|
 A hammermill is a common machine in several industries, including the food, animal feed, mineral and waste management fields. This device can be used for grinding, shredding or pulverizing and is one of the simplest tools in a processing line. It is also one of the oldest implements found in industrial processing. The earliest iteration of this technology is traced back to 1830, when a patent was issued for a box that used a revolving drum to crush rocks placed inside. This machine never went into full production, but the technology would be implemented in future devices.
In the 1920s, the first hammermill for grain was created. It was designed by the Gehl Company and was the standard for 30 years before others improved on the concept. Today, this technology comes in three designs, made up of rock crushers, grain grinders and screenless machines. The rock grinders are the oldest versions of the technology and are designed for mining operations. They consist of an inclined plate where the rocks are fed into the machine. Inside the device, a rotor spins between 650 and 1,600 revolutions per minute. Hammers are attached to the rotor at right angles to the interior walls of the machine. These crushers spin at incredible speeds and strike the material hard enough to shatter it into pieces. Larger pieces are thrown against breaker plates inside the device and broken down further. At the bottom sits a grate that allows pieces of acceptable size to pass through. Anything that can’t fit is crushed until it can. These devices are also effective at breaking down organic waste or large metal objects like automobiles.
A grain grinding hammermill operates using the same principles, but it is designed with some minor differences. A grain grinder uses a feed hopper or intake shaft to insert material into the machine. Inside, several plates are connected to a rotor that spins at high speeds. Hammers are attached to the plates and reduce the size of the grains by smashing them open. Double or triple reducers also come with cutting edges that are effective at removing stems or fibers from the grains. A screen runs along the interior and can vary in size (usually between 1/64 inch and 2 inches). The screen is designed to separate smaller particles out for further processing.
Screenless machines have only been around since the 1990s. Carl Bielenberg created his hammermill and showed it to MIT students, encouraging them to improve on the design and create a better version. Amy Smith was the student who took up the task and she successfully produced a machine that could run without interruption and without getting backed up. Smith designed her hammermill to be easily produced in poor countries, which makes it possible for third-world communities to grind grain at a lower cost. Screens are pricey and have to be imported into the community, so when they break, poor villages have trouble replacing them. Instead of screens, these machines use air pressure to separate out smaller particles. Smith and other MIT students improved on the design by increasing air pressure inside of the device. This increased the rate of output and made it more reliable when separating particles.
|
