USA 03Mass Production and the Two World Wars

Ford, special-purpose machines and World War I (1900–1918)

The machine tool makers form an association

Around the turn of the 20th century, most American machine tool makers were small companies. In June 1902, 17 lathe makers came together to form the National Machine Tool Builders' Association (NMTBA, today's AMT). Lathe makers from Cincinnati and Worcester were at its core, and its aim was to stop price-cutting wars and put business practices in order^[1][2][3]. The association later held trade shows, collected statistics and in wartime served as the contact point with the government. Only a 1914 commemorative volume gives the founding year as "1901"; three sources agree on 1902, including the president's remark at the 1922 convention that it was the "20th year", so this chapter adopts 1902^[64].

Highland Park: machines in process order

The Ford Motor Company, founded in 1903, moved in 1910 to a new plant in Highland Park, north of Detroit. Many of its buildings were designed by Albert Kahn, known for his factory architecture, and they were extended again and again until 1922 to keep up with Model T orders^[4].

What Ford's engineers did here was not so much to invent new machines as to change how the machines were arranged. Until then, it was normal for factories to group machines by type: lathes in the lathe area, drilling machines in the drilling area. Work was carried from department to department and waited each time. In 1914–15 Ford rearranged more than 500 machine tools part by part, in the order of operations. Arnold and Faurote, who reported on the plant at the time, summed up the method in three points: placing tools and workers in the order of operations to keep the movement of parts as short as possible; using chutes, so that a finished part placed in a set spot slid by gravity to the next worker's hand; and the moving assembly line^[6]. The machines were also packed as close together as possible. Floor space carried overhead costs too, and Arnold compared it by saying that "even the most closely packed New England shops still waste floor space"^[6].

Special-purpose machines: "standard machines plus elaborate fixtures"

The Model T's four-cylinder, one-piece cast cylinder block was machined in a total of 45 minutes including loading and unloading, with no hand finishing. A Foote-Burt multi-spindle drilling machine drilled 45 holes at once from four directions, and Ingersoll milling machines milled the faces. On milling machines with long tables, blocks were clamped in a string and fed through, and taken off one by one as they cleared the cutters. Sharpened spare cutters were kept ready and changed every shift^[6]. Arnold writes that most of Ford's machines were standard commercial models, but that instead the jigs and fixtures were elaborate, so the operator needed no special care^[6]. Fitting a general-purpose drilling or milling machine with a multi-spindle head and fixture dedicated to one part to make a "special-purpose machine": the way of thinking about special machines and fixtures in today's mass-production plants was essentially complete here.

The machine tool makers, too, began offering machines for mass production. In 1913 Cincinnati Milling Machine, with designs by A. L. De Leeuw, brought out a bed-type milling machine for production (manufacturing miller) that automatically repeated table rapid approach, cutting feed and rapid return, and by 1916 offered single- and double-head models^[5]. Unlike general-purpose knee-type milling machines, it was a machine for cutting thousands of a single part with the same setup (for details, see Chapter 7).

The moving assembly line

The moving line was first tried on small parts. In spring 1913 at Highland Park, the assembly of the flywheel magneto was divided into 29 operations, and the work was moved past the workers. A job that took about 20 minutes per unit when one person assembled the whole thing fell to 13 minutes 10 seconds, and with further improvements to 5 minutes^[6]. The same book gives the installation date two ways, around April 1 and around May 1, so this chapter says “spring.”

Next came the chassis. In August 1913, stationary assembly took 12 hours 28 minutes of labor per car. An experiment hauling the chassis across the floor with a rope and windlass cut this to 5 hours 50 minutes, and on October 7 assembly began on a moving line about 46 m long: 140 workers assembled 435 chassis in a day (9 hours), or 2 hours 57 minutes of labor per car. On April 30 the following year, 1914, three chain-driven raised lines assembled 1,219 cars in 8 hours, or 1 hour 33 minutes of labor per car^[6][4]. A National Park Service document also gives “from 728 minutes to 93 minutes.” Model T output grew from 13,840 cars in 1909 to 189,088 in 1913 and 585,388 in 1916^[10], and the price fell from $850 in 1908 to $260 in 1924^[4].

