Mechanization

Mechanization
A water-powered mine hoist used for raising ore. This woodblock is from De re metallica by George Bauer (pen name Georgius Agricola, ca. 1555) an early mining textbook that contains numerous drawings and descriptions of mining equipment.

Mechanization or mechanisation (BE) is providing human operators with machinery that assists them with the muscular requirements of work or displaces muscular work. In some fields, mechanization includes the use of hand tools. In modern usage, such as in engineering or economics, mechanization implies machinery more complex than hand tools and would not include simple devices such as an un-geared horse or donkey mill. Devices that cause speed changes or changes to or from reciprocating to rotary motion, using means such as gears, pulleys or sheaves and belts, shafts, cams and cranks, usually are considered machines.

Contents

History

Water wheels date to the Roman period and were used to grind grain and lift irrigation water. By the 13th century water wheels powered sawmills[1] and power trip hammers to full cloth and pound flax and later cotton rags into pulp for making paper. Trip hammers are shown crushing ore in De re Metallica (1555).

Water powered bellows for blast furnaces were in use in the 15th century.

The Newcomen steam engine was first used, to pump water from a mine, in 1712.

The Industrial Revolution started mainly with textile machinery, such as the spinning jenny (1764) and water frame (1768). Demand for metal parts used in textile machinery led to the invention of many machine tools in the late 1700s until the mid 1800s, and it was during this time that iron replaced wood in gearing and shafts in textile machinery.[2]

Mechanized agriculture began in the late eighteenth and early nineteenth centuries with horse drawn reapers and horse powered threshing machines.[3] By the late nineteenth century steam power was applied to threshing and steam tractors appeared. Internal combustion began being used for tractors in the early twentieth century. Threshing and harvesting was originally done with attachments for tractors, but in the 1930s independently powered combine harvesters were in use.

Categories

Two involute gears, the left driving the right: Blue arrows show the contact forces between them. The force line (or Line of Action) runs along a tangent common to both base circles. (In this situation, there is no force, and no contact needed, along the opposite common tangent not shown.) The involutes here are traced out in converse fashion: points (of contact) move along the stationary force-vector "string" as if it was being unwound from the left rotating base circle, and wound onto the right rotating base circle.

In manufactruing, mechanization replaced hand methods of making goods.[4]

Inside factories, warehouses, lumber yards and other manufacturing and distribution operations, material handling equipment replaced manual carrying or hand trucks and carts.[4]

Mechanized agriculture See: list of agricultural machinery See also: Productivity improving technologies (historical) Section 4

In mining and excavation, power shovels replaced picks and shovels.[4]

Bulk material handling systems and equipment are used for for a variety of materials including coal, ores, grains, sand, gravel and wood products.[4]

Powered machinery

Powered machinery today usually means either by electric motor or internal combustion engine. Before the first decade of the 20th century powered usually meant by steam engine, water or wind.

A step beyond mechanization is automation. Early production machinery, such as the glass bottle blowing machine (ca. 1890s), required a lot of operator involvement. By the 1920s fully automatic machines, which required much less operator attention, were being used.[4]

Military usage

The term is also used in the military to refer to the use of tracked armoured vehicles, particularly armoured personnel carriers, to move troops that would otherwise have marched or ridden trucks into combat. Mechanization dramatically improved the mobility and fighting capability of infantry. In the armed forces of industrialized countries, all infantry is typically mechanized, with the possible exception of airborne forces.[citation needed]

Mechanization may also refer in the broader military sense to "motorization" or the replacement of horses with motor vehicles for all functions, including logistics, artillery tractors, etc.[citation needed]

Mechanical vs human labour

When we compare the efficiency of a labourer, we see that he has an efficiency of about 1%-5.5% (depending on whether he uses arms, or a combination of arms and legs). Internal combustion engines mostly have an efficiency of about 20%,[5] although large diesel engines, such as those used to power ships, may have efficiencies of nearly 50%. Industrial electric motors have efficiencies up to the low 90% range, before correcting for the conversion efficiency of fuel to electricity of about 35%.[6]

When we compare the costs of using an internal combustion engine to a worker to perform work, we notice that an engine can perform more work at a comparative cost. 1 liter of fossil fuel burnt with a IC engine equals about 50 hands of workers operating for 24 hours or 275 arms and legs for 24 hours.[7][8]

In addition, the combined work capability of a human is also much lower than that of a machine. An average human can provide work good for around 250Wh/day, while a machine (depending on the type and size) can provide for far greater amounts of work. For example it takes four days of hard labour to deliver only one kWh - which a small engine could deliver in less than one hour while burning less than one litre of petroleum fuel. This implies that a gang of 20 to 40 men will require a financial compensation for their work at least equal to the required expended food calories (which is at least 4 to 20 times higher). In most situations, the worker will also want compensation for the lost time, which is easily 96 times greater per day. Even if we assume a the real wage cost for the human labour to be at US $1.00/day, an energy cost is generated of about $4.00/kWh. Despite this being a low wage for hard labour, even in some of the countries with the lowest wages, it represents an energy cost that is significantly more expensive than even exotic power sources such as solar photovoltaic panels (and thus even more expensive when compared to wind energy harvesters or luminescent solar concentrators).[9]

Levels of Mechanization

For simplification, Mechanization can be studied under different steps.[10] Many students refer to this as a basic to advanced form of Mechanical society.

  1. Hand/ Muscle power
  2. Hand tools
  3. Powered hand tools, e.g. electric controlled
  4. Powered tools, single functioned, fixed cycle
  5. Powered tools, multi-functioned, program controlled
  6. Powered tools, remote controlled
  7. Powered tools, activated by work piece, e.g. coin phone
  8. Measurement
  9. Selected signaling control, e.g. hydro power control
  10. Performance recording
  11. Machine action altered through measurement
  12. Segregation/rejection according to measurement
  13. Selection of appropriate action cycle
  14. Correcting performance after operation
  15. Correcting performance during operation

See also

References

  1. ^ McNeil, Ian (1990). An Encyclopedia of the History of Technology. London: Routledge. ISBN 0415147921. 
  2. ^ Roe, Joseph Wickham (1916), English and American Tool Builders, New Haven, Connecticut, USA: Yale University Press, LCCN 16-011753, http://books.google.com/books?id=X-EJAAAAIAAJ&printsec=titlepage . Reprinted by McGraw-Hill, New York and London, 1926 (LCCN 27-024075); and by Lindsay Publications, Inc., Bradley, IL, USA (ISBN 978-0-917914-73-7).
  3. ^ Rumely 1910.
  4. ^ a b c d e Jerome, Harry (1934). Mechanization in Industry, National Bureau of Economic Research 
  5. ^ IC Engine 20% efficient
  6. ^ Electrical engines with combined power converter / motor at 86% efficiency
  7. ^ 1 liter of fuel yielding 100 arms for 24 hours, when efficiency is 40% which is never
  8. ^ Home documentary by Yann Arthus Bertrand too stating that 1 liter of fuel yields 100 arms for 24 hours; probably from same calculation
  9. ^ Combined work capability of human vs machines
  10. ^ Mechanization and its level

Bibliography

Further reading

  • Jerome, Harry (1934). Mechanization in Industry, National Bureau of Economic Research 

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