A stop-on-detect system stops the conveyor and raises an alarm when inspection identifies a failed product. The item is removed under a defined operator procedure before the line can restart. It can suit heavy, awkward or slow-moving products, but it is not a substitute for automatic rejection where continuous high-throughput operation or secure unattended removal is required.
A deliberate reject strategy
How does stop-on-detect rejection work?
The inspection system sends a fail signal to the conveyor controls. Instead of firing an ejector, the system brings product movement to a controlled stop and alerts the operator. The failed product is identified and removed before an authorised reset permits production to resume.
The approach can be appropriate where a pack is too heavy, unstable or awkward for a conventional pusher, air blast or flap, or where the production rate is low enough that a short interruption is acceptable. The complete method must be assessed against the process risk and site procedure.
Preventing the wrong product being removed
A stop signal alone does not identify which pack failed. The line layout, product tracking and stopping distance must leave the suspect product in a clear, controlled position. An indicator, HMI message or illuminated zone can support identification, while access controls and reset logic reduce the chance of an incorrect pack remaining on the line.
If products can coast, accumulate or move after the stop command, the tracking strategy must account for that movement. The procedure should also define what happens to adjacent products within the affected inspection window.
Interlocks, alarms and restart conditions
Typical monitored conditions can include conveyor stopped status, guarded access, removal confirmation, operator acknowledgement and reset from a designated location. The line should not restart merely because an alarm has been silenced.
Oxford Vision Systems can review how the stop-on-detect sequence interfaces with existing inspection equipment, upstream machines and downstream conveyors. Restart behaviour, retained product data and safe recovery after power loss are agreed during the controls review.
When automatic rejection is the better choice
Continuous lines, unattended processes and applications requiring secure containment may need automatic physical rejection with independent verification. A product trial and risk review help decide whether stop-on-detect is a proportionate solution or whether a pusher, sweep, diverter or powered transfer is needed.
Key project considerations
- Heavy or awkward packaged products
- Low-rate production lines
- Limited reject-side space
- Manual controlled removal
- Alarm and HMI identification
- Interlocked restart sequence