Wood Waste Equipment

A basic introduction to the choices available in machinery for chipping and grinding sawmill and wood-shop scrap wood. November 13, 2008

Reprinted with permission from MLS Machinery, Inc.

This category basically covers wood waste equipment. This type of equipment is used where companies have large amounts of off cuts and waste pieces that have been created at different machines. These normally cost a lot of money to take to the local dump site or landfill. Therefore to cut down on moving many large containers of wood waste, hogs will crush the obsolete off cuts and parts down to a form of sawdust thereby having less truckloads of waste sent to the landfill. Even though the quantity is the same, the volume becomes drastically reduced. If not hogged or ground companies would be shipping more containers because there would be a lot of fresh air in the container.

Most of these machines are very noisy especially the hammer mills because they constantly beat at the wood waste until broken down small enough to fit through a screen and then sucked away into a storage silo, dust collector or dumping bin. Some grinders or hogs can be top loaded so that a fork lift with a whole bin of garbage can just dump the load into the hopper of the machine, which is at the top of the machine.

In some cases where there are long rippings and long pieces of waste they can be horizontally fed into a horizontal wood hog. Long pieces are very difficult to load into a top loaded hog, most people will use horizontal feed for narrow and long pieces, and top loaded machines for smaller off cuts. Horizontal hogs are used more in moulding operations where there are lot of long off cut rippings.

Some other types of machines are knife hogs that use a knife which constantly beats at the wood and chops it into little pieces. Some units are low noise grinders which are more popular, they only turn at 90-100 rpm as opposed to 1700 rpm as most of the machines discussed above and run on a lot less power, the big hammer mills normally run on 60-300 HP. Low noise grinders are much quieter and can run on only 20-40 HP motors. These are much slower therefore making less noise. Some work on a ram action where a ram pushes the wood waste against the knife or knives and breaks the wood waste until it will fit through a screen as previously described. Some will work purely by gravity, the weight of the garbage dumped into the hopper feeds into the hammers or knives.

There are also big hogs or hammer mills somewhere between 250-300 HP with 72" openings that can be used for chopping up complete skids and pallets, especially for plants that use big volumes of pallets. Many of these units will have a magnetic separator that will remove the nails once the wood has been chopped into pieces before the waste is sent to a storage container or dust collector.

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