Calculation of the Pull Interval 
Use
You can use the pull interval to define the following:
The time interval between the transfers of requirements from the demand source (consumer) to the supply source (supplier)
The time interval between the delivery timespots at which the supplier delivers material to the consumer
The pull interval is used as a buffer in the calculation of a control cycle. It increases the number of kanban containers in a control cycle.
Integration
The pull interval always relates to the working times (factory calendar, shift grouping, and shift sequence) that you have specified for the consumer. If you have not defined any working times for the consumer, the system uses the working times of the supplier.
Prerequisites
You have specified the pull interval in the calculation profile , in the production supply area (PSA) , or in control cycle maintenance . If you have specified the pull interval multiple times (at different points), the system takes it into account with the following priorities:
1: Control cycle maintenance
2: PSA
3: Calculation profile
You can specify the pull interval in workdays or in hours and minutes . If you specify both values, the system uses the specification in hours and minutes for the kanban calculation.
Features
You can use the pull interval if the supplier cannot deliver the required material on a continual basisbut only at certain points in time (at the end of a pull interval). In this case, the replenishment lead time is rounded up to a multiple of the pull interval.
If the consumer’s requirements are made known at certain points in time only, an additional pull interval is likewise needed.
Example
Example 1
The replenishment lead time is 1 h. The pull interval is to be 4 h .
Because the replenishment lead time is less than the pull interval, the system calculates twice the pull interval for the replenishment lead time with pull interval.
2*PI = 2*4h= 8h
Example 2
The replenishment lead time is 5 h. The pull interval is to be 4 h .
Because the replenishment lead time exceeds the pull interval, the system calculates as follows:
3* PI = 3*4h= 12 h
If you are using sub-day scheduling in the kanban calculation and have specified the pull interval in days, the system converts the pull interval into hours taking the shift sequence at the supply source into account.
Example
You have specified 1 day as the pull interval. The supply source works on a 1-shift basis. The system converts the day into 8 hours. In the case of a 2-shift system, the system converts the day into 16 hours.
Example
Example 1: Pull Interval in Days
The person who replenishes the PSA arrives at 8 a.m. each day to pick up empty kanbans (kanban cards) and deliver full ones. In this case, the pull interval amounts to 1 day.
Example 2: Pull Interval in Hours
Your production works on a one-shift basis from 8.00 a.m until 16.00 p.m. This information is defined in the shift sequence.
The person who replenishes the PSA arrives at 8 a.m. and 12 noon each day to pick up empty kanbans (kanban cards) and deliver full ones. In this case, the pull interval amounts to 4 hours.
Example 3: Calculation Results With and Without Pull Interval
In the following, the results of the kanban calculation with and without consideration of the pull interval amounting to 4 hours is illustrated with the use of sub-day scheduling.
Daily requirement: 100 pc
Quantity per kanban: 10 pc
Hours of production per day: 8 h
Average requirement per hour: 12.5 pc
Pull interval: 4 h
Simplified Formula for Kanban Calculation in Case of Sub-Day Scheduling:
Number of kanban containers = ((replenishment lead time * average requirement per hour)/quantity per kanban)
In the case of values with places after the decimal point, the calculated number of kanban containers is always rounded up to the next integer
Replenishment lead time (in hours) |
Number of kanban containers |
Replenishment lead time with PI |
Number of kanban containers (with PI) |
1.0 |
2 |
8.0 |
10 |
2.0 |
3 |
8.0 |
10 |
3.0 |
4 |
8.0 |
10 |
4.0 |
5 |
8.0 |
10 |
5.0 |
7 |
12.0 |
15 |
6.0 |
8 |
12.0 |
15 |
7.0 |
9 |
12.0 |
15 |
8.0 |
10 |
12.0 |
15 |
9.0 |
12 |
16.0 |
20 |
10.0 |
13 |
16.0 |
20 |
11.0 |
14 |
16.0 |
20 |
12.0 |
15 |
16.0 |
20 |
As you can see from the table, a replenishment lead time of 4 hours leads to a number of kanban containers amounting to 5 (that is, 50 pc of the material). This quantity suffices to cover half the daily requirement. With a pull interval of 4 hours, 10 kanban containers are needed. With 10 kanban containers, you can cover the requirements of two full pull intervals.