Mass production is the
production of large amounts of standardized
products, including and especially on assembly
lines. With job production and batch
production it is one of the three main production methods.
The term mass production was
popularized by a 1926 article in the Encyclopedia Britannica supplement
that was written based on correspondence with Ford Motor Co. The New York
Times used the term in the title of an article that appeared before
publication of the Birtannica article.
The concepts of mass production are
applied to various kinds of products, from fluids and
particulates handled in bulk (such as food, fuel, chemicals,
and mined minerals) to
discrete solid parts (such as fasteners) to assemblies of such parts (such as household appliances and automobiles).
Mass production is a diverse field,
but it can generally be contrasted with craft
production or distributed manufacturing. It has
occurred for centuries; there are examples of production methods that can best
be defined as mass production that predate the Industrial Revolution. However, it has been
widespread in human experience, and central to economics, only since the late
19th century.
Overview
Mass Production involves making
many copies of products, very quickly, using assembly line techniques to send
partially complete products to workers who each work on an individual step,
rather than having a worker work on a whole product from start to finish.
Mass production of fluid matter
typically involves pipes with centrifugal
pumps or screw conveyors (augers) to transfer raw materials
or partially complete products between vessels. Fluid flow processes such as
oil refining and bulk materials such as wood chips and pulp are automated using
a system of process control which uses various instruments to
measure variables such as temperature, pressure, volumetric and level,
providing feedback
Bulk materials such as coal, ores,
grains and wood chips are handled by belt, chain, slat, pneumatic or screw
conveyors, bucket elevators and mobile equipment such as
front-end loaders. Materials on pallets are handled with
forklifts. Also used for handling heavy items like reels of paper, steel or
machinery are electric overhead cranes, sometimes called bridge cranes
because they span large factory bays.
Mass production is capital
intensive and energy intensive, as it uses a high proportion of machinery
and energy in relation to workers. It is also usually automated
while total expenditure per unit of product is decreased. However, the
machinery that is needed to set up a mass production line (such as robots and machine
presses) is so expensive that there must be some assurance that the product
is to be successful to attain profits.
One of the descriptions of mass
production is that "the skill is built into the tool", which means
that the worker using the tool may not need the skill. For example, in the 19th
or early 20th century, this could be expressed as "the craftsmanship is in
the workbench
itself" (not the training of the worker). Rather than having a skilled
worker measure every dimension of each part of the product against the plans or
the other parts as it is being formed, there were jigs
ready at hand to ensure that the part was made to fit this set-up. It had
already been checked that the finished part would be to specifications to fit
all the other finished parts—and it would be made more quickly, with no time
spent on finishing the parts to fit one another. Later, once computerized
control came about (for example, CNC), jigs were obviated, but it remained true that the skill (or
knowledge) was built into the tool (or process, or documentation) rather than
residing in the worker's head. This is the specialized capital required for
mass production; each workbench and set of tools (or each CNC cell, or each fractionating column) is different (fine-tuned
to its task).
History
Before the Machine Age
This woodcut from 1568
shows the left printer removing a page from the press while the one at right
inks the text-blocks. Such a duo could reach 14,000 hand movements per working
day, printing around 3,600 pages in the process.
Crossbows
made of bronze were mass-produced in China during the Warring States period. The Qin Emperor
unified China at least in part by equipping large armies with these weapons,
which were equipped with a sophisticated trigger mechanism made of
interchangeable parts.[4] Ships of war were
mass-produced at a moderate cost by the Carthaginians
in their excellent harbors, allowing them to efficiently maintain their control
of the Mediterranean. Venice themselves
also mass-produced ships using prefabricated parts and assembly
lines many centuries later. The Venetian
Arsenal apparently produced nearly one ship every day, in what was
effectively the world's first factory which, at its height, employed 16,000 people. Mass
production in the publishing industry has been commonplace since the Gutenberg
Bible was published using a printing
press in the mid-15th century.
