Which of the following is NOT a method of joining?

The method that is not considered a joining technique is drilling. Drilling is primarily a machining process used to create holes in materials. While it can be used in conjunction with other joining methods—such as providing access for screws or bolts—its primary purpose is not to join materials directly.

In contrast, welding, bonding, and mechanical joining are all techniques specifically designed to connect or fasten materials together. Welding involves the heating of materials to their melting point, allowing them to fuse together upon cooling. Bonding typically refers to the use of adhesives to create a bond between surfaces, while mechanical joining utilizes methods such as bolts, screws, or rivets to physically connect parts.

Understanding the distinct purposes and applications of these methods clarifies why drilling does not fit into the category of techniques used for joining materials directly.