Paper machine
Many modern papermaking machines are based on the principles of the Fourdrinier Machine, which uses a specially woven plastic fabric mesh conveyor belt (known as a wire as it was once woven from bronze) in the forming section（成形部）, where a slurry of fibre （纤维悬浮液）(usually wood or other vegetable fibres) is drained to create a continuous paper web. After the forming section the wet web passes through a press section （压榨部）to squeeze out excess water, then the pressed web passes through a heated drying section（干燥部）.
The original Fourdrinier forming section used a horizontal drainage area, referred to as the drainage table.
Paper machines have four distinct operational sections:
Forming section（成形部）, commonly called the wet end, is where the slurry of fibres filters out fluid a continuous fabric loop to form a wet web of fibre.
Press section （压榨部）where the wet fibre web passes between large rolls loaded under high pressure to squeeze out as much water as possible.
Drying section（干燥部）, 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.
Calender section （压光部）where the dried paper is smoothened under high loading and pressure. Only one nip (where the sheet is pressed between two rolls) is necessary in order to hold the sheet, which shrinks through the drying section and is held in tension between the press section (or breaker stack if used) and the calender. Extra nips give more smoothing but at some expense to paper strength.
Paper machines are long-lived assets that usually remain in service for several decades. It is common to rebuild machines （纸机改造）periodically to increase production and improve quality or to change the paper grade.
