the working principle of hammer mills (step-by-step guide)
SaintyCo hammer mills are high precision machines for grinding solid and hard granules. Our hammer mills guarantee uniform grinding, noiseless operation and less heat buildup in all pharmaceutical processes.
Whether you need standard or customized hammer mills, SaintyCo offers many series for specialized shredding applications. The cGMP compliance and innovative design make SaintyCo hammer mills the most sough-after in this industry.
Every part/component you see in the image above plays an integral role in the overall working principle of hammer mills. However, the milling process mainly takes place in the crushing chamber (part 3).
Hammer mills crushing tools may be coupled directly to a motor or driven by a belt. As opposed to direct connection, the belts can cushion the motor from shock and allows for accurate speed adjustment.
In case youre new to hammer mills in pharmaceutical and food processing industries, here are three crucial steps that will help you understand how this equipment works. Before that, you can watch this video to see how hammer mills work:
Basically, within this chamber, the material is hit by a repeated combination of knives/hammer impact and collision with the wall of the milling chamber. Moreover, collision between particles to particles play an instrumental role in this size reduction process.
In most cases, the mechanical process of reducing large size particles into small particle may result in a fine or coarse finish. How is then is this possible when you use the same pharmaceutical hammer mill equipment?
design & construction of hammer mill machine | afribary
Processing involves conversion of raw materials into varied forms of finished products. It is carried out in different fields of science and engineering. Agro and Agro allied industry, food manufacturing, pharmaceutical, ceramic, civil engineering industries etc are involved in processing.
The breakdown of large stones to an acceptable size for road construction is the business of the quarry industry (civil engineering). The grinding (milling) of clay materials for the purpose of production of glazes, angobes and ceramic wares eg cups, plates, wall and floor tiles is the business of the ceramic industry.
In pharmaceutical industry, a collection of different drug materials are crushed and homogenously mixed to form drugs for human consumption. In the chemical industry, certain chemicals are extracted by first crushing the raw materials to an acceptable particle size before extraction can be effectively achieved.
The process of breaking down large particles to medium size particles and in turn milling them, to micron sizes is achieved. These machines are designed on different principles eg compression, impacts, attraction etc.
In compression, the materials to be reduced in size are compressed between two metallic surfaces eg roller-shafts, thereby causing them to break to pieces. This is then carried on continuous bases to achieve high productivity in impact operations, the materials to be reduced in size are given a high radial force and are compelled to hit a metallic anvil as in cracker machines thereby achieving the breaking of the raw materials to several smaller particles. Also, the raw materials could be compelled to hit a stationary metallic surface (anvil) or could be directed to hit a dynamic (rotational) metallic hard surface eg rotational hammers thereby achieving the breakage of the raw materials.
In attrition principle, the materials to be broken down to smaller particles are given a rotational motion, causing them to rub against one another or against, harder materials on continuous basis. This brings about continuous wear of the materials. The worn off materials are collected later and are used for the desired purpose.
The use of any of these equipments depends on productivity, particle size requirement and nature of materials to be handled. These machines could as well be employed in particle size reduction in the food processing industry. Hammer mills, micro-mills especially serve this purpose.
The hammer mill and micro mill machines are very much alike. The difference lies on the particle size achieved with the two machines. While the particle size achieved with the micro-mill lies in the neighbourhood of (1-30) micron, that of the hammer mill lies between (30-100) micron. The micro-mill has extra gadgets connected to it for the collection of the dust particles. Both the hammer mill and micro-mill operate at high angular velocities (speed) depending on the requirement of the materials being handled. These machines can be used to crush different kinds of dry and hard materials ranging from palm kernel shells, bones, dry seeds, coal, plastics, rubber materials and even stones.
Hammer mill by nature is a robust machine in order to withstand the vibration, which may arise as a result of high speed requirement of the machine. The speed range is in the neighbourhood of (2,500 10,000) rpm depending on the material being crushed.
All the components enumerated above are systematically assembled and are all carried by the structural base of the machine. The pulley on the electric motor is connected to the pulley on the shaft via the double v-belt. The shaft is suspended on bearings mounted on their sitting on the two sides of the bottom casing. The bottom casing is bolted strongly on the structural base. The hammers, discs and their hangers and separators are carried at the middle of the shaft inside the bottom casing. The bottom casing is connected to the top casing using robust hinges, so that the top casing can open in one direction only. When closed they are held together by a locking device. The parabolic top casing is open to some extent at the top. On this opening the inclined hopper with its regulatory device is connected. The hopper and the top casing form one component.
The semi-circular particle sieve is mounted inside the bottom casing. The inclined outlet channel is connected on one side of the bottom casing immediately below the sieve. Because of the incline, particles that drop from the sieve of the incline, rush down straight to the outlet channel where they are collected into a receiver. The bolts and nuts, locking devices, split pins, lock nuts are used for securing components on their correct positions.
The high speed of the electric motor is transmitted to the shaft via the pulleys, belts and bearings. The hammers at their different positions then stand upright during the high-speed operation in between the spacing discs. The walls of the casings housing the hammers and the hammers themselves are made so close that no incoming materials will escape being hammered before dropping on the sieve. The angular speed of the hammers are so high that, this is imparted on the incoming materials from the hopper, thereby splitting the materials into several small particles continuously which will then pass through the tiny holes on the sieve on to the outlet channel.
The little vibration undamped helps to push the materials from the hopper to the hammers and then the particles from the sieve to the outlet channels, thereby making the machine self-acting. The crushed materials are collected in a receiver.
The local design, construction and testing of this machine will encourage our scientists, engineers, technologists to aspire for higher goals in design and construction of more complicated and precision industrial machineries.
The objective of this project is to design, construct and test a hammer mill for particle size reduction of dry and hard materials used for industrial product processing so as to enhance productivity and reduce human labor to the bearest minimum.
2). Based on the literature review the concepts of hammer mill design will be developed. The concepts will be reviewed severally and sketches of various concepts made. Finally the required design will be developed.
8). Test runs of the machine will be carried out. First the machine will be tested for dynamic synchronization of running parts without load. Secondly the machine will be tested again severally on load.
Mbanefo, Chibuzo. "DESIGN & CONSTRUCTION OF HAMMER MILL MACHINE" Afribary.com. Afribary.com, 09 Jul. 2018, https://afribary.com/works/design-construction-of-hammer-mill-machine . Accessed 08 Jul. 2021.
Mbanefo, Chibuzo. "DESIGN & CONSTRUCTION OF HAMMER MILL MACHINE". Afribary.com, Afribary.com, 09 Jul. 2018. Web. 08 Jul. 2021. < https://afribary.com/works/design-construction-of-hammer-mill-machine >.