Hammer mills are used for a wide variety of applications across many industries, including agriculture, chemicals, food processing, mining, pharmaceuticals, and other sectors. These versatile industrial machines have become vital to many industries even as they evolve and integrate with more modern technologies. Still considered one of the most versatile milling machines in use today, the advantages of hammer mills lie in their ability to be customized to fit just about any size of operation or application.
Diverse Uses for Hammer Mills
One of the primary advantages of hammer mills is their versatility in multiple applications and for a wide array of industries. Used for grinding and processing countless materials, the hammer mill consists of hammers attached to a rotating shaft that reduces material fed into the mill. The uses of hammer mills range from grinding grains into animal feed, processing medications for the pharmaceutical industry, recycling operations, sugar production, and the performance of myriad other industrial processes.
The applications and industries for which hammer mills are used include:
- Aiding quicker dissolution of materials into mixtures for the pharmaceutical, food processing, and chemical industries.
- Blending various ingredients for food processing applications.
- Breaking down materials into intermediary powders for industries like the chemical and pharmaceutical sectors can be broken down further by other equipment if needed.
- Ease recycling and scrapper processes by crushing metal to make it melt more quickly.
- Enhancing the effectiveness of active ingredients by creating more surface area on particles is particularly useful for products like pharmaceutical medications, nutritional supplements, and animal feed.
- Facilitating mixing dry ingredients in food processing applications or for premixes found in supermarkets.
- Grinding herbs and spices to preserve nutritional value and enhance taste.
- Handling woody plant material for biofuels, briquettes, fire starters, plywood, and other products made from wood.
- Interspersing together two fibrous or powdered solids into consistent mixtures.
- Processing beans, grains, groundnuts, legumes, nutshells, soybeans, and other food products.
- Reducing pharmaceutical material to grain-sized particles that can fit inside capsules of medicine.
Design Advantages of Hammer Mills
The design advantages of hammer mills stem from their versatility, especially the ability to handle just about any material. With their basic design, hammer mills are easier to build than many other types of processing machinery, and this simplicity also makes them more cost-effective to maintain and repair. To understand the design advantages of hammer mills, let’s evaluate the machine’s constituent components.
Most hammer mills are made up of the following:
- Feed inlet: Point at which raw material enters the grinding chamber, which in most cases is positioned at the top of the machine.
- Rotor: With hammers attached, the hammer mill’s rotor provides the rotational force used to crush material; rotors are typically made from various types of steel or cast iron to withstand the impact of these hammering implements.
- Hammers: Connected to the rotor, hammers come in various sizes and shapes depending on the application and desired reduction in particle size; hammers vary widely, with some having flat surfaces that produce a pure impact force, while others have serrated or curved edges that shred or grind material.
- Grinding chamber: As coarse raw material is fed into the chamber, hammers operating at high speeds impact airborne particles while crushing or grinding this material against stationary plates.
- Screening devices: These are normally located at the lower end of the machine, allowing only material that’s been ground to specified particle sizes through the screens or grates; specific modern models use pneumatic forces rather than screening devices to achieve the desired particle size range more efficiently.
- Discharge chute: Normally positioned at the bottom of the machine, this is where material exits the hammer mill after passing through screening devices. It then continues on to a storage bin or for further processing.
- Power source: Modern hammer mills generally use a drive system to power the rotor and control speed, which usually is made up of an electricity-powered motor, chain drive, and belt, along with a direct drive system or gearbox, unlike ancient water-powered hammer mills, modern iterations can precisely control rotor speed to obtain the desired particle size and to grind material more efficiently.
- Safety features: These often include emergency shut-off buttons, safety guards, and interlock systems that shut the machine down to protect operators or other workers from accidental injury when the machine is operating.
Let’s look at how these components function together to make a hammer mill work.
How Hammer Mills Work
One of the advantages of hammer mills is their simplicity of operation. Operating on the principle of impact, hammers attached to a rotor spin at high speeds, striking material and crushing it. This material then passes through a screening device so only particles smaller than a certain size exit the machine.
Hammer mill operations generally follow these steps:
- Material is fed into the machine from a hopper into the feed inlet; feeding the machine can be either automated or performed manually.
- Once inside the grinding chamber, hammers rotating at high speeds generate centrifugal forces to cause significant impacts against the material.
- With repeated impacts from the rotating hammers, material is crushed and pulverized into a specific particle size range.
