Two Lanes, One Sorter, and No Room to Slow Down
A high-speed MDR sorter downstream needed a single, cleanly singulated stream of cartons, arriving with a consistent gap, at a rate the building's volume demanded. The supply came from two separate lanes.
The conventional way to solve this is to meter: stop one lane while the other releases, then swap. It works, and it is slow. Every stop is throughput you do not get back, every restart is an opportunity for product to shift, and the rate the sorter can achieve gets capped by the merge feeding it rather than by the sorter itself. The other common outcome is worse: a merge that runs continuously but produces inconsistent gaps, so the scanner no-reads and the sorter mis-sorts, and someone stands at the merge all shift clearing the results.
The engineering approach
The merge was solved in logic rather than mechanically. Instead of a fixed release timer, the PLC tracks what is actually present on both lanes and calculates each release so the carton is placed into a gap that already exists in the combined stream, the way two lanes of traffic zipper together at speed. Neither lane has to stop to make room.
- Dynamic gapping rather than static timing, so the release is computed from real product positions instead of an assumed carton length.
- Lane priority and sequencing that keeps both lanes flowing rather than starving one behind the other.
- Gap sized to the downstream requirement, tight enough not to waste throughput, wide enough for a clean barcode read and a clean divert window.
- Zone-level diagnostics so that when something does go wrong, the fault names the zone and the device rather than announcing that the merge is unhappy.
- Logic written and simulated before commissioning, so the first time the sequence ran was not in front of the operations team.
The result
The merge runs at over 80 cartons per minute in production, combining two lanes into one continuous singulated stream with zero stops to meter and no operator stationed at the merge to manage it. It supplies the volume being sorted on the high-speed MDR sorter behind it.
The number that matters is not the peak. It is that the rate is sustained, and that recovery after a normal minor jam does not cost a minute of throughput every time.
Why this is the hard part of a conveyor project
Steel and rollers can be bought from a hundred vendors. Cutting and forming are processes many good shops perform well. The engineering that decides what to cut, and the logic that keeps 80 cartons a minute singulated and correctly gapped, is not something you can order. That is why controls and commissioning are the two steps Sunshine State Automation never subcontracts.