Coated Sheets for Additive Manufacturing Void Elimination
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Solution Overview
Problem
Sheet-based additive manufacturing techniques, such as LOM, often result in objects with reduced structural integrity due to voids formed between sheets, which compromise the strength of the final product.
Innovation Solution
The use of coated sheets in additive manufacturing, where a base polymer layer is coated with a polymer material having a higher dielectric loss factor, allowing for selective dielectric heating and improved inter-layer bonding, thereby enhancing the structural integrity of the built object. The coated sheets are formed by applying a liquid coating to a base polymer sheet, drying it, and then dielectrically heating the interface areas using electromagnetic radiation to fuse adjacent sheets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If sheet-based additive manufacturing is used to manufacture parts, then manufacturing efficiency is improved, but structural integrity deteriorates due to voids between sheets
Solution Approach 1:
The patent applies parameter changes by modifying the dielectric loss factor of the coating layer to enable selective dielectric heating. The coating layer is formulated with a higher dielectric loss factor than the base polymer layer, allowing it to absorb electromagnetic energy and generate heat preferentially at the interfaces between sheets during additive manufacturing. This targeted heating parameter change ensures complete fusion at sheet interfaces, eliminating voids and improving structural integrity while maintaining manufacturing efficiency.
Solution Approach 2:
The patent employs composite materials by creating a multi-layer structure consisting of a base polymer layer and a coating layer with different dielectric properties. The coating layer is formed by applying a liquid coating containing polymer material to the base polymer sheet. This composite structure enables differential heating responses, where the coating layer with higher dielectric loss factor absorbs electromagnetic energy and transfers heat to the interface regions, ensuring complete bonding between sheets and preventing void formation.
2Use of energy by moving object
If conventional heating is used to fuse sheets, then energy consumption is high, but heating uniformity deteriorates leading to void formation
Solution Approach 1:
The patent applies local quality by creating a coating layer with spatially varying dielectric properties that concentrate heating at the sheet interfaces. The coating layer is applied only to specific regions of the base polymer sheet, and its higher dielectric loss factor causes it to absorb electromagnetic energy and generate heat locally at the interfaces between sheets. This localized heating approach ensures uniform fusion at critical bonding regions while reducing overall energy consumption compared to conventional bulk heating methods.
Solution Approach 2:
The patent replaces conventional thermal conduction heating with dielectric heating using electromagnetic radiation. Instead of using external heat sources that rely on thermal conduction, the system applies electromagnetic energy that is absorbed by the coating layer and converted to heat through dielectric loss. This substitution enables direct, uniform, and controlled heating at the sheet interfaces, eliminating the heating uniformity problems and void formation associated with conventional heating methods while reducing energy consumption.
3Strength
If a coating layer with higher dielectric loss factor is applied, then inter-layer bonding is improved, but material complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-forming the coating layer on the base polymer sheets before the additive manufacturing process. The liquid coating is applied to the base polymer sheet and dried to form a coating layer with the desired dielectric properties before the sheets are stacked and heated. This preliminary preparation ensures that the coating layer is already in place with the correct thickness and dielectric loss factor, enabling effective dielectric heating and inter-layer bonding during manufacturing without adding complexity to the manufacturing process itself.
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 method prevents the formation of voids between sheets, resulting in objects with improved structural integrity and enhanced bonding between layers, leading to stronger and more reliable final products.
Implementation Method 1
dielectrically heating at least the coating polymer layer of the first coated sheet and the coating polymer layer of the second coated sheet using electromagnetic radiation, thereby to fuse the first coated sheet to the second coated sheet
Data Source
AI summary
A coated sheet for use in additive manufacturing includes a base polymer layer formed of a base polymer material and a coating polymer layer formed of a coating polymer material. At least the coating polymer material is susceptible to dielectric heating in response to electromagnetic radiation, thereby promoting fusion between adjacent coated sheets during the additive manufacturing process. Specifically, when electromagnetic radiation is applied to at least an interface area between adjacent coated sheets, the polymer coating layer of each coated sheet melts to diffuse across an interface area, thereby preventing formation of voids. The base polymer material and the coating polymer material also may have similar melting points and compatible solubility parameters to further promote fusion between sheets.