Reduction strategy

What is Reduction Strategy Reduction strategy is applied to an Order when lead time(Scheduled dates) of an order is greater than basic dates in order. Reduction strategy reduce the lead time of an order tries to shorten the lead time by applying reduction measures.

Reduction strategy Before getting into details of reduction strategy, we better understand how scheduling is happening in SAP. Please refer the previous tutorial “PP Scheduling”. https://sap-certification.info/pp/sap-pp-training/sap-pp-scheduling/ When system try to schedule a Production order, the following dates are determined.

Basic Start date Basic finish dates Schedule Start date Schedule Start time Schedule Finish date Schedule Finish time In backward scheduling system calculates Basic finish date from the requirement date

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Requirement date/Basic Finish date Schedule Finish date/time Schedule Start date/time Basic Start date

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Total Operation lead time = Inter operation times (Queue+Wait+Move) + Activity times in all Operations.

Queue time is defined in Work center and routing also.

1. Standard Queue time 2. Minimum Queue time Wait time and Move time are defined in Routing operation detail.

1. Standard Move time and Minimum Move time 2. Standard Wait time and Minimum wait time

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The reason is wait time is related to the process, for example drying time. After certain time before moving the material to next work station the material must be dried for 30 mins. This is known as wait time which cannot minimize or Ignore.

Basic Start dates and finish dates are calculated based on material master data.

1. Basic Start date 2. Basic Finish date

Material Mater scheduling data

When we create Production Order

System calculates Basic start date as follow: Basic start date = Basic finish date – (GR Processing time (1 day) + Inhouse time (3 days)) = 12-DEC-2017 – (1 + 3) 12-DEC-2017 – 4 = 08-Dec-2017 Similarly, Schedule start date and finish dates are calculated from Basic finish date.

Schedule Finish date = Basic finish date - (GR Processing time + Schedule after production) = 12-Dec-2017 – (1 +0) = 11-DEC-2017 Schedule Start date = Schedule Finish date – (Total operations lead time + Float before production)

When schedule start date is calculated before Basic start date, system try to perform below scheduling approach and try to adopt schedule dates with in Basic dates.

1. After today scheduling also if system find schedule dates not lies within basic dates, it applies minimum time (wait, queue and move time) from routing.

2. After scheduling with minimum inter operation time also if system find schedule finish dates lies after basic finish dates, it try to apply “Reduction strategy” in 6 steps.

3. After Today scheduling: When schedule start date lies before basic start date, system start today scheduling i.e. It starts Basic start date as current date and try to schedule and calculated basic finish date and schedule dates.

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We can define our own reduction strategy in customization. In all 6 steps system try to reduce the Inter operation time gradually except “Wait time” in order to adopt the schedule dates within basic dates. As explained previously Wait time can not be reduced as it is related to “Process”. The reason is wait time cannot be reduced is as it is related to the process, for example drying time. After certain time before moving the material to next work station the material must be dried for 30 mins.

Overlap time and Minimum send ahead quantity: System also try to reduce the operation time by means of overlap time which means, next operation starts before the previous operation has finished when minimum send ahead quantity is produced. The lead time of an operation also reduced by splitting the operation defined in work center. (number of splits) Let we look into the below reduction strategy defined in IMG.

Reduction strategy in IMG

Reduction strategy assignment is Routing Operation.

As per this reduction strategy ,it applies reduction level still it find schedule dates are lies within basic dates.

Reduction Level Reduction 1

reduce the queue time by 30 % and reschedule.

Reduction 2

reduce the queue time by 50 % and completely reduce Move time then reschedule.

Reduction 3

reduce the queue time by 70 % , completely reduce Move time and applies operation split then reschedule.

Reduction 4

reduce the queue time by 100 % , completely reduce Move time and applies operation over lap then reschedule. reduce the queue time by 100 % , completely reduce Move time ,applies operation overlap and also applied operation split then reschedule.

Reduction 5

Even after reduction strategy also if system unable to fit schedule dates within basic dates, It gives scheduling log and schedule the order as per actual dates.

Example of reduction strategy: This example is explained without screen shots as some of the screens may be difficult to understand for beginners.

Let say for manufacturing a Product “A” produced 100 KG/hour MRP 2 view of material master.

Field In house Production time GR processing time Schedule margin Key

Value 2 1 FBP – 1 Day FAP – 1 Day Release period 1 day

Unit of Measure Days Days day

Time 60 24 12

Unit Min/ 100 KG Hours Hours

Settings in Routing: Field Machine time Standard Queue time Minimum Queue time

Standard Wait time Minimum wait time Standard Move time Minimum wait time  

24 18 30 10

Hours Hours Mins Mins

Let say we have only one resource used to produce Product ‘A’ available all days(working day) and its available time (capacity) is - 24 Hours/day.

When we create Order with requirement dates of 30-JAN-2018 for 3000 KG for the product ‘A’ system calculates dates as follows.

Basic Dates calculation Basic Finish date = Requirement date = 30-Jan-2018 Basic Start date = Basic finish date – (GR processing time+ Inhouse production time) = 29-Jan-2018 – ( 2+1) = 26-Jan-2018

Schedule dates calculation:

Schedule Finish date

= Basic Finish dates – (Float after production) = 30-Jan-2018 – 1 day = 29-Jan-2018 at 00:00 hours

Schedule Start date operation time) Total operation time

= Schedule finish date – (Total operation time + Float before production + Inter = (60 mins /100 Kg) * 3000 Kg = 1800 mins

Inter operation time (Considering standard time) = Queue + Wait+ Move = 24 hours + 24 hours + 30 mins = 2910 mins.

Float before production = 1 day = 24 hours = 1440 mins

Schedule Start date

= Basic finish date – (1800 + 1440 + 2910) Basic finish date – 6150 mins = 4 days 6 hours 30 min

= 29-Jan-2018 00:00 hours - 4 days 6 hours 30 min = 25-Jan-2018 18:30 hours Here schedule start date is not lies between Basic dates. So system try to apply minimum Inter operation times instead of standard time.

Inter operation time (Minimum time) = Queue + Wait+ Move = 12 hours + 18 hours + 10 mins = 1810 mins.

Schedule Start date

= Basic finish date – (1800 + 1440 + 1810) 29-Jan-2018 – ( 3 days 12 hours 10 minutes ) = 25 Jan-2018 11:50 hh:mm

After using of minimum interoperation time also schedule start dates not lies between Basic dates, so here system will try to apply reduction strategy level by level.

Reduction Levels in Reduction strategy.

For every reduction step the system will reschedule the order. When system find schedule start dates lies within basic dates, it stops reduction and schedule the order.