Math Is Fun Forum

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1299.

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#8371. When is the 'World Meteorological Day'? (World Meteorological Day was established in 1961 to commemorate the World Meteorological Organization creation on in 1950. This organization announces a slogan for World Meteorology Day every year, and this day is celebrated in all member countries.)

#8372. When is the 'World Down Syndrome Day'? (marked each year, beginning in 2006. It was selected to signify the uniqueness of the triplication (trisomy) of the 21st chromosome which causes Down syndrome.

Every year on on this day, World Down Syndrome Day is observed to create awareness about Down syndrome. It is a condition in which a child is born with an extra 21st chromosome.)

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#5322.

1354) Cardboard

Cardboard is a generic term for heavy paper-based products. The construction can range from a thick paper known as paperboard to corrugated fiberboard which is made of multiple plies of material. Natural cardboards can range from grey to light brown in color, depending of the specific product; dyes, pigments, printing, and coatings are available.

The term "cardboard" has general use in English and French, but the term cardboard is deprecated in commerce and industry as not adequately defining a specific product. Material producers, container manufacturers, packaging engineers, and standards organizations, use more specific terminology.

Statistics

In 2020, the United States hit a record high in its yearly use of one of the most ubiquitous manufactured materials on earth, cardboard.  With around 80 per cent of all the products sold in the United States being packaged in cardboard, over 120 billion pieces were used that year. In the same year, over 13,000 separate pieces of consumer cardboard packaging was thrown away by American households, combined with all paper products and this constitutes almost 42 per cent of all solid waste generated by the United States annually.

However, despite the sheer magnitude of paper waste, the vast majority of it is composed of one of the most successful and sustainable packaging materials of modern times - corrugated cardboard, known industrially as corrugated fiberboard.

Types

Various card stocks:

Various types of cards are available, which may be called "cardboard". Included are: thick paper (of various types) or pasteboard used for business cards, aperture cards, postcards, playing cards, catalog covers, binder's board for bookbinding, scrapbooking, and other uses which require higher durability than regular paper.

Paperboard

Paperboard is a paper-based material, usually more than about ten mils (0.010 inches (0.25 mm)) thick. It is often used for folding cartons, set-up boxes, carded packaging, etc. Configurations of paperboard include:

* Containerboard, used in the production of corrugated fiberboard.
* Folding boxboard, comprising multiple layers of chemical and mechanical pulp.
* Solid bleached board, made purely from bleached chemical pulp and usually has a mineral or synthetic pigment.
* Solid unbleached board, typically made of unbleached chemical pulp.
* White lined chipboard, typically made from layers of waste paper or recycled fibers, most often with two to three layers of coating on the top and one layer on the reverse side. Because of its recycled content it will be grey from the inside.
* Binder's board, a paperboard used in bookbinding for making hardcovers.

Currently, materials falling under these names may be made without using any actual paper.

Corrugated fiberboard

Corrugated fiberboard is a combination of paperboards, usually two flat liners and one inner fluted corrugated medium. It is often used for making corrugated boxes for shipping or storing products. This type of cardboard is also used by artists as original material for sculpting.

Recycling

Most types of cardboard are recyclable. Boards that are laminates, wax coated, or treated for wet-strength are often more difficult to recycle. Clean cardboard (i.e., cardboard that has not been subject to chemical coatings) "is usually worth recovering, although often the difference between the value it realizes and the cost of recovery is marginal". Cardboard can be recycled for industrial or domestic use. For example, cardboard may be composted or shredded for animal bedding.

History

The material had been first made in France, in 1751, by a pupil of Réaumur, and was used to reinforce playing cards. The term cardboard has been used since at least 1848, when Anne Brontë mentioned it in her novel, The Tenant of Wildfell Hall. The Kellogg brothers first used paperboard cartons to hold their flaked corn cereal, and later, when they began marketing it to the general public, a heat-sealed bag of wax paper was wrapped around the outside of the box and printed with their brand name. This development marked the origin of the cereal box, though in modern times the sealed bag is plastic and is kept inside the box. The Kieckhefer Container Company, run by John W. Kieckhefer, was another early American packaging industry pioneer. It excelled in the use of fiber shipping containers, particularly the paper milk carton.

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1298.

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#5321.

