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Hammer Mill Improves Craft Brewery’s Efficiency [Case Study]

Posted by Cassie Brown

Jul 31, 2013 10:07:00 AM


Tin Man Brewing Companytin man brewing company logo

1430 West Franklin Street

Evansville, IN 47710




Processing:  Wheat, rye, malted barley, unmalted barley

End product:  Beer


Forward Thinking Brewers

The Tin Man Brewing Company of Evansville, Indiana is an early adopter in the craft brewery world.  They are one of the first craft breweries to utilize a mash filter in their brewing process. It’s a relatively simple, yet highly effective concept.  Tin Man’s Head Brewer Sean O’Rear describes the mash filter as a plate and frame filter that is loaded with brewer’s mash, a mixture of water and grains. The filter is then compressed to extract the liquid “wort”. The collected wort is then boiled with hops to produce beer.  Bonus:  the remaining solid portion, called spent grain, is given to a local farmer for use as cow feed!

The key benefit of mash filtering is that it allows for capturing up to 98% of the available sugar in the brewing grains, compared to 75% captured by more traditional methods. 

 tin man brewing company mash filter

Size Reduction Challenge

In order to achieve the goal of capturing 98% of the sugar, the grains had to be processed to a very small particle size prior to filtering. Initially, Tin Man was utilizing a two-roller stripper mill to reduce the grains. Unfortunately, the results were inconsistent at best, producing flour, uncracked kernels, and everything in between.  This  caused backups in filtering to occur, leading to significant loss of sugar portions from the grains, and prevention of the complete enzymatic activity that converts the grain starches to sugars. Ultimately, due to the inconsistency of the roller mill finished particle size, only 87% of the possible 98% grain efficiency was achieved. As a result, Tin Man was required to add approximately 10% more grain to their beer recipes to achieve the desired quality.

 tin man brewing company. grains

Roller Mill Out, Hammer Mill In

Unlike roller mills that reduce materials by compression, a hammer mill reduces by impact. A hammer mill is essentially an enclosed steel container, housing a rotor which spins at very high speed.  Flat steel hammers are attached to the rotor. As the rotor spins, the hammers flail out, and repeatedly impact material in the grinding chamber until it is able to pass through the steel mesh screen covering the mill’s discharge opening. Finished particle size is determined by a combination of rotor speed, hammer size, hammer configuration, and screen size.

In effort to solve their issue with finished particle size consistency, Tin Man purchased a Schutte- Buffalo Hammer Mill Model 18-7-301B Circ-u-Flow hammer mill. Custom configured to suit their specific materials, and production goals, the mill features a 10 hp motor, abrasion resistant steel hammers, and a 1/8” screen. 

The model 18-7-301B is a full circle screen hammer mill with 300 degree screen coverage of the rotor,  compared to  the 150 degree screen coverage seen in more traditional industrial hammer mill models. This means the properly sized material has a larger area to evacuate the grinding chamber. As a result, the full circle screen hammer mill has the highest throughput to horsepower ratio of all hammer mill styles.

model 187301b full circle screen hammer mill

O’Rear reports that following the hammer mill installation, the process improvements were instantly remarkable. The grains were processed to a very fine, consistent finished particle size with no additional milling time required, and thus no impact on labor. The resulting mash was much less viscous, and the loading of the mash filter was fast and easy, with no backups.

 Immediate Impact

The first beer produced from the hammer milled grain using the old grain weights came out with significantly higher sugar loads than the beers produced with the same weight of roller milled grain. According to O’Rear, the efficiency went from 87% to 94% immediately! As a result, they are able to reduce production costs by dropping grain amounts by 8.5%.

 tin man brewing company

“We will continue to optimize the system to achieve 98% mash efficiency, but no other improvement will have as large or as immediate an impact as our Schutte-Buffalo hammer mill.”

Sean O’Rear, Head Brewer
Tin Man Brewing Company


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Topics: finished particle size, hammer mill, full circle screen hammer mills, size reduction, brewing grains, grains, grain efficiency

Hammer Mill Application Focus: Grinding Grains for Animal Feed

Posted by Cassie Brown

Mar 29, 2013 9:37:00 AM

Producers of animal feed all know a simple truth: when processing cereal grains for animal feed, finished particle size matters.  A lot.corn before and after hammer mill processing

Blendability, and digestibility – even the economics of feed production – are all affected by the finished particle size of the grains.  But this is not a one-size-fits-all situation.¹  The ideal finished particle size varies by the grain being processed, and depending on the species, the life stage of the animal.²  With all of this in mind, selecting the proper method of size reduction is a critical decision.


