Industrial Roller Mill vs. Hammer Mill: What’s the Difference?

When deciding on the right milling equipment for your industrial grinding operations, it’s essential to understand your options. Two primary types of machinery available are roller mills and hammer mills. RMS also offers the VersaMill, a more advanced, direct-drive roller mill that allows for even greater control.

Here, we dig deeper into the most commonly asked questions about the differences between industrial hammer mill grinders and roller mills, their benefits and applications, and what machine owners can expect in regard to maintenance for each type of equipment.

How Do Roller Mills and Hammer Mills Work?

A hammer mill acts as the name implies, milling grain with a smashing motion. If you took a kernel of corn and smashed it, you would have multiple pieces with variation in size. Whether it’s a mineral or a feed hammer mill, the operation is the same.

A roller mill uses compression and cutting. As one roller spins against another, it creates a shearing effect. Roller mill particle size generally sees lower variance than hammer mills, which results in a more consistent grind.

Hammer mills use different screen sizes to adjust the particle size for either a coarser or finer material size. You typically need to shut down operations entirely to change a screen.

On the other hand, roller mills can alter the grind simply by changing the roll position. If you want to achieve a finer grind, you can move the rolls in. For a coarser grind, you move the rolls outward.

The VersaMill can also control the speed of each roller. Different roll speeds allow for greater shear and an even finer grind than with a traditional roller mill.  This allows for another machine setting that can improve grind size and consistency, which improves conversion rates and yields.

Which Mill Produces a Better Grind?

A mill for spices, minerals, animal feed, and many other applications needs to be precise and consistent. Roller mills excel at precision particle size reduction for any given application.

One key benefit of a roller mill is its ability to produce a consistent grind profile. Due to its grinding process, the distribution of particle sizes is far more uniform than that of a hammer mill.

While previously a roller mill struggled to get to some of the finer size requirements compared to hammer mills, the VersaMill, with its patented differential rolls speed adjustment, has increased its ability to go finer from 350 micron (45 mesh) to sub 100 micron (140 mesh).

Energy Efficiency

Another main benefit of a roller mill vs. a hammer mill grinder is that it uses substantially less energy. The roller milling process does not produce excess heat and other energy-consuming effects as hammer milling does.

Energy efficiency is becoming a top priority for many mill owners, and roller mills are typically around 25% to 30% more energy efficient than their hammer mill counterparts. The VersaMill is even more efficient than a traditional roller mill because it does not use belts.

Cost of Ownership

Both types of mills have parts that wear down over time and need to be replaced. Roller mills tend to have higher maintenance costs. However, the total cost of ownership of a roller mill is less when you also include the energy savings and quality of the product.

This table highlights the costs of ownership and other important comparison factors between a roller mill and a hammer mill:

Which Industries and Applications Typically Use Roller Mills?

Many industries rely on roller mills for their operations. Many are upgrading directly from hammer mills to the VersaMill:

Agriculture

This industry relies heavily on roller mills for feed applications, where it previously relied on grain hammer mills. Integrators and toll mills that feed cows, chickens, and pigs are implementing roller mills because the machines are an efficient way to achieve the appropriate feed particle sizes for different animals. A feed hammer mill generally cannot compete with the benefits of a roller mill.

Breweries & Distilleries

These industries depend on a consistent crush profile for the different grains they use to create their products. Because of their reputation for a consistent crush, roller mills are becoming the mill equipment of choice for breweries and distilleries in the United States and overseas.

Fertilizers

Many companies and farms on the West Coast are looking to reduce the amount of unabsorbed materials in their products to create a more even application. They need a consistent, fine grind to increase the absorption rate into the water because they’re looking to spray the liquid through a fertilizing unit. A better grind not only allows for better coverage, but it also prevents blocking in the application units.

Food

Some businesses in the coffee industry have been employing roller mills to grind up coffee beans for larger companies. For those businesses, the coffee grounds must be a consistent grind, and the roller mill is an optimal way for them to do that.

A roller mill is a superior flour mill grinder because consistency and precision in grain particle size are crucial to the quality of the final product.

Biomass

This is a newer industry integrating roller mills. One example is biochar. This is used as a fertilizer and as a filter to clean out contaminants in water sources and other applications. Biochar comes from wood that’s been burned in a vacuum chamber. Often, this wood has to be sized at a consistent output before it can be utilized.

Minerals

Roller mills and roll crushers are essential in mineral industries for precise particle size reduction. They use compression and cutting to create a consistent grind profile, typically in the 2” to 100 mesh range, while generating fewer fines than hammer mills. This precision, combined with 25% to 30% greater energy efficiency, makes them a cost-effective choice for mineral operations.

Contact us to learn more about which equipment is right for your processes.