You can select boundary edges of a model and merge them (or sew them) to create one common edge using the Targe Weld tool.
Merging edges can reduce your polygon count. For example, you can merge the boundary edges of a model and then delete the interior edges, resulting in fewer faces.
Note: You can only merge edges that are part of the same polygon mesh.
If you want to merge edges from different mesh objects, you must first combine the meshes into a new mesh using the Combine feature (Mesh > Combine).
To merge polygon edges
- Do one of the following:
+ 
-click an edge and select Merge/Collapse Edges > Target Weld Tool. - In the Mesh Editing Tools section of the Modeling Toolkit window, click Target Weld.
The Target Weld tool opens.
- Click the first border edge you want to merge.
- Drag your cursor to the edge you want to merge.
The two edges merge, creating a single edge.
To merge multiple polygon edges
- Select the edges you want to merge and choose Edit Mesh > Merge Components >
. - Set the Threshold value to control how close edges must be to merge.
- Click Merge.
Notes
- To make it easier to distinguish between border edges and interior edges, turn on the display of border edges by selecting Display > Polygons > Border Edges.
- You cannot merge non-manifold edges.