1353) Carding

Summary

Carding, in textile production, is a process of separating individual fibres, using a series of dividing and redividing steps, that causes many of the fibres to lie parallel to one another while also removing most of the remaining impurities. Carding may be done by hand, using hand carders (pinned wooden paddles that are not unlike steel dog brushes) or drum carders (in which washed wool, fleece, or other materials are fed through one or more pinned rollers) to prepare the fibres for spinning, felting, or other fabric- or cloth-making activities.

Cotton, wool, waste silk, other fibrous plant materials and animal fur and hair, and artificial staple are subjected to carding. Carding produces a thin sheet of uniform thickness that is then condensed to form a thick continuous untwisted strand called sliver. When very fine yarns are desired, carding is followed by combing, a process that removes short fibres, leaving a sliver composed entirely of long fibres, all laid parallel and smoother and more lustrous than uncombed types. Carded and combed sliver is then spun.

Details

Carding is a mechanical process that disentangles, cleans and intermixes fibres to produce a continuous web or sliver suitable for subsequent processing. This is achieved by passing the fibres between differentially moving surfaces covered with "card clothing", a firm flexible material embedded with metal pins. It breaks up locks and unorganised clumps of fibre and then aligns the individual fibres to be parallel with each other. In preparing wool fibre for spinning, carding is the step that comes after teasing.

The word is derived from the Latin Carduus meaning thistle or teasel, as dried vegetable teasels were first used to comb the raw wool before technological advances led to the use of machines.

Overview

These ordered fibres can then be passed on to other processes that are specific to the desired end use of the fibre: Cotton, batting, felt, woollen or worsted yarn, etc. Carding can also be used to create blends of different fibres or different colours. When blending, the carding process combines the different fibres into a homogeneous mix. Commercial cards also have rollers and systems designed to remove some vegetable matter contaminants from the wool.

Common to all carders is card clothing. Card clothing is made from a sturdy flexible backing in which closely spaced wire pins are embedded. The shape, length, diameter, and spacing of these wire pins are dictated by the card designer and the particular requirements of the application where the card cloth will be used. A later version of the card clothing product developed during the latter half of the 19th century and was found only on commercial carding machines, whereby a single piece of serrated wire was wrapped around a roller, became known as metallic card clothing.

Carding machines are known as cards. Fibre may be carded by hand for hand spinning.

History

Science historian Joseph Needham ascribes the invention of bow-instruments used in textile technology to India. The earliest evidence for using bow-instruments for carding comes from India (2nd century CE). These carding devices, called kaman (bow) and dhunaki, would loosen the texture of the fibre by the means of a vibrating string.

At the turn of the eighteenth century, wool in England was being carded using pairs of hand cards, in a two-stage process: 'working' with the cards opposed and 'stripping' where they are in parallel.

In 1748 Lewis Paul of Birmingham, England, invented two hand driven carding machines. The first used a coat of wires on a flat table moved by foot pedals. This failed. On the second, a coat of wire slips was placed around a card which was then wrapped around a cylinder. Daniel Bourn obtained a similar patent in the same year, and probably used it in his spinning mill at Leominster, but this burnt down in 1754. The invention was later developed and improved by Richard Arkwright and Samuel Crompton. Arkwright's second patent (of 1775) for his carding machine was subsequently declared invalid (1785) because it lacked originality.

From the 1780s, the carding machines were set up in mills in the north of England and mid-Wales. Priority was given to cotton but woollen fibres were being carded in Yorkshire in 1780. With woollen, two carding machines were used: the first or the scribbler opened and mixed the fibres, the second or the condenser mixed and formed the web. The first in Wales was in a factory at Dolobran near Meifod in 1789. These carding mills produced yarn particularly for the Welsh flannel industry.

In 1834 James Walton invented the first practical machines to use a wire card. He patented this machine and also a new form of card with layers of cloth and rubber. The combination of these two inventions became the standard for the carding industry, using machines first built by Parr, Curtis and Walton in Ancoats, and from 1857 by Jams Walton & Sons at Haughton Dale.

By 1838, the Spen Valley, centred on Cleckheaton had at least 11 card clothing factories and by 1893, it was generally accepted as the card cloth capital of the world, though by 2008 only two manufacturers of metallic and flexible card clothing remained in England, Garnett Wire Ltd. dating back to 1851 and Joseph Sellers & Son Ltd established in 1840.

