Corn Cleaning Machines: How to Improve Grain Quality and Reduce Losses

Corn is one of the most in-demand grain crops in the world. In America, cornfields cover over 90 million acres — that’s an area equivalent to some entire countries, like Germany. Nearly every year, the U.S. harvests record or near-record amounts of corn, and you’d think that the grain processing technology is already perfected.

But that’s not the case. With the Metra corn cleaning machine, this process can be made cheaper and faster while ensuring the highest quality grain for the next planting season. Spoiler: this investment pays off after just one season of use, sometimes even sooner.

Traditional Corn Cleaning Approach

Usually, grain is processed in several stages, depending on the crop’s cleanliness, available and functioning equipment, and the intended use of the grain.

In short: cleaning quality is ensured by a series of specialized machines—typically at least 3-4 in one lineup. Some remove light organic debris, while others separate harder-to-remove impurities. The strictest cleaning standards apply to grain set aside for the next planting season.

The standard corn cleaning and sorting process includes:

• Pre-cleaning. The goal is to remove all trash—soil, animal residues, etc.—and prepare the raw material for drying.
• Primary cleaning. At this stage, all types of impurities and defective grains are separated from the main batch.
• Secondary cleaning. This step calibrates the grain into different quality and size fractions—feed, seed, processing, and waste.

Three Drawbacks of the Traditional Approach

• Traditional grain cleaners can’t detect fungus-infected or diseased grains. Contaminated kernels don’t always differ in weight from healthy ones, and early-stage infections may be hard to spot visually. Yet, just one gram of infected grain can contain thousands of harmful microorganisms—enough to ruin half the harvest.
• These machines don’t differentiate colors. Uniform color affects the final product price just as much as weight does. Most corn grown in bulk is yellow or white, but rainfall, drought, or soil changes can alter coloration. Additionally, corn comes in multiple colors, including black, purple, and red.
• Corn is delicate. Older-generation corn harvesters don’t always handle each kernel gently, and technological losses can reach up to 10%, depending on the equipment quality.

Modern Corn Cleaning Approach

Metra grain cleaners handle corn gently and carefully. This approach boosts next-season yields by ensuring high germination rates and uniform sprouting. Plus, this equipment can distinguish colors and remove kernels damaged by fungi or pests.

And the benefits don’t stop there.

Metra machines use patented technology based on aerodynamic principles. This means they never damage raw materials and can carefully sort not just corn but any grain—from poppy seeds to beans. Switching to another crop takes no more than 10 minutes, which is invaluable during peak harvesting time.

Metra machines handle all traditional processing stages—pre-cleaning, primary, and secondary—on their own. In other words, they work fast and replace multiple machines. Plus, they dry grain up to 2% in one pass, which is crucial for storage preparation.

“Light impurities—trash and mold—are separated and removed via the dust collector and auger; large and small impurities exit through the waste discharge pipe. The remaining material is separated from the grain by an airflow system and lands on a platform, where it is sorted by relative density. Quality grain goes into a separate compartment, where it is divided into 3-5 fractions based on size, shape, or other parameters set by the owner.”—(Metra employee explaining the technology)

Each Metra corn cleaner saves labor time—simply because there’s no need to service multiple separate machines. It also cuts energy costs.

For example, cleaning 200 bushels of grain per hour consumes only 0.75 kWh—less than a household washing machine, which uses 0.8 to 1.5 kWh per cycle. Processing 8,000 bushels per hour requires 22 kWh, still 2.5 to 3 times less than comparable older-generation machines.

Final Thoughts

Today, corn is used in over 500 different products—including plaster, glue, industrial filters, and alcohol. But this is just a bonus to its primary value: feeding people. Corn has been a staple food for thousands of years, and the range of maize-based products keeps expanding.

A corn cleaner will never sit idle—whether in small farms processing limited acreage or large elevators handling massive harvests of corn and other grains. Metra’s solutions are guaranteed to meet your specific processing needs. Contact us, and we’ll help you find the right equipment for your operation.

Ready to transform your grain cleaning process?

Get in touch with Metra Grain Cleaners today and see the difference for yourself!