In the Industrial Revolution simple mass production
techniques were used at the Portsmouth Block Mills to make ships' pulley
blocks for the Royal Navy in the Napoleonic
Wars. These were also used to rather limited extent to make clocks and
watches, and to make small arms, though parts were usually non-interchangeable.
Though produced on a very small scale, Crimean War
gunboat engines designed and assembled by John Penn of Greenwich are recorded as the
first instance of the application of mass production techniques (though not
necessarily the assembly-line method) to marine engineering. In filling an
Admiralty order for 90 sets to his high-pressure and high-revolution horizontal
trunk engine design, Penn produced them all in
90 days. He also used Whitworth Standard threads throughout.
During and since the Machine Age
Prerequisites of a world filled
with mass production were interchangeable parts, machine
tools and power, especially in the form of electricity.
Some of the organizational
management concepts needed to create 20th-century mass production, such as scientific management, had been pioneered by
other engineers (most of whom are not famous, but Frederick Winslow Taylor is one of the
well-known ones), whose work would later be synthesized into fields such as industrial engineering, manufacturing engineering, operations research, and management consultancy. Although after
leaving the Henry Ford Company which was rebranded as Cadillac and
later was awarded the Dewar Trophy in 1908 for creating interchangeable
mass-produced precision engine parts, Henry Ford
downplayed the role of Taylorism in the development of mass production at his
company. However, Ford management performed time studies and experiments to
mechanize their factory processes, focusing on minimizing worker movements. The
difference is that while Taylor focused mostly on efficiency of the worker,
Ford also substituted for labor by using machines, thoughtfully arranged, wherever
possible.
The United States Department of War
sponsored the development of interchangeable parts for guns produced at the
arsenals at Springfield, Massachusetts and Harpers Ferry, Virginia (now West
Virginia) in the early decades of the 19th century, finally achieving reliable
interchangeability by about 1850. This period coincided with the development of
machine
tools, with the armories designing and building many of their own. Some of
the methods employed were a system of gauges for checking dimensions of the various
parts and jigs and fixtures
for guiding the machine tools and properly holding and aligning the work
pieces. This system came to be known as armory practice or the American system of manufacturing,
which spread throughout New England aided by skilled mechanics from the
armories who were instrumental in transferring the technology to the sewing
machines manufacturers and other industries such as machine tools, harvesting
machines and bicycles. Singer Manufacturing Co., at one time the
largest sewing machine manufacturer, did not achieve interchangeable parts
until the late 1880s, around the same time Cyrus
McCormick adopted modern manufacturing practices in making harvesting machines.
Mass production benefited from the
development of materials such as inexpensive steel, high strength steel and
plastics. Machining of metals was greatly enhanced with high
speed steel and later very hard materials such as tungsten
carbide for cutting edges. Fabrication using steel components was aided by
the development of electric welding and stamped steel
parts, both which appeared in industry in about 1890. Plastics such as polyethylene,
polystyrene
and polyvinyl chloride (PVC) can be easily formed
into shapes by extrusion, blow
molding or injection molding, resulting in very low cost
manufacture of consumer products, plastic piping, containers and parts.
A very influential article that
helped to frame the 20th century's definition of mass production appeared in a
1926 Encyclopædia Britannica supplement. It was written based on
correspondence with Ford Motor Company.
Factory electrification
Electrification of factories began
very gradually in the 1890s after the introduction of a practical DC motor by Frank
J. Sprague and accelerated after the AC motor was
developed by Galileo Ferraris, Nikola
Tesla and Westinghouse, Mikhail Dolivo-Dobrovolsky and others.
Electrification of factories was fastest between 1900 and 1930, aided by the
establishment of electric utilities with central stations and the lowering of
electricity prices from 1914 to 1917.
Electric motors were several times
more efficient than small steam engines because central station generation were
more efficient than small steam engines and because line shafts
and belts had high friction losses.Electric motors allowed also more
flexibility in manufacturing and required less maintenance than line shafts and
belts. Many factories saw a 30% increase in output just from changing over to
electric motors.
