Conveyor Jam Detection and Prevention: How It Works

For a musician, jamming with other musicians is fun because it means to “improvise and create music together.” Unfortunately, warehouse conveyor operators know a different kind of “jamming” that is definitely not fun. Conveyor jams happen when products become stuck in the conveyor system. You don’t want jams, because they create warehouse headaches like system shutdowns, delivery delays, and expensive equipment damage.

The Condition Monitoring & Reliability (CM&R) Group helps managers keep warehouse conveyor systems running smoothly, and the best way to do that is through conveyor jam detection and prevention systems. But what are these systems, and how do they work? First, let’s look at the three main types of conveyor jams: overloading, incorrect dimensions, and merge points.

3 Types of Conveyor Jams

Overloading simply means too many packages move through the system at one time, more than the system was designed to handle. The packages and products build up, which leads to jams.

Out-of-spec products (incorrect dimensions) are packages that are much larger or smaller than the conveyor system was designed to handle. Packages that are too large don’t fit properly and get stuck, while packages that are too small can fall through cracks. Products without flat, continuous bottoms can also cause issues, for example, a “canoe” bottom where the flaps are not flat.

No matter how advanced the conveyor system’s design is, running packages through a system it wasn’t built for will eventually cause jams.

Merge points are locations where outlet conveyors feed into the main line. Ideally, the system waits for gaps in the main line before adding a package from the outlet. If the timing or control systems are off, the system sends packages into the merge points at the same time as packages from the main line, causing jams at the merge points or further down the line.

Conveyor jam detection and prevention systems work together to catch these issues during or even before a jam occurs. Let’s take a closer look.

Data Systems and Singulation Flow Monitoring

Data systems, such as singulation flow monitoring, use predictive analytics to track conveyor speed, dimensions, and flow. Flow is the number of packages the system can handle per unit time; for example, 25 packages per minute. The goal of these systems is singulation flow.

Singulation is a single stream of packages on the conveyor at regular intervals, rather than packages stacked on top of each other, side by side, or spread out with massive gaps. Data systems use technologies such as vision sensors, photoelectric sensors, and motor monitors to monitor the conveyor’s speed, dimensions, and flow.

Photo eyes and zero-pressure accumulation

Photo eyes can monitor different zones to detect large gaps between packages or indicate where packages are piling up. This is called zero-pressure accumulation: your system should be designed with predictable time and distance intervals between each item to keep the flow smooth. Conveyor monitoring makes sure those flow intervals hold.

Sensors for out-of-dimension packages

Sensors can detect packages that are out of dimension and monitor them in two ways.

First, you can set a sensor just above the height of the system’s tallest package. Properly sized packages never reach the sensor, so it detects nothing. If a larger-than-normal package enters the system, it crosses the sensor’s beam and sends an alert.

Second, you can set the sensor at product height so it “sees” every package that passes. If a long gap passes with no product, the sensor detects the absence and triggers an alert. Which setup to use depends on the individual warehouse and its product sizes.

Conveyor motor monitoring

Conveyor motor monitors detect changes in temperature (a motor getting hotter) or energy current (a rise in power) to flag potential issues. During a jam, the motor works harder, which generates heat and draws more electricity to move items along, and that increase triggers an alert. This kind of condition monitoring is a core part of predictive maintenance for conveyor systems.

Root Cause Detection

Jams often occur in the “downstream” part of the system, but the root cause may sit farther back, or “upstream.” Video cameras with wide overviews can capture where the jam originally started, which helps when the problem is a merge point, but you don’t know which one.

You can also find the root cause by running a simulation or emulation analysis. This is useful when you want to introduce a new product size into an existing system. Digital twin software models the existing system to see whether it can handle new dimensions (x/y) and to find choke points that you can correct in advance.

Innovative Materials

Specialized materials matched to the products on the conveyor can also help prevent jams. For example, silicon rollers reduce friction so items don’t stick, while rubber, canvas, or plastic materials keep items from slipping. A CM&R industry member can help you find the right materials for your system, and the right ongoing conveyor maintenance plan to keep them performing.

Keep Your Warehouse Running

Conveyor jam detection and prevention systems do more than solve jams. They make your warehouse more efficient and cost-effective. Fixing jams quickly when they happen, or preventing them in the first place, helps warehouses avoid costly shutdowns and equipment repairs, and keeps customers happy by shortening or avoiding delays. When paired with regular conveyor belt maintenance, these systems protect both uptime and equipment lifespan.

Watch the short video above to learn more, then visit MHI’s Solutions Community to find a CM&R provider who can help you prevent a jam session in your warehouse.

Contributor: Nathan Hibbs, Beckhoff Automation

Reviewed by Solutions Community Condition Monitoring & Reliability Committee

For more information about the Solutions Community: mhi.org/solutionscommunity

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