Roller Mill vs. Hammer Mill: Choosing Feed-Processing Equipment

For cracked grain with a consistent, coarse texture, we usually recommend a roller mill. A hammer mill is worth comparing when the feeding program calls for a finer grind or several screen choices. Either milling method can be part of a grinder mixer, so the next decision is whether you need processed grain delivered to an existing mixer or a machine that also mixes and unloads the ration.

Keast Enterprises offers roller mills, hammer mills and grinder mixers from RENN and Art's Way. We narrow the choice by the grain, finished particle size, amount of feed made each day and equipment already on the farm. The intake and unloading arrangement deserve just as much attention as the mill itself.

How roller mills and hammer mills process grain

Roller mills

A roller mill draws grain between grooved rolls. Compression breaks the kernels, while a difference in roll speeds can add a shearing action. Roll spacing, groove pattern and speed differential influence the finished grain. Those settings need to suit the crop and the feed you want to produce.

This is a useful arrangement when the objective is to crack or roll grain while limiting fine material. A consistent coarse product is often the main reason to choose a roller mill. It also makes sense when the farm already has a mixing system and needs a separate machine to prepare grain for it.

Roller mills aren't all set up for the same result. The coarse rolls used to process corn at a high rate differ from the finer grooves selected for another grain or a smaller particle size. Include the roll specification when comparing machines. Two mills with the same roll width can have different power requirements and production rates.

Hammer mills

A hammer mill breaks grain by impact. Hammers rotating inside the grinding chamber strike the material until it can pass through the screen. Changing screens gives the operator a way to adjust the grind as the grain or feeding requirement changes.

The screen is an important part of that adjustment, but its hole size is not the finished particle size of every piece of feed. Grain breaks into a range of sizes. Moisture, grain characteristics, feeding rate and the condition of the hammers and screen all influence the result. Kansas State's particle-size guidance explains why sampling the processed feed is more useful than relying on the screen opening alone.

Finer grinding generally reduces capacity because the grain requires more processing before it leaves the chamber. A rate achieved with a coarse screen should not be used to size a machine for fine meal. We want to compare output at the grind the feeding operation actually needs.

Before choosing either type of mill, identify the grain and desired texture. If your nutritionist has specified a particle-size target, bring that recommendation. There isn't one ideal grind for every species, ration and feeding program.

Do you need a mill or a grinder mixer?

A separate mill processes grain for another part of the feeding system. It can discharge into a stationary mixer, a suitable mixing wagon or storage for later use. That arrangement allows the milling and mixing equipment to be sized separately and can make good use of a mixer the farm already owns.

A grinder mixer combines grain processing with a mixing tank and unloading equipment. It is worth considering when you want to prepare and deliver batches with one machine. The choice still starts with the milling method: a grinder mixer can use a hammer mill or a roller mill.

Art's Way's 6105 models show the difference clearly:

• The 6105 grinder mixer combines a 20-inch hammer mill with a 105-bushel mixing tank.
• The CattleMaxx 6105 combines a 20-inch roller mill with a 105-bushel mixing tank.

Art's Way specifies a 540-RPM PTO and a 40-to-100-horsepower tractor range for both. The CattleMaxx rolls grain into the mixing tank, where a central auger mixes the ration. The hammer-mill 6105 provides screen choices for controlling the grind before mixing.

The 105-bushel tank figure describes volume. The weight of a complete batch depends on the ingredients and their bulk density. Include grain, supplements and the other ingredients in the batch calculation, then check the usable fill and mixing requirements in the manufacturer's instructions. Increasing the grain portion alone can leave too little room for the rest of the ration.

The loading sequence also matters. Consider where the ingredients are stored, how they will enter the machine and where the finished feed will be unloaded. A grinder mixer should reduce handling work across that whole routine. A separate mill may be the better investment when the existing mixer already does its job well.

RENN roller mills and Art's Way PHM26 stand-alone mills

RENN RMC24 roller mill

The RENN RMC24 uses 16-inch-diameter by 24-inch-wide steel rolls. The gap is adjusted through a worm-drive system with spring retention, and different groove patterns are available for the grain and finished texture.

RENN rates the RMC24 at up to 2,500 bushels per hour for coarse corn processing with four-groove-per-inch rolls. Other grains and finer processing have different capacity and power requirements. The crop, moisture, roll selection and available tractor power must be close enough to the rated application for that figure to be useful in a buying decision.

