Woodchipper

Key takeaways

Woodchipper belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Woodchipper to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Woodchipper from memory before moving on to harder problems.

Reference excerpt

A tree chipper or woodchipper is a machine used for reducing wood (generally tree limbs or trunks) into smaller woodchips. 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 from 2 to 700 kilowatts (3 to 1,000 horsepower). There are also high-power chipper models mounted on trucks and powered by a separate engine. These models usually also have a hydraulic winch. 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 2.5–5 cm (1–2 in) across in size. The resulting wood chips have various usages such as being spread as a ground cover or being fed into a digester during papermaking. Most woodchippers rely on energy stored in a heavy flywheel 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 woodchippers are frequently equipped with grooved rollers in the throats 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.

History The woodchipper was invented by Peter Jensen (Maasbüll, Germany) in 1884; the "Marke Angeln" 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 15 to 45 cm (6 to 18 in). Industrial-grade chippers (tub grinders) are available with discs as large as 4 m (160 in) in diameter, requiring 3,000 to 3,700 kW (4,000 to 5,000 hp). One application of industrial disk chippers is to produce the wood chips used in the manufacture of particle board.

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 25 to 60 cm (9 to 24 in). 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 exist. "Whole-tree chippers" and "recyclers", which can typically handle material diameters of 60–180 cm (2–6 ft), 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 2.4 m (8 ft) 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 150–750 kW (200–1,000 hp). Most are so heavy that they require a semi-trailer truck 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 4–10 cm (1+1⁄2–4 in) across by 15–30 cm (6–12 in) long. They vary in thickness from about 4–5 cm (1+1⁄2–2 in). Chipper blades are made from high-grade steel and usually contain a minimum of 8% chromium for hardness.

City services Fallen branches, especially when it is suspected that they are infested by beetles or their larva, are chipped to prevent further infestation. City governments acquire and operate chippers as needed, including for seasonal use.

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.

In popular culture Joel and Ethan Coen's film Fargo features an infamous scene in which Peter Stormare, as Gaear Grimsrud, feeds the remains of Steve Buscemi'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. It was claimed that Saddam Hussein used chippers to murder dissident citizens of his country, although there was extremely little evidence to support this claim. Horror films Tucker and Dale vs. Evil (2011) and Winnie-the-Pooh: Blood and Honey (2023) contain scenes depicting the use of a woodchipper as a murder weapon.

Illustrations

Worked examples

Example 1 — a first encounter with Woodchipper

Start with the simplest possible case. Write down what Woodchipper claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Woodchipper before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Woodchipper ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Woodchipper

In research: Woodchipper appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Woodchipper in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Woodchipper is common in secondary-school and first-year university syllabi. It links to neighbouring topics Agricultural machinery, Forestry equipment, Gardening tools, so understanding it makes those chapters shorter.
In everyday life: Look for Woodchipper outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study Woodchipper in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Woodchipper means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Woodchipper out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Woodchipper in simple terms?

A tree chipper or woodchipper is a machine used for reducing wood (generally tree limbs or trunks) into smaller woodchips. They are often portable, being mounted on wheels on frames suitable for towing behind a truck or van.

Why does Woodchipper matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Woodchipper?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Woodchipper.