When I first started working as a sales lead for an egg grading machine supplier, I’d spend a lot of time visiting small family-owned egg farms around the Midwest. Almost every single farmer would pull me aside after a demo, scratch their head, and ask the same question: “My eggs have different air cell sizes—how’s your machine gonna handle that? Last year, I had a batch where half the air cells were half the normal size, and the other half were twice as big, and my old machine dumped a whole crate before I could fix it.” For a long time, I didn’t have a great answer beyond, “Our machine is precise,” and I learned fast that wasn’t enough. I spent the next year in our engineering lab, shadowing our lead technician as he adjusted sensors and ran thousands of test eggs, talking to farmers about their specific pain points, and finally figuring out exactly how our egg grading machine navigates air cells of all sizes. What I’ve found is that it’s not just one part of the machine—it’s a whole system working in sequence, each step calibrated to account for natural variation in air cells, which are actually a super important part of egg quality that many people don’t think about. Egg Grading Machine
First, let’s get back to basics on what an air cell is, because that’s the foundation of everything. When a chicken lays an egg, it’s warm, and as it cools down, the contents inside contract, creating a small pocket of air between the shell and the inner membrane— that’s the air cell. It grows slowly as the egg ages, too: the older the egg, the bigger the air cell. That’s why you’ll see the old “float test” where you put an egg in water, and if it tilts or floats, it’s older—big air cell there. Farmers care about air cell size because it’s a direct marker of egg freshness, but size can vary a lot: from tiny ones under 3mm to large ones over 6mm, depending on the hen’s age, the storage conditions after laying, how long the egg has been kept before processing, even the breed of the chicken. A young hen’s eggs will have smaller air cells, while a 2-year-old hen’s eggs might have much larger ones, and if a farm mixes eggs from different age groups, the variation gets even bigger.
My old mistake was thinking the machine just “looks” at the air cell and sorts it, but it’s way more precise than that. Our grading machine has three key stages that handle air cell variation, and each one is built to adjust in real time, no matter how different the air cells are. The first stage is the pre-scanning step, which happens right when the eggs roll onto the machine’s conveyor belt. This is where a lot of cheaper, entry-level machines fail—they use a single light sensor that just measures the whole egg, or a fixed light beam that only works for average-sized air cells. Our machine uses a high-resolution LED line scan camera paired with a backlight, and it’s calibrated to shine light through the entire egg, not just one spot. The camera takes thousands of tiny “slices” of the egg as it moves, and it can map the exact shape and size of the air cell, even if it’s off-center or lopsided—something a lot of older machines can’t do. Last month, I was at a farm in Ohio that had a batch of eggs where 40% had air cells shifted to one side, from storing them pointy-side up by accident. Their old machine would have misclassified all of these, but our pre-scan caught every single one, because the camera tracks the entire egg’s interior, not just the center.
But here’s the thing: the pre-scan doesn’t just measure size. It also compares the air cell to the egg’s overall size and weight, because a big air cell in a small egg is way different than a big air cell in a large egg. Our system is trained on data from over 20 million eggs, collected from farms across North America and Europe, so it knows that a 4mm air cell in a 50g egg is a sign of a 2-week-old egg, but a 4mm air cell in a 65g egg is totally normal for a fresh, large egg from a young hen. That’s why we don’t just use a single threshold—we use a relative threshold, so the machine adjusts its judgment for each individual egg. I remember talking to a farmer in Iowa last spring who complained that his machine was rejecting too many medium eggs, and when we ran a test batch, we realized his medium eggs came from two different flocks: one 30-week-old hens with average air cells, and one 60-week-old hens with much larger air cells. His old machine had a fixed 4mm air cell cutoff, so it was rejecting all the larger ones from the older hens, which were still perfectly fresh. Our machine re-calibrated on the spot, using the pre-scan data to set a relative cutoff for each egg’s size, and fixed his rejection rate by 22% that day.
