assembly lines – The OM Blog by Heizer, Render, & Munson

OM in the News: Building Airplanes Quickly–A Bit of History

When I worked at McDonell Douglas (now Boeing) in St. Louis in the late 1960’s, the Viet Nam war was in full swing. The demand for F-4 Phantom Jet fighters was strong and we managed to move the assembly line fast enough to produce two jets a day. It was quite a feat. But it didn’t compare to the Michigan factory that produced one B-24 bomber an hour during World War II. This was one of the most astonishing tales of ingenuity in manufacturing history, writes The Wall Street Journal (May 14, 2025).

As 1939 began, the U.S. had fewer than 2,000 military aircraft. With war looming, President Franklin D. Roosevelt knew the country desperately needed to remedy the situation. He turned to America’s top manufacturers for help. One of them was the Ford Motor. In 1940 workers began constructing an enormous manufacturing-and-assembly plant and an airfield called Willow Run near Detroit. It was finished within 6 months.

After the Pearl Harbor attack, the plant was ready to mass-produce B-24 Liberators: bombers that weighed 18 tons, were 67 feet long and had wingspans of 110 feet. Could massive warplanes be built with the same assembly-line method as family automobiles? It had never been tried before.

Ford’s production genius, Charlie Sorensen, was put in charge. Soon 42,000 workers filled the factory floors in around-the-clock shifts. With so many Americans off fighting in Europe and the Pacific, some of the men and women at Willow Run had never done manufacturing jobs before. So a school was set up near the plant: Some 8,000 employees a week were taught to build airplanes.

Those four-engine B-24s each contained 1.2 million parts held together by more than 300,000 rivets. “Rosie the Riveter” entered the American lexicon, as women who had never before done such work helped manufacture the Liberators.

How long should it take to build an airplane? By the time Willow Run was operating at full capacity, a B-24 was rolling off the mile-long assembly line every 55 minutes. The nation needed those planes, and it got them. By war’s end, factories across the U.S. had built nearly 300,000 military aircraft.

Classroom discussion questions:

Why does it take so much longer to build planes today?
Which of the 10 Operations Management decisions (that your Heizer/Render/Munson text is built around–see Table 1.2) do you think were faced by Sorenson?

Teaching Tip: The Vaccination Assembly Line

The Orange County Convention Center, here in Orlando, is a massive and magnificent building. At 7 million square feet (something like 146 football fields over 22 acres), it is the second largest facility of its kind in the U.S. The main exhibit hall alone seats 139, 857 people, enough to easily handle conventions such as MegaCon (68,940 in attendance), NCAA Volleyball Championships (72,000), and Design Week (85,000). But during COVID, the Center has largely sat empty, as tourism and its 125,000 related jobs in Orlando have declined dramatically.

But alas. The Convention Center has a new purpose. Its underground unloading area has been turned into a COVID-19 vaccination drive-thru assembly line! Here is an interesting example of a service assembly line (Ch.9) and a multichannel, multiphase queuing system (Module D) that you can share with your students. I just went through the system this week and was impressed by the operations planning and execution.

Work Station 1: Outside the building, a single channel queue greets you, with the server checking the bar code on your cell phone to be sure you are eligible to enter.

Work Station 2: Inside the building, the medical team scans your barcode again, takes your temperature, and attaches a barcode sticker to your arm. You drive forward 10 yards.

Work Station 3: Your arm barcode sticker is scanned and you are asked a series of medical questions. The brand of shot you will receive is announced (no choice) and you are provided informational material. You drive forward 10 yards to parallel Bays A, B, or C as directed.

Work Station 4: Your arm barcode is scanned again, you get the shot, with band aid applied. You are told to exit the building and wait in your car in the adjacent lot to see if there is a negative side effect. You are to honk your horn if you are ill.

Work Station 5: You sit in the lot for 15 minutes.

Work Station 6: You are scanned again as you exit the property and asked if you had any side effects. You never leave your car.

Total time in system, including 15 minutes in parking lot, is 25 minutes.

Classroom discussion questions:

Clearly the system is efficient, but can it be made more so?

2. Can it be easily replicated in every city?

OM in the News: Tesla’s Changing Assembly Line

The Model 3’s third assembly line, under a tent.

