The Full paper making process

Timber
De-Barker
Chipping Machine
Chemical Pulping Process
Mechanical Pulping Process
Hydrapulper
Blend Chest
Waste Paper
De-inking
Refining
Screening and Cleaning
Papermaking Machine
Conversion and Printing

Chemical Pulping Process

Chips from the storage bins are fed into a digester to which chemicals have been added. The woodchips are then 'cooked' to remove lignin. Lignin is the binding material which holds the cellulose fibres together.
The chips are 'cooked' by heat and pressure in caustic soda and sulphur.
The chemical process is energy self-sufficient as nearly all by-products can be used to fire the pulp mill power plant. The chemical pulping process produces lower fibre yield than mechanical pulping, typically 50-60%.

Chipping Machine

Stripped logs are chipped into small pieces by knives mounted in massive steel wheels (used in chemical pulping process).
The chips pass through vibrating screens, whereby both undersized chips, dust etc and oversized chips are rejected.
Accepted chips are then stored in huge bins ready for the next process.
De-Barker
Bark is stripped from the logs by knife, drum, abrasion, or hydraulic barker. The stripped bark is then used for fuel or as soil enrichment.

 Papermaking Machine

The Paper Machine is a very large piece of machinery. A typical machine is about the length of two football pitches and around 4 metres wide. It can run up to speeds of 2000 m per minute - or 60 miles per hour! The machine itself consists of 7 distinct sections. The flow box, wire, press section, drier section, size press, calendar and reeling up.
The first section of the machine is called the 'Wet End'. This is where the diluted stock first comes into contact with the paper machine. It is poured onto the machine by the flow box which is a collecting box for the dilute paper stock. A narrow apperture running across the width of the box allows the stock to flow onto the wire with the fibres distributed evenly over the whole width of the paper machine.
The machine is operated by computer control. The computer will monitor the paper for moisture content, weight etc and computer screens will show pictures of the process and should any adjustments need to be made, an alarm will sound.
                      

Mechanical Pulping Process

Mechanical pulp yields over 90% of the wood as fiber is produced by forcing debarked logs, about two meters long, and hot water between enormous rotating steel discs with teeth that literally tear the wood apart. Alternatively, logs can be pressed against grindstones which is why this process is also known as ground wood pulp.
Trees contain up to 30% lignin, a material which is sensitive to light and degrades, and turns brown in sunlight, which explains why papers made from mechanical pulp will discolor. An example of this is newsprint. Newsprint is designed to have a short life span, and if left for a long period of time will lose its whiteness and strength. The special advantages of mechanical pulp are that it makes the paper opaque and bulky.

Conversion and Printing

Once the paper is made, a great deal of it is converted into a product. Converters specialize in transforming reels and sheets of paper and board into a vast array of finished products for distribution such as boxes, cartons and stationery. Converters sell their products to the public or to other manufacturers.
Not all paper and board is processed by converters. Some papermakers do their own converting, for example, the manufacturers of soft tissues market their own products and sell directly to the public.
The printing industry converts large quantities of paper and board, much of which reaches the customer as newspapers, magazines or books.

Refining

This is where the cellulose fibers pass through a refining process which is vital in the art of papermaking. Before refining, the fibers are stiff, inflexible and form few bonds. The stock is pumped through a conicle machine which consists of a series of revolving discs. The violent abrasive and bruising action has the effect of cutting, opening up and declustering the fibers and making the ends divide. This is called fibrillation. In this state, the fibers are pliable and have greater surface area, which significantly improves the fiber bonding. The properties of the paper are directly related to the refining process. Refining used to be called beating.

Screening and Cleaning

Pulps contain undesirable fibrous and non-fibrous materials, which should be removed before the pulp is made into paper or board.
Cleaning involves removing small particles of dirt and grit using rotating screens and centrifugal cleaners.