Moving assembly was about assembly, but its effect on machine tools was large. The line assumed that parts would fit together just as they came. If even one part was off-size and had to be fitted by hand, the whole line stopped. So machining needed machines that held the same dimensions day after day, and gauges to check them. And if one line assembled hundreds of cars a day, the machining that fed it had to flow at the same pace. This demand led to the centerless grinders and transfer machines we will see later.

Orders from World War I

When war broke out in Europe in 1914, arms orders from Britain, France and others poured into American factories. The 1914 census put machine tool output at $31.45 million, and by NMTBA estimates shipments of metal-cutting machine tools rose from $35.3 million in 1914 to $220.6 million in 1918, about six times as much^[7]. The unit index (1913 = 100) also stood at 192 in 1917^[16]. The war also exposed a shortage of gauges. Gauge blocks could only be bought from Europe, so in 1917 the inventor William Hoke brought his method to the National Bureau of Standards (NBS), and with Army Ordnance funds 50 sets of 81 blocks were made^[11].

Between the wars: slump, centerless grinding, gauge blocks and carbide (1919–1938)

The postwar slump

The 1919 census still put machine tool output at $212.4 million^[7], but in 1921, with war orders gone, shipments fell to $23 million. The unit index also dropped from 192 in 1917 to 20.5 in 1921, close to a tenth^[15][16]. Machine tools are durable and last 15 years or more. Machines bought for the war stayed in the plants and ate up orders for years to come. The memory of this slump is also why the industry hesitated to expand on the eve of World War II^[38]. What revived shipments in the 1920s was mass production in the auto industry.

Centerless grinders: the wheel became a consumable

The biggest headache of auto mass production was grinding. Grinding small hardened round parts (piston pins, valve stems, bearing rollers) one at a time between centers could not keep up with the line. What came into practical use was centerless grinding (grinding without centers). The work is not held on centers; it sits between a fast grinding wheel and a rubber-bonded regulating wheel turning slowly in the opposite direction, supported from below by a blade. The regulating wheel acts as a brake, and the difference in speed between the two wheels does the grinding. Setting the work center slightly above the line joining the two wheel centers produces roundness^[9].

The key regulating-wheel-and-blade arrangement was patented by L. R. Heim of Ball and Roller Bearing Co., a Connecticut bearing maker: filed in March 1915 and granted in January 1917. Woodbury and Ashburn write “the 1915 patent,” but 1915 is the filing year^[8][9]. Heim built the machine to bring bearing rollers to uniform size^[18]. Cincinnati Milling Machine acquired the patent and brought out a production centerless grinder in 1922. The grinding wheel was 20 in. (about 510 mm) in diameter and the regulating wheel 12 in., and it could also grind shouldered push rods and valve tappets. The trade journal American Machinist introduced it as “recently placed on the market” in August 1923^[9][17].

What changed on the shop floor? According to a 1925 trade journal, it ground 350 six-inch valve stems an hour, or 225–325 piston pins, and the regulating wheel needed dressing only once or twice a shift. Woodbury sums up that centerless grinding taught factories that “the wheel is a consumable, and in mass production its cost is small.” Skilled grinders were no longer needed; instead, people good at setup were^[9]. Ashburn, a former editor of American Machinist, counts Heim's centerless grinder, along with Norton's crankshaft grinding, Heald's internal grinding and double-disc surface grinding, among the four developments in grinding that supported the auto industry^[10] (for how grinding machines evolved, see Chapter 8; for setting up centerless grinding today, see the Grinding page).