Just outside Tesla’s sprawling electric-car Fremont, Calif. plant, an unusual structure has taken shape in the past few weeks: a tent, about 50 feet high and several hundred feet long. Its purpose is as notable as its hasty construction, writes The New York Times (July 1, 2018). The tent houses a 3rd assembly line — part of a desperate effort to speed up production of the Model 3. Just 2 years ago, Tesla envisioned 2018 as a breakthrough moment. With a high-speed, high-tech assembly process, the company’s sales would soar more than fivefold, to half a million vehicles. It hasn’t turned out that way. As CEO Elon Musk said: “the company faced a prolonged period of manufacturing hell.”

Tesla has raced to iron out kinks in the assembly process, mainly by scrapping some complicated robots that proved ill-suited to certain tasks and hiring hundreds of workers to replace them. On the factory floor, it’s a frantic race that has taken a toll on some employees. Trying to break with standard auto-industry practices, Tesla is searching for ways to shorten the time that robots take to weld parts. It is even making seats, a component most car companies leave to specialized suppliers. And it is doing this while trying to root out bottlenecks and glitches in the manufacturing process.

Established car companies master the process with assembly-line workers and then find ways for machines to take over some of the work. Tesla did the opposite. It designed a highly automated production line populated by over 1,000 robots. But the most efficient lines use a lot of manual labor. “The most automated ones are at the bottom of the list,” said one industry expert.

Adding a new assembly line, even temporarily, is a rare and risky move in the auto industry. A line set up hastily, in an untested environment, might not achieve the quality Tesla promises. The first step in auto quality is stability.

Classroom discussion questions:

What do you think is the impact on the workers on the Model 3 lines?
What did Tesla do wrong?

OM in the News: Construction Sites That Look Like Lego Kits

Katerra staffers and robots build prefab wall panels on an assembly line

On the floor at Katerra’s cavernous 250,000-square-foot Phoenix factory, workers and robots hammer pallets of Douglas fir into finished wall panels and put them on an assembly line, where other machines and craftspeople add windows and plumbing before a crane stacks the finished walls on a flatbed. When the truck arrives in Lodi, Calif., 3 days later, a construction materials manager uses an RFID scanner to see what’s arrived and an iPad to show where cranes should set each piece of a 4-story retirement home.

This process is a radical change for the construction industry and a threat to decades of this-is-just-how-we-do-it attitudes. While other construction tech startups try to modernize some parts of the business, designing modular homes or building robot-run factories to make prefab parts, Katerra puts all these pieces together, from design to finished building. The company wants to control everything from “womb to tomb,” says one customer. “Almost everywhere you look, there’s money to be saved,” says Katerra’s CEO. “It’s so inefficient in so many ways, it kind of takes your breath away.”

Katerra saves money by buying everything from wood to toilets in bulk and using software and sensors to closely track materials, factory output, and construction speed. Its architects use software to build a catalog of standard buildings, rather than starting from scratch on each project, and to ensure contractors aren’t making impulsive structural decisions. Each generation of buildings has become steadily more prefab, requiring less work on-site and speeding construction.

The idea of modular housing goes back more than a century—Sears, Roebuck & Co. sold more than 70,000 home kits from 1908 to 1940—but the construction business has been changed far less by technology than any other major U.S. industry, writes Businessweek (June 25, 2018).

Classroom discussion questions:

What the OM advantages of Katerra’s approach?
The disadvantages?

Video Tip: Starting Your Semester with the History of OM and the Ford Model T

Many instructors like to start the semester with a bit of OM history (see Figure 1.4). Your students will enjoy this 5 minute video featuring the Ford Model T, which changed the way Americans live, work and travel. Ford’s revolutionary advancements in assembly line automobile manufacturing made the Model T the first car to be affordable for a majority of Americans. More than 15 million Model Ts were built in Michigan, and the automobile was also assembled at a Ford plant in Manchester, England, and at plants in continental Europe.

The Model T was built from 1908 until 1927. It quickly became prized for its low-cost, durability, versatility, and ease of maintenance. Assembly line production allowed the price of the car to be lowered from $850 in 1908 to less than $300 in 1925.