- Once reduced to the proper size, material passes through the screen, which is normally positioned at the bottom of the machine; larger particles remain in the grinding chamber until they reach the proper size range.
- The processed material is collected or conveyed for packaging or further processing.
The simplicity of its operation provides hammer mills with many advantages.
The Many Advantages of Hammer Mills
Hammer mills offer many advantages. Their versatility and diversity in design make these machines suitable for reducing a wide range of materials efficiently and cost-effectively. They can be especially successful at processing friable materials, including agricultural products, chemicals in solid form, organic materials for biomass production, various types of minerals, and waste material in recycling operations. Other advantages of hammer mills include their easy maintenance and low risk of contamination during processing.
Varying Hammer Types & Configurations
Hammer mills can utilize various hammer designs and configurations depending on the application. For example, hammers can be made from different materials to perform specific tasks. More malleable materials like rubbers, plastics, and even brass are used to make softer hammers. These often feature sharp edges that can slice through materials to produce a narrower range of particle size distribution and make materials more uniform.
Assorted steels and cast iron are often used to make harder hammers with flatter surfaces that can extensively fragment material. Some hammers have tips made from tungsten carbide and other coatings to make them more durable, while other types have thinner profiles that make them more knifelike. While most hammer mills are configured with hammers that swing on the rotor, some feature stationary hammers instead. These differing hammer configurations, sizes, and shapes define the machine’s capacity and capabilities.
Suitable for a Diverse Range of Materials
One of the primary advantages of hammer mills is that they can process abrasive, brittle, and dense materials. In particular, they’re very effective at fragmenting friable materials that have their natural defects. This makes them ideal for reducing substances into granulates or powders. Hammer mills also can reduce lumps in agglomerated materials as well, making them useful for processing materials that tend to coalesce into lumps like sand or sugar.
Efficiency
Hammer mills efficiently reduce nearly any material, often outperforming newer milling technologies regarding particle size reduction. With the right hammer and other configurations, hammer mills optimize the production of certain types of cosmetics and plastics in which tighter particle distributions and sizes are necessary.
Cleaning & Maintenance
One of the advantages of hammer mills when it comes to cleaning is the simple design of their grinding chamber. Hammer mill construction facilitates cleaning, with easier access than with other types of mills. Generally, using flatter rather than sharper implements also limits contamination from the hammers. Mills equipped with sharper blades or milling media tend to wear out faster, contaminating the processed material.
Their straightforward design makes hammer mills easier to maintain than other milling machines. This offers advantages, with hammer mills generally requiring considerably less downtime. There’s no need for specially trained personnel to service many of these machines in most cases, as operators can be easily trained to conduct basic maintenance.
Overall Operational Effectiveness
One of the advantages of hammer mills is their high overall equipment effectiveness (OEE) metric.
OEE measures three basic factors in relation to hammer mills, which are:
- Availability: Proportion of time a hammer mill remains up and running compared to the time planned for production.
- Performance: Actual throughput of a hammer mill when compared against the maximum potential throughput.
- Quality: Proportion of defective product in comparison to total production.
This high OEE score shows one of hammer mills' advantages: providing cost-effective solutions for material processing applications.
Disadvantages of Hammer Mills
While hammer mills have many advantages, there are also a few disadvantages. Hammer mills tend to be noisier than other material processing equipment and use an inordinate amount of energy compared to more modern milling machines. They also generate substantial dust and can present more significant safety hazards for operators or maintenance personnel. Models with screens also can’t handle viscous materials well, as the material gets stuck between the apertures. Additionally, hammer mills have limitations on producing uniform particle sizes.
Prater Hammer Mills
Prater Industries has been producing hammer mills since 1925. With nearly a century of experience, Prater engineers have developed innovative designs using the most advanced material handling technology. The advantages of hammer mills made by Prater come from our expertise in meeting our customers’ processing challenges, often with creative, tailored solutions.
Prater makes two basic types of hammer mills:
- Prater’s Full Screen Hammer Mill, also referred to as our G-series model, can handle high throughputs while producing uniform particle size, while doing so in an energy efficient manner.
- Prater’s Mega Hammer Mill was designed to fill a gap between our G-series hammer mills and fine grinding machines, which uses produces less heat and noise, while also uniformly grinding material.
To learn more about the advantages of hammer mills made by Prater and our other processing equipment, contact the material handling experts at Prater today.
