The Moving Assembly Line Turns 100
Several mega-forces were behind Ford Motor Co.’s engineering milestone.
This month marks the official celebration of the world’s first moving assembly line. On Oct. 7, 1913, 140 assemblers stationed along a 150-foot chassis line at a Ford Motor Co. plant just north of Detroit stood in place as the work came to them.
With the aid of three-wheeled dollies, chassis were pushed by hand along parallel rails embedded in the floor of the Highland Park plant. Six months earlier, Ford engineers had experimented with a movable line for assembling flywheel magnetos, a key component in the electrical system of the Model T.
By raising the height of the assembly line, moving the magnetos with a continuous chain and lowering the number of operators to 14, the Ford engineers eventually achieved a daily output of 1,335 flywheel magnetos, which translated into five minutes per magneto vs. 20 minutes with a static assembly process. That success encouraged the engineers to experiment in other parts of the factory.
The chassis line that debuted a century ago dramatically reduced Model T assembly time to less than three hours. In contrast, the traditional static assembly process took more than 12 hours. By December 1913, the line had doubled in length and 37 more assemblers were added to various workstations. Assembly time was further reduced by 20 minutes.
In January 1914, Ford engineers ramped up a line that was equipped with an endless chain conveyor. Over the next four months, they raised, lowered, sped up and slowed down the assembly line. They also made numerous changes in workstation positions and the number of assemblers. Continuous improvement eventually whittled the time required for assembly to 93 minutes.
By May 1914, when three parallel assembly lines were in operation on the ground floor of the Highland Park factory, assemblers were producing more than 1,200 chassis per eight-hour shift. The assembly process was methodically divided into 45 separate operations.
That success prompted Ford engineers to expand their experiments. On June 1, 1914, front axle assemblies were produced on a chain-driven line. Assembly time dropped by 150 minutes to 26 minutes. Moving lines were soon installed for many other subassemblies, including dashboards, rear axles, crank shafts, engines, bodies and seats.
By using a moving line, engine assembly time was slashed from 594 minutes to 226 minutes. A Model T engine traveled 4,000 feet during assembly in 1909, but this distance was reduced to just 340 feet by 1914.
According to historian Douglas Brinkley, “the [assembly line] process grew like a vine and eventually spread to all phases of the manufacture of Ford cars, and then through the entire world of heavy industry.”
Because of the moving assembly line, Model T production skyrocketed from 13,840 cars in 1909 to 230,788 units in 1914 to 585,388 units in 1916. At the same time, retail prices dropped from $950 in 1909 to $490 in 1914 to $360 in 1916.
Despite all that success, the first moving assembly line received no fanfare 100 years ago. In fact, there wasn’t even any mention of it in the Ford Times, the automaker’s monthly magazine. The first article about it in a trade magazine didn’t appear until the following year. By then, people from around the world were flocking to the “crystal palace” in Highland Park to marvel at the assembly line.
Ironically, there were no patents issued to protect production equipment or processes. In fact, Henry Ford vehemently opposed patent laws and attorneys. He believed they shackled, rather than promoted invention and progress.
“The assembly line wasn’t a planned development; rather, it emerged in 1913 from a dynamic situation,” says David Nye, author of America’s Assembly Line(MIT Press). “It is quite telling that Ford’s executives didn’t even have a name for the assembly line at first, and that the term ‘assembly line’ was little used even in the technical press in 1913 and 1914. The Ford innovation wasn’t a research and development goal, nor was it first developed as a theory and then put into practice.”
Many outside influences, inventions and innovations led up to the events that transpired at Ford’s Highland Park factory 100 years ago. But, three key things made the moving assembly line possible, and they’re valuable lessons that still apply to manufacturing today:
- Hire talented people and give them room to experiment.
- Benchmark best practices and look outside the box for new ideas.
- Develop and implement state-of-the-art production tools and technology.
Hire Diverse Talent
The assembly line did not spring up overnight; it was the result of a long period of trial and error. Although Henry Ford didn’t have a formal engineering education, he surrounded himself with people who shared his fascination with mechanization and automation.
