Resistive Heating-Compression for Composite Additive Manufacturing
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Solution Overview
Problem
Current additive manufacturing methods face limitations in materials palette and slow build speeds, particularly due to non-linear scaling of heating time and energy costs when creating large three-dimensional objects using oven heating in Composite-Based Additive Manufacturing (CBAM).
Innovation Solution
The implementation of resistive heating, where a stack of powdered substrate sheets is heated by passing current through the body, allowing for rapid and efficient heating and compression of the stack, reducing heating time and energy consumption by adjusting voltage and current based on the stack's electrical resistivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If oven heating is used to heat the stack of substrate sheets, then the heating process is simple and uniform, but the heating time increases non-linearly with the square of the smallest stack dimension and energy costs increase
Solution Approach 1:
The patent replaces the thermal conduction-based oven heating system with an electrical resistive heating system. Instead of using an oven that heats the stack from the outside through thermal conduction, the invention applies electrical current directly to the stack, which generates heat internally through Joule heating. This substitution of heating mechanism eliminates the non-linear time scaling problem because electrical heating does not depend on heat diffusion distance.
Solution Approach 2:
The stack of substrate sheets serves its own heating function through resistive heating. When electrical current passes through the stack, the material itself generates the heat needed for processing through Joule heating. This self-heating mechanism eliminates the need for external oven heating and resolves the time scaling issue because the heating rate depends on electrical resistance and power input, not on heat diffusion distance.
2Ease of manufacture
If oven heating is used to heat the stack of substrate sheets, then the heating process is simple and uniform, but energy costs increase non-linearly with the square of the smallest stack dimension
Solution Approach 1:
The patent replaces the thermal conduction-based oven heating system with an electrical resistive heating system. Instead of using an oven that heats the stack from the outside through thermal conduction, the invention applies electrical current directly to the stack, which generates heat internally through Joule heating. This substitution of heating mechanism eliminates the non-linear time scaling problem because electrical heating does not depend on heat diffusion distance.
Solution Approach 2:
The stack of substrate sheets serves its own heating function through resistive heating. When electrical current passes through the stack, the material itself generates the heat needed for processing through Joule heating. This self-heating mechanism eliminates the need for external oven heating and resolves the time scaling issue because the heating rate depends on electrical resistance and power input, not on heat diffusion distance.
3Reliability
If traditional oven heating is used in CBAM, then the process is well-established, but the build speed is slow and cannot scale linearly with object size
Solution Approach 1:
The patent replaces the thermal conduction-based oven heating system with an electrical resistive heating system. Instead of using an oven that heats the stack from the outside through thermal conduction, the invention applies electrical current directly to the stack, which generates heat internally through Joule heating. This substitution of heating mechanism eliminates the non-linear time scaling problem because electrical heating does not depend on heat diffusion distance.
Solution Approach 2:
The patent changes the fundamental heating parameter from thermal conduction (dependent on distance) to electrical resistance heating (independent of distance). By controlling electrical current and power input, the heating rate can be adjusted independently of stack dimensions, enabling linear scaling of build speed with object size while maintaining process reliability.
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
Resistive heating significantly reduces heating time and energy costs, enabling the creation of larger objects in a shorter time frame while maintaining control over compression, and simplifies the process by allowing for remote handling and easier temperature management, compared to traditional oven heating methods.
Implementation Method 1
Resistive heating according to the present invention is, in a preferred embodiment, employed in the heating—compression step of Composite-Based Additive Manufacturing (CBAM)... the stack is heated by passing current through the body of the stack
Implementation Method 2
the sheets are stacked upon one another, and then the stack is heated and compressed to form a 3D object... heated to a temperature required to convert the deposited thermoplastic to the liquid state (above the glass transition temperature, Tg, if amorphous, or above the melting temperature, Tm, if partially crystalline)
Implementation Method 3
After enough time has passed at the temperature required to melt the thermoplastic, the stack is compressed to the desired thickness to form the 3D object
Data Source
AI summary
A method and apparatus for resistive heating usable in composite-based additive manufacturing is disclosed. The method includes providing a prepared stack of substrate sheets, placing the stack between electrode assemblies of a compression device, applying a current to thereby heat the stack to a final temperature to liquefy applied powder, compressing the stack to a final height, cooling the stack, and removing the cooled, compressed stack from the compression device. The apparatus comprises at least two plates, a power supply for providing current, a first electrode assembly and a second electrode assembly.