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A tree chipper or woodchipper is a machine used for reducing
wood Wood is a porous and fibrous structural tissue found in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulose fibers that are strong in tension and embedded in a matrix of lignin ...
(generally tree limbs or trunks) into smaller
woodchips 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 ...
. They are often portable, being mounted on wheels on frames suitable for towing behind a truck or van. Power is generally provided by an
internal combustion engine An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal co ...
from . There are also high power chipper models mounted on trucks and powered by a separate engine. These models usually also have a hydraulic
winch A winch is a mechanical device that is used to pull in (wind up) or let out (wind out) or otherwise adjust the tension of a rope or wire rope (also called "cable" or "wire cable"). In its simplest form, it consists of a spool (or drum) attach ...
. Tree chippers are typically made of a hopper with a collar, the chipper mechanism itself, and an optional collection bin for the chips. A tree limb is inserted into the hopper (the collar serving as a partial safety mechanism to keep human body parts away from the chipping blades) and started into the chipping mechanism. The chips exit through a chute and can be directed into a truck-mounted container or onto the ground. Typical output is chips on the order of across in size. The resulting wood chips have various uses such as being spread as a ground cover or being fed into a digester during
papermaking Papermaking is the manufacture of paper and cardboard, which are used widely for printing, writing, and packaging, among many other purposes. Today almost all paper is made using industrial machinery, while handmade paper survives as a speciali ...
. Most woodchippers rely on energy stored in a heavy
flywheel A flywheel is a mechanical device which uses the conservation of angular momentum to store rotational energy; a form of kinetic energy proportional to the product of its moment of inertia and the square of its rotational speed. In particular, as ...
to do their work (although some use drums). The chipping blades are mounted on the face of the flywheel, and the flywheel is accelerated by an electric motor or internal combustion engine. Large woodchoppers are frequently equipped with grooved rollers in the throat of their feed funnels. Once a branch has been gripped by the rollers, the rollers transport the branch to the chipping blades at a steady rate. These rollers are a safety feature and are generally reversible for situations where a branch gets caught on
clothing Clothing (also known as clothes, apparel, and attire) are items worn on the body. Typically, clothing is made of fabrics or textiles, but over time it has included garments made from animal skin and other thin sheets of materials and natura ...
.


History

The woodchipper was invented by Peter Jensen (Maasbüll, Germany) in 1884, the "Marke Angeln" woodchipper soon became the core business of his company, which already produced and repaired communal- and woodworking-machinery.


Types


Disc

The original chipper design employs a steel disk with blades mounted upon it as the chipping mechanism. This technology dates back to an invention by German Heinrich Wigger, for which he obtained a patent in 1922. In this design, (usually) reversible hydraulically powered wheels draw the material from the hopper towards the disk, which is mounted perpendicularly to the incoming material. As the disk is turned by a motor, the blades mounted on the face of the disk cut the material into chips. These are thrown out the chute by flanges on the edges of the disk. Commercial-grade disk-style chippers usually have a material diameter capacity of . Industrial-grade chippers (tub grinders) are available with discs as large as in diameter, requiring . One application of industrial disk chippers is to produce the wood chips used in the manufacture of
particle board Particle board, also known as chipboard or low-density fiberboard, is an engineered wood product manufactured from wood chips and a synthetic resin or other suitable binder, which is pressed and extruded. Particle board is often confused with ...
.


Drum

Drum chippers employ mechanisms consisting of a large steel drum powered by a motor. The drum is mounted parallel to the hopper and spins toward the chute. Blades mounted to the outer surface of the drum cut the material into chips and propel the chips into the discharge chute. Commercial-grade drum-style chippers usually have a material diameter capacity of . Conventionally-fed drum chippers use the drum as the feed mechanism, drawing the material through as it chips it. These are colloquially known as "chuck-and-duck" chippers, due to the immediate speed attained by material dropped into the drum. Chippers of this type have many drawbacks and safety issues. If an operator becomes snagged on material being fed into the machine, injury or death is very likely. Hydraulically-fed drum chippers have largely replaced conventionally-fed machines. These chippers use a set of hydraulically powered wheels to regulate the rate of feed of material into the chipper drum.


Other

Much larger machines for
wood processing Wood processing is an engineering discipline in the wood industry comprising the production of forest products, such as pulp and paper, construction materials, and tall oil. Paper engineering is a subfield of wood processing. The major wood pro ...
exist. "Whole tree chippers" and "Recyclers", which can typically handle material diameters of may employ drums, disks, or a combination of both. The largest machines used in wood processing, often called "Tub or Horizontal Grinders", may handle a material diameter of or greater, and use carbide tipped flail hammers to pulverize wood rather than cut it, producing a shredded wood rather than chip or chunk. These machines usually have a power of . Most are so heavy that they require a
semi-trailer truck A semi-trailer truck, also known as a semitruck, (or semi, eighteen-wheeler, big rig, tractor-trailer or, by synecdoche, a semitrailer) is the combination of a tractor unit and one or more semi-trailers to carry freight. A semi-traile ...
to be transported. Smaller models can be towed by a medium duty truck.


Blades

Although chippers vary greatly in size, type, and capacity, the blades processing the wood are similar in construction. They are rectangular in shape and are usually across by long. They vary in thickness from about . Chipper blades are made from high grade
steel Steel is an alloy made up of iron with added carbon to improve its strength and fracture resistance compared to other forms of iron. Many other elements may be present or added. Stainless steels that are corrosion- and oxidation-resistan ...
and usually contain a minimum of 8%
chromium Chromium is a chemical element with the symbol Cr and atomic number 24. It is the first element in group 6. It is a steely-grey, lustrous, hard, and brittle transition metal. Chromium metal is valued for its high corrosion resistance and hard ...
for hardness.


Safety

Thirty-one people were killed in woodchipper accidents between 1992 and 2002 in the US, according to a 2005 report by the ''
Journal of the American Medical Association ''The Journal of the American Medical Association'' (''JAMA'') is a peer-reviewed medical journal published 48 times a year by the American Medical Association. It publishes original research, reviews, and editorials covering all aspects of b ...
''.


In popular culture

Joel and Ethan Coen's film '' Fargo'' features an infamous scene in which
Peter Stormare Rolf Peter Ingvar Storm (born August 27, 1953), better known as Peter Stormare (), is a Swedish actor who holds both Swedish and American citizenship. He played Gaear Grimsrud in the film '' Fargo'' (1996) and John Abruzzi in the television ser ...
, as Gaear Grimsrud, feeds the remains of
Steve Buscemi Steven Vincent Buscemi ( ,As stated in interviews by Buscemi himself, some may insist that his pronunciation of his own name is "wrong" because it does not match the original Italian pronunciation as well. It is not uncommon for people to pronou ...
's character, Carl Showalter, into a woodchipper. The scene, according to the film's special edition DVD, was based on the 1986 murder of Helle Crafts. The woodchipper used in the scene is now a tourist attraction at the Fargo-Moorhead Visitors Center.


See also

* Mulcher * Ramial chipped wood


References


External links


brush chipper for biomass, Vermeer IndiaChipper/Shredder Safety, Kansas State University
{{Forestry tools Agricultural machinery Organic farming Gardening tools Woodworking machines Forestry equipment