Arena Packaging: How Do I Model Pucks?
By Gail Kenny, Simulation Consultant
Published: January 23, 2017
Categories: Tips & Tricks
Sometimes, a high speed packaging line must handle products that need to be stabilized during movement because of their size, shape, or spill potential. When this situation occurs, a common solution is to place the product into a puck, or carrier, during conveyance through the line operations. However, this can present a challenge to the modeler in exactly how to represent the introduction of empty pucks to the line, marrying the product with the puck, and de-pucking the product when complete. The following example discusses how to use pucks in a 1:1 relationship to product on a line.
Introducing the Pucks:
Many times there is an established limit to the number of pucks allowed on the line, or this limit must be discovered as a result of running the simulation. The Storage module allows us to define the initial inventory available for loading the line at the start of the run. In this case, the line is being run with 270 available pucks.
The Palletizer module can then be used to introduce the pucks onto the line from the Storage. The Palletizer module is set to be of type Depalletizer in order to remove pucks from storage and place them onto the line.
Note that you will need to use the Merge module to merge the incoming pucks from puck storage with pucks that have already cycled through the line and are ready to go through the line again. Since the Merge module only accepts incoming conveyor connections, you can connect the Palletizer to a Merge with a “dummy” conveyor, a conveyor that is set to run at a high enough velocity to incur negligible time to transfer.
Marrying the Product with the Puck:
Now that empty pucks have been introduced to the line, we can marry them with product. The product is introduced to the line with a Basic Machine module specifying the rate (in cycles per minute) at which product arrives. Also, make sure the Machine Begins a Line option is checked.
Next, the product goes into an Assembly Machine, which has been connected to the Basic Machine with the Machine Link module. In order to combine a unit of product with a puck, the empty pucks must go into the same Assembly Machine. Notice that two Entry Lines have been defined and one unit is required from each line in order to make the assembly. One line is for the incoming product and the other line is for empty pucks, and they are assembled in a 1:1 relationship. Outgoing units are pucked product.
The logic for marrying the product with the puck may look something like this:
De-Pucking the Product:
The logic for de-pucking the product requires a bit more understanding of the nuances of Arena Packaging than the steps above. Because we have the puck and the product coming into the Machine married together, yet we want to essentially break them apart (a divorce, if you will), we use an Assembly Machine. We chose to use an Assembly Machine because it represents discrete, non-fluid products and it does not have capacity; the process is instantaneous and capacity is 0.
However, notice that we are using the Assembly Machine in a different way than expected. We have a single entry line specified for pucked product and are requiring only 0.5 units per assembly. Also, the cycles per minute are set at 448, which is twice the rate of the other machines in the system. Notice that this rate is the same as saying we consume 1 unit per cycle at a rate of 224 cycles per minute. The difference between the two setting definitions is the number of units produced from the Assembly Machine.
Setting the cycles per minute to 224 and the units per entry line to 1 would result in 224 assemblies leaving the Assembly Machine each minute. This doesn’t suit our purposes since we actually want to have twice that number leave the Assembly Machine: 224 units of product and 224 pucks. Therefore, we doubled the cycles per minute to 448 and only require 0.5 units per entry line to make an assembly. This results in two units leaving the Assembly Machine for every one unit consumed from the entry line.
Next, we must use the Split module to send the product to further packaging operations and the puck back to the beginning of the line. Remember to use a “dummy” conveyor to connect the Assembly Machine to the Split module.
The Split is defined as a Fixed type with 50% of incoming units taking one branch and 50% taking the other branch. A Fixed Split will always divide the product with the exact percentages you have specified. Whichever branch you decide will represent the pucks can then be merged with any pucks still being introduced to the line from the Depalletizer via another “dummy” conveyor. Your logic might end up looking something like this:
So for your next Arena Packaging model, remember “to puck, or not to puck - that is the question.”
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