Flat sorters come in all shapes and sizes. However, some guiding principles of sorting transcend the differences and apply to all. One of these principles is adding multiple infeed positions to increase the overall througput of a sorter.
A sorter’s throughput is limited by the speed and size of the trays. This is often translated to the number of trays per hour. With one infeed zone, the maximum amount of products that can be inserted equals the number of trays per hour. But by increasing the number of infeed positions, the throughput can be increased to double the number of trays per hour.
Scenario 1: 12.000 items per hour
To explain this, we will use our slide tray sorter as an example. This sorter can reach a maximum of 12.000 products per hour with one infeed zone. However, when adding an extra infeed the throughput will increase. Some of the trays will be emptied before reaching infeed 2. This allows operators to insert another product in the same round.
Scenario 2: 15.960 items per hour
However, when adding an extra infeed the throughput will increase. Some of the trays will be emptied before reaching infeed 2. This allows operators to insert another product in the same round. We use the capacity factor to calculate the additional throughput. With this set-up, we use factor 1.33 to estimate the expected throughput. Instead of 12.000 products per hour, the throughput is increased to 15.960 products per hour.
But as mentioned earlier, this factor can be increased even more. To reach a capacity factor of 2, we should dive deeper into the art of batch picking. The first two scenarios were based on one batch pick that was randomly distributed to the two infeed positions. To reach more throughput, we should create a more efficient distribution of our batch.
Scenario 3: 24.000 items per hour
Capacity factor 2 can be reached by picking in separate batches. All items picked for infeed 1 will be sorted before reaching infeed 2. All trays enter this infeed empty and available for induction. Items from infeed 2 will be sorted before reaching infeed 1.
Single SKU scenario
When working with boxes that contain single SKU’s, an alternative solution should be considered to prevent inefficient picking or a high amount of opened boxes with leftover items. A conveyor carrousel that connects the infeed zones is a proven solution for this scenario. When a single SKU is required for both infeed zones, its box can be opened at one infeed and the leftovers can be forwarded to the second infeed.
Scenario 4: 24.000 items per hour
By using conveyors as a carousel, items can be allocated to the correct station and single SKU boxes can be transported easily between zones. Capacity factor 2 applies to this scenario as well. This solution has been successfully applied to our installation at fashion brand Jennyfer.