How Automation Solved the Strawberry Clamshell Labeling Bottleneck
When the berry industry moved away from traditional baskets and embraced plastic clamshell packaging, it solved one problem and created another. Clamshells protect the fruit beautifully and look great on the shelf—but getting them labeled quickly and consistently turned out to be a real challenge on high-volume packaging lines.
Here's the engineering behind why clamshell labeling is harder than it looks, and how the right machine architecture turns that bottleneck into a smooth, continuous process running at up to 200 parts per minute.
The Problem: Nested Containers, Two Labels, and Rising Volumes
Clamshell containers arrive tightly nested straight from thermoforming equipment. Before a single label goes on, those containers have to be separated—reliably, one at a time, without jamming. Then comes the labeling itself, which for most retail produce isn't one label but two: a branded top label and a UPC label, often on the bottom. Add high production volumes to the mix, and processors need fast, consistent placement on both surfaces just to keep their lines moving.
Many operations tried to handle this manually or with semi-automated setups. It worked—until production ramped up. Then the cracks started to show: label placement varied from container to container, operators were constantly stopping to adjust equipment, and throughput simply couldn't keep pace with demand.
Why Clamshell Labeling Is Harder Than It Looks
To understand the solution, it helps to understand why the obvious approach struggles.
In a traditional inline system, containers travel down a straight conveyor belt, get spaced out with a timing screw or spacing wheels, and pass fixed labeling heads. The trouble is that the container is essentially floating on a friction belt. It can shift sideways, vibrate, or twist as it moves. To label multiple surfaces, you have to bolt on awkward overhead hold-down belts or secondary turning mechanisms—and the moment your container shape changes even slightly, you're into a round of manual, fine-tune mechanical adjustments. Worse, lightweight clamshells are exactly the kind of container that tips over when you try to speed an inline belt up, which puts a hard ceiling on throughput.
A rotary approach solves this at the architectural level. Instead of letting containers ride loose on a belt, a continuous rotary machine captures each container, locks it in place between an overhead bell and a bottom platform, and carries it through on its own rotating plate. That single change—taking the container off a loose conveyor and fixing it into a rigid, predictable path—neutralizes the variables that cause inline lines to fail:
Container control — Total mechanical capture instead of floating on a belt. No lateral shift, no micro-vibration, no skewing.
Multi-side labeling — Each plate can rotate the product to present any angle to a compact labeling head, so top and bottom labels go on in a single pass rather than requiring a string of separate heads down a conveyor.
Throughput — Because every container is clamped solid, speeding the machine up doesn't tip light containers over. The line stays stable at full production speed.
That's why AB Technology built its Label Line as a continuous rotary machine: the relationship between the container's position and the label application is absolute, not approximate.
The AB Technology Solution: One Continuous Process
AB Technology's automated labeling system handles the entire job in a single continuous process, denesting, labeling, and restacking clamshell and pocketed containers without manual handling in between:
Denesting — A proven Denester platform separates clamshells from their stacked bundles, one at a time.
Controlled conveyance — Each container is captured and held in a consistent, repeatable position.
Dual label application — Two German-made Cab IXOR applicators apply both the customer's branded label and the UPC label simultaneously, for full retail compliance and branding in one pass.
Upstacking — Labeled clamshells are automatically restacked and prepared for filling at the end customer.
The result is high-speed accuracy that holds up under real production demands: up to 200 parts per minute on standard clamshells (160–170 for larger shapes), across a clamshell range of roughly 4 oz to 18 oz.
A few things make it practical for round-the-clock operation:
No-tool changeovers let the same machine run different clamshell sizes without a pile of changeover parts—a direct answer to the inline system's "manual readjustment nightmare."
An open, modular frame gives operators full visibility down the machine length, with fast access for service and simple fault recognition through a centralized HMI.
It's built to last, designed for continuous operation with only periodic lubrication, and core components rated for 10 to 20 years of service.
The Result: Faster, More Reliable Labeling
By implementing automated clamshell labeling, processors transform their production floor into a high-efficiency powerhouse. The system achieves speeds of up to 200 PPM while maintaining pinpoint accuracy on both surfaces, ensuring every container meets retail standards. Because branded and UPC labels are applied in a single pass, compliance is simplified and throughput is maximized.
Flexibility is built directly into the workflow, allowing operators to switch container sizes without the need for specialized tooling. This versatility, combined with a rugged design intended for 24/7 uptime, significantly reduces manual handling and the costly line stoppages that typically plague manual operations.
The payoff is a faster, more reliable labeling process—one built to keep up with the high-volume demands of modern berry packaging, and proven across 15+ years in leading global fruit packaging operations.
More Than Just Strawberries
AB machines handle strawberries, but also blueberries, blackberries, grapes, and eggs. And through a combined label-and-pad configuration on one modular platform, AB Technology applies the same continuous-process approach to proteins and other foods packed in clamshells and thermoformed containers and trays.
If you're running a thermoformed production line, let's talk about how we can help.
Get in touch to talk about a labeler.