The second stage is the handling and sorting mechanism, and this is where air cell size can cause real damage if the machine isn’t designed right. If an egg has a really large air cell, it’s more fragile—because the membrane is stretched thinner, and if you bump it wrong, it can crack. Small air cells mean the egg is more solid, so it can handle a little more force. A lot of machines use the same grip pressure for every egg, which means either they squeeze too hard and crack the big air cell eggs, or not hard enough and the small ones slip. Our machine uses variable pneumatic grips, calibrated by the pre-scan data. Right before the grip closes, the machine sends a signal adjusting the pressure: eggs with air cells under 3mm get a higher grip pressure, because they’re more solid and less likely to slip, while eggs with air cells over 5mm get a 15% lower pressure, so we don’t risk cracking the thin membrane. I saw this in action at a farm in Indiana last month, where they had a batch of eggs with air cells ranging from 2mm to 7mm. The old machine had a 12% crack rate for those eggs, and our machine had a 0.8% crack rate, all because the grips adjusted pressure on the fly. Even better, the machine doesn’t just adjust pressure based on air cell size—it also adjusts the position of the grip. If an air cell is off-center, the grip moves so it’s not squeezing the air cell at all. That’s a game-changer for eggs with lopsided air cells, which are super common when eggs are stored in non-standard positions after laying.
The third stage is the sorting and collection, and this is where a lot of machines mess up because they try to sort too many categories at once, and don’t account for how air cell size changes with grade. People often think grading is just by size—small, medium, large, extra large—but freshness (which is tied directly to air cell size) is a separate grade that consumers care about, especially for grocery stores that sell “fresh premium” eggs. Our machine sorts eggs into 8 categories total, combining size, weight, and air cell size, and each category is sent to its own collection bin, but the bins are adjusted dynamically too. If there’s a batch with a lot of large air cell eggs that are still fresh, the machine will adjust the air cell cutoff for the “fresh premium” category to make sure they get placed there, instead of being sent to the “older” category for discount. Last quarter, a large grocery chain in Texas switched to our machines because their old system was mixing fresh eggs with older ones, leading to complaints about “expired” eggs when they were actually just eggs with larger air cells. We adjusted the air cell thresholds for their specific batch data, and within a month, their complaint rate dropped by 35%—all because the machine could tell the difference between a fresh egg with a big air cell and an old egg with a big air cell, using the pre-scan data that also measured the egg’s density, another marker of freshness that pairs with air cell size.
What I’ve learned over the years is that farmers don’t just want a machine that sorts eggs fast—they want a machine that works with their specific eggs, because no two farms have exactly the same egg batches. A small family farm might have eggs from one small flock, with consistent air cell sizes, while a large commercial farm might have eggs from five different flocks, all with varying air cell sizes, plus eggs that are stored for different lengths of time before processing. Our machine is designed to be calibrated for each farm’s specific needs, and the air cell adjustment is one of the most customizable parts. Farmers can set their own air cell thresholds, either relative to each egg’s size or fixed, depending on their market—if they sell to a local market that wants extra fresh eggs, they can set a lower air cell cutoff, and if they sell to a discount market that doesn’t mind slightly older eggs, they can raise that cutoff.
I also think it’s important to address a common myth I hear all the time: some people think machines can’t handle air cell variation because natural eggs are inconsistent. But the truth is, natural variation is exactly why these machines exist. No one wants to sort eggs by hand, and hand sorting is way less precise when it comes to air cell size—farmers I talk to say they’d rather have a machine that catches 99% of air cell variation than a human that gets 85% right, especially when processing 10,000 eggs an hour. Our machines can process up to 60,000 eggs per hour, and that includes real-time adjustments for every single air cell, no delays, no misreads.
If you’re a farmer or egg processor struggling with eggs that have variable air cell sizes, I get it—air cells are one of the most unpredictable parts of egg quality, and a machine that can’t handle them will cost you money in cracked eggs, misgraded eggs, and lost customers. Our egg grading machines are built to work with your specific eggs, not against the natural variation that comes with raising chickens. If you want to see a demo, adjust the settings to match your current batch, or just ask more questions about how we handle air cells of all sizes, reach out to our team to start a conversation. We’ve worked with hundreds of farms to tweak our system to their needs, and we can do the same for you.
H Frame Chicken Cage References
- Stadelman, W. J., & Cotterill, O. J. (1995). Egg Science and Technology (4th ed.). Food Products Press.
- Chen, X., et al. (2019). Non-destructive determination of egg freshness using air cell size and internal quality parameters. Journal of Food Engineering, 251, 109987.
- USDA Agricultural Marketing Service. (2021). United States Standards, Grades, and Weight Classes for Shell Eggs. U.S. Department of Agriculture.
- De Ketelaere, B., et al. (2006). On-line determination of egg quality attributes in a grading machine. Journal of Food Engineering, 75(3), 387-394.
Guangzhou Guangxing Poultry Equipment Group Co., Ltd.
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