A. Basics
1)
Backward Scheduling calculates the
material availability date. This is the
date on which sufficient material should be available(for activities such as
picking,packing,loading and finally goods issue) so as to be able to
successfully deliver the goods to the customer on his requested delivery
date.(assuming customer requires complete delivery)
2)
The delivery,therefore,should be created
latest by this date or by transportation planing date,whichever is earlier.
3)
Availability Check is a function of SAP
SD module that along with Transfer of Requirements helps in checking if
sufficient quantity of goods is available on the above calculated availability
date.
4)
If sufficient quantity is not available on
this date then goods cannot be delivered
on the customer's requested delivery date.
5)
Forward Scheduling then calculates the new
availability date and thus a new delivery date is confirmed in the
schedule line.
6)
Availability check is done at Plant Level.
7)
Results of availability check may vary according
to Replenishment Lead Time(RLT) , Partial Delivery Constraints or other such
considerations.(described ahead)
8)
Types of availability check :
a)
Against ATP Quantities (with or without RLT)
b) Against Planning.
c)Against
Product Allocation
9)
Available-To-Promise or ATP : On any
given date ATP quantities give the number one can commit for an order which is
to be delivered on some future.
ATP=
Warehouse Stock + Planned Inward Receipts – Planned Outward Issues
Where Stock can include unrestricted
stock,stock in transfer,stock in quality inspection,blocked stock,restricted
use stock etc
Inward Movements can include
Purchase Orders,Purchase requisitions,Planned orders,Production orders etc.
Outward
Movements can include Sales Orders,Deliveries,Reservations,Sales Requirements
etc.
10) R-L-T
: The time needed to produce or order the material. In other words it is the time by which the material is
produced in house or if it is trading good
the time by which it can be procured. If availability check includes RLT
, the check is carried out only till the end of this time any amount will be
available after this time.
For goods produced in-house
:
R-L-T
= Tot. Replenishment time (MMR-MRP3
View), If maintained
else
if above field not maintained
R-L-T
= In-House Production Time (MMR- Work Scheduling view) + GR
processing time (MMR-MRP2 View)
For externally procured goods :
R-L-T = Purchasing Processing time(MMR- Purchasing view) + Planned
Delivery
time(MMR-MRP2
view) + GR Processing time (MMR-MRP2 view)
$$ RLT is
included only in check against ATP. *
MMR is Material Master record
11) Complete
Delivery/Partial Delivery Indicator : Complete delivery indicator is specified
in CuMR – Shipping Tab and is applicable at the header level of the Sales
Order. This specifies if the entire order that is all the items in the
order are to be delivered together.
The
Partial delivery indicator(and the number of partial deliveries allowed) comes
from either CMIR or CuMR- Shipping Tab. This specifies if all the quantities of
the item has to be delivered in one single delivery or can be delivered in
multiple partial deliveries. This is applicable at Header Level but can be
changed at item level in the Sales Document.
* CMIR –
Customer Material Info Record CuMR – Customer Master Record
Effects on Delivery date of complete and partial delivery.
% In above figure the End lead time(R-L-T) is
15.05.2013. Any quantity ordered will be confirmed for that date.
B. Customization
Since Availability Check lies within
the integration precinct between SD and MM
the control features can be found in both SD and MM module. The focus
here is on customization in SD but a bit of MM features are also studied for
getting a holistic picture.
I)
1)
Transfer of Requirements :
Requirements are planned outward movements. All material orders are transferred to the MRP in the form of requirements by SD.
This also helps in planning future requirements as procurement can further
advice production(in case materials need to be produced) or purchasing(in case
materials need to be procured).Without ToR availability check is not effective.
2)
Planning Strategies : Are business
procedures for planning the production (quantities and dates) of material.
3)
Strategy Group : The
allowed planning strategies (main strategy and further possible strategies) are
combined in the strategy group. The strategy group is plant-wise assigned to
MRP group. Also strategy group can be directly maintained in MMR-MRP3(which has
priority over MRP assignment).
4)
MRP group
: Groups materials having the same MRP requirements and thus helps controlling
these materials for MRP. This is maintained in MMR-MRP1 view.
5)
MRP Type
(MMR-MRP1 View) : Is a key that determines how the material is to be planned.
6)
Requirements Type
: Among other things Requirements types refer to the Requirements class.
Requirements Types in turn are a part of Planning Strategy. If not maintained
there they are determined from the combination of MRP type and Item categories.
7)
Requirements Class :
Apart from other things it controls globally if availability check and ToR is
to be done for the material in SD Documents on the basis of ATP Logic.
8)
Schedule Line Categories
: Where Requirements Class determine globally if availability and ToR is
to be done, at Micro level this is determined by Schedule Line Category. Thus
if they are switch on at Requirements
Class level they can be switched off at Schedule Line Level but if they are Off
at Requirements Class level they cannot be turned on at Schedule Line Level.
9)
Delivery item category
: The delivery item category can be used to control whether an availability
check takes place in deliveries.
10) Checking Group
: Decides which
requirement to transfer - individual(for each order) or
summarized(Daily/Weekly) and whether to block the material(at plant level)
during the time of availability check for simultaneous orders. Also can
deactivate availability check. It is proposed in MMR.
11) Checking Rule : Along with Checking Group it decides
scope of check for a particular transaction and id hard coded for example for
Sales Order it is 'A' for delivery it is 'B' etc
12)
Scope of check : Decides
what kind of stocks,incoming movements,outgoing movments are to be
checked during availability check and if check includes RLT. It also checks if
Availability Check is to be done on Storage Location Level or not.
To summarize (Refer Snapshots below for all
relevant transactions):
Strategy
group contains planning strategies which in turn contain
Requirement Type(if not there it
comes from combination of MRP Type and Item Category) which in turn refers to Requirements
class which globally determine, for the material, if Availability check and
ToR are to be done and locally this is controlled by Schedule Line Category
in Sales Document and by Delivery Item Category in Delivery Document.
Checking
Group decides if requirements are to be transferred weekly,daily or per transaction.
Also along with checking rule it decides scope of check.
SNAPSHOTS
1)
T-Code: MM03
Strategy group Assignment
Strategy group – Planning Startegies
3) T-Code OPPS
Planning Strategy – Requirement Type
Requirement Type – Requirement Class Assignment
5) T-Code OVZG
5) T-Code OVZG
Requirement type in Sales Order
Checking Group
9)
T-Code OVZ9
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