The Model T was offered in several body styles. All bodies were mounted on a uniform 100-inch-wheelbase chassis. The car was mass-produced in only one color—black. The engine was simple and efficient, with all four cylinders cast in a single block and the cylinder head detachable for easy access and repair. The engine generated 20 horsepower and propelled the car to top speeds of 40–45 miles per hour. The engine was started by a hand crank. The transmission, consisting of two forward gears and one reverse, was controlled by foot pedals. Throttle was controlled by a hand lever on the steering column. The 10-gallon fuel tank was located under the front seat. Because gasoline was fed to the engine only by gravity, and also because the reverse gear offered more power than the forward gears, the Model T frequently had to be driven up a steep hill backward.

OM in the News: The Pentagon’s F-35 Push

Lockheed's F-35 assembly line in Fort Worth, Texas — Lockheed’s F-35 assembly line in Fort Worth, Texas

When I worked as a design engineer at McDonnell Douglas in the late 1960s, the F-4 Phantom fighter jet assembly line was one floor above my basement office. We rolled out one Phantom a day, a very efficient line, with volume stable and constant. This has not been the case with our nation’s latest fighter jet, the F-35. Lockheed’s mile-long assembly plant in Fort Worth currently produces only four F-35s a month.

But now “the Pentagon plans to push Congress to approve a deal for more than 400 F-35 jets, worth $34 billion, in what would be the largest-ever weapons’ contract,” writes The Wall Street Journal (May 30-31, 2015). The Pentagon said that committing to buy that many jets over 3 years starting in 2018 could yield cost savings as suppliers would be able to plan with more certainty, buy materials in bulk and triple production from existing levels to about 150 planes a year.

Boosting production is crucial to cutting the cost of the F-35 from the $108 million average paid for the jet in a 43-plane deal agreed last November. Lockheed recently submitted proposals for the next 2 batches of aircraft, and alongside other suppliers have pledged to cut the average cost to $80-$85 million by 2019. Even a rise in output to 150 jets a year would fall short of the 200-plane capacity of the Lockheed plant. Analysts believe official projections of demand for more than 3,000 jets won’t be realized. (Italy and Japan also plan to assemble some jets). Lockheed’s earlier F-16 fighter jet had more than 4,500 orders, and experts expect the F-35 to secure at most 2,000.

Classroom discussion questions:

1. This cost savings plan requires knowledge of learning curves (see Module E). What is the typical learning rate in this industry and how does it impact the analysis?

2. Why will increasing production rates decrease unit costs?

OM in the News: New Product Design is Choking McDonald’s

“McDonald’s menu may have grown too big to succeed,” writes The Wall Street Journal (Dec.4, 2014). The fast-food giant has added oatmeal, snack wraps and lattes to its offerings in recent years to appeal to a wider swath of customers. But swelling menus have made the company’s kitchen operations increasingly complex. Its McCafé drinks, for example, require a separate station behind the counter equipped with coffee grinders and blenders, causing longer waits. The menu has expanded from 85 items seven years ago to 121 today.

McDonald’s isn’t alone in struggling with the temptation to add too many new products. General Motors expanded its offerings for decades only to kill off its Saturn and Pontiac brands in 2009. The typical U.S. grocery store now stocks up to 50,000 products, up from 15,000 in 1991.

Some products can stall the food-assembly line. The Premium McWrap, a 10-inch flour tortilla is referred to as a “showstopper” behind the counter. “Our kitchen comes to a halt when we get an order for a McWrap,” says one franchisee. It’s supposed to take 60 seconds or less to assemble the ingredients, fold them in the tortilla and squeeze the McWrap into a box. But it usually takes some 85 seconds–too long given McDonald’s goal of getting customers through its drive-throughs in 90 seconds or less. Last year McDonald’s clocked its slowest average speed of service in the past 15-years: 189.49 seconds, more than twice the chain’s goal.

“The totality of the products we’re serving is what’s challenging us,” says another manager. “We’ve recognized that we’ve overtaxed our restaurants and need to take a step back on that.”

Classroom discussion questions:
1. Why does McDonald’s continue to add menu items?

2. Where do you think McDonald’s falls in figure 5.1 on page 156 of the text?

OM in the News: Toyota’s Assembly Line Advances

Today’s Wall Street Journal (Nov.29,2011) features the pressures facing Toyota–overcapacity, weak demand, an exchange rate for the yen that makes Japanese-made cars expensive, quality problems that forced the recall of 10 million vehicles, and the supply chain issues caused by the March earthquake and tsunami. Competitors like Honda and Nissan are moving more manufacturing overseas, to plants closer to customers. But Toyota, long a proponent of corporate social responsibility to protect Japanese jobs, has also pledged to build at least 3 million cars annually in Japan, with 1/2 for export. So the company, which wrote the book in the 1960’s on lean manufacturing and JIT, is looking for new ways to wring out efficiencies from its production systems.

