Here is the basic explanation for the two sheet metal options.
- Flat Wall → Gives you control over the profile of the wall.
- Flange wall → Gives you control over the cross section of the wall.
It purely depends upon the shape of the part that decides which one to use. Below is the basic example of the flat and flanged walls.
As I said before, in the flat walls you can control the shape of the profile. The side view/ section remains straight from the selected edge to the other end of the wall. No matter if it is 90 deg bend or 60 deg bend, the wall’s section remains straight.
On the other hand, the section can be controlled using the flange wall option. As you can see above, the flange wall’s profile looks rectangular with no cuts, etc., but the side view/ section has many bends. The section was straight in flat wall. Here, the section can have many bends, curves, splines etc.
If you want a cut in this flange wall like in the flat wall, you can add a separate extrude cut feature.
Although flat wall has unique options, many people prefer to use the flanged wall since it has more flexibility. If you want a wall like the first one shown in this article using flange wall, you can simply create a straight cross section flange wall and then make a separate extrude cut feature for the recess.
Another advantage of using flange wall is you have the option of selecting multiple edges in one single flange wall feature whether the edges are tangent are not. The only requirement is the edges needs to be continues. In flat wall you will need to add separate walls for each edges.