Roller Mill or Hammer Mill

Unlike the angular shaped particles produced in a roller mill, the pulverizing action of the hammer mill results in particles that are more rounded. These smoother surfaces make it easier for the grains to be blended with other components of the feed.²


So Many Hammer Mills

A hammer mill is essentially a steel box surrounding a rotor. Swinging hammers attached to the rotor, flail out when the rotor spins. A screen covers the discharge opening to regulate the finished particle size.

As material enters the hammer mill, it is pulverized by a combination of hammer blows, particle on particle contact, and impact with the walls of the hammer mill. The material remains in the grinding chamber until it is able to pass through the screen covering the discharge area.

But those are just the basics. There are myriad styles of hammer mills: industrial mills, full circle screen hammer mills, horizontal grinders, tub grinders, and more.  As for size, hammer mills can range in size from 6” to more than 60” rotor widths.  Choosing the right hammer mill for your purposes depends greatly upon the material you are processing, and your production goals.


The Full Circle Solution

The design of the full circle screen hammer mill makes it the ideal method of size reduction when processing cereal grains for animal feed.  Let’s take a closer look:


With swine operations reporting that up to 75% of their budget is allocated for feed production,³  the need for energy efficiency cannot be overstated.

As its name suggests, the full circle screen hammer mill differs from the traditional industrial hammer mill because it has nearly double the screen coverage of the rotor:

 screen coverage for full circle screen hammer mill                       screen coverage for industrial hammer mills                                     

    Full Circle Screen Hammer Mill                                 Industrial Hammer Mill


The greater screen coverage of the full circle mill means that there is more area for the material to evacuate the grinding chamber. As a result, a higher throughput rate can be achieved at a lower horsepower in comparison to industrial hammer mill models.  

Particle Size Flexibility

Precision and consistency of the finished particle size has a strong effect on the digestibility of the feed.  A finished particle size that is either too large or too small will have adverse effects on animal performance.²

The primary factor determining finished particle size is the measurement of the perforations in the screen covering the discharge area. The size of these perforations is equal to the maximum finished particle size of the material processed.

The ideal particle size range of 650 to 750 microns³ can easily and consistently be achieved through proper screen selection. In addition, screens can easily be changed to accommodate the processing goals of a variety of grains using the same hammer mill.

The secondary factor in determining finished particle size if the speed of the hammer mill. When the rotor spins, the hammers flail out and impact the material with great severity causing it to break down.  As a result, the higher the rotor speed, the greater the number of hammer mill blows, and thus a finer end product.  An optional component for the full circle screen hammer mill is a variable frequency drive electrical control. This control panel allows the operator to raise or lower the rotor speed as needed for different applications.



The pulverizing action of the hammer mill produces a finished particle that is easily blendable. The nearly 360 degree screen coverage of the full circle screen hammer mill allows for the greatest throughput to horsepower ratio of all hammer mill designs. A consistent and precise finished particle size can be achieved by screen selection. Finally, the ability to change screen size, and the option of a variable speed frequency drive control, enable processing a variety of grains using the same hammer mill.



¹ Steinhart, Terry L., Iowa State University (2012). Swine Feed Efficiency: Influence of Particle Size. Retrieved from  http://www.swinefeedefficiency.com

²Pork Production in Mississippi is Particle Size Important for Swine Diets?(2013). http://www.msucares.com/livestock/swine/particle.html

³Sayler, Julie. (2012). Small Particle Size Makes a Big Difference.http://swineperformance.vitaplus.com/2012/04/small-particle-size-makes-a-big-difference/  

intro to size reduction ebook

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Topics: finished particle size, full circle screen hammer mills, variable frequency drive, size reduction equipment, corn, animal feed, cereal grains

Full Circle Screen Hammer Mills: Low Horsepower, High Throughput

Posted by Cassie Brown

Jul 20, 2012 12:59:00 PM

high production full circle screen hammer millSize reduction equipment comes in a wide variety of shapes and sizes: vertical or horizontal hammer mills, jaw crushers, roller mills and ram-fed grinders, just to name a few. For the most part, the size and shape of the mill/grinder/crusher plays a key role in the functionality of the machine, and for the applications it is best suited for. Nowhere is this truer than with the Full Circle Screen Hammer Mill.


