The Chamfer tool adds a bevelled or angled corner to the edge of a part. They can be used to remove sharp external edges created in castings or machined parts
Click on the Chamfer tool.
Typically, you will want to create a Chamfer using a length and angle definition. Your CATIA may have the “length and length” setting selected as default, which can be changed by entering the drop down menu and selecting the “length and angle” option as shown below.
Click the chamfer tool, and then select an edge to chamfer. Choose the desired parameters. A representation of your selection should be shown in green on the edge that you have selected.
Click OK, and the part should look like this.