Throughput is a system property
Conveyor throughput is the number of items, or the amount of material, that passes a point in a given time. It is easy to assume that a faster belt means more throughput, but in practice the output of a line is set by its weakest link. A conveyor can run at full speed all day and still deliver less than hoped if items arrive unevenly, stop at a merge, or wait for a downstream machine.
This article is about getting more from a conveyor system that already exists, through layout, speed matching and upkeep. Choosing the type of conveyor is a separate subject, covered under conveyor types.
Start by measuring
Before changing anything, find out what the line actually does. Useful, low-cost measurements include:
- How many items pass a chosen point per hour, over several different shifts.
- How often and for how long the line stops, and why.
- Where items queue up, and where gaps appear.
- Which machine upstream or downstream sets the pace.
Even simple counts with a stopwatch or a basic counter can show whether the problem is the conveyor or something around it. Without this step, money is easily spent on the wrong place. Wider tools for this kind of analysis fall under industrial data analytics.
Match speeds along the line
Two conveyors in series that run at different speeds cause trouble. If the downstream one is slower, items bunch up and can jam or fall off. If it is faster, gaps open between items, which may be wanted or may waste capacity.
Some general principles:
- Match the feed rate of each section to what the next one can accept.
- Where spacing matters, such as feeding a scanner, labeler or sorter, a slightly faster section can be used to separate items, with the designer making sure the spacing is steady.
- Where one machine runs slower than the line around it, the slow machine controls the whole output, and speeding up conveyors will not fix it.
Controlling motor speed through variable speed drives allows adjustment without mechanical changes, which also lets a line be tuned as products change.
Layout matters
How the conveyor path is arranged can limit performance.
- Merges and diverts. Where several lines join into one, items compete for space. Orderly merging, with sensors and controlled release, helps prevent collisions and jams.
- Curves and transfers. Transfers between conveyors are common places for jams, especially with small or unstable items. Smooth, well-aligned transfer points reduce stoppages.
- Length and buffering. A stretch of accumulation conveyor between two machines acts as a buffer, so a brief stop in one does not immediately stop the other. Too little buffer makes the line fragile. Too much takes space and adds handling.
- Straight, short paths. Unnecessary detours add cost and failure points. But layout also depends on space, access and safety, so ideal paths are not always possible.
The overall flow of material through a building is discussed under conveyor material flow.
Use accumulation and zoning sensibly
Zoned accumulation lets items queue without touching each other, which protects products and keeps the line moving when something downstream pauses. Sensors detect when a zone is occupied, and a controller decides when to release. This is a classic use of sensors and logic working together, as covered in the basics of industrial automation. Poorly placed or dirty sensors are a frequent cause of false stops, so they deserve attention.
Keep loads within design
Overloaded or badly positioned items cause belt wander, motor strain and uneven wear. Keeping product size, weight and spacing within what the conveyor was designed for is one of the cheapest efficiency measures. Checking with the manufacturer’s documentation before changing the product is a sensible habit.
Maintenance protects throughput
Many conveyor stoppages come from ordinary wear: worn rollers, loose or stretched belts, dry or worn chain, misaligned components, failing bearings and dirty sensors. A planned conveyor maintenance routine with regular conveyor inspections typically costs less than the unplanned downtime it prevents. Common items to check are:
- Belt tracking and tension.
- Roller condition and free rotation.
- Chain lubrication and stretch.
- Gearbox and motor condition, including unusual noise or heat.
- Guards, emergency stops and pull cords.
- Sensors and their cleanliness.
Where bearing trouble is common, bearing wear patterns offer clues to causes. Condition-based methods, such as vibration or temperature monitoring, are sometimes used to give early warning, which is part of predictive maintenance.
Servicing must follow the manufacturer’s instructions, use lockout tagout, and be done by trained people, because conveyors can start unexpectedly and have many pinch points.
Beware of false economies
It is tempting to run a conveyor faster to catch up on a backlog. Higher speed can increase wear, noise, product damage and the chance of jams, and the gain is lost if the bottleneck is elsewhere. Sometimes the best fix is a smoother flow at a moderate speed.
A hypothetical example
Imagine a packing line, with made-up figures for illustration. A conveyor delivers cartons to a taping machine. The taper can handle one carton every 4 seconds, which is 15 per minute. Cartons arrive in bursts and sometimes bunch at a merge, so the taper stands idle between bursts and the line averages 11 cartons per minute. Adding a short accumulation section before the taper and smoothing the merge lets cartons arrive steadily, and the line moves closer to 15 per minute. The belt speed never changed; the improvement came from steadier supply. In this made-up case, the ceiling of 15 per minute is set by the taper, and only a different taping method would raise it.
This article is general information, not engineering advice.