Additive Manufacturing Overhang Control via Coalescence Modifier
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Solution Overview
Problem
Additive manufacturing machines face issues with unwanted solidification of build material due to coalescing agents, leading to poor dimensional accuracy and surface roughness, especially in objects with overhangs, as the heat generated can propagate and solidify surrounding material.
Innovation Solution
A new additive manufacturing process is developed that uses a coalescence modifier agent to inhibit interlayer fusing by dispensing it on the first layer where a second slice will overhang, preventing the build material in the second layer from fusing with the first layer, thereby maintaining smooth and well-defined overhangs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a coalescing agent is used to solidify build material in additive manufacturing, then the build material solidifies to form layers, but heat generated causes unwanted solidification of surrounding unpatterned build material, degrading dimensional accuracy and surface quality
Solution Approach 1:
A coalescence modifier agent is introduced as an intermediary substance that counteracts the effects of the coalescing agent. The modifier agent is dispensed on unpatterned build material surrounding the patterned area, preventing heat-induced solidification of surrounding material while allowing the coalescing agent to effectively solidify the patterned build material.
Solution Approach 2:
The build material surface is treated with different substances in different locations: the coalescing agent is applied only to patterned areas where solidification is desired, while the coalescence modifier agent is applied to unpatterned surrounding areas where solidification should be prevented. This creates spatially varying properties that address the contradiction locally.
2Productivity
If heat is generated to solidify patterned build material, then layers are formed, but heat propagates into surrounding material causing excessive surface roughness and poorly defined edges
Solution Approach 1:
The coalescence modifier agent acts as a thermal and chemical barrier that intercepts heat propagation from the patterned area. It allows rapid layer formation through the coalescing agent's light-absorbing properties while simultaneously preventing heat from causing unwanted solidification in surrounding areas, thus maintaining surface quality.
Solution Approach 2:
The heat that would normally cause harmful unwanted solidification is converted into a beneficial effect by the coalescence modifier agent, which uses or redirects this heat to enhance the solidification of the patterned area while protecting surrounding areas. The harmful thermal energy is thus transformed into a controlled solidification process.
3Strength
If build material in the second layer fuses with the first layer to create strong bonds, then interlayer strength is improved, but overhang surfaces become rough and poorly defined
Solution Approach 1:
Interlayer bonding is controlled locally: in areas where strong bonding is desired, the coalescing agent enables fusion, while in overhang areas, the coalescence modifier agent prevents fusion. This spatial differentiation allows the object to have both strong bonds where needed and smooth overhang surfaces where required.
Solution Approach 2:
The build platform is segmented into different functional zones: patterned areas where coalescing agent promotes solidification and interlayer bonding, and unpatterned overhang areas where coalescence modifier agent prevents solidification and maintains surface quality. This segmentation allows simultaneous achievement of strength and surface quality in different regions.
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 process effectively controls unwanted fusing between layers, resulting in improved dimensional accuracy and surface smoothness of overhangs by preventing the build material in the second layer from solidifying with the first layer, thus enhancing the overall quality of the manufactured object.
Implementation Method 1
LAP coalescing agents absorb light to generate heat that sinters, melts or otherwise solidifies (or initiates solidification of) the patterned build material
Implementation Method 2
heat generated in the patterned build material can, under some circumstances, propagate into and solidify surrounding, unpatterned build material
Data Source
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AI summary
In one example, a non-transitory processor readable medium with instructions thereon that when executed cause an additive manufacturing machine to inhibit build material from coalescing in an area of a first layer of build material where a second slice of an object will overhang a first slice of the object formed in the first layer of build material.