As any good production scheduler will tell you, figuring out what capacity a plant really has and when it will be available can be a bit like trying to pick the best slot machine in a casino. You’ve got a pretty good idea how it’s going to go but sometimes it’s great and other times it’s a disaster. The variables that can affect plant capacity are numerous and wide ranging depending on the industry. Everything from staffing to ambient temperature to supply chain to equipment stability can and will affect capacity. So the best that most systems can do is provide a framework for building a capacity plan. This blog discusses 2 major areas to help with the planning process: Shop Calendars, work/machine center settings and routings.
Shop calendars are designed to provide a picture to NAV as to when production will be operating. In order to properly calculate capacity and completion dates, shop calendars must be set up. In the search bar type in “shop calendars”. Select the Administration options. NAV will display the following:
You can create as many shop calendars as you will need. In some cases, part of a plant will run 2 shifts and part will run 1 shift. You will add the proper calendar code to the work center that utilizes the appropriate calendar.
Once you have created the proper shop calendar master record you will need to enter the working days for each calendar. Click on the “Working Day’s” icon in the ribbon. NAV will display the following screen:
Enter the time range for each day. This specifies when the shop will be working during that time. The days listed here are for the shop calendar that you selected earlier. They are specific to that calendar. You will need to enter days for each calendar you plan to use.
Holidays can be entered by selecting the “holiday Icon” from the ribbon on the shop calendar screen. This allows you to tell NAV when the plant will not be working and for how long.
Work Centers will utilize the shop calendars for scheduling and capacity calculations. To assign a shop calendar to work center, open the work center card and in the scheduling fast tab select the proper calendar.
After applying the proper shop calendar code, select the “Calculate work center Calendar” from the ribbon on the work center list. Enter the date range you wish to create the calendar for and click ok. This will create daily schedules for the work center. The time unit scheduled will be based on the “unit of measure code” selected on the work center. While it defaults to “minutes”, many companies find it is easier to work in “hours”.
You can view the Work Center calendar by clicking on the “Calendar” icon on the ribbon on the work center card. The “absence” icon will show you when the work center will not be operational. Clicking on the “matrix” icon will show the detail time for each day.
Machine centers are part of a work center. Their calendars will be built from the work center calendar created in the previous step. You can view a machine center calendar by clicking on the “calendar” icon in the Ribbon on the machine center card. Clicking on the “matrix” icon will show the detail time for each day.
Capacity and Resource Constraints
In Dynamics NAV all capacites are set up as infinite by default. For a work center the calculation for capacity is calculated based on: the number of resources x the capacity of the shop calendar code x the work center capacity x efficiency / 100
However, work centers and machine centers can be set with a finite load where the center may have limited resources and create a bottle neck. In the machine center and work center cards there is a scheduling fast tab which allows for control of the constraint.
The capacity field represents the number of concurrent resources in the machine center. A capacity of 1 is used for a constrained resource. The efficiency field represents the percentage of time that actually will be producing output. The queue time fields allow for time to move product from one work center to another and have it wait until capacity is open or time for finishing a process. It is important to note that the fields listed above will not be used if the consolidated calendar field is checked.
There are 3 good reports which provide basic work center load and capacity information. The Work Center List will allow for a basic overview of the capacity for each work center. The Work Center Load provides a breakdown of current load on a work center for a given date range. The Work Center Load/Bar report shows capacity by work center and production order. This is the most detailed report for current production capacity.
There are several 3rd party scheduling systems which utilize the capacity settings in NAV to software which can help companies schedule production orders with a good GUI interface. Most of them allow for a “drag and drop” interface but all will still look at NAV to provide the work orders and basic capacity information. Proper implementation of the capacity fields will provide a good road map for scheduling production and work.
While scheduling is a very dynamic process and can take a lot of time, the proper set up is helpful. Reviewing actual capacity verses project capacity is important to do at least once a year. As companies change, add new equipment, add staff and see sales fluctuate, you need to review your settings to make sure they are providing you with the proper information.
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