How To Extend the Life of Rolls in a Flour Mill

Flour mill rolls are a critical asset in the milling industry. The quality and sharpness of the rolls impact cwt/hr, energy efficiency, and ultimately, the quality of the flour. Maintaining your mills’ rolls should be a critical part of your processes and operations.

How Long Should Flour Mill Rolls Last?

How long the rolls last in your roll stands depends on several factors, the most important of which is proper maintenance. According to the International Association of Operative Millers, consistent maintenance can extend the expected lifetime of milling machinery from eight to 10 years.

What Causes Premature Roll Wear in a Flour Mill?

Even the most durable rolls will eventually dull. Several factors can lead to early failure and increase the need for more frequent flour mill re-corrugation:

• Foreign Materials. Stones, metal fragments, or other foreign debris that bypass cleaning house magnets can cause deep nicks in the corrugations.
• Poor Paralleling. If rolls are not perfectly parallel, one end will experience higher pressure and heat, leading to uneven wear across the roll face.
• Running Empty. Allowing rolls to make metal-on-metal contact without a consistent feed of grain is the fastest way to flatten corrugations.
• Heat Stress. Poorly adjusted scrapers or excessive grinding pressure can lead to thermal fatigue, causing the metal to crack.

How Can the Life of Roller Mill Rolls Be Extended?

Proper maintenance and operation can extend the life of the roll in your flour milling machine, including optimized tempering. Properly conditioned wheat is easier to grind. The high-protein kernels of Hard Red Winter and Hard Red Spring require exact moisture targets to prevent excessive friction, while Durum—the hardest of all wheat classes—requires a specialized approach to prevent roll strain.

Regular parallel checks will ensure your rolls are exerting even pressure. Maintaining a consistent roll gap is an effective way to prevent localized wear.

It’s also important to be sure you aren’t getting too much foreign material in your mills. According to K-State experts, grates and magnets help keep a lot of this debris out of the grind and protect your rolls. Clean magnets regularly.

One of the best ways to extend the life of your rolls is to use a better roll. Our Endurance Roll Program installs our proprietary rolls that have been proven to outlast standard rolls by 3-5 times.

How Often Should Roller Mill Rolls Be Re-Corrugated?

Your re-corrugation schedule depends on your CWTs and milling stage. Break rolls, for instance, often need to be serviced every 6 to 24 months.

Mids, the smooth rolls that process wheat flours, can last longer up to 48 months.

What Are the Signs That Mill Rolls Need Sharpening?

Watch for these characteristic signs that your rolls need sharpening:

• Profile Wear. As the rolls process material the profile will begin to wear down.   As the profile wears the rolls start to shear the material less and begin to crush more.
• Visible Roll Scaring. You can see areas where the corrugation has completely flattened, usually due to foreign material.
• Energy Consumption. As rolls begin to dull over time the rolls begin to crush the material vs shear it. This crushing requires more energy and can be a tell tale sign that rolls are nearing their sharpening point.

How Does Roll Wear Affect Flour Quality and Extraction Rate?

Worn rolls are a drain on your mill’s operations and profitability. Dull rolls tend to mash rather than shear grains. This results in important extraction losses.

They also degrade the quality of your final product. Dull rolls use more pressure, which generates heat. This damages the starch, resulting in poorer quality performance of the flour in baking.

Ash content goes up when you use dull rolls. This is because the rolls are shattering the husk, increasing the amount of bran in the final product. A higher ash content denotes a lower quality flour. If you have rolls that last longer, like our Endurance Rolls, you can reduce the ash content, producing higher quality flour for longer.