Toyota sees its first new plant in Japan in 18 years as the answer. Here is why: The Miyagi factory is designed for advanced low-volume, hyperefficient production, with 1/2 the workers and 1/2 the square footage of Toyota’s 16 other plants. Inside, half-built Corollas and Yaris sit side-by-side, rather than bumper-to-bumper, shrinking the assembly line by 35% and requiring fewer steps by workers. Instead of car chassis dangling from overhead conveyor belts, they are perched on raised platforms. This is 50% cheaper, and also reduces cooling costs by 40% because of lower ceilings. Finally, the assembly line uses quiet friction rollers to move the cars along. The rollers use fewer moving parts than typical chain-pulled conveyor belts.

This is a timely article to share with your class when you discuss assembly line layout in Chapter 9. And if you show the Wheeled Coach layout video for this chapter, the 2 assembly lines make for a good comparison.

Discussion questions:

1. How can Toyota’s new layout help improve the challenges facing the company?

2. Why are other Japanese auto manufacturers moving production to the US?

Video Tip: Assembly Lines at Wheeled Coach Ambulance

Wheeled Coach , the world’s largest manufacturer of ambulances, is the kind of firm you would want to take your students to tour to see how factories work. The firm uses 5 parallel assembly lines, fed by work cells, in which 5 ambulances move forward to the next work station each day. The work cells feed the main assembly lines on a JIT basis and perform all the pre-assembly work, such as painting, carpentry, upholstery, electrical wiring , etc.

When I show the video (7 min.) in class, I simultaneously draw the 5 parallel lines, and label in each day’s work station as it is described. You can discuss how the work cells are more efficient than having the tasks they perform done as part of the line.

Some interesting aspects are not shown. First, these are real factory jobs, often dirty, non-union, low paying, and all hot! (There is no A/C –or heat– in most factories here in Florida). So staffing is usually difficult (this recession being an exception, of course).

When we filmed, workers did 5 standard 8-hours shifts, starting 6:30am. When hiring was really tough, Wheeled Coach switched to four 10-hour days to make the job more attractive. That made line balancing even more difficult, since each vehicle still needed to move forward once a day. It took a few years before the firm realized this only made matters worse, as quality fell dramatically in the last 2-3 hours of the shift. It returned to the 5 day week recently.

How else could efficiency improve? Last time I visited, the smaller “van conversion” models were moved to a different building on their own line, with 3 or 4 flowing off every day, since they are much simpler designs.

OM in the News: The (Gentler) Chicken-Killing Assembly Line

I was 7 years old when my Dad proudly took me to the Dubuque (Iowa) Packing Co. to show me what he did as a supervisor in the cow butchering department. I won’t go into graphic detail as to how the animals were queued up to have their throats slit. They were stunned first to make the process as pain free as possible.

Maybe you can see why yesterday’s New York Times (Oct.22,2010) front page headline, “New Way to Help Chickens Cross to the Other Side”, caught my attention. It turns out that chicken producers, egged on by animal rights groups, are also switching to a system of killing their birds more humanely. The new process uses gas to render the chickens unconscious before they are hung by their feet to have their throats slit.

“When you grab a chicken, turn it upside down and put it on the line, its stress, stress, stress”, says one chicken producer. The new system is not only meant to be kinder to the animals, but to plant workers as well. Dealing with struggling, flapping chickens–like dealing with bellowing cows who sense impending doom– makes meat processing plant jobs among the worst in the country.

This topic can fit in your OM course in 3 ways: (1) students have strong opinions about the issue of how we slaughter animals (see the Ethical Dilemma box on pig production in Ch.7, Process Strategy); (2) when you discuss job satisfaction/motivation in Ch.10, it makes the point that not all jobs are easy to staff/manage; and (3) this is a classic case of an assembly line, in Ch.9’s photo, at the end of the chapter.

Discussion questions:

1. Does killing chickens this way make you more comfortable with the production process?

2. How are most chickens raised in preparation for slaughter?

3. Will it be easier to market a chicken as “killed stress-free”?