In many history books, Ford gets most of the credit for inventing the assembly line. That’s because of an influential article that was ghost-written under his name for Encyclopedia
Britannicain 1926. Ford also controlled a powerful PR machine that often distorted myth into legend. In reality, many people had a hand in the development of the first assembly line.
“It appears that Henry Ford didn’t first conceive of the assembly line and then delegate its development to his managers,” claims Nye. “Rather, development came from the bottom up as managers synthesized their knowledge and drew on the experiences of workers.”
However, Henry Ford does deserve credit for hiring talented individuals, and then giving them the freedom to experiment and try new ideas.
“Ford’s Highland Park facility brought together managers and engineers who collectively knew most of the manufacturing processes used in the United States,” says Nye. “People with many different technical backgrounds were hired by a rapidly expanding company.
“Together they sought ways to improve productivity, and when they moved into a new, spacious factory in 1910, they pooled their ideas and drew on their varied work experiences to create a new method of production,” adds Nye. “[The assembly line] emerged in a company that was distinctly unbureaucratic, that encouraged managers to experiment and that didn’t have rigid walls between its departments.”
Ford and his team of engineers were searching for new ways to increase production speed to keep up with consumer demand for the Model T, which debuted in 1908. They decided that the best way to achieve higher production volume was to change the way assemblers worked.
People such as Carl Emde, William Klann and William Knudsen all played key roles in early automation efforts at Ford’s Highland Park factory. They helped lay out the factory floor and were responsible for efficiently arranging thousands of machine tools, and coordinating the flow of materials.
Movement of parts and subassemblies had to be mapped out before machinery and equipment could be installed. According to Emde, an engineer who joined the company in 1906, the universal goal was “to reduce hand labor, to give the operations more speed and to conserve floor space.”
Two individuals were essential to the success of the moving assembly line: Clarence Avery and Charles Sorensen. Their “little experiment” ushered in the age of mass-production.
Sorensen, the architect of the modern assembly line, served as Ford’s production chief for 40 years. According to his great grandson, Cliff Sorensen, “Henry Ford may have been able to get an idea, but it was Charles Sorensen who would take his cocktail napkin and turn it into a reality.”
Under the guidance of Sorensen, Ford installed numerous overhead conveyors to bring components to subassembly lines. For instance, Sorenson installed belt conveyors that took radiator parts, carried them past a bench line of assemblers, and automatically transferred the assemblies to another belt at right angles which passed them under the hands of solderers.
Before the advent of the moving line, the process of assembling a Model T chassis was very laborious. Gangs of workers moved from workstation to workstation performing a specific task or series of tasks.
“The idea occurred to me that assembly would be easier, simpler and faster if we moved the chassis along, beginning at one end of the plant with a frame and adding the axles and the wheels; then moving past the stockroom, instead of moving the stockroom to the chassis,” recalled Sorensen in his memoirs, My Forty Years With Ford (Wayne State University Press).
Over a five-year period, Sorensen and his assistant, Avery, experimented with moving assembly lines and made numerous changes in speed, workstation positions and the number of assemblers. “This called for patient timing and rearrangement until the flow of parts and the speed and intervals along the assembly line meshed into a perfectly synchronized operation,” said Sorensen.
Avery had a background in education and some people believe he is the person who first pitched the idea of a moving line. “However, we cannot assign a precise date, or cite a ‘eureka’ moment that anyone recognized at the time or recalled later,” says Nye.
“Perhaps the most important man in figuring out how it all would work was Clarence Avery, a high school shop teacher who had instructed Edsel Ford,” adds Vincent Curcio, author of Henry Ford(Oxford University Press). “Under Sorensen, he spent eight months mastering every type of manufacturing operation at Highland Park, complete with motion and time studies, and once he had done this, he and Sorensen began to lay out the chassis assembly. It is Avery who came to be called ‘the father of the assembly line.’”
Benchmark and Borrow Ideas
Benchmarking played a key role in the development of mass-production. “The modern assembly line did not spring full blown from the head of Zeus,” says Curcio. “It was figured out by studying various processes and techniques that had been used in other industries for quite some time.”
“Rather than seeing the members of the Ford team that invented the assembly line as extraordinarily gifted, it is more accurate to see them as the heirs of centuries of development in machine design and manufacturing processes,” says Nye. “Throughout the 19th century, other factories had intermittently worked on the problem of how to speed up production, contributing various technical elements that came together in the Ford solution.”
