Liquefier Liner Resolves Hot Melt Weld Plugs
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Solution Overview
Problem
Additive manufacturing systems face issues with the formation of 'hot melt weld plugs' and 'deformed filament plugs' in liquefier assemblies, leading to printing delays and reduced reliability, due to the cooling profile and thermal gradients within the liquefier tubes.
Innovation Solution
A lined liquefier assembly is introduced, featuring a hollow liner with a low surface energy and the same inner diameter as the liquefier tube, which reduces the risk of plug formation by allowing continuous cooling air flow and preventing adhesion of molten material, thereby eliminating hot melt weld and deformed filament plugs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cooling air is blown toward the inlet end of the liquefier tube to prevent deformed filament plugs, then deformed filament plugs are reduced, but hot melt weld plugs form at the inlet end
Solution Approach 1:
A hollow liner is introduced as an intermediary component between the cooling air flow and the filament material. The liner with its low surface energy material prevents direct adhesion between molten material and the surface it contacts, allowing cooling air to flow continuously without forming hot melt weld plugs while still preventing deformed filament plugs
2Reliability
If purge cycles are implemented to remove hot melt weld plugs, then hot melt weld plugs are eliminated, but printing time increases and productivity decreases
Solution Approach 1:
The hollow liner acts as a disposable protective layer that prevents plug formation in the first place. By using a low surface energy material that resists adhesion, the system eliminates the need for time-consuming purge cycles, maintaining continuous printing operation without sacrificing reliability
3Reliability
If the inner surface of the liquefier tube has high surface energy, then molten material adheres to prevent hot melt weld plugs, but deformed filament plugs form due to adhesion in the transition zone
Solution Approach 1:
The hollow liner serves as a mediator with low surface energy that prevents direct adhesion between molten material and the liquefier tube surface. This intermediary layer allows the system to avoid both hot melt weld plugs and deformed filament plugs by enabling continuous cooling air flow without material adhesion
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 lined liquefier assembly significantly increases the reliability of printing operations by reducing plug formation, allowing continuous operation without the need for additional purge cycles, and extending the time between maintenance, thus enhancing the overall efficiency of additive manufacturing systems.
Implementation Method 1
the liner inner surface has a low surface energy
Implementation Method 2
allowing continuous cooling air flow
Implementation Method 3
heating the liquefier tube, feeding a filament of a thermoplastic material through the hollow liner and into the liquefier tube while blowing the air and while heating the liquefier tube, melting the thermoplastic material
Data Source
AI summary
A liquefier assembly for use in an additive manufacturing system, the liquefier assembly comprising a liquefier tube, a rigid sleeve secured to an inlet end of the liquefier tube, an extrusion tip secured to an outlet end of the liquefier tube, and a hollow liner disposed at least partially within the rigid sleeve such that inner surfaces of the liquefier tube and the hollow liner are substantially flush, and where the inner surface of the hollow liner has a low surface energy.