Home | Services | Simulation Modeling & Animation | Order Picking
The Challenge
To develop a simulation model of a proposed order picking system. The system contained 12 case pick zones and 2 carousel pick zones. The system did not have a high throughput requirement and therefore, the conveyor designers streamlined the conveyor system. In doing so, they were concerned that the two main bi-directional Right Angle Transfers (RATs) would be over-utilized. Additionally, each of the manual pick areas had a limited queue size. The smaller the queue size, the more case recirculations there will be. The conveyor designer decided at the last minute to simulate the system in order to verify the system concept.
The objective of the model were are follows:
- the merge and divert points on the conveyor
- the number of picking operators
- the size and divert logic into each manual pick area
- the range of order profiles which the system operated best. (Access Front End)
- Complete the model and the analysis in two weeks.
The model included the following items:
- Case Conveyor
- Carousels - 2 Pods & Pick tables
- Picking Operators
- Picking areas
Each of the 14 areas of the model could induct orders into the system. The manual areas could, however, only induct orders which did not have any carousel picking and had at least one line to pick in that particular zone. In addition, the operator of the zone would only start picking if there were four or more cases to pick into. In order to accurately model the order flow into the system, an Access database front-end was built. This front-end had an order generator which allowed the user to parameterize an order profile. The system would build the orders and store them in a database table. Every time the simulation model would induct an order, it would find one in the Access Database. If none was found, no order would be inducted.
Cases with orders assigned to them would travel to each of the pick zones. If the destination pick zone was full, it would bypass that zone and go to another zone (if any). The case would then recirculate the system until all the zones in that order were picked. The case would then be conveyed to the shipping sorter (not modeled) .
Results
The simulation results showed that the conveyor system could in-fact handle the flow of cases without congestion. However, the system operation was dependent on several factors:
- The optimal number of zones per order was less than 5. The slotting of product in each zone would help control how many zones an order had to visit.
- Each manual pick queue required at least 6 queue positions given their current order profile data.
View Animation Screen Images
NOTE: This page may take a while to load (~ 1 min at 28.8K), but it is well worth it.