How Automotive Assembly Lines Work

By: Jamie Page Deaton  | 
Assembly line employees at work at Ford Motor Company in 1913.
Workers are photographed on a flywheel assembly line at the Ford Motor Company's Highland Park, Mich., plant in 1913. See more electric car pictures.
AP Photo/Ford Archives

If you need something nowadays, typically it's pretty easy to get. You simply hop in the car, hit up Target or Wal-Mart, and in a little while you have what you need. You don't really need to think about how it's made, although the production method commonly used — assembly lines — is pretty fascinating.

But even if you worked at the factory that produced whatever it is you bought, chances are you might not have a complete understanding of how the entire product was made. That's because on assembly lines, workers assemble or produce just one part of the whole product. In many cases, they only work on that one part, day after day or even year after year. So, while someone may work for many years at a plant that builds a specific product, they might never have a complete understanding of what it takes to build that product from start to finish.


While all assembly lines are interesting, in this article we're going to explore automotive production lines. You'll learn the basic principles behind an automotive production line and the web of jobs that are tied to them. We'll also explore how the American economy changed as people moved from farm or craftwork to production line work. And later, you'll read about the most recent innovations in automotive production, including companies that mass produce cars without using traditional production lines, and even a few car companies that still hand-build cars.

A New Era of Mass Production

Automotive production lines revolutionized the automotive industry, as well as American life. They made building cars more efficient. Because of the increase in efficiency, the cost to produce a car went down and when production costs were lowered, so was the retail price of the cars. This price reduction meant more people could afford to buy a vehicle of their own.

Also, because of the massive number of workers needed to staff these lines, millions of Americans moved away from farms and into the cities, transforming the economy from one based on agriculture to one based on manufacturing. At the same time, the relatively high wages and good benefits offered by automotive manufacturers helped pull many families into the American middle class, changing America's social makeup for generations to come.


The Beginnings of Assembly Line Production

Asian man building a saxophone in a factory.
Third generation owner and head craftsman Zhang Zhong-Yao assembles a handmade saxophone at the Lien Chen Saxophone Company in Houli, Taiwan.
AP Photo/Wally Santana

Production lines seem like something that sprang up at the turn of the 19th century, but they've actually been around for longer than that. Basically, a production line uses a division of labor. In a division of labor system, instead of each person doing an entire job from start to finish by themselves, everyone takes a small piece of the job, bringing the smaller parts together until the work is done.

Of course, people have always divided up work around the house or farm. But for most of human history, if something had to be built or crafted, one person would make it from start to finish. Skilled craftspeople perfected the art of making one particular product. They'd train others to do the same work, taking a product from start to finish. Once the product was complete, the craftsman could then trade the finished product for other goods that he or she needed.


The only problem with this system is that it's very time consuming. In addition, it may take several years of training to become a skilled craftsperson. It also made the goods that craftspeople made very expensive.

The Manufacturing Process Evolves

When craftspeople began parsing out the individual tasks involved in building a specific product, they found that the work went a little faster. Initially, people were still doing semi-skilled labor in their own homes. For example, a milliner might have one person at home cutting hat patterns, while another assembled fake flowers, another tied ribbons into bows and another sewed the fabric together, and finally another person assembled the finished hat. Still, those jobs required a little skill, and the process was a bit on the slow side.

With a more mechanized process, however, people soon discovered the process could move a lot faster. Also, with more machinery involved, the people making the product could be less skilled. For instance, instead of having to find a worker who knew how to cut hat fabric to fit a pattern, a milliner now only needed to find a person who could load fabric into a cutting machine. Instead of knowing how to sew, workers simply had to run fabric through a sewing machine. The process was faster, and because the labor was unskilled, it was cheaper, too. The shift to add machines into the production process made it possible to mass produce a variety of products — including cars.


The Early Automotive Production Line

The first cars were built largely by coach builders. Early automakers would buy engines from a manufacturer and install them in a modified horse coach. In fact, that's why even today companies that hand-build cars are sometimes referred to as coach builders. For the most part, those builders employed skilled craftspeople to make their coaches custom tailored to meet each order. Buyers could choose exactly what they wanted their new automobile to look like — inside and out.

However, coach builders soon discovered they could build more cars faster if they standardized the design and parts. Rather than fabricating every part in each car, the vehicle's components could all be made using molds and machines. The workers would then simply assemble the finished product.


Who Used the Automated Assembly Line First?

Don't rush to credit the Ford Motor Company for establishing the first modern assembly line. While many people think that Henry Ford invented the automotive assembly line, it was actually invented by Ransom Eli Olds. Olds had worked on cars for most of his life, including steam-powered cars in the 1880s and 1890s. His assembly line allowed him to be the first mass-producer of cars in the United States, and he dominated the American automotive industry from 1901 to 1904.

However, the reason most people think Henry Ford invented the automotive production line is because Ford took the idea and improved it. Ford's assembly line was actually based on a slaughterhouse's de-assembly line. While Olds' assembly line for cars may have been the first, Henry Ford's assembly line was built on essentially the same idea and was far more efficient.

Ford's line assigned workers to one specific production task. Each task had a production station. A car would arrive at the station, and the worker would perform the specified task — over and over again on each car that came by. Because each worker had one task and worked on just one car at a time, it meant that hundreds of cars were being built simultaneously throughout the factory. At Ford's original factory, a Ford Model T could be assembled in 93 minutes from start to finish. In fact, every three minutes, a completed car rolled off the production line.

Having the product come to the worker and assigning the worker to perform the same task on each car made production much more efficient and brought the cost of producing the cars down, too. This brought new vehicle prices down considerably and put cars into the hands of people that formerly couldn't afford such a luxury.


