Desktop Client: How does iGrafx handle more than one operator for a single step in a Lean VSM?
In the Lean Value Stream Map diagram type, iGrafx will use the number of operators that you enter for a step in its calculations of Production Time and Capacity, and essentially treats the number of operators as the number of parallel and identical operations being performed at a step.
In particular, iGrafx will calculate Production Time (also known as Cycle Time; the amount of time between pieces coming out of the step) as follows:
Production Time = Processing Time / ((100 - Defect%) * (Operators * Availability%))
In addition, because Operators is a part of Production Time, it will also affect Capacity. The calculation for the capacity of a step is:
Capacity = ((Available Time - C/O) * #Shifts * Uptime%) / Production Time
Notice that "Processing Time" is labeled in the default Lean Value Stream Map (VSM) template as total cycle time or "Total C/T". Processing Time is the overall amount of time, including any Non-Value-Add (NVA) time, that it takes to produce a single piece. Note that the Processing Time will be the same as Production Time if you have 1 operator that is 100% available to the operation, and 0% defects.
If you enter more than one operator for a step, production time is reduced and capacity is increased. This will be shown in the work balancing graph (which shows Production Time), but will NOT be shown on the timeline. The timeline is not affected because it shows Processing Time and not Production Time; each piece is still produced in the processing time entered, even if (for example) there are multiple operators each performing the exact same steps in parallel.
If work occurs in parallel by the operators, then show the number of operators that are performing the work.
Another way to think of how iGrafx handles more than one operator is to think of this field as the number of parallel operations. The assumption is that each operator is performing identical work, and thus there are identical operations. So this can be useful in handling batch processing, as it is similar to an identical operation on more than 1 piece at a time; and this can thus be thought of as a number of parallel operators all doing the same operation in synchronization. For more information about how to handle a batch in a Lean VSM (and how this relates to the Operators data field), please see "How do I properly represent a batch operation in a Lean VSM (in iGrafx)?" in our Knowledge Base.
If you have more than one operator for a step, and they are not performing the exact same work in parallel, then either:
- Break up the steps into separate steps on the VSM, showing any inventory explicitly, or
- Create a custom field. If there is data that you want to capture that is not currently shown, such as the number of operators that are not performing identical tasks, you may also create your own field of data that is user-defined and not calculated by iGrafx. Click the Setup button and click the New button to create a new field with a Lean Types choice of 'User Specified'. You could rename the iGrafx Operators field to 'Parallel Operations' and create your own 'Operators' field that gives the number of operators. You can even change the indicators on the shape to not show the operator icon, or show your own custom icon (starting in iGrafx 2011 custom indicators can be created).
You can always ask yourself how you'd represent some behavior of your Value Stream with pencil-and-paper, and that may help with how to represent it in iGrafx. In addition, if desired, you can make the diagram look however you'd like; you can create your own properties, and even export/import to/from Excel to do calculations.
Please see the iGrafx Help system (Help menu > iGrafx Help) for more information on how iGrafx performs calculations, how to export/import data, and other Lean VSM topics; from the Help menu, choose iGrafx Help. There are also Knowledge Base articles on our website for handling export/import of data from a Lean VSM, and on other Lean topics.