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Our hammer mills are universal and flexible grinders suitable for a wide range of products.
Whether coarse or fine grinding, small or high throughputs, a wide range of requirements is covered by our wide product range. Our mills are characterized by their robust design and well-engineered technology.
The machines are often used by our customers for several decades. Our focus is on an efficient and economical grinding process. All our mill types are designed to be maintenance-friendly and thus have a high availability.
The large chamber hammer mills are designed for high capacity grinding. The special design allows the rotors to start up very quickly despite their size, and the support frame allows the beaters to be changed quickly and easily in just a few minutes. Both reduce downtime and increase throughput.
Depending on the design, screen changes can be performed manually, semi-automatically or fully automatically during operation (when the grinding chamber is empty). This also increases the throughput of the machines and the individual performance of our mills.
High speed hammer mills are universal hammer mills. These grinders are considered to be a high-quality standard option for feed production, ethanol production and fibre processing. Our high speed mills are used for grinding dry materials as well as for wet crushing. Our robust designs have proven themselves over decades, are technologically mature and particularly easy to use. The service life of the machines often exceeds 30 years.
In wet grinding, crushing or shredding, the particle size of the wet or moist material is reduced and mixed with liquids. Following the product is pumpable.
Due to the wet process, corrosion and acid reactions must be excluded in the process. Therefore, all parts of Tietjen machines for wet shredding that are in contact with the product are made of stainless steel. This is how we guarantee reliability and durability in wet shredding.
Our machines for wet biomass process are used for biogas substrate preparation as well as in food processing.
As a manufacturer Tietjen has machines in operation worldwide and the field of application is very wide. And the number of mainly natural raw materials and biomass that are ground increases continuously. Tietjen’s main focus in the grinding of raw materials is on:
The machines grind a wide variety of input materials until the material reaches the desired particle size. Another important quality criterion besides the particle size is the uniformity or distribution of the particle size (both factors together determine the so-called grist spectrum).
The exterior view of a design by Tietjen shows that the main components are
Inside the cylindrical grinding chamber there is a rotor, which is connected to the electric motor via the coupling. At the top of the grinding chamber there is the inlet for the material to be ground. The inlet flap can be adjusted depending on the direction of rotation. To the right and left of the inlet are the impact zones and the remaining area is equipped with screens. Tietjen hammer mills have a particularly large sieve area for a high passage or throughput of the mill. At the bottom of the grinding chamber there is a collecting container for impurities, such as stones or metal parts. With the help of our AGS AD feeding system these impurities can be automatically separated and discharged.
At the beginning of the process, the material to be ground is fed into the grinding chamber with a feeding or dosing device. The feeding process needs to be as uniform as possible – in terms of quantity per unit of time and per distribution over the width of the grinding chamber. The feeding device is as well used to ensure good ventilation of the hammer mill. This aspiration is necessary for transporting the material to be ground through the hammer mill, keeping the screens free, and cooling the grinding chamber. The aspiration is to be optimally controlled based on the specifications for vacuum and volume flow.
In the grinding chamber of the hammer mill, the rotor rotates at high speed. A defined number of removable beaters are attached to the outer circumference of the rotor. These beaters are also called hammers. They are precisely balanced to avoid vibrations. In Tietjen hammer mills, these beaters can be replaced very quickly and easily.
During the process the rotating beaters grip the material to be ground as it enters the beating circle of the rotor. The impact of the beaters achieves the greatest particle size reduction effect. The beaters throw the pieces/particles at the impact plates and screens, where they are further broken by the impact. The ground material remains in the grinding chamber until it is so crushed that it can pass the screens in the grinding chamber.
The screen has the function of limiting the size. The oversize can be changed by replacing the screen. In addition to the screens, the aspiration, the beaters, and the speed have an influence on the particle size. Each of these factors can be individually adjusted to the customer’s recipe with Tietjen’s hammer mills. In general, it can simplified be saying:
the finer the end product. However, a lot of experience is required to obtain the most uniform particle size (“narrow particle band”) possible, which is matched to the customers’ recipes or the targeted pellet size and quality.