A Peek Inside...

The full circle screen hammer mill gets its name from the 300 degree screen coverage of the rotor, while all other styles of hammer mills typically have closer to 180 degree coverage of the rotor. 

describe the image                    

 Full circle screen hammer mills                                 


Ideal Applications

To achieve the circular, nearly full coverage of the rotor requires that the screen be somewhat pliable, and therefore relatively thin. In addition, the full circle screen mills use thin, notched hammers that reduce material with a tearing/grinding action, as opposed to the pulverizing effect of the large, heavy hammers often used in the industrial hammer mills. As a result, the full circle mills are best suited for light, easy to grind materials that do not require initial grinding against a breaker plate. 

Some examples include:

 cuf application.wordle resized 600

 Size Reduction 101

When material enters the grinding chamber, it is repeatedly struck by hammers that flail out as the shaft spins.  A combination of these hammer blows, particle on particle impact, and impact with the walls of the grinding chamber all work together to break the material down. The material remains in the grinding chamber until it is reduced to a size that will pass through the screen. 

The larger the screen area, the greater the opportunity for the material to evacuate the mill. As a result...

 full circle mills.throughput

 Additional Considerations

Once you have decided that the full circle screen hammer mill is best for your material, determining the following criteria will ensure so that the mill is configured to meet your production goals:

  • Material being processed -  Material characteristics such as: friability, flowability, moisture content, and infeed size
  • Desired finished particle size  - Sawdust, granules, coarse or fine powder?
  • Desired production rate - 10 lbs/hr, 10 tph, etc.

With this information, the following can then be determined:

  • Hammer mill size - Rotor diameter and internal mill width.
  • Hammer size and style - Number of hammers, size, style and metallurgy.
  • Screens  - Style and thickness of screen, and size of openings.
  • Choice of proper RPM
It's Optional
Finally, once the the mill is configured, the last determination is whether or not any optional peripheral equipment is needed. For this, the following questions must be answered:
  • How will the material be fed into the mill? By hand, auger, or belt conveyor?
  • How will the material be taken from the mill? Gravity, air assist, or full air evacuation?
  • Is dust a concern?

Answers to these questions will help to determine the best types of optional equipment such as belt conveyors, augers, rotary feeders, and dust collection, as well as the most efficient design of the infeed and discharge chutes.  


intro to size reduction ebook





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Topics: full circle screen hammer mills, particle on particle contact, biofuels, briquetting, bio-fuel applications, circular hammer mill, corn, animal feed, corn meal, corn flour, hammer mill design styles

Hammer Mills: 5 Key Styles You Need to Know About

Posted by Cassie Brown

Apr 12, 2012 3:50:00 PM


You Need a Hammer Mill for That…

So, you have a material that you would like to make smaller for a given purpose. Sounds simple, right?  Well, in most cases it is. However, there are a number of considerations that must be made to get you to the finish line in the most efficient and  most economical way.  

But First a Little Background

Hammer mills are just one type of machinery among the much larger category of size reduction equipment that also includes:  shredders, jaw crushers, ram fed grinders, roll mills, ball mills, and more. Looking a bit closer, even within hammer mills, there are several styles to choose from. Among those styles, the functionality of a hammer mill remains basically the same:
  • Material is fed into a grinding chamber
  • Contact with moving hammers, and interior mill components reduce the material’s size
  • Material remains in the hammer mill’s grinding chamber until it is able to pass through a screen or grate with certain size openings.
The following is a comparison of five key styles of hammer mills:


Gravity Discharge Industrial Hammer Mills

Industrial hammer mills have the simplest and most recognizable funtionality. A rectangularindustrial hammer mill steel chamber houses a shaft to which swinging hammers are attached. As the shaft rotates at high speed, the hammers flail out impact the material. In addition to the hammers, size reduction occurs through particle on particle contact and through contact with the breaker plate inside the grinding chamber. Because of their simplicity, the industrial hammer mill is easily adaptable to different sizes and milllab scale hammer mill  designs.
Important to know: Replaceable steel liner plates protect the mill's interior from wear caused by grinding abrasive materials.
Ideal Applications: glass, coal, coke, dry chemicals, metals, resin, porcelain, aggregates, brass, ceramics.



