Advantages and disadvantages about hammer mills
The hammer mill has been applied to cement clinker grinding and ultra-fine grinding in the circuit operating for a long time. Besides the roller press, it is the best type for producing the final products in good shape and granularity on the market.
In the feed processing process there may be a number of ingredients that require some form of processing. These feed ingredients include coarse cereal grains, corn which require particle size reduction which will improve the performance of the ingredient and increase the nutritive value. There are a many ways to achieve this particle size reduction, here we are looking at using hammer-mills, for information on roller mills, see the related links at the bottom of this page.
Both hammering and rolling can achieve the desired result of achieving adequately ground ingredients, but other factors also need to be looked at before choosing the suitable method to grind. Excessive size reduction can lead to wasted electrical energy, unnecessary wear on mechanical equipment and possible digestive problems in livestock and poultry. For more in depth information regarding what actually occurs to the ingredients during size reduction please refer to this link: particle size reduction.
Hammer mills Advantages:
1. are able to produce a wide range of particle sizes
2. work with any friable material and fibre
3. ease of use
4. lower initial investment when compared with a roller mill
5. minimal maintenance needed
6. particles produced using a hammermill will generally be spherical, with a surface that appears polished.
Hammer mills Disadvantages:
1. less energy efficient when compared to a roller mill
2. may generate heat (source of energy loss)
3. produce greater particle size variability (less uniform)
4. hammer mills are noisy and can generate dust pollution
Hammer mills work on the principle that most materials will crush, shatter, or pulverize upon impact using a simple four step operation:
1.Material is fed into the mill’s chamber typically by gravity.
2.The material is struck by ganged hammers (generally rectangular pieces of hardened steel) which are attached to a shaft which rotates at a high speed inside the chamber. The material is crushed or shattered by the repeated hammer impacts, collisions with the walls of the grinding chamber as well as particle on particle impacts.
3.Perforated metal screens, or bar grates covering the discharge opening of the mill retain coarse materials for further grinding while allowing properly sized materials to pass as finished product.
4.Hard, heavy materials such as glass, stone or metals exit the mill via gravity.
Hammer mills process material with a pulverizing action. Rectangular steel hammers are attached to a shaft inside of a steel grinding chamber. As the shaft spins, the hammers flail out, bringing them into contact with the material being processed. A combination of hammer blows, particle on particle impact, and contact with the mill interior, work in unison to reduce the material until it is able to pass through the screen or heavy bar grate covering the mill’s discharge opening.