What could cause load failures during shipment when nothing has changed with the machine settings, stretch film, or load configuration?
Hello Hal,
Thanks for sending in your question!
If you haven’t experienced this issue yet, chances are you will at some point. It’s one of the most common and frustrating challenges in load containment. Let’s walk through the likely causes and, more importantly, how to prevent them.
The best place to start is with a process of elimination. You’ve already established that the stretch film, load configuration, and machine settings have not changed, so we can eliminate those variables. Let’s also assume the pallet quality, tertiary packaging, and primary packaging remain unchanged. (Interestingly, even something as simple as a change in package graphics or ink coverage can alter layer-to-layer friction and contribute to load shift.)
With those factors eliminated, our attention turns to the stretch wrapper itself to determine what may be causing degradation in wrapping performance.
To understand where problems develop, it helps to understand how the machine creates load containment.
Stretch film performs best when a certain amount of stretch has been achieved. As the film stretches, its resistance to further stretching increases while its elastic “memory” causes it to retract after being applied to the load. This stretch and retraction generates the Force-to-Load that unitizes the load and resists movement during transportation. Force-to-Load is one of the most widely used indicators of load containment. It is crucial for the stretch wrapping machine to consistently stretch the film to a precise level every cycle to maintain optimized load containment.
The most likely cause of your loss of load containment is that the machine is no longer stretching the film to the intended percentage.
Diving in a little deeper, we know that there are two zones in the machine where stretch occurs: The first is pre-stretch, which takes place inside the film carriage. The second occurs after the film exits the carriage and is applied to the load. A problem in either zone, or both, can reduce load containment.
Many years ago, I had the privilege of driving a race car in the Daytona 24-hour race. By the end of the race, the car simply didn’t perform to the same level as it did on the first lap. Stretch wrappers are much the same. Every wrap cycle creates wear on critical components, resulting in a gradual decline in machine performance over time. Machine manufacturers understand this, which is why wear components are designed to be inspected and replaced.
Let’s begin with pre-stretch.
The carriage creates pre-stretch by maintaining a speed differential between two rollers. This is accomplished through different gear ratios, different roller diameters, or a combination of both. The pre-stretch rollers also have textured surfaces that grip the film during stretching.
Over time, components such as gears, chains, belts, cogged pulleys, the textured roller coatings, and idler roller adjustments wear. As these components degrade, the amount of pre-stretch gradually decreases, reducing load containment performance.
The second stage of stretch occurs between the carriage and the load. Here, film tension is created by a speed differential caused by the rotation speed of the wrapper being faster than the film exiting the carriage. This system also relies on belts, chains, gears, cogged pulleys, and tensioners, all of which are subject to wear.
We know for certain that wear happens and performance degrades. The challenge is that it occurs so gradually that the resulting loss of containment often goes unnoticed until load failures begin to appear.
Periodic stretch wrap machine audits help identify when load containment has fallen below standard. However, audits only capture a snapshot in time. Hundreds or even thousands of pallets may be wrapped between audits.
Now consider a different scenario.
What happens if there is a sudden component failure such as a pre-stretch belt or chain breaking?
The wrapper may continue operating, but load containment could drop dramatically. Visually, the wrapped pallet may appear perfectly normal, making the failure nearly impossible to detect. Without continuous monitoring, you may have no idea when the problem occurred or how many pallets left your facility with inadequate containment.
That’s why routine maintenance and periodic audits remain essential, but you can’t monitor every pallet.
Or can you?
We’ve spent years studying the physics of load containment and developing technologies that optimize containment while reducing film consumption. The next logical step was creating a system that continuously verifies that every pallet you wrap meets your load containment standard.
Rapid IQ can be installed on virtually any stretch wrapper in about an hour. It continuously monitors the key parameters that affect both load containment and stretch film cost per pallet.
If performance changes, even suddenly, Rapid IQ immediately sends an alert via text or email to the appropriate personnel. More importantly, the alert identifies both the source of the problem and the recommended corrective action.
In addition, we provide visualized data through a portal you can access, which includes trend analysis. Using this tool, you can see wear happening in real time. Instead of reacting to disruptive unplanned downtime, maintenance can be scheduled proactively when it’s most convenient.
To further support our customers, we also have a nationwide footprint of highly qualified Field Service Engineers who can inspect, maintain, and repair stretch wrap machines.
Machine wear is inevitable. Load failures don’t have to be.
Rapid IQ is the audit tool that will ensure every pallet you wrap meets your cost and load containment standards.
Thanks for asking!