Planning calendar is use at material level and you can assign this in MRP2 view along with lot size procedure (period lot size according to planning calender PK).
By doing this procurement proposals will be created according to the periods defined in the planning calendar. for example period start date in Friday in the planning calendar and periods are weekly then during MRP for all requirements which falls under this weeks will cumulated and MRP will create single procurement proposal (planned order) on Friday for this total weeks requirements.
Create one Planning calendar in MD25 specifying each period as per your requirement.
Maintain Lot size as PK (MRP 1 view) and Planning calendar(MRP 2 view) in material master.
After MRP system will group all the requirements in each period and creates PR according to the planning calender.
The planning calendar can be created using transaction MD25.
For Eg: If you need to plan the requirements only on monday of every week,then for weekdays option monday is set & the valid from & to dates are given.
Then this planning calendar is assigned to the material master , a corresponding lot size (to consider the planning calendar) is entered in the material master.
When MRP is run , the requirements in a week are planned only monday.
Planning calender is used to define flexible periods for a period lot size for MPS & MRP.
ie, You can define period every 10 days once procurement proposal has to create.
Like wise You can define every Thursday or Friday procurement proposal has to create.
And you can define these periods for certain periods. That you have to mention. After this period system will create proposal according to normal setting.
System groups together purchase order proposal which will fall within the period defined in the planning calender, to form a lot.
Create planning calender by MD25.
Assign the planning calender in mrp 2 view of material master.
While creating PIR in MD61, in the initial screen select period – Calender format. Then only system plan according to this.
Only period lot size procedure will use ie, WB,MB,TB.