A paper machine (or paper-making machine) is an industrial machine which is used in the pulp and paper industry
to create paper in large quantities at high speed. Modern paper-making machines are based on the principles of the Fourdrinier Machine, which uses a moving woven mesh to create a continuous paper web by filtering out the fibres held in a paper stock and producing a continuously moving wet mat of fibre. This is dried in the machine to produce a strong paper web.
The basic process is an industrialised version of the historical process of hand paper-making, which could not satisfy the demands of developing modern society for large quantities of a printing and writing substrate. The first modern paper machine was invented by Louis-Nicolas Robert in France in 1799, and an improved version patented in Britain by Henry and Sealy Fourdrinier in 1806.
The same process is used to produce paperboard on a paperboard machine.
Paper machines usually have at least five distinct operational sections:
Forming section, commonly called the wet end, is a continuous rotating wire mesh which removes water from the paper by sucking it out of suspension via vacuum.
Press section, where the wet fibre web passes between large rolls loaded under high pressure to squeeze out as much water as possible.
Drying section, where the pressed sheet passes partly around, in a serpentine manner, a series of steam heated drying cylinders. Drying removes the water content down to a level of about 6%, where it will remain at typical indoor atmospheric conditions. Infra-red driers are also used to supplement cylinder drying where required.
Size Press section, where the semi-dried paper is applied with a thin layer of starch and/ or other chemicals to improve several paper properties, reduce dusting and air permeability, increase stiffness, bursting strength and short span compression
Calender section, where the dried paper is smoothened under high loading and pressure.
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Paper is a thin sheet material produced by mechanically or chemically processing cellulose fibres derived from wood, rags, grasses, or other vegetable sources in water, draining the water through a fine mesh leaving the fibre evenly distributed on the surface, followed by pressing and drying. Although paper was originally made in single sheets by hand, almost all is now made on large machines—some making reels 10 metres wide, running at 2,000 metres per minute and up to 600,000 tonnes a year.
The kraft process (also known as kraft pulping or sulfate process) is a process for conversion of wood into wood pulp, which consists of almost pure cellulose fibres, the main component of paper. The kraft process involves treatment of wood chips with a hot mixture of water, sodium hydroxide (NaOH), and sodium sulfide (Na2S), known as white liquor, that breaks the bonds that link lignin, hemicellulose, and cellulose. The technology entails several steps, both mechanical and chemical. It is the dominant method for producing paper.
A paper mill is a factory devoted to making paper from vegetable fibres such as wood pulp, old rags, and other ingredients. Prior to the invention and adoption of the Fourdrinier machine and other types of paper machine that use an endless belt, all paper in a paper mill was made by hand, one sheet at a time, by specialized laborers. History of paper Historical investigations into the origin of the paper mill are complicated by differing definitions and loose terminology from modern authors: Many modern scholars use the term to refer indiscriminately to all kinds of mills, whether powered by humans, by animals or by water.
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