Gauge blocks: putting the length standard in the factory

For parts to fit when assembled, every gauge in the factory has to agree with the same standard. In 1896 C. E. Johansson of Sweden came up with steel blocks that could be combined to make many sizes. When two faces are lapped flat and parallel, they cling together through a very thin film of oil (wringing), and the film, about 25 nm thick, can be ignored when adding up sizes^[11]. A handbook from the US National Institute of Standards and Technology (NIST) says Henry Ford adopted them eagerly, and that his example made them the length standard of industry^[11].

Johansson returned to the US in 1919 and began selling angle blocks and other products through the American company C. E. Johansson, Inc. The factory was in Poughkeepsie, New York^[12]. In November 1923 Henry Ford bought the company, and Johansson himself moved to Ford. The US rights to the gauges and the method also became Ford's, and gauge blocks went on being sold under the Ford name^[13][20]. The 1937 catalog was published by Ford and calls Ford's engineering laboratory in Dearborn “the American home of Johansson gage blocks”^[21]. Instead of each plant making and keeping hundreds of gauges, a few blocks could be combined into a reference for any size. This put mass-production inspection and the toolroom that made jigs and gauges on the same standard (for how gauges are used today, see the Gauges page).

From special machines to transfer machines

Once machines were arranged in process order, the next step was to cut the people carrying work between them. In 1920 A. O. Smith in Milwaukee installed an automatic production line for car frames. Ashburn calls it the first continuous automatic line in the modern sense^[14][10]. In 1924, at Morris's works in Coventry, England, a machine was built that lined standard machines up on one long bed, synchronized the heads with a common shaft, and performed 53 operations on cylinder blocks. It was 181 ft (about 55 m) long, with a cycle of 4 minutes per part. It is regarded as the first true transfer machine^[14]. In the US, in 1929, the automaker Graham-Paige introduced a system for machining cylinders that clamped the fixtures automatically and moved the work from machine to machine with a transfer bar. Ashburn (1955), Shils (1963) and Flink (1988) all cite it as an early US example with all the elements of today's transfer machine^[14][32][33].

How the machines themselves were driven also changed. In 1927 Cincinnati Milling Machine brought out a standard milling machine whose table feed was driven hydraulically, with a steplessly variable feed rate^[5]. Unlike machines that selected feeds through gear steps, it made it easy to automate the switch from rapid traverse to cutting feed, which suited the automatic cycles of production machines. Transfer machines are covered in detail in Chapter 10.

Carbide tools: the cutter outran the machine

Made by sintering tungsten carbide powder with cobalt or other metals, cemented carbide grew out of research at Osram, the German lamp maker. Karl Schröter's US patent was filed in October 1923, granted in August 1925 and assigned to General Electric (GE)^[19]. According to a commentary in the University of Chicago's law review, Osram took out the US patents in 1922–25, licensed GE for lamp use only, and the remaining rights went to Krupp^[29]. Carbide tools went on the market in Europe in 1926^[22], and at the Leipzig fair in March 1928 Krupp demonstrated cutting with Widia. A US trade journal reported in May that it cut mild steel at 560 ft/min (about 170 m/min) and cast iron at 780 ft/min (about 240 m/min)^[25][26]. That was several times the speed of high-speed steel.

In October 1928 GE put the carbide tools made in its laboratory on sale under the name “Carboloy” and set up a new company, Carboloy Company. According to GE's S. L. Hoyt, the hardness was 2,100–2,500 Brinell (hardened steel: 850–1,000), but the bending strength was only about 60% of high-speed steel^[27]. In November GE and Krupp signed an agreement, and GE also gained Krupp's US patent rights. GE set the price of carbide at $453 a pound, about ten times that of earlier imports^[29][30]. This high price and the way the patents were pooled later led to an indictment in October 1941 and a guilty verdict in October 1948 (antitrust law)^[31][29]. The judgment found that GE's manufacturing cost was 6–12 cents a gram, yet it set the price at $1 a gram.

