If you look at a car's interior metal panels, from time to time you will see a small dimple. These dimples are spot welds and are made by welding robots. These robots are large, standing about eight feet tall. They do not look like human being robots like in the movies. They have only one "arm" mounted on a base and control a welding gun with its "hand." Body panels are fed into the beginning of a line, and robots move and weld all the panels together. Robots are extremely versatile. A robot can have different devices mounted on its hand, such as welding guns or cranes to move car bodies around. ABB Robots is a large manufacturer of assembly line robots.
Most tools used on the assembly line are power tools, instead of hand tools.These include power wrenches and power screwdrivers. This is a time-saving feature. The operator simply pushes a button, and the tool head spins. This saves a lot of time over a person having to work the tool by hand. Another important reason why power tools are used is the torque setting on bolts. Torque setting refers to how tight a bolt should be. With a hand tool, the operator may under-tighten some bolts, leaving them loose. Other times, the bolt may be over-tightened, risking breakage over time. A power tool has a built in torque setting. When the bolt is tightened "just right," the tool stops turning. This is a great aid to quality control.
The car body moves down an assembly line track. The body is too heavy to lift by hand, but wheels are not attached yet. The solution is to mount the body on a railroad-like track. A dolly has wheels that line up with the track, and it moves the car body from assembly station to assembly station. The dolly may be computer controlled, so after the robots finish with the body at one station, it is automatically moved to the next station by a motorized dolly.
Cranes, or overhead hoists, are sometimes used to lift heavy objects so an assembly line technician or a robot can secure the component. For example, an engine has to be lowered into the front of a car. Engines are heavy, and humans cannot lift them. A crane is used to do the job of lifting and lowering the engine.