At one time, auto factories were hives of human activity. Thousands of workers walked through the gates each day and essentially built each vehicle from the ground up.

Over the years, for better or for worse, machines gradually took over many of the tasks. In today’s factories, it’s common to see huge areas with no workers in sight, just long lines of robots adding pieces or welding panels as the cars file by them.

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It’s been a long road to this point. The earliest automobiles were built in shops by workers who finished one car and then moved on to the next.

Oldsmobile is believed to be the first to use an assembly line process, in 1901. Teams of workers set up stations, and the cars were pulled from one to the next, built up gradually as they made their way from start to finish.

It was still a laborious system, because many of the components were handmade, and it took some tweaking and hand-fitting to get everything to line up. Cadillac was the first to employ a system of standardized parts, and in 1908, it presented a demonstration where engineers disassembled three cars, scrambled the parts, reassembled the cars, and then drove them away.

That standardization opened the door for Henry Ford, who took Oldsmobile’s system to the next level in 1913 with a line that moved continuously, and with each worker performing a single task as the cars went by. This new method of assembly was monotonous and tiring, and Ford’s famous “five-dollar day,” which doubled worker wages over what other manufacturers were paying, was primarily an effort to rein in the company’s astronomical absentee and employee turnover rate. But the moving assembly line was here to stay, and with the exception of a few hand-built niche vehicles, it’s the way all cars are produced today.

The second half of the equation, the industrial robot, was developed in 1959 by a company named Unimation. The Unimate robot weighed two tons and followed commands programmed onto a magnetic drum. In 1961, it was toiling at a General Motors plant in New Jersey, where it stacked hot pieces of freshly-cast metal. A year later, Ford had six robots in one of its plants as well.

The degree of automation depends on several factors, including the factory itself: retrofitting an old plant is more of a challenge than designing automated lines into a new facility. There are also jobs that still need a human touch, primarily in fitting interior trim or other hard-to-reach parts, and in quality control.

A visit to Honda’s new Yorii factory in Japan, which makes bodies and assembles vehicles using engines produced at another plant, illustrates the difference that automation can make. In comparison with the older Sayama factory nearby, which has two assembly lines and five worker shifts, Yorii has only one line and three shifts, but its production is 40 per cent more efficient. Some of the changes at the new plant include the high-speed transfer of parts between stamping operations, machines that join panels by rolling their seams together instead of pressing them, and improved paint shop technology.

That last item is a major one for all automakers, because the paint process is energy-hungry. In some cases, the paint shop can account for more than half of the energy consumption of the entire factory. New finishes and application processes used by manufacturers today can eliminate some of the high-heat “baking” steps needed to dry and cure the various coats, which results in energy and environmental savings, and often a smaller footprint for the paint area.

At the Yorii plant, Honda uses new robots that are faster and smaller than those it previously used, which not only speeds up the process, but reduces the space needed to house them. Eventually, the plants themselves may become smaller as the assembly lines do, which can also reduce their energy costs and overhead.

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Robots don’t take time off, and their repetitious precision eliminates human error, but the resulting reduction in employees when older plants are retrofitted can be an issue, especially in communities that originally sprang up to supply manpower when the factory was new and consequently suffer economic slowdown and unemployment. Even the Honda robots aren’t immune: a new process at the Yorii plant “laid off” six robots when a process was streamlined over the old method used at the Sayama factory.

But automation is here to stay, and it’s a process that continues to evolve, with new types of robots, new methods of programming and controlling them, and new production methods that will make the assembly line leaner and “greener” in future. Cars may still use some of the same basic parts that they did in 1901, but when it comes to putting them together, it’s a whole new world.