Electrothermal Heater Mat Low-Temperature Shaping
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Solution Overview
Problem
The production of thermoplastic composite heater mats for aircraft ice protection systems is hindered by the need for high-temperature processing, requiring expensive steel tooling and potentially damaging the electrical components during formation.
Innovation Solution
A method of manufacturing electrothermal heater mats using a preform of laminated thermoplastic dielectric layers with a central reinforcement layer, heated to a temperature below the melting point for shaping into a desired configuration, allowing the use of standard aluminum tooling and minimizing impairment to electrical components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If thermoplastic composite heater mats are processed at high temperatures for shaping, then the desired complex shapes can be achieved, but expensive steel tooling is required and electrical components may be damaged
Solution Approach 1:
The patent changes the temperature parameter from high-temperature processing (requiring steel tooling) to low-temperature processing (using aluminum tooling). Specifically, the thermoplastic material is processed at temperatures below 150°C instead of the typical 400°C+, enabling the use of cheaper aluminum tooling and protecting electrical components from thermal damage
Solution Approach 2:
The patent utilizes the phase transition of thermoplastic materials from solid to a softened state at relatively low temperatures. By heating the thermoplastic dielectric layers to a temperature above their melting point (but below 150°C), the material becomes formable and can be shaped using aluminum tooling, then solidifies upon cooling to retain the desired configuration
2Ease of manufacture
If standard aluminum tooling is used for shaping thermoplastic heater mats, then production costs are reduced, but the thermoplastic material requires temperatures below its melting point which limits forming capability
Solution Approach 1:
The patent modifies the temperature parameter range for processing thermoplastic materials, specifically using temperatures between 100°C and 150°C (below the melting point but above the glass transition temperature). This parameter change enables aluminum tooling to be used while still achieving adequate forming capability for complex heater mat configurations
Solution Approach 2:
The patent applies preliminary heating to the thermoplastic dielectric layers before forming operations. By pre-heating the material to the appropriate temperature range, the material becomes sufficiently formable for shaping with aluminum tooling, and then cools to lock in the desired shape
3Shape
If electrical components are exposed to high temperatures during heater mat formation, then the shaping process can be completed, but the electrical characteristics of the heater elements may be impaired
Solution Approach 1:
The patent changes the temperature parameter from high-temperature processing (400°C+) to low-temperature processing (below 150°C). This parameter change protects electrical components such as heater elements and wiring from thermal damage while still enabling the thermoplastic material to be shaped into the desired configuration
Solution Approach 2:
The patent uses temperature control as an intermediary mechanism to separate the forming process from thermal damage. By maintaining temperatures in the 100-150°C range, the process provides sufficient heat for thermoplastic forming while acting as a protective barrier against temperatures that would damage electrical components
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 reduces production costs, preserves the electrical characteristics of the heater elements, and enables the creation of heater mats with complex shapes without the need for high-temperature steel tooling, while maintaining the integrity of the thermoplastic matrix and functional components.
Implementation Method 1
a heater element formed by flame spraying a metal layer onto one of the dielectric layers
Implementation Method 2
heating the preform to a temperature between the glass-transition temperature of the thermoplastic material and the melting point of the thermoplastic material
Data Source
AI summary
In manufacturing an electrothermal heater mat, there is provided a preform which comprises a laminated stack of dielectric layers which are made of thermoplastic material and include a central layer or group of layers which include(s) reinforcement and first and second outer groups of layers which do not include reinforcement. The preform includes a heater element and the preform has a first configuration. The preform is then heated to a temperature (e.g. 180° C.) between the glass-transition temperature of the thermoplastic material and the melting point of the thermoplastic material, and the heated preform is formed into a second configuration which is different to the first configuration so as to produce the heater mat.