Buffer Management

Key Concepts

The buffer management workbench is the primary tool used to monitor risky buffer penetration. Monitoring time buffers allows planners to focus on jobs at risk of critical delays that can affect on-time delivery and possibly starve drum resources.

The buffer management workbench view is used for three main purposes:

  1. First, identify which manufacturing orders and purchase orders are at risk concerning their various DBR buffers so that they can be expedited.
  2. Determine the level of urgency as you clarify the risk level in terms of throughput and revenue.
  3. Compare plant performance in terms of buffer penetration.

The Buffer Management view can be accessed from the Views drop-down menu found in the top right corner of the screen.

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Options: This top section can control what is shown in the graphical chart and the bottom grids. This section allows the user to focus on the information of interest. After changing the values found in this section, click on “Apply” to update the chart and grids based on the current options.

  • Plants: This section displays a list of all plants. Click on one or more plants to filter data for those specific plants.
  • Buffer Types: Buffers are used to minimize delays by accounting for possible variability in the schedule. In the buffer management view, the information shown in the bar graph can be filtered to show only the relevant types of buffers. The buffer types available are Material, Drum, Shipping, and Stock Buffers. 
    • Material: Material buffers pertain to purchase orders.
    • Drum: Drum buffers pertain to manufacturing orders.
    • Shipping: Shipping buffers pertain to manufacturing orders.
    • Stock: Stock buffers pertain to purchase orders. 
  • Warning Levels: There are four warning levels related to the amount of buffer penetration occurring. If only one warning level is checked, the chart is colored according to the selected warning level. The higher the buffer penetration, the closer the operation is to be late. 
    • Late (Red): More than 100% buffer penetration. 
    • Critical (Orange): More than 66% buffer penetration.
    • Warning (Yellow): Between 33% and 66% buffer penetration.
    • OK (Green): Less than 33% buffer penetration.

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Note: The warning level filter works in conjunction with the M.O. Penetration Type described below for manufacturing orders. The warning level is based on the level of the penetrance type specified below.

  • M.O. Penetration Type: There are two types of buffer penetration for manufacturing orders:
    • Current: This is based on the current PC time and the manufacturing order’s current status.
    • Projected: This is based on where the manufacturing order is currently scheduled.

Note: Purchase orders only have current penetration since they are not scheduled.

  • Chart Controls: These values only affect the chart, not the grids.
    • Primary/Secondary Group: These settings work together to determine how the data is displayed in the chart.
      • Primary and Secondary Values can be grouped by Plant, Buffer Type, or Warning Level.
      • If the Secondary Group option is set to “None,” then a simple graph is shown using the options specified for the Primary Group.
      • If the Secondary Group option is set to another value, those values are shown grouped within the Primary Group.

Note: If warning levels are shown as the primary group, and the second group is set to “None,” then the chart is colored in Green/Yellow/Orange/Red according to the warning level.

  • Values: This control determines what type of data is plotted along the Y-axis of the chart.
    • Throughput: The sum of the throughputs of the manufacturing order jobs. Note that if the same job appears more than once on the list, it is only counted once.
    • Revenue: The sum of the revenues for the manufacturing order jobs. Note that if the same job appears more than once on the list, it is only counted once.
    • Count: The total number of purchase orders and manufacturing orders included in the grids.
    • Item Quantity: The sum of the quantities of the manufacturing orders. Note that if the same manufacturing order appears more than once on the lists, it is counted only once.
    • Drum Work Hours: The sum of the work hours scheduled on the drums for all drum buffer manufacturing orders in the grid.

Chart: The chart provides an easy way to compare various buffer-related measures specified in the top section.

Grids: The grids section is used to view the amount of buffer penetration for each purchase order of manufacturing order to easily identify which orders are at risk of being late or causing a delay. The grids are divided into four tabs according to buffers: Material, Drum, Shipping, and Stock. Users can see current and projected penetration percentages, the warning level associated with the amount of penetration, and any additional information about the purchase order or manufacturing order. 

Buffers are used in scheduling to reduce the risk of delays due to variability. They are set on different objects based on their type, but they generally add a span of time before an item is due. Buffer penetration is calculated as a percentage based on the time the predecessor operation moves into the buffer span, which will set the warning level. 

Note: The Drum Buffers and Shipping Buffers tabs allow users to drill down into the Job/Manufacturing Order by clicking the "Open Job" button or double-clicking the row selector. 

Drum Buffers are a time span added before constrained resources (called "Drums") to avoid starving those resources and prevent reducing throughput.

Shipping buffers are added from the manufacturing order's need date to set the shipping need date. Therefore, manufacturing orders should be done before the shipping need date to avoid Shipping Buffer Penetration.