Minimum wait time issue in operation

[Former Member]

Dear Experts,

I have maintained the following setting is routing, but i am getting incorrect minimum wait time results in scheduling. It is getting as 2.50days instead of 4 days:

Product A

Base qty = 200 units

Operation Nos: 10, 20, 30 and 40

Operation 10 minimum wait time maintained as 24 hours

Operation 20 minimum wait time maintained as 24 hours

Operation 30 minimum wait time maintained as 24 hours

Operation 40 minimum wait time maintained as 24 hours

Refer below screen shot

[Former Member]

????????

[Former Member]

Hi,

System schedule the wait time from 0:00 to 24:00 hours in a day even if your workcenter availability for 8 hours. System considers all the week days including holidays to schedule the wait time.

Suppose if one operation finishes at end of the working time, wait time will start after that in the same day and it will continue in the next day working time.

Consider the above point and check the scheduling calculation.

Regards,

Dharma

[Former Member]

I have considered all this factor and still the results are not convincing me. If system is considering 24 hours then results should show 4 days, but it is showing at 2:50 days.

Why it is so ?

[sap_pp13]

Your WC timings now are 10:00-18:00. So for the Forward scheduling you do in the routing starting 19/11, the results are as follows:

First operation-    Setup      Process      Wait
                           19/11       21/11       23/11 18:00 till 24/11 day beginning which is 6 hours -->   6/24=0.25 days. Remaining part of 18 hrs starting 24/11 is not relevant as its a non-working day

Second operation    26/11       27/11       4/12 18:00 hrs till 5/12 18:00 hrs where 5/12 is a working day (1 day)

Third operation     6/12           14/12      17/12 18:00 hrs till 18/12 18:00 hrs where 18/12 is a working day (1 day)

Fourth operation   19/12         24/12       28/12 18:00 hrs till 29/12 day beginning which is 6 hrs 6/24 =0.25 days
Remaining part of 18 hrs starting 29/12 is not relevant as its a non-working day

So its 0.25+1+1+.25 = 2.5 days for wait time/Inter-op time.

Change your WC times to be say 11:00-19:00.
In this case the scheduling results for Interop/Wait time will show as 2.42 days.

Because in this case it will be 24-19 = 5 hrs-->5/24 will be 0.208333 approx 0.21. So it will work out to .21+1+1+.21=2.42 days.

Gradually if you make your Workcenter timings as 16:00-24:00, the scheduling result will show it as 0+1+1+0 = 2 days.

Hope the calculation is clear now.
(Easy way to follow the complete calculation will be by creating a production order with Basic order start date as 19/11 and Scheduling forwards and checking in the Operation overview -->Operation details-->Dates tab).

[Former Member]

Dear Sir,

In wait times as per the definition non-working days are also consider. Wait times are considered as 24:00 hours.

[sap_pp13]

True. Wait time is scheduled in the non-working days/time also. In the calculation above, where Wait time falls in the work day/time is highlighted (For ops 1 and 4 the wait time comes into picture for 6 hrs each respectively during work day timings) and this is considered in the scheduling calculation.

Outside of this the wait time is still scheduled. Routing scheduling using CA02 does not show all the details and that is why i said the easiest way is to create a production order for your material F-T0015/1215 and look at the details.

FYI when you try to create a production order, you will see that the wait time for First operation is between 23/11 18:00 hrs till 24/11 18:00 hrs and similarly for last operation 28/12 18:00 till 29/12 18:00 hrs.

23/11 18:00 hrs till 24/11 00:00 hrs is working and after that it is a non-work day and similar is the case for 28/12 18:00 till 29/12 00:00 hrs.

Have a look at the screenshots of the four operations and the details of scheduling for more clarity and especially the dates/times at which Wait time is scheduled across the 4 operations.