Baird from Scotland took carding to Leicester, Massachusetts in the 1780s. In the 1890s, the town produced one-third of all hand and machine cards in North America. John and Arthur Slater, from Saddleworth went over to work with Slater in 1793.

A 1780s scribbling mill would be driven by a water wheel. There were 170 scribbling mills around Leeds at that time. Each scribbler would require 15–45 horsepower (11–34 kW) to operate. Modern machines are driven by belting from an electric motor or an overhead shaft via two pulleys.

Tools

Predating mechanised weaving, hand loom weaving was a cottage industry that used the same processes but on a smaller scale. These skills have survived as an artisan craft in less developed societies- and as art form and hobby in advanced societies.

Hand carders

Hand cards are typically square or rectangular paddles manufactured in a variety of sizes from 2 by 2 inches (5.1 cm × 5.1 cm) to 4 by 8 inches (10 cm × 20 cm). The working face of each paddle can be flat or cylindrically curved and wears the card cloth. Small cards, called flick cards, are used to flick the ends of a lock of fibre, or to tease out some strands for spinning off.

A pair of cards is used to brush the wool between them until the fibres are more or less aligned in the same direction. The aligned fibre is then peeled from the card as a rolag. Carding is an activity normally done outside or over a drop cloth, depending on the wool's cleanliness. Rolag is peeled from the card.

Carding of wool can either be done "in the grease" or not, depending on the type of machine and on the spinner's preference. "In the grease" means that the lanolin that naturally comes with the wool has not been washed out, leaving the wool with a slightly greasy feel. The large drum carders do not tend to get along well with lanolin, so most commercial worsted and woollen mills wash the wool before carding. Hand carders (and small drum carders too, though the directions may not recommend it) can be used to card lanolin rich wool.

Drum carders

The simplest machine carder is the drum carder. Most drum carders are hand-cranked but some are powered by an electric motor. These machines generally have two rollers, or drums, covered with card clothing. The licker-in, or smaller roller meters fibre from the infeed tray onto the larger storage drum. The two rollers are connected to each other by a belt- or chain-drive so that their relative speeds cause the storage drum to gently pull fibres from the licker-in. This pulling straightens the fibres and lays them between the wire pins of the storage drum's card cloth. Fibre is added until the storage drum's card cloth is full. A gap in the card cloth facilitates removal of the batt when the card cloth is full.

Some drum carders have a soft-bristled brush attachment that presses the fibre into the storage drum. This attachment serves to condense the fibres already in the card cloth and adds a small amount of additional straightening to the condensed fibre.

Cottage carders

Cottage carding machines differ significantly from the simple drum card. These carders do not store fibre in the card cloth as the drum carder does but, rather, fibre passes through the workings of the carder for storage or for additional processing by other machines.

A typical cottage carder has a single large drum (the swift) accompanied by a pair of in-feed rollers (nippers), one or more pairs of worker and stripper rollers, a fancy, and a doffer. In-feed to the carder is usually accomplished by hand or by conveyor belt and often the output of the cottage carder is stored as a batt or further processed into roving and wound into bumps with an accessory bump winder.

Raw fibre, placed on the in-feed table or conveyor is moved to the nippers which restrain and meter the fiber onto the swift. As they are transferred to the swift, many of the fibres are straightened and laid into the swift's card cloth. These fibres will be carried past the worker / stripper rollers to the fancy.

As the swift carries the fibres forward, from the nippers, those fibres that are not yet straightened are picked up by a worker and carried over the top to its paired stripper. Relative to the surface speed of the swift, the worker turns quite slowly. This has the effect of reversing the fibre. The stripper, which turns at a higher speed than the worker, pulls fibres from the worker and passes them to the swift. The stripper's relative surface speed is slower than the swift's so the swift pulls the fibres from the stripper for additional straightening.

Straightened fibres are carried by the swift to the fancy. The fancy's card cloth is designed to engage with the swift's card cloth so that the fibres are lifted to the tips of the swift's card cloth and carried by the swift to the doffer. The fancy and the swift are the only rollers in the carding process that actually touch.

The slowly turning doffer removes the fibres from the swift and carries them to the fly comb where they are stripped from the doffer. A fine web of more or less parallel fibre, a few fibres thick and as wide as the carder's rollers, exits the carder at the fly comb by gravity or other mechanical means for storage or further processing.

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#4495. What does the adjective limber mean?

#4496. What does the noun limelight mean?

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1297.