Minimizing the number of stations (called Type I balance) requires the user to specify a Takt time in order to determine which tasks get assigned to each stations. In this situation, ProBalance tries to minimize the number of stations required for the available list of tasks, while ensuring that the precedence relationship is maintained.
Steps to create a Type I Line Balance
| 1. | After defining task, resource, and model information, save the scenario and click on the "Balancing Station View" under the view option. A cell phone example scenario is provided in this manual and will be referenced in this Type I line balance section. To load this scenario data click on “File => Open Scenario” and then click Cellphone.xml. |
2. Next go to the Balance Station View and click on the "Auto Balance" icon in the menu bar.
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3. |
The auto balance option screen will appear. Select the balance type as "Minimize number of stations" and select Weighted Average Balance. |
4. |
Next provide the desired Takt time and click OK. If using the cell phone scenario, type in 20 as the desired Takt time.
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5. |
The line balance graph below shows that five stations were needed for the Takt time of 20 for the cell phone example. Below the figure is a list of details to notice in the generated line balance. |
1. |
Station 1 contains only two tasks, T01 and T02. If the next task in the precedence graph was added to this station, it would exceed the user defined Takt time. Also note that there is no resource violation in this station. Fixture01 was required for task T01 and is present at station ST01. |
2. |
Station 2 contains an option activity T04 for models M03 and M04. Note how the graph displays a larger time for both of these models due to the extra activity required. It is also important to notice the resource violation due to the absence of the required soldering gun. |
3. |
Station 3 contains a monumental resource violation. Fixture02 is not available at station ST03. The user can rebalance the line and this time check the monumental resource box to ensure no monumental resource violations occur in the generated line balance. To view this in the cell phone example, click on the following link: monumental resources |
4. |
Station 4 has times exceeding Takt time for models M02 and M04. However this is not a problem since the average time is still below the set Takt time. This is the advantage of using the weighted average algorithm. Even though a few models exceed Takt time, the station on average is below. |
6. |
Next balance the line again, but this time select the peak model balance algorithm. Again, use 20 as the Takt time value. |
7. |
The line balance graph shows that 5 stations were again needed. Below the figure is a list of details to notice in the peak model balance output.
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1. |
The task assignments for station ST01, ST02 and ST03 are identical to those in the weighted average balance. |
2. |
Station 4 does not contain as many tasks as it did in the weighted average balance. This is because the peak model logic does not allow any models being produced in a single station to contain a number of tasks which total time exceeds the set Takt time. The weighted average logic on the other hand considers it acceptable as long as the average time for the station is below Takt time. In this case, task T11 (attaching antenna) was moved to station ST05. |
8. |
Users have the option to reassign work after the line balance has been generated. Reference the Reassign Work section of this manual for more details. |