One of my first impressions of Fusion 360's Generative Design outcomes was that the 3 axis milling outputs were too organic and looked nothing like what current manufacturers are producing. I questioned if the companies I worked with would be willing to adopt the software for that reason. Recently, I have come to the realization that I was way wrong in my early impression. Part of the process of defining your manufacturing criteria is that you define the smallest mill you are going to use. So as long as you create your CNC program with that as your smallest mill, you will be able to manufacture what Generative Design produces. Creating your toolpaths for a 3 axis milling outcome from Generative Design can be as simple as using Adaptive Clearing to remove most of the stock then using Parallel, Scallop, and/or Morphed Sprial with a Ball Endmill that matches the diameter and length specified in the Generative Design study.
I decided to try creating toolpaths for a Generative Design outcome, using the same mill settings used in the Generative Design study. I know this feels a little obvious because this is the way the software works. However, I feel this is necessary to prove my first impression wrong and perhaps give fellow users more confidence in their ability to create these toolpaths.
So I had to find something that would make a good candidate for a Generative Design study. I thought about a flat screen wall mount, and I remember I had one in a data set I have been using for years. This design had two arms and a link. I felt it was best to focus on just one arm. Looking at the existing geometry, I realized that it already had well-defined preserves and a starting shape that I could leverage.
Since I was starting in Inventor, I used "Send To Fusion" to send the model to my Fusion Team project. From there, I was able to open the model and add a couple bodies that will be identified as obstacles.
Here is a video demonstration of these steps.
My next step was to jump into the Generative Design workspace. There I was able to identify my obstacles and preserves. Then, I defined my 3 Axis milling criteria, including which orientations of the model I planned on having setups for, the finishing tool I planned on using, and which materials I was considering.
Here is a video demonstration of these steps.
After the Generative Design study is completed, I was able to explore the models that were created by the study. In this case, there are two outcomes because the study contained one manufacturing method and two materials. Fusion 360 will calculate each model's weight, volume, safety factor, and many other properties. This allows the user to weigh different options and decide on the best model to suit their application. In my example, I chose the one made out of aluminum because it was lighter and its safety factor was higher.
Here is a video that shows how to explore the outcomes and generate a model from that outcome. In my workflow, I had a small area that I wanted to clean up. This video demonstrates that process as well.
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After the model file has been generated and cleaned up, Fusion 360's Manufacturing workspace can be used to create the toolpaths for the CNC program. For me, the process is going to be to do a couple adaptive clearing operations to get rid of most of the excess material. Then use operations like Parallel, Scallop, and Morphed Sprial as finishing operations using a ball endmill that matches the parameters I entered in the Generative Design study. I am not sure what took me this long to realize that is the process. Perhaps you saw that connection right away. Once I realized the process, I realized that this wasn't as difficult as I thought and wanted to try it out. Which was the motivation for this blog post.
Here is a video that demonstrates creating the toolpaths for this part.
The last step in this whole workflow was to send the completed model back to Inventor. The main point of this blog post was to talk about creating the toolpaths for a part that was created in Generative Design. However, since I started in Inventor, I feel like I have to end there with the completed design.
Fusion 360 lets users export an IPT from the design files. In my case, I exported an IPT from the completed arm model. Then in Inventor, I was able to place the new model in the original assembly.
Here is a video that demonstrates that portion of the workflow. I also spend a little bit of time comparing the original model to the Generative Design model.
This blog post may have felt obvious. As I stated before, I wanted to go through this process to help myself feel more confident in my ability to create toolpaths for the models created by Generative Design. I think what took me the longest to learn was the types of toolpaths that should be used to mill these organic shapes. Since I have learned some of the best operations to use, I wanted to share that knowledge with fellow users out there and hopefully allow them to feel more confident in their ability to program these models as well.
