Thomas Stock
The arrangement of components within a 3D printer’s build volume is crucial for maximizing the utilization of the printer’s capacity, minimizing waste, and optimizing production processes. This is especially true for Selective Laser Sintering (SLS) and Multi-Jet Fusion (MJF) workflows, both of which are possible in Autodesk Fusion.
When it comes to the process of packing parts, also known as 3D nesting, the choice between different packing methods can significantly impact efficiency and outcomes since each have their own distinct methodologies and performance characteristics.
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Autodesk Fusion offers three distinct methods for 3D nesting: Bounding Box, Monte Carlo, and True Shape. The reason that we provide three different options is because each method has its own relative strengths and users might find certain methods are more favorable in certain applications.
This blog will cover this alongside the advantages and limitations of each method.
Bounding box packing
Bounding Box packing is the most straightforward method among the three and is a great option for those who are new to packing parts. This method uses the bounding box of an object to calculate how to pack the parts into a 3D volume. The main advantage of nesting with Bounding Box is its simplicity and ease of use.
However, the simplicity of Bounding Box packing comes with limitations. It does not offer any option to rotate parts, which can lead to inefficient use of space. Additionally, it cannot duplicate parts during the packing process. Parts must be duplicated prior to packing. Despite these drawbacks, Bounding Box Packing ensures no interlocking parts and can pack parts around no-build zones as well as preplaced parts. Therefore, Bounding Box packing will be most suitable for simple block-like parts.
Key points:
- Bounding box dependency can cause lower density packing outcomes
- Ensures no interlocking parts
- Can accommodate no-build zones and locked parts
- Does not rotate parts during packing
- Does not duplicate parts during packing
Monte Carlo packing
Packing parts with Monte Carlo is a more advanced compared to Bounding Box. It is a translation-based nester that uses a random initial arrangement of the parts before translating them down into available space during the packing process. The Monte Carlo packer arranges parts in a way that prevents them from interlocking by avoiding interference during translation. However, due to its random initial arrangement of parts, the results are not repeatable, which can be a disadvantage in scenarios requiring consistency.
Unlike the Bounding Box method, Monte Carlo packer has a preprocessing step, which allows for parts to be rotated prior to packing. This preprocessing step increases the efficiency in space utilization. It also can handle no-build zones. Overall, its ability to rotate parts prior to packing and its voxel-based packing algorithm make it a better option compared to the Bounding Box packer for users looking for improved efficiency, especially for more complicated parts.
Key points:
- Voxel-based approach
- Translation based nester with random initial arrangement
- Ensures no interlocking parts
- Can accommodate no-build zones and locked parts
- Can rotate parts prior to packing
- Does not rotate parts during packing
- Path dependency can cause lower density packing outcomes
- Does not generate repeatable outcomes due to random initial part placement
- Does not duplicate parts during packing
True Shape packing
True Shape is a new packing method that acts as the successor to Monte Carlo, and provides users another high performing nesting option. It also uses a voxel-based approach, checking the voxel representation of the available build volume before placing parts. This method also offers full rotation control during packing. This means for any given part you can control which rotation can be considered before placing the part in the build volume. The rotational control options available with this packer greatly increases the efficiency in space utilization.
One of the main advantages of True Shape packing is its ability to create duplicates during the packing process. This approach is much faster and more efficient than creating duplicates before packing. With True Shape packing, once a part is voxelized, it doesn’t need to be re-processed for each duplicate, saving time and computational resources. This makes the True Shape packer the fastest method for nesting multiple copies of a given part.
Key points:
- Voxel-based approach
- Ensures no interlocking parts
- Can accommodate no-build zones and locked parts
- Can rotate parts during packing
- Can duplicate parts during packing
- Generates repeatable outcomes
Conclusion
In conclusion, all three arrangement methods allow users to prioritize packing parts by their volume or selection order, offering flexibility in packing strategies. The Bounding Box packer is a great option for beginners because of its simplicity and ease of use, but it lacks efficiency and flexibility.
Monte Carlo and True Shape packers provide significant improvements with their ability to rotate parts prior to packing and during packing process respectively and use voxel-based packing algorithms. However, when comparing overall packing performance, True Shape packing is the clear winner.
While Monte Carlo is a fantastic option, the True Shape packer excels as the superior method. It offers full rotation control, adaptability to complex geometries, part duplication during packing, and repeatable results. For users with a commercial license of Fusion, True Shape Packing is undoubtedly the best choice for efficient and reliable 3D nesting.