Carbide was the moment “the cutter outran the machine.” Cutting fast with carbide, which is hard but brittle, needs a machine with high rigidity and little vibration. Without enough rigidity the edge chips, and chatter was fatal. At low speeds it wears quickly. Lathes with 900 rpm spindles and vertical boring mills cutting at 1,000 ft/min soon appeared, but then the Great Depression struck and capital spending stopped. A full lineup of rigid machines built for carbide arrived only in 1939^[10]. Even so, fine boring with single-point carbide tools at high speed and fine feed began, and the finishing of cast-iron cylinders started to shift from grinding to boring^[10]. In 1930 the National Bureau of Standards tested whether Taylor's tool-life equation also held for carbide^[22] (for today's cutting conditions for carbide, see the Machining page).

Trade shows and the Great Depression

On September 19–23, 1927, NMTBA held the first machine tool show (National Machine Tool Builders' Exposition) at the Cleveland Public Auditorium, with 180 exhibitors. The second show, in 1929, grew to 270^[23][24]. This was the start of today's IMTS^[3]. Shipments in 1929 were $185 million, the peak of the 1920s, but the Great Depression drove them down to $22 million in 1932, about one-eighth^[15][16]. The third show, in 1935, displayed six years' worth of new machines^[35].

World War II: the Arsenal of Democracy (1939–1945)

A cancelled show, and export licensing

The show planned for September 1939 in Cleveland was cancelled at the last minute when war broke out in Europe. American Machinist wrote that the 1939 models designed for the show became the mainstay of wartime production^[36]. On July 2, 1940, Proclamation No. 2413, issued under the act to strengthen the national defense, put metal-cutting and grinding machine tools and other items under export licensing. The aim was to keep them for domestic arms plants, and from here machine tool exports to Japan also came to a halt^[37] (see “Links with Japan” below).

The industry was flooded with British and French orders, and some makers had backlogs of more than 18 months. Even so, they hesitated to expand. An executive of Warner & Swasey in Cleveland is said to have still been looking out the window in 1940 at a plant building put up in World War I and never used. The worry was that overselling today would eat tomorrow's market^[38].

Pool orders: the government takes the risk of unsold machines

On December 29, 1940, in a radio address, President Roosevelt called on America to become the “arsenal of democracy” and urged a quick expansion of plants and machines^[39][40]. The same month, the Defense Plant Corporation (DPC), a subsidiary of the Reconstruction Finance Corporation, began placing pool orders for machine tools. The government ordered machine tools before the arms plants that would buy them were known, and took back any that went unsold. Makers could now stock materials ahead of demand and expand. After Pearl Harbor, pool orders also came with a 30% interest-free advance payment^[38]. DPC also put about $92 million into 35 new plants for machine tool builders and equipment purchases for 131 plants^[38]. Pool orders totaled about $1,945 million, and the $1,699 million of pool-built machine tools shipped came to nearly half of the industry's output in 1941–1945. Machines that found no buyer and were taken back by DPC are said to have come to less than $3 million^[38].

Allocation orders and peak production

On January 16, 1942, Executive Order 9024 created the War Production Board (WPB), and machine tool allocation also moved to WPB^[43]. Order E-1-a in January set delivery priorities by dividing machine tools into two groups, and E-1-b in May assigned up to 75% of each maker's monthly deliveries of new machine tools, by type and size, to the Army, Navy and Maritime Commission^[45][44]. Machine tools had become a “rationed good,” with the government deciding which plant got how many and when.

Shipments in 1942 reached $1,320 million, an all-time high. That was about 6.6 times 1939 ($200 million), and December alone saw $132 million shipped^[41][42]. A 1943 trade journal reported that labor (skilled workers lost to the draft) rather than space or machines had become the problem, and that work began to fall off first at makers of standard machines such as engine lathes, milling machines and planers^[42]. Once the arms plants had their machines, shipments in 1944 were $497 million, less than 40% of 1942^[15].

Wartime machine tool building was about “the same machines, many of them, fast” rather than new designs. Major design advances had to wait for the postwar 1947 show^[36]. But the war spread mass-production thinking to armaments, and taught plants across the country how special machines, jigs and gauges let unskilled workers make parts.