In the early 1900s, some of the most automated factories in the world were not located in Detroit—they were 300 miles away in Chicago. The Windy City was home to a wide variety of bakeries, breweries, meat-packing plants, canneries and mail-order catalog houses that used conveyors and other forms of automation.
Henry Ford and his team of engineers found inspiration for the moving assembly line during several trips to Chicago. For instance, they visited meat-packing plants on the southwest side of the city, such as Armour & Co., Swift & Co. and Wilson & Co. In his autobiography, My Life and Work(CRC Press), Ford claims that the “overhead trolley that the Chicago packers use in dressing beef” served as a model for flow production at the Highland Park plant.
Ford and his colleagues also visited the Sears, Roebuck & Co. plant that processed orders for the company’s famous mail-order catalog. The 40-acre operation was called “the world’s greatest mercantile institution.”
Shortly after the huge facility on the west side of Chicago opened in 1906, Ford was one of the first visitors and he delighted in its operation. The Sears warehouse contained numerous elevators, conveyors, endless chains, moving sidewalks, gravity chutes, pneumatic tubes and “every known mechanical appliance for reducing labor” to reduce time and improve productivity.
Another source of inspiration for the moving assembly line came from Ford’s visit to Chicago’s Continental Can Co. Its plant used automated machinery and an elaborate conveyor system to mass-produce tin cans for the food industry.
“Those working at the Ford Motor Co. when the assembly line was created had experience in arms manufacturing, bicycle production, meat-packing, steelmaking and brewing,” says Nye. “The assembly line synthesized practices from all those industries, and became more than the sum of its parts.”
Ford engineers were infatuated with production flow. To open up floor space and streamline material handling, they created a complex system of slides, troughs and conveyors at the Highland Park plant. Gravity slides made of inclined sheet iron were built next to workstations on the upper levels of the four-story factory.
“To keep production moving quickly and smoothly, [conveyors, chutes and slides] were essential and [were] omnipresent by the time [moving assembly] lines were pervasive throughout the plant,” adds Curcio. “They alone were estimated to save 30 percent of assembly time.”
Another philosophy that led to the success of the moving assembly line was the constant redesign of the Model T. Many components were tweaked regularly to make the vehicle easier to assemble. In 1913 alone, Ford made more than 100 design changes every month.
For example, engineers eliminated a separate forged body bracket at the rear of the frame by using a longer rear cross member. Each bracket was held in place with three screws, three nuts and three cotter pins. In addition, each bracket had four holes that had to be drilled. That minor modification trimmed approximately one minute off assembly time per vehicle.
Use State-of-the-Art Technology
Henry Ford and his colleagues successfully harnessed the biggest game-changer of their day: electricity. This allowed the widespread use of conveyors, power tools and other time-saving devices.
When the Highland Park plant opened in 1910, it was a new kind of factory. According to Nye, it was “built on the assumption that electrical light and power should be available everywhere. The floor plan was more open and more flexible than those of older facilities, and it encouraged innovation.”
In 1912, a 64-page booklet entitled Ford Factory Factswas published to promote the marvels of the new factory. It explained how “a mammoth gas engine, which in turn drives an equally huge dynamo, [generates] a powerful electric current that is distributed by cables all over the entire plant: to the motors which drive the machinery in each department and to the thousands of arc and incandescent lights.”
The engine was 58 feet long and 25 feet wide. It featured two double-acting cylinders and a 42-ton flywheel. A huge dynamo generated a 240-volt current that was carried by heavy copper cables to every corner of the plant.
“It was difficult to make absolutely standardized parts with machines not driven by individual electric motors,” says Nye. “Likewise, electrical heating spoiled fewer materials than other kinds of heating and increased the speed of some steps in the assembly process, such as drying paint on individual parts. Overall, electrification permitted a higher and more predictable standard of parts production.”
Electric fans operated continuously to ensure ventilation. “Dust was extracted from the air by passing it through a dense mist,” says Nye. “The air was then dried and pumped into work areas. Pure air improved the workers’ health and kept the machinery cleaner and more accurate.”
