Which synchronous modeling command can merge cylindrical and conical split faces?

The command that can merge cylindrical and conical split faces is "Optimize Face." This command is specifically designed for refining and enhancing face geometry within a model. When applied, it intelligently simplifies the surface by merging adjacent faces, creating a more unified and coherent geometry. This is crucial in synchronous modeling, where maintaining clean and efficient models is necessary for both performance and clarity.

In the context of merging split faces, "Optimize Face" effectively identifies compatible edges and vertices to create a seamless transition between the different types of faces, such as cylindrical and conical surfaces. This not only improves the aesthetics of the model but also enhances manufacturability and reduces potential issues in downstream applications.

Other commands, like "Divide Face," focus on splitting faces rather than merging them, "Split Body" pertains to segmenting the entire body into parts, and "Make Coaxial" assists in aligning axes rather than modifying face geometry. Hence, "Optimize Face" stands out as the best choice for the specified task of merging split faces.