehicle panels using Light Weight Reinforced Thermoplastics (LWRT) face limitations in achieving complex geometries due to the material's limited elongational properties and require multiple steps for adding features to the B-side, which can result in unreliable welds and structural weakness, especially when trying to integrate injection molded features with a soft or non-woven A-side finish.
Innovation Solution
The LWRT plus fabric injection overmolding process allows direct injection molding of thermoplastic features onto the B-side of a formed LWRT panel with an A-side finish, using mold filling CAE analysis for pressure and temperature control, adjustable tool standoffs for tonnage building, and low linear shrinkage resins, enabling features of any shape and strength without secondary welding or A-side damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If injection molded features are added to the B-side of an LWRT panel after forming, then features can be added to the panel, but the features are structurally weak because they cannot exceed 40% of the nominal wall thickness
Solution Approach 1:
The LWRT panel is pre-formed with the desired geometry and A-side finish before the injection molding process. This preliminary formation allows the panel to have optimized structural integrity while accepting injection molded features on the B-side that can exceed the traditional 40% wall thickness limitation, as the pre-formed panel provides a stable substrate.
Solution Approach 2:
The patent combines the LWRT panel formation and injection molding of B-side features into a single integrated manufacturing process. The panel is formed and then immediately subjected to injection molding of features on the B-side without separation, creating a unified structure with enhanced strength and eliminating the need for secondary welding operations.
2Reliability
If welding is used to add features to the B-side of an LWRT panel, then features can be added, but the welds are unreliable and may cause A-side read-through
Solution Approach 1:
The patent replaces the welding process (thermal/mechanical joining method) with injection molding (volumetric forming method). Instead of attaching features through welding that risks A-side read-through and unreliable bonds, the features are directly molded onto the B-side of the panel, eliminating the harmful effects of welding while providing superior attachment reliability.
3Adaptability or versatility
If multiple steps are used to add B-side features to an LWRT panel with A-side fabric finish, then features can be added, but the process is complex and time-consuming
Solution Approach 1:
The patent merges the LWRT panel formation and B-side feature addition into a single integrated process. The panel is formed with its A-side fabric finish intact, then immediately undergoes injection molding of B-side features in the same manufacturing cycle, eliminating multiple separate steps and significantly reducing production time while maintaining full versatility in feature design.
Solution Approach 2:
The A-side fabric finish is applied and finalized before the injection molding of B-side features. This preliminary completion of the A-side allows the B-side features to be added afterward without compromising the finish, enabling a streamlined single-step process that maintains high adaptability.
4Adaptability or versatility
If traditional injection molding is used to add features to an LWRT panel, then features can be added, but the features are limited to 40% of nominal wall thickness
Solution Approach 1:
The LWRT panel is pre-formed with optimized wall thickness and structural geometry before injection molding of B-side features. This preliminary formation creates a stable substrate that can support features exceeding the traditional 40% wall thickness limitation, thereby expanding design freedom while maintaining or enhancing structural strength.
Solution Approach 2:
The integration of panel formation and feature molding into a single process allows for features that can violate traditional injection molding limitations. The pre-formed panel provides the structural foundation that enables larger, more complex features to be molded onto the B-side without compromising strength, achieving both design versatility and structural integrity.
Data Source
AI summary
An LWRT plus fabric injection overmolding process for the direct injection molding of thermoplastic features onto the B-side of a formed, finished Light Weight Reinforced Thermoplastic panel. The panel having an A-side finish cloth, non-woven, TPO, Vinyl or similar material placed into the injection molding press and injection molding tool, and then the features are injection molded onto the panel without damaging the A-side finish.