Using a backward scheduling simulation (routing of the assembly) the latest possible start date is calculated for the complete order related item structure. This corresponds to the start date of the sub-assembly which must be produced first. Lot size is the requirement quantity.
Important: The order multiples, lot size, existing time reservations on resources are not taken into account during calculation.
If calculation of the lead time was disabled, the item lead time is used as reference. The lead time is the sum of a single lead times of the order related sub-assemblies.
Example 1: Lot size and setup time.
Assembly A with operation sequence A1, 10 days setup time, lot size is 10.
Company calendar: Every day is a working day.
Customer order, delivery date 30.12.
Pos 1 100 pieces: Calculated: 10 days, start 20.12.
Pos 2 100 pieces: Calculated: 10 days, start 20.12.
Pos 3 200 pieces: Calculated: 10 days, start 20.12.
Example 2: Lot size and time for processing.
Assembly A with operation sequence A1, time for processing 1 hr/piece, lot size is 10.
Company calendar: Every day is a working day.
Resource has 1x10 hrs/day.
100 pieces = 10 days
Customer order, delivery date 30.12.
Pos 1 100 pieces: Calculated: 10 days, start 20.12.
Pos 2 100 pieces: Calculated: 10 days, start 20.12.
Pos 3 200 pieces: Calculated: 20 days, start 10.12
Apparently, there is a problem, there is only one single resource, capacity limits and time reservations are not taken into consideration. This problem can only be avoided by the production orders being created as planned orders. Using APS, planned orders can be correctly scheduled and necessary resource times can be reserved.
|