Electrification enabled modern mass
production, as with Thomas Edison’s iron ore processing plant (about 1893) that
could process 20,000 tons of ore per day with two shifts of five men each. At
that time it was still common to handle bulk materials with shovels,
wheelbarrows and small narrow gauge rail cars, and for comparison, a canal
digger in previous decades typically handled 5 tons per 12 hour day.
The biggest impact of early mass
production was in manufacturing everyday items, such as at the Ball
Brothers Glass Manufacturing Company, which electrified its
mason jar
plant in Muncie, Indiana, USA around 1900. The new automated
process used glass blowing machines to replace 210 craftsman glass blowers and
helpers. A small electric truck was used to handle 150 dozen bottles at a time
where previously a hand truck would carry 6 dozen. Electric mixers replaced men
with shovels handling sand and other ingredients that were fed into the glass
furnace. An electric overhead crane replaced 36 day laborers
for moving heavy loads across the factory.
According to Henry Ford:
”The provision of a whole new
system of electric generation emancipated industry from the leather belt and line shaft,
for it eventually became possible to provide each tool with its own electric
motor. This may seem only a detail of minor importance. In fact, modern
industry could not be carried out with the belt and line shaft for a number of
reasons. The motor enabled machinery to be arranged in the order of the work,
and that alone has probably doubled the efficiency of industry, for it has cut
out a tremendous amount of useless handling and hauling. The belt and line shaft
were also tremendously wasteful – so wasteful indeed that no factory could be
really large, for even the longest line shaft was small according to modern
requirements. Also high speed tools were impossible under the old conditions –
neither the pulleys nor the belts could stand modern speeds. Without high speed
tools and the finer steels which they brought about, there could be nothing of
what we call modern industry.”
The assembly plant of the Bell
Aircraft Corporation in 1944. Note parts of overhead
crane at both sides of photo near top.
Mass production was popularized in
the late 1910s and 1920s by Henry Ford's Ford Motor Company, when introduced
electric motors to the then-well-known technique of chain or sequential
production. Ford also bought or designed and built special purpose machine
tools and fixtures such as multiple spindle drill presses
that could drill every hole on one side of an engine block in one operation and
a multiple head milling machine that could simultaneously machine
15 engine blocks held on a single fixture. All of these machine tools were
arranged systematically in the production flow and some had special carriages
for rolling heavy items into machining position. Production of the Ford
Model T used 32,000 machine tools.
All processes in the factory were
capable of turning out high precision work within tolerances.
Ford's contribution to mass
production was synthetic in nature, collating and improving upon existing
methods of sequential production and applying electric power to them, resulting
in extremely-high-throughput, continuous-flow mass production, making the Model
T affordable and, as such, an instant success.
Although the Ford Motor Company
brought mass production to new heights, it was a synthesizer and extrapolator
of ideas rather than being the first creator of mass production. The following
paragraphs touch on precursors from prior eras.
Use of assembly lines
Ford assembly line, 1913. The
magneto assembly line was the first.
Mass production systems for items
made of numerous parts are usually organized into assembly
lines. The assemblies pass by on a conveyor, or if they are heavy, hung
from an overhead crane or monorail.
In a factory for a complex product,
rather than one assembly line, there may be many auxiliary assembly lines
feeding sub-assemblies (i.e. car engines or seats) to a backbone
"main" assembly line. A diagram of a typical mass-production factory
looks more like the skeleton of a fish than a single line.
Vertical integration
Vertical integration is a business practice
that involves gaining complete control over a product's production, from raw
materials to final assembly.
In the age of mass production, this
caused shipping and trade problems in that shipping systems were unable to
transport huge volumes of finished automobiles (in Henry Ford's case) without
causing damage, and also government policies imposed trade barriers on finished
units.
