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The Challenge
To develop a simulation model of a proposed loading and unloading dock operation for a large bakery in the Chicagoland area. The proposed system would provide a means to load pallets of bread from the bread making lines onto trucks and unload stacks of empty pallets from the trucks to the palletizing machines. The system needed to be sized to handle the high volume of traffic during the early morning bread deliveries. Additionally, the system was to be installed into an existing system with minimal interruptions to the work inp process.
The objective of the model were are follows:
- the AGVS system layout
- the number of AGV vehicles required
- the best number of truck docks
- the number of buffer lanes in each sorter
- expected truck load and unload time
The model included the following items:
- Automated Guided Vehicles (AGVS)
- Semi-Trailers
- Palletizing Equipment
- Stackers and DeStackers
Truck unloading consisted of removing stacks of empty plastic trays from the inbound trucks to the bread processing lines. The loading was from the bread palletizing operation on two separate floors.
Trays were unloaded from the trucks and taken to a depalletizing operation. The singulated trays were placed on a conveyor run through a tray dump and a tray wash system. The trays were then queues on the conveyor to wait to be loaded with loaves of bread from one of several bread lines. Each bread line could be running a different type of bread. The loaded trays were then brought to a queuing buffer with several sort lanes. The lane was dynamically assigned a bread type. When enough bread of single type was present in a lane to complete one stack of bread, the lane was closed and the pallets were released into a single stream to the palletizing operation. Once the trays were palletized, an AGV was requested to take the pallet to the destination truck.
Results
It was determined through simulation that three AGV vehicles would be required.
One dedicated to unloading trucks, and two dedicated to loading trucks.
The AGV system was very simple, consisting of a single backbone running along
10 dock doors. With only three AGV's and dedicating them to specific areas,
network blockages were eliminated. The sorting buffers each required 6 lanes.
The simulation results showed that 5 lanes were actually required, however,
the number of lanes is dependant on the bread mix schedule. Therefore, the
teams recommendation was to add a sixth lane for future contingency.
View Animation Screen Images
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