Before you begin
- Nested PMs are not compatible with multi-asset scheduled maintenance or event triggers.
- Nested PMs cannot be fully set up through importing and requires either partial or full manual setup.
Plans: Professional and Enterprise
Permissions: Access to scheduled maintenance
Nested planned maintenance (nested PMs) is a scheduled maintenance (SM) feature that allows you to manage an asset’s repeating tasks that can be completed together, but at different intervals. It can reduce the number of SMs and unnecessary work orders for an asset.
Nested PMs properties
Nested PMs are assigned to tasks or task groups on an SM. You can view and edit them in the Nested PMs tab:
In the example above, we have 3 nested PMs, each occurring at different time intervals and assigned to a different task group. With this setup, we have the following result:
- Every week, a work order is generated with the weekly task group
- Every 4 weeks, a work order is generated with both the weekly and 4-weekly task groups
- Every 8 weeks, it is generated with the weekly, 4-weekly, and 8-weekly task groups.
This way, each generated work order only has the appropriate task groups added for each time interval.
As shown above, nested PMs have a code, a parent, and a multiplier (aside from the PM with the greatest frequency). Here, you can also view which nested PMs will be included in the next iteration.
The following table defines each property:
| Nested PM property | Definition | Example |
| Code | The identifier that is automatically assigned to a nested PM based on the order of its creation. |
The first nested PM created on the SM is N1, the second is N2, and so on. |
| Parent | Any pre-existing nested PM that the PM uses to calculate its own interval. When creating a new nested PM, you select which PM to use as a parent. Any nested PM can be a parent; however, N1 PMs can only be a parent, and never a child. |
In the example above, N1 is the parent to all the other nested PMs.
|
| Multiplier |
A value that is set by the user and determines the time or meter reading interval of each maintenance procedure. The most frequent PM (N1) will never have a multiplier. You can use the following formula: parent’s interval x multiplier = child’s interval |
In the above example, the multiplier for N2 is 4, since its interval is 4 times longer than its parent N1 (weekly). |
| Iteration | A specific instance where the relevant trigger is set off and a work order is generated. |
Since N1 is weekly and N2 is monthly, iterations 1, 2, and 3 (the first 3 times a work order is generated) will only include N1 tasks. Iteration 4 (the fourth generated work order) will include both N1 and N2. |
Why use nested PMs?
Nested PMs should be considered when you have too many redundant work orders being generated due to overlapping SMs.
For example, an asset may have the following SMs:
- SM01, generates a work order every 500 km, has tasks A and B
- SM02, generates a work order every 1000 km, has tasks A, B, C, and D
- SM03, generates a work order every 2000 km, has tasks A, B, C, D, E, and F
At 1000 kilometers, SM01 and SM02 both generate a work order. The generated work order from SM01 is completely redundant with that of SM02, which already contains tasks A and B. At 3000 kilometers, all 3 SMs generate a work order. Here, the generated work orders from SM01 and SM02 are both redundant with SM03. An administrator must process unnecessary work orders every 2 out of 3 times SM01 is triggered.
With nested PMs, all 3 of these tasks can be consolidated on 1 SM and assigned nested PMs. Only 1 work order is ever generated at a time, and only the appropriate tasks for each interval are included on each work order (e.g. at 1000 km, tasks A, B, C, and D are included, while at 1500 km, only tasks A and B are included).
If there are multiple instances of the above situation, resulting in a considerable number of unnecessary work orders, then nested PMs may be the best option.
Limitations
Before going forward with nested PMs, consider the following:
- Nested PMs require at least partial manual setup. Creating task groups for nested PMs is a different process than that of creating them for regular SMs and requires manual configuration. It may sometimes be easier to set up nested PMs without importing instead (fully manually).
- You may not get the same level of resource planning and record-keeping with nested PMs as you would with regular SMs. For example, since multiple SMs are consolidated into a single SM, you can only have one priority level for all the work orders generated from that SM.
- Nested PMs are not compatible with multi-asset SMs or event triggers.