Postwar: surplus machines, Detroit Automation and the Korean War (1945–1950s)

700,000 surplus machines

When the war ended, it was estimated that up to 700,000 government-owned machine tools (acquisition cost $1.8 billion) would become surplus. Two-thirds of the pool-built machines had become government property^[38]. Disposal of the surplus fell to the War Assets Administration, which became an independent agency in March 1946, and about 170,000 machine tools had been sold by March 1947. Cheap used machines flooded the market and squeezed sales of new ones. New machine tool sales in 1946 came to only $375 million^[38]. Shipments hit their postwar low of $249 million in 1949^[46].

The government did not sell everything. The National Industrial Reserve Act of July 1948 provided for keeping some government plants and a “national reserve of machine tools” ready for immediate use in the next emergency^[52][38].

The postwar show

In September 1947 the first postwar show was held at the Dodge-Chicago plant in Chicago, which had built aircraft engines during the war, with about 2,000 machines on display under power^[50][51]. New designs held back during the war all came out here at once.

Automation: Ford's new department

In April 1947, within its manufacturing division, Ford set up an Automation Department. “Automation” is credited to Ford vice president D. S. (Del) Harder. Ashburn's 1955 article says it began when Harder, asked for a way to handle parts without delays from human hands, said “we need more automation,” and that the word first appeared in print in the October 21, 1948 issue of American Machinist^[14][48]. That issue defined it as the technique of loading and unloading work into equipment, turning it over between operations and removing chips, all timed to the machine motions, so that a line could be run by push button. The first target was presses: from its start the department designed more than 500 devices ($3 million) and expected to raise output by 20% on average. Each device had to cost no more than $3,000 per worker's job eliminated and pay for itself within a year^[48].

Automation spread to machining lines at the Cleveland engine plant that Ford started up in 1951. Cylinder blocks, heads, crankshafts, camshafts and more were machined on automatically linked lines, and the block line was said to have more than twice the capacity of the latest semi-automatic lines. Devices that counted how many times each tool had been used signaled when to change tools on the transfer machines^[54][53]. In the 1950s transfer machines became the mainstay of US engine plants and were called “Detroit automation”^[59].

The weakness of transfer lines. A transfer line is built for one part only, so even a small change in the car's design means rebuilding it, and if that model does not sell, the whole line has to be scrapped. Changing a single tool also stopped the entire line, so lines were divided into sections with banks of work in progress between them, and tools were changed in groups according to their life counts. By the end of the 1950s a “building-block” approach was devised, rebuilding a line for other parts by rearranging standard units^[10][59]. What solves this problem of “line flexibility” is NC and the machining center, in the next chapter.

The Korean War and aging equipment

When the Korean War began in 1950, machine tools ran short again. On February 28, 1951, National Production Authority Order M-40 revived government pool orders. At first the terms were unattractive and few makers took them up, but after revised contracts were offered in August, 61 companies took on 35,150 machines worth $806 million within four months^[55]. Shipments reached $1,191 million in 1953, close to the World War II peak^[46]. Yet American Machinist's equipment survey of November 1953 found that 55% of the 1,941,612 machine tools in US metalworking were more than 10 years old^[56]. The machines installed in bulk during the war were simply growing old.

What it means on the shop floor. Much of what was born in this era is now taken for granted in mass-production plants: machines arranged in process order (today's cells and lines), work-specific fixtures and multi-spindle heads, centerless grinding, limit gauges calibrated with gauge blocks, rigid machines built for carbide tools, and transfer lines. When you hear about a used special machine or transfer line, ask “can it be changed over for other parts?” and “is it a building-block type whose units can be rearranged?” and you will know the machine's generation and what it can be used for.

