Computation order proposal date

Using a backward scheduling simulation (routing of the assembly) the latest possible start date is calculated. Lot size is the requirement quantity. Order multiples are not taken into account here.

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.

•With the Issue material with first operation setting the Processing time – Start time is the first reportable, active routing position.

•With the Issue material later setting, the Processing time – Start time is the last reportable, active routing position.

•If there is no reportable routing position, the delivery date is used as reference. If in the MRP wizard Consideration of link to routing was disabled, the start time of the work order position is used. If this was not set, the delivery date is used.

From the date computed this way, the first working day is determined according to factory calendar.

Then the Item – lead time is subtracted in calendar days, then the lead time – safety days as per configuration wizard is subtracted in work days.

If dealing with a purchase part, the Goods receipt – Idle time is also subtracted.

If the resulting date is in the past, the order recommendation date is the next work day starting from the current day.

See Order recommendation – Requirement.