The defibrator is a machine used as part of the manufacturing process for MDF man-made wooden board. It produces fine wooden fibres, finer than the cut chips used to make chipboard. Although small, these fibres retain good structural integrity. The machine itself is a

thermo mechanical pulp Pulp is a fibrous lignocellulosic material prepared by chemically, semi-chemically, or mechanically isolating the cellulosic fibers of wood, fiber crops, waste paper, or rags. Mixed with water and other chemicals or plant-based additives, pul ...

ing refiner in which the pulp material, such as

wood chips Woodchips are small- to medium-sized pieces of wood formed by cutting or chipping larger pieces of wood such as trees, branches, logging residues, stumps, roots, and wood waste. Woodchips may be used as a biomass solid fuel and are raw materia ...

, is ground in an environment of

steam Steam is water vapor, often mixed with air or an aerosol of liquid water droplets. This may occur due to evaporation or due to boiling, where heat is applied until water reaches the enthalpy of vaporization. Saturated or superheated steam is inv ...

between a rotating grinding disc (rotor) and a stationary disc (stator) each with radial grooves that provides the grinding surface. Wood chips are fed into the centre and are broken down as the centrifugal force pushes them towards the circumference of the discs where the grooves are finer to produce

wood fibre Wood fibres (also spelled wood fibers, see spelling differences) are usually cellulosic elements that are extracted from trees and used to make materials including paper Paper is a thin sheet material produced by mechanically or chemicall ...

. The size of the

refine Refining is the process of List of purification methods in chemistry, purification of a (1) chemical compound, substance or a (2) Theory of Forms, form. The term is usually used of a natural resource that is almost in a usable form, but which is m ...

d fibres can to some extent be controlled by altering the distance between the discs where a closer distance produces finer fibres but also requires higher grinding force. The capacity per machine is largely determined by the size of the machine, as well as the motor speed, which can be 1,500 or 1,800

rpm Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min, or r⋅min−1) is a unit of rotational speed (or rotational frequency) for rotating machines. One revolution per minute is equivalent to hertz. Standards ISO 80000-3:2019 def ...

History

In 1931 the Swedish engineer

Arne Asplund Dr. Arne Asplund (1903 – 1993) was a Swedish inventor. He invented the Defibrator pulping refiner and the defibrator-method (also called Asplund-method) for pulping wooden chips in 1930s. His invention resulted in the company AB Defibrator ...

filed a patent on a method to defibrate wood chips. As opposed to the

Masonite Masonite board Back side of a masonite board Isorel, Quartrboard, Masonite Corporation, Masonite, also called Quartboard or pressboard, is a type of engineered wood made of steam-cooked and pressure-molded wood or paper fibers. The fibers ...

-method, the defibrator-method (also known as the Asplund-method) uses pressurised steam to soften the wood chips, then grinding discs to pull the wood fibres apart. This grinding unit is what Asplund called the defibrator. It became the key product of his company, AB Defibrator. The Defibrator trademark is now held by

Valmet Valmet Oyj, a Finnish company, is a developer and supplier of process technologies, automation systems and services for the pulp, paper, energy industries. Flow control serves a wider base of process industries. History 1999–2012 Valmet ...

, the successor of AB Defibrator, for its line of refiners for the panelboard industry.

References

Papermaking Pulp and paper industry {{Tool-stub