Modern Assembly Lines in the Automotive World

Modern assembly line at Porsche factory in Germany.
Employees of car manufacturer Porsche assemble the Porsche 911 on a production line in Stuttgart, Germany, in 2008.
AP Photo/Thomas Kienzle

What's striking about modern assembly line work is that it hasn't changed all that much from the basic Ford system from so long ago. The cars still come to the workers at individual work stations, each worker performs a specific task and when all the tasks are done, at the end of the line, you'll see brand new ready-to-drive cars rolling off the assembly line.

On modern production lines, many of the parts that go into assembling a car aren't made on-site. Instead, car companies buy parts (like brake rotors or transmissions) from other companies — suppliers — many of which have their own assembly lines. In some cases, the car company itself will have factories where the parts are made. So, for example, before a Chevrolet Malibu is assembled at one plant, its engine and transmission must be delivered from the plants where they were assembled.


One key to the automotive production line is the standardization of the product. As Henry Ford once said about his Model T, "You can have any color you want, so long as it's black." Ford was actually making a point about the production line: because each stage is interdependent on the others to make a complete car, changing one stage means changing others, and that means slowing down a very efficient system.

Still, to stay in business today, car companies need to offer lots of different models — something that's hard to do when you're dependent on a production line. So, car companies do something called platform sharing. With platform sharing, a car company will design its cars to share parts. It saves the company money, makes production easier and still gives consumers what they want. Platform sharing means that a Chevy Silverado and a Chevy Tahoe look alike and have similar capabilities because they share parts. In fact, the Tahoe and Silverado, along with the Chevy Avalanche, GMC Yukon and Sierra, Cadillac Escalade and Hummer H2 all share parts, making it easy for GM to offer consumers what they want.


Machine Learning: Automated Assembly Lines

Employees work on a red vehicle in an assembly line at a BMW factory.
Workers fit the body of a BMW 1 in the BMW plant in Leipzig, Germany, in 2007.
AP Photo/Eckehard Schulz

While the basic principles of automotive production lines are the same, recent innovations have changed things a bit. Mechanization of tools and parts revolutionized production once, and now it's happening again. Robots now perform some of the tasks that human autoworkers formerly were asked to perform. Since production line work involves repetitive movements, it's easy, and sometimes safer, for a robot to take over a role a human used to play. While that unfortunately costs an autoworker a job, it tends to lower production costs, too.

It's probably safe to say that most of us have seen the old newsreel footage of auto workers building cars in greasy, grimy, dirty factories; however, new automotive production lines have been praised for their clean, light and open architecture. The BMW assembly line in Leipzig, Germany, is a great example of that. The assembly line winds its way through the factory, which is itself a light-filled maze of glass. Everyone who works there — from the executives to the cleaning staff — can look into the production line and see the heart of the company: its cars.


Production lines aren't just cleaning up their architecture. Some are working to clean up the environment. At the Subaru plant in Lafayette, Ind., 99.8 percent of the plant's waste is recycled. At the factory, which builds the Subaru Tribeca, Legacy and Outback, as well as the Toyota Camry, the goal is to contribute zero waste to landfills. Other automakers, including Honda and Toyota, also use the practice, which cuts their costs as well. The companies persuade suppliers to take back and reuse packaging, which brings the supplier's costs down, too, because they have to buy fewer packaging supplies. Even imperfect parts that might be otherwise thrown away are recycled. For instance, at the Subaru plant, flawed plastic bumpers are ground into plastic pellets to make new bumpers.

Alternative Automotive Production Lines

An employee works on the production line at Toyota Motor Corp in Japan.
A Toyota Motor Corp. employee works on Lexus engines at the Japanese automaker's flagship production line for luxury Lexus models in Tahara, Japan.
AP Photo/Koji Sasahara

One of the problems that car companies have constantly run up against in automotive assembly lines is how to keep the workers happy and interested in the products they build. Alienation is a common problem for production line workers because the tasks they perform can often be boring and extremely repetitive. Some may also not feel like they have any ownership or stake in the product they're building.

Toyota's method of production and assembly helps address that problem. Toyota factories are designed to be happy places, and they have policies in place to protect that work culture. If a worker spots a problem, he or she is encouraged to stop the production line and fix it — even though stopping and starting the line is very expensive. Also, as a group, employees exercise together and workers are continually invested in and given a stake in the company. After seeing Toyota's success, other car makers have started using some of the same principles.


Some car companies have never really applied the production line process to their product — their cars remain entirely hand-crafted. High priced cars from automakers like Aston Martin and Ferrari are hand-built to their customer's specifications. In some cases, car makers will even custom mold the driver's seat to the buyer's shape.

Other cars are built using a combination of these two techniques. The Chevrolet Corvette, for example, has a hand-built engine, but other parts of the car are assembled on the production line.

For more information about production lines and other related topics, follow the links on the next page.


Lots More Information

Related HowStuffWorks Articles
More Great Links

  • Arnot, Chris. "When the wheels came off the dream." The Guardian. Feb. 25, 2009. (March 9, 2009)
  • "Taking A Page From Toyota's Playbook." Aug. 22, 2005. (March 10, 2009)
  • Design Build Network. "BMW Car Production Plant, Leipzig, Germany." (March 10, 2009)
  • Kanellos, Michael. "Inside Toyota's hybrid factory." CNET News. Oct. 10, 2006. (March 9, 2009)
  • PI International. "Automobile Production at OPEL, Bochum (Germany)." (March 10, 2009)
  • Woodyard, Chris. "It's waste not, want not at super green Subaru plant." USA TODAY. Feb. 19, 2008. (March 10, 2009)