⛩Links with Japan

The 1940 export licensing and Japanese machine tools

US export licensing in July 1940 was a major turning point for Japan's machine tool industry. Chapter 1 of the Japanese archive lists “US bans machine tool exports to Japan” in its timeline for that year, and notes that until then more than 80% of Japan's machine tool imports had come from the US^[65] (timeline of Chapter 1 of the Japanese archive). With imports cut off, Japan had no choice but to build for itself the American machines it had used as models, and, as with the gear cutting machines of Chapter 4, prototypes copied directly from first-class foreign machines were ordered (Japanese Archive, Chapter 4).

Centerless grinding and gauge blocks

The centerless grinder, nurtured by the US auto industry, spread in Japan along with the mass production of bearings. Chapter 3 of the Japanese archive marks with a ★ the start of centerless grinder production at Nisshin Kikai Seisakusho in 1940^[66] (Japanese Archive, Chapter 3). In gauge blocks, Taisuke Tsugami began research in Tokyo in 1923 and in 1937 founded Tsugami Seisakusho (today's Tsugami) to produce gauge blocks^[67] (People). That 1923 was the same year Ford bought Johansson's company.

Reparations removals, and their cancellation

After the war, the US considered removing Japan's industrial equipment as reparations and giving it to Asian countries. Ambassador Pauley's final report, submitted to the President in November 1946, listed machine tools for “substantial removal,” in addition to removing all arms plants^[47]. In April 1947 a directive was issued to transfer in advance 30% of the equipment cleared for removal to China, the Philippines and others^[49]. But with the start of the Cold War the policy changed: on May 12, 1949, the US withdrew this advance-transfer directive and announced it would seek no further removals^[49]. Japan's machine tools stayed in the country and were used for postwar recovery.

Technical tie-ups in the 1950s

While the US itself was struggling with a machine tool shortage during the Korean War, Japanese makers began taking in American mass-production machine and tool technology. In November 1953 Fujikoshi Steel Industry (today's Nachi-Fujikoshi) tied up with Michigan Tool of the US to make shaving cutters^[58] (Japanese Archive, Chapter 4), and in July 1954 Niigata Engineering tied up with Sundstrand of the US to build production milling machines^[57] (Japanese Archive, Chapter 2). The “production milling machine” and “mass-production gear finishing” technologies seen in this chapter would, 20 to 30 years later, support Japan's own auto mass production. And the story of Japanese machine tools flowing back into the US continues in Chapter 5.

FAQ

What did Ford's moving assembly line change about machine tools?

It changed how machines were arranged and used. In 1914–15 Ford rearranged more than 500 machine tools in the order of part machining rather than by type of machine, and turned general-purpose drills and milling machines into special machines by fitting work-specific multi-spindle heads and fixtures. To keep the line moving, parts had to hold their dimensions day after day so they could be assembled without hand fitting, and this led to the spread of centerless grinders, gauge blocks and transfer machines.

Who built the first transfer machine?

The machine US sources agree on as “the first true transfer machine” is the one at Morris's works in Coventry, England, in 1924 (53 operations, about 55 m long). Early US examples are A. O. Smith's automatic frame line of 1920 and Graham-Paige's cylinder machining of 1929. Transfer machines spread in the 1950s at plants such as Ford's Cleveland engine plant and were called “Detroit automation.”

Since when have carbide tools been used?

Sintered tungsten carbide tools went on the market in Europe in 1926, and in March 1928 Krupp demonstrated cutting with Widia in Leipzig. In the US, GE put them on sale under the Carboloy name in October 1928. But at first they were expensive, $450–500 a pound, and rigid machines suited to carbide did not become available until around 1939.

How many machine tools did the US make in World War II?

Shipments rose from $200 million in 1939 to $1,320 million in 1942, about 6.6 times and an all-time high. Through “pool orders,” in which the government's Defense Plant Corporation ordered machine tools in bulk before buyers were known, it took on about $1.9 billion worth, nearly half of the industry's output in 1941–45. After the war, up to 700,000 machines were estimated to be surplus, and used machines circulated cheaply.