Reliable electric motors, which had been invented in the 1890s, made it possible for Ford assemblers to tighten fasteners with power-driven socket wrenches.
“A certain operation might first be accomplished by a socket-wrench with a T-form handle,” says Allan Nevins, co-author of Ford: The Times, The Man, The Company(Charles Scribner’s Sons). “This would be replaced by a speed-wrench having a knob for one hand and a crank for another; it could be turned at enhanced speed, with less energy.
“It would be replaced by an electric-driven wrench unit, suspended from above and counterweighted for ease of manipulation—a common power tool in the Ford plants,” adds Nevins. “The operator now had only to apply the socket to the bolt head and touch the grips, spinning the shaft. Speed increased again, but the job became far easier.”
Electric motors also allowed Ford engineers to fill the Highland Park plant with a wide variety of cranes, conveyors and elevators. For instance, overhead monorail conveyors made by Sprague Electric Works were a key part of the factory.
Other conveyors were soon introduced throughout the plant, which, by 1915, boasted 50 miles of belting and 1.5 miles of conveyor track. According to Nevins, the most elaborate was in the motor assembling room. “An endless belt installed close to the roof took motor components, swept them along, and delivered them as wanted through gravity slides to two widely separated lines of motor assemblers,” says Nevins.
However, plant layout was constrained by the overhead line shafts that distributed mechanical power throughout the plant. “Few machines ran on individual motors in the Ford factories even as late as 1918,” says Biggs. “Usually medium-sized electric engines provided power for a bank of machines.”
Continuous experimentation was the rule rather than the exception at Ford’s Highland Park plant.
Ford engineers were constantly redesigning and tweaking jigs and fixtures, and planning new machine tools or fixing old ones, to achieve higher production.
“Highland Park was full of arresting novelties,” adds Nevins. “Old machines were ruthlessly discarded as fast as they could be improved. Sometimes a simple improvement made an astonishing difference.”
A wheel-painting machine allowed Ford to turn out 2,000 painted, varnished and dried wheels a day, with half as many employees as other plants would have needed for the work. Other production equipment developed in-house included a double-end machine tool for pressing tubes in radiator fins; a machine tool for curling the heads of gasoline tanks two at a time; and a filleting machine for crankshaft bearings.
“The radiator assembly machine in use by 1913 was also unique,” says Nevins. “Most radiator makers worked slowly with much hand labor; the Ford device made it possible to put together 45 or 50 tubes and fins in a single operation.”
Another novelty was “a screwdriving machine [that] allowed [assemblers] to throw the screws at random into the pans of hoppers at the top of the magazines,” add Nevins. “The machine placed and installed the screws, leaving the worker nothing to do but turn the handle to move the work through the machine. While the worker operated the machine, his helper removed the previous piece from the rack where it fell when completed.”
“Everywhere in Highland Park by the end of 1914 continuous motion was the rule; a kinetic spirit pulsed through the plant; its circulatory system was as elaborate and vital as that of the human body,” notes Nevins. “Moving assemblies were geared precisely with lines of component supply. This permitted a close spacing of machines to save lifting, and a minute subdivision of operations.”
Highland Park Today
At its prime, the Highland Park factory comprised two dozen buildings set on 130 acres, with more than 2 million square feet of factory space. But, the plant where Ford achieved a 900 percent jump in labor productivity between 1913 and 1915 became outdated soon after the moving assembly line was unveiled.
Ford transferred the bulk of its production operations to the vertically integrated Rouge complex on the other side of Detroit. The Highland Park plant remained in use assembling tractors and interior trim components. In recent years, some of the buildings have been used by Ford to store documents and artifacts.
The complex was designated a National Historic Landmark in 1978. And, it was recently featured in a PBS television show entitled “10 Buildings that Changed America” because of the role it played in creating the middle class economy.
There’s currently a campaign underway to renovate two of the buildings, which are in disrepair. A nonprofit organization called the Woodward Avenue Action Association wants to purchase the 40,000-square-foot administration building, along with the 8,000-square-foot executive garage and three acres of land. They aim to create an Automobile Heritage Welcome Center that features state-of-the-art interactive technology and educational displays.
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