Ford built the Ford River Rouge Complex with the idea of
making the company's own iron and steel in the same large factory site as parts
and car assembly took place. River Rouge also generated its own electricity.
Upstream vertical integration, such
as to raw materials, is away from leading technology toward mature, low return
industries. Most companies chose to focus on their core business rather than
vertical integration. This included buying parts from outside suppliers, who
could often produce them as cheaply or cheaper.
Standard
Oil, the major oil company in the 19th century, was vertically integrated
partly because there was no demand for unrefined crude oil, but kerosene and
some other products were in great demand. The other reason was that Standard
Oil monopolized the oil industry. The major oil companies were, and many still
are, vertically integrated, from production to refining and with their own
retail stations, although some sold off their retail operations. Some oil
companies also have chemical divisions.
Lumber and paper companies at one
time owned most of their timber lands and sold some finished products such as
corrugated boxes. The tendency has been to divest of timber lands to raise cash
and to avoid property taxes.
Today the trend is toward platform
companies, where the value added is in market analysis, engineering and product
design. The platform company contracts production to outside suppliers, often
in low wage countries.
Advantages and disadvantages
The economies of mass production
come from several sources. The primary cause is a reduction of nonproductive
effort of all types. In craft production, the craftsman must bustle about
a shop, getting parts and assembling them. He must locate and use many tools
many times for varying tasks. In mass production, each worker repeats one or a
few related tasks that use the same tool to perform identical or near-identical
operations on a stream of products. The exact tool and parts are always at
hand, having been moved down the assembly line consecutively. The worker spends
little or no time retrieving and/or preparing materials and tools, and so the
time taken to manufacture a product using mass production is shorter than when
using traditional methods.
The probability of human error and
variation is also reduced, as tasks are predominantly carried out by machinery.
A reduction in labour costs, as well as an increased rate of production,
enables a company to produce a larger quantity of one product at a lower cost
than using traditional, non-linear methods.
However, mass production is
inflexible because it is difficult to alter a design or production process
after a production line is implemented. Also, all products produced on one
production line will be identical or very similar, and introducing variety to
satisfy individual tastes is not easy. However, some variety can be achieved by
applying different finishes and decorations at the end of the production line
if necessary. The starter cost for the machinery can be expensive so the
producer must be sure it sells or the producers will lose a lot of money.
The Ford Model T produced
tremendous affordable output but was not very good at responding to demand for
variety, customization, or design changes. As a consequence Ford eventually
lost market share to General Motors, who introduced annual model changes, more
accessories and a choice of colors.
With each passing decade, engineers
have found ways to increase the flexibility of mass production systems, driving
down the lead
times on new product development and allowing greater customization and
variety of products.
Socioeconomic impacts
In the 1830s, French political
thinker and historian Alexis de Tocqueville identified one of the
key characteristics of America that would later make it so amenable to the
development of mass production: the homogeneous consumer base. De Tocqueville
wrote in his Democracy in America (1835) that "The
absence in the United States of those vast accumulations of wealth which favor
the expenditures of large sums on articles of mere luxury... impact to the
productions of American industry a character distinct from that of other
countries' industries. [Production is geared toward] articles suited to the
wants of the whole people".
Mass production improved productivity, which was a contributing factor to
economic growth and the decline in work week hours, alongside other factors
such as transportation infrastructures (canals, railroads and highways) and
agricultural mechanization. These factors caused the typical work week to
decline from 70 hours in the early 19th century to 60 hours late in the century,
then to 50 hours in the early 20th century and finally to 40 hours in the
mid-1930s.
Mass production permitted great
increases in total production. Using a European crafts system into the late
19th century it was difficult to meet demand for products such as sewing
machines and animal powered mechanical harvesters. By the
late 1920s many previously scarce goods were in good supply. One economist has
argued that this constituted "overproduction" and contributed to high
unemployment during the Great Depression. Say's law
denies the possibility of general overproduction
and for this reason classical economists deny that it had any role in the Great
Depression.
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