Pneumatic Discharge Hammer Mills

The grinding mechanism of this group is quite simliar to the gravity discharge hammerhigh production industrial grindermills. However, the pneumatic mills typically use a thinner hammer and the interior wall of the grinding chamber features a ribbed liner plate. This plate has a washboard effect on the material, and works in unison with the hammers and particle on particle impact to reduce the material. finish grinding hammer mill with integral fanThe biggest difference of course is the group's the use of air assitance to evacuate material from the mill. Whether attached to the main mill shaft, or as a separate optional component in a high production model, the fan pulls the the material through the mill, and conveys it to storage.
Important to know:  Specially designed notched hammers are ideal for tearing and shredding. In addition to assisting the evacuation of  light or low density materials, the pneumatic suction can increase throughput up to 400% over gravity discharge hammer mills. 
Ideal Applications:  hogged wood scrap, wood chips, green wood, biomass, paper, carpet, meat and bone meal 


Full Circle Screen Hammer Mills         

This next group also features the same grinding mechanism as the first two, and the same thin hammers as the pneumatic hammer mills. The amount of screen coverage is what sets the full circle screen hammer mills apart.  
high production full circle screen hammer mill The nearly 300 degree coverage of the rotor translates to a greater surface area for the processed material to evacuate the grinding chamber. As a result, compared to the industrial mills, you get greater throughput per horsepower with full circle screen hammer mills.
diagram of circ-u-flow screen coverageImportant to know: To achieve the circular, nearly full coverage of the rotor requires that the screen be somewhat pliable and therefore relatively thin. Because of this, the full circle screen mill is best suited for light, easy to grind materials to that do not require initial grinding against a breakerplate.
Ideal Applications: corn, grain, spices, grasses, planer shavings, sawdust


Horizontal Infeed Hammer Mills

The unique quality of the horizontal infeed mills is that material is fed into the side of the hammer mill, instead of the top. This design makes them ideal for long, linear or horizontal trim scrap grinderotherwise large, geometric materials to be processed with out a pre-grind. This group includes trim scrap grinders and pallet grinders. As with the prior styles, the horizontal mills use heavy duty screens covering the discharge area to determine finished particle size.
Important to know:  the style and design of the hammers aggressively moves the material into the mill. Feed rolls are ideal to properly control the rate that material enters the grinding chamber.
Ideal Applications: trim scrap, truss palnt scrap, 2x4s, whole pallets, pallet scrap



The Lumpbreaker is quite different from the prior categories in both designsingle rotor lump breaker and functionality. Instead of swinging hammers attached to a shaft rotating at high speed, the lumpbreaker has stationary hammers attached to a slower moving shaft. As the shaft rotates, the hammers remain rigid, and pass between combs attached to the wall of the grinding chamber. Lumpbreakers do not use screens for sizing. Instead, the configuration of spacing between the hammers and combs, along with hammer size and RPM allows some control over the finished particle size.
Important to know: The open infeed, fixed hammers and slow shaft rotation give the lumpbreaker the ability to accept a certain amount of a headload, making it suitable for large blocky materials, de-agglomerating, de-lumping, and returning materials to a flowable consistency.
Ideal Applications: sugar, cement, dry chemicals, agglomerated powders

Broad Categories

For the purpose of this post we broadly examined five of the more common styles of hammer mills. It is important to note that each of these categories could be further broken down to highlight the scope of its variables.

intro to size reduction ebook   



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Topics: full circle screen hammer mills, particle on particle contact, size reduction equipment, industrial hammer mill, hammer mills, hammer mill design styles, gravity discharge industrial hammer mill, liner plates, pneumatic discharge hammer mills, ribbed liner plates, air assist, low density materials, abrasive materials, horizontal infeed hammer mills, trim scrap grinder, pallet grinders, feed rolls, stationary hammers, hammers and combs, deagglomeration, delumping

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