This RMC24 package includes an 8-inch by 12-foot low-profile hydraulic feed auger and a 10-inch by 12-foot folding hydraulic discharge auger. The low intake is useful when collecting grain beneath a low outlet. The discharge auger carries the rolled grain to the next part of the feeding system.

RENN RMC48 roller mill

For farms processing larger volumes, the RENN RMC48 provides 16-inch-diameter by 48-inch-wide cast rolls, twice the roll width of the RMC24. The conveyor-discharge configuration uses a 1,000-RPM PTO and differential roll drive, which turns the rolls at different speeds.

RENN lists a maximum corn capacity of 5,000 bushels per hour for the RMC48. Moisture, roll configuration and the required particle size affect actual output, so compare the rate for your grain and grind before using that figure to plan a feeding day.

The PTO-driven S-transition discharge conveyor folds hydraulically for transport. When comparing it with an auger-discharge mill, measure the available space beside the machine and the height of the receiving equipment. The wider mill is worth considering when grain processing limits daily output and the grain supply, receiving equipment and tractor can keep up.

Art's Way PHM26 portable hammer mill

The Art's Way PHM26 provides a 26-inch hammer mill without an integrated mixing tank. The linked package includes a hydraulic trough feed auger, a discharge auger with mechanical lift and swing, and the first screen. It is an option for grinding grain into an existing mixer or a separate receiving point.

The hammers have four usable cutting edges, allowing them to be repositioned as the edges wear. Additional screens are available when the machine will process feeds requiring different grinds. Choose the first screen for the main job and include any additional screens needed for the feeding program in the quote.

The PHM26 is offered in 540- and 1,000-RPM PTO versions. These are different drive configurations; the version ordered must match the tractor. The PTO choice belongs in the original equipment discussion, along with tractor power and hydraulic connections.

Size the equipment for a complete feeding day

The busiest feeding day gives a more useful capacity target than annual grain volume alone. Start with how much grain must be processed and the time available. Then account for the work that cannot happen while the mill is running, such as moving between locations or handling ingredients with the same tractor.

For example, suppose you need to process 800 bushels in two hours. If other work takes 45 minutes and cannot overlap with milling, the mill has 75 minutes, or 1.25 hours, to process the grain:

800 bushels ÷ 1.25 hours = 640 bushels per hour.

That is a planning requirement, not a performance claim for a particular mill. A machine averaging 400 bushels per hour would use the full two hours on milling alone. The comparison should be against a mill capable of maintaining the required rate with your grain and grind, with time left for normal interruptions.

A larger mill is most valuable when milling is what slows the feeding operation. If the mixer takes longer to finish each batch than the mill takes to supply it, additional milling capacity may simply produce more waiting. Timing several complete batches can show whether the useful improvement is in grinding, ingredient handling, mixing or unloading.

Check intake height and unloading reach

At the intake, measure the grain outlet's height and the room available beneath it. Allow space to position the mill and operate the feed auger without blocking access to bins, wagons or ingredient storage.

At the discharge, measure both the height and horizontal distance to the receiving opening. An auger's tube length alone doesn't establish whether it will reach over the side of a wagon or into a mixer. Its working angle and the position of the machine affect the usable reach.

Make the same checks at every regular feeding location. A machine that unloads comfortably into one bin may need a different auger arrangement to reach another. Photos showing the complete approach, outlet and receiving equipment help us compare those arrangements before the machine is ordered.

What to include in the quote

For a PTO mill, include the tractor's make and model, available power, PTO speed and hydraulic connections. A stationary electric installation also needs the motor requirements, voltage, phase and available electrical service checked before equipment is selected.

Service access belongs in the comparison too. Hammers, screens, rolls and adjustment parts must remain in suitable condition to maintain the intended grind. Look at how those parts are reached and changed, especially if screen changes will be part of the regular routine. Follow the machine's instructions for adjustment and maintenance.

To compare a roller mill, hammer mill or grinder mixer, send us:

• The grains, typical moisture and desired finished texture or particle-size recommendation.
• Grain processed on the busiest day, time available and normal batch ingredients and weight.
• The mixer or other feeding equipment already in use.
• The tractor and power available for the new machine.
• Intake and discharge heights, horizontal reach, and photos of the loading areas.

Email sales@keastenterprises.com with those details. We can compare the mill, mixing capacity, augers and drive equipment together and quote the arrangement that fits how you make and handle feed.