In the first part of this blog, we discussed various ways of working with large assembly designs in Autodesk Inventor. I shared some insights into what part and part files are, what assembly and assembly files are, and how Inventor references files. I also compared how modelled and actual threaded information on fasteners would greatly impact Inventor's performance under large assembly design workflows. In this second part, I discuss innovative ways of working with and managing large assemblies with Autodesk Inventor, sharing practical tips to enhance your design workflows along the way. Today, we will discuss more innovative strategies for managing large assemblies with Inventor, building on what we discussed earlier in Part 1, focussing mainly on reducing assembly constraints with the Joint tool.
Reducing Assembly Constraints with The Joint Tool
Effectively managing assembly constraints in Inventor can significantly enhance the software's performance. One effective method is to use Inventor's Joint Tool, which streamlines the assembly of components within the assembly workspace. The tool is found on the Relationships panel of the Assemble tab. Let’s look at a practical scenario of assembling the diesel generator enclosure. The top-level assembly would have an access panel frame, various access panels, and fasteners. The primary fasteners for this scenario would be the skid anchor bolts, nuts and washers for the base skid and screws for the access panels. In a conventional method using the Constraint Tool, each anchor bolt would need several constraints to ensure it is properly aligned and positioned to the access panel frame. The same would apply to the washers and nuts. For this demo, let’s keep it simple.
For each anchor bolt, you would have to apply individual constraints, such as:
- Mate Constraint (axis to axis): position the bolt’s axis to the hole axis on the panel frame.
- Mate constraint (face to face): to hold the lower part/face of the head of the bolts against the access panel frame.
The exact process would be followed for each mounting hole's anchor washers and nuts until all six are covered. Suppose the above assembly included hundreds of fasteners (bolts, nuts, and washers); the number of constraints would increase exponentially. Constraints can be considered separate calculations Inventor must perform to determine how each part/component fits and moves within your assembly.
As the number of constraints grows, so does the complexity and the number of “calculations” Inventor has to perform to resolve the assembly model in the assembly workspace. This can slow down your system and make managing the large assembly more challenging.
For the second scenario, let’s consider using the Joint tool for the same genset enclosure assembly. Instead of applying multiple constraints for each fastener using the constraint tool, you can use a single joint to define how each interacts with other components/parts in the assembly. For instance, applying a single Rigid Joint between the anchor washer and the access panel frame locks the two components together. This, therefore, means the washer will remain fixed in both position and orientation relative to the panel frame, with no movement or rotation possible between them. In other words, the two components will move as a single unit. On the other hand, a single Cylindrical Joint between the axis of the anchor bolt and that of the hole of the access panel will allow the bolt to move along a cylindrical path related to this axis. The cylindrical joint ultimately defines the degrees of freedom (DOF) of the said part wholly.
This single joint constraint, therefore, defines two motion constraints.
- Translation: This means the bolt can slide back and forth along the axis of the cylindrical joint. Remember, in this case, the cylindrical joint's axis is either defined by the hole's axis on the access panel frame or the hole on the washer.
- Rotation: This dictates the bolt to rotate around the cylindrical axis, but it can’t move away from this axis or rotate in other directions. The rotation is constrained to that particular axis.
The result? Killing two birds with a single stone, the bolt will move back and forth as it rotates along the cylindrical axis. If you have a large assembly, this can quickly compound, and you will enjoy the benefits of using the Joint tool. The Constraint and Joint tools play important roles in assembly design. However, it's best to use the Constraint Tool only when necessary. Opt for the Joint Tool whenever you can to create more efficient, robust, and streamlined assemblies.
The two scenarios above also show that joints typically need fewer operations since they define movement and interactions more comprehensively. With fewer assembly constraints, Inventor executes fewer “calculations”, which lessens the computation load on your PC. You also get to save time with fewer strategically placed assembly constraints with the joint tool. With fewer constraints, troubleshooting becomes easier and faster whenever errors arise (and, of course, they do every time!). This enhancement boosts performance and streamlines the management of assemblies and sub-assemblies, leading to a more seamless and efficient workflow.
See the joint tool in action with these tutorials on the channel.
And this one, too.
