Paper Machine

Paper Machine

This article contains a glossary section at the end.

Most modern papermaking machines are based on the principles of the Fourdrinier Machine. It has been used in some variation since its inception. The Fourdrinier uses a specially woven plastic fabric mesh conveyor belt, known as a wire as it was once woven from bronze, in the wet end to create a continuous paper web transforming a source of wood pulp into a final paper product. The original fourdrinier forming section used a horizontal drainage area, referred to as the drainage table.

Paper machines have four distinct operational sections:

The forming section, commonly called the wet end, is where the slurry of fibers is filtered out on a continuous fabric loop to form a wet web of fiber.

The press section where the wet fiber web passes between large rolls loaded under high pressure to squeeze out as much water as possible.

The 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.

The calender section where heavy steel rolls smooth the dried paper. Only one nip 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 periodically to increase production and improve quality or to change the type of paper grade.