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Background
Background
Traditional injection molding cooling channels are milled from a solid block using round mill bits. The creates a channel or network of channels composed of paths with circular cross sections. In specific cases, it may be advantageous to have flattened or rectangular cross-sectional channels to provide cooling to parts with large thermal masses or with large surface areas.
However, when manufacturing these "flat" channels using additive manufacturing (our application utilizes DMLS), support structures needs to be generated or will result in part failure during manufacturing. Because these channels may be fully enclosed, removal of support structures is often impossible without destroying the part itself. Additionally, the support structures generated automatically by many slicer software applications cannot guarantee continuity in the channel or may result in significant reductions in fluid flow rate.
Example of a Wide-path Cooling Channel
Problem Statement:
Eliminate the need for support structures generated by slicer software applications. Incorporate support structures into mold design to guarantee fluid flow continuity
Process:
Evaluate existing software products in lattice generation to determine complexity of use, robustness, and applicability in DMLS lattice support generation
Products Assessed
Products Assessed
Fathom Manufacturing
Digifabster
Gen3D
nTopology
After exploring many software options from a variety of different companies of varying sizes, each product was assessed through product demos and trials. For reasons ranging from complexity of use and lack of print verification, each software was assessed to be unfit for our application. While each product could offer a variety of different lattice structures across a variety of complexities, very few presented the option for print verification. After meeting with many representatives for product demos and experimenting with software through product trials, no software was found to contain the features we desired.
Process:
Create a process to automatically generate lattice structures to enable DMLS additive manufacturing without compromising fluid flow. Create a process other engineers can use without significant additional training or complex mathematical computations.
Concept
Concept
Combine print verification principles with face-centric lattice structure to create individual lattice units. Each unit is composed of face centric vertical columns with pyramidal peaks across the voids. The size of the vertical columns is determined from an infill percentage provided by the user. The angle of the corresponding pyramids is specified by the user as the maximum overhang angle of the printer. This unit is patterned across the entire path.
Sample of Individual Unit with 45° at 50% Infill
Challenges:
Enabling lattice generation in conjunction with vertical inlet/outlet channels
Optimizing lattice generation to reduce objects and computations needed
Results
Results
Sample of Channel Positive
Sample of Channel Positive
A sample square-shaped channel negative to be removed from a injection molding block. Peaks of lattice structure created at maximum support angle, inputted by user.
Sample of Channel Negative in Block
Sample of Channel Negative in Block
Cross-sectional view of channel created by subtracting channel positive from a solid block
Example of a Wide-path Cooling Channel
Example of a Wide-path Cooling Channel
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Example of Cooling Path with Vertical Inlet/Outlet Channels
Example of Cooling Path with Vertical Inlet/Outlet Channels
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