SAPTechno

Note 661684 - MFBF/MF70: Separated backflush and discontinued part

Header
Version / Date 2 / 2003-09-23
Priority Correction with medium priority
Category Program error
Primary Component PP-MRP-PP Procurement Proposal
Secondary Components PP-REM-ADE Backflushing

Summary
Symptom

When you use discontinuation and follow-up items in repetitive manufacturing scenarios, which are backflushed by separated backflush processes, it results in incorrect material postings and postprocessing records for discontinuation and follow-up components.

Other terms

MFBF, MF70, separated backflush, discontinued part, planned order,
part to be discontinued, follow-up material, MD04, MD05, postprocessing record ...

Reason and Prerequisites

The problem is caused by a program error for the specification of default quantities for withdrawal postings and the calculation of withdrawal quantities for planned order components.

Solution

As a solution for the above problem, implement the program corrections described in this note.

In the following, some general questions regarding processing and system behavior in separated backflush processes will be answered.

General processing of separated backflush processes
    1. Goods receipt posting using Transaction MFBF (GR)

              By the goods receipt posting via Transaction MFBF, in addition to the goods receipt posting, a reduction of the open receipt quantity of one or several planned orders is executed.

              This is performed by updating a corresponding GR quantity in the planned order. The total quantity of the planned order and the requirement quantities of the planned order component are not changed by this processing step.

    2. Goods issue posting using Transaction MF70 (GI)

              By the goods issue posting via Transaction MF70, for a quantity of goods receipts posted previously, the withdrawals of components used for that are performed subsequently in an aggregated way.

              As a first step for this purpose, the GI quantities to be posted for the components are determined. This can happen in two different ways:

      a) Backflush without planned order reference

                       Backflushes without planned order reference are existing, if - in a make-to-stock production scenario - you post goods receipts without an explicit specification of the planned order to be reduced.

                       In this case, the GI quantities to be posted for the components are determined by a BOM explosion with the amount of the cumulated GR quantities.

      b) Backflush with planned order reference

                       Backflushes with planned order reference are existing, if - in a stock scenario - the goods receipt is posted with reference to an actual planned order. In addition, all GR postings in make-to-order or production by lot production scenarios are processed as backflushes with planned order reference.

                       In this case, the GI quantities to be posted for the components are determined from the referenced planned orders by a proportional quantity adjustment of the components. The component quantities of several planned orders determined this way are aggregated before the actual GI posting is performed.

              In addition to the postings of corresponding goods issues, a reduction of the component requirements of the planned orders posted for goods receipt is also carried out in the processing of Transaction MF70. Regarding this planned order reduction, 2 basic scenarios are distinguished:

      a) Make-to-stock production

                       In the make-to-stock production, the planned order reduction is performed by reducing the total quantity of the planned order (new total quantity = old total quantity - old GR quantity). The old GR quantity is reset during the reduction.

                       If the planned order is completely backflushed, the system deletes the planned order with its components. Otherwise, a reduction of the component requirements is performed by proportionally reducing the requirement quantities of the components.

      b) Make-to-order/production lot production

                       In make-to-order production scenarios, the planned order reduction is performed by updating a goods issue quantity for the planned order (new GI quantity = old GR quantity). The total quantity of the planned order remains unchanged.

                       If the planned order is completely backflushed, the system deletes the planned order with its components. Otherwise, the reduction of the component requirements is performed by proportionally calculating and updating a withdrawal quantity for the components.

              In the goods issue, the calculation of the component quantities to be withdrawn (posting quantities for GI) and the reduction of corresponding planned orders and their components in principle are 2 completely separated processes (also refer to the explanations in Note 513874).

              Thus, it is not mandatory that the reduction of component requirements must be performed synchronously to the withdrawal of component stocks. For this reason, the withdrawal quantity calculated for reducing the component requirements (make-to-order production scenario) may deviate from the withdrawal quantity actually posted.

              The withdrawal quantity of the component requirements is only used for requirement reduction and not for tracking executed withdrawal postings!

Discontinued part in separated backflush scenarios


The result from the processing explained above are some special features for the discontinued part of planned order components which are explained below.

    1. Withdrawal quantities in make-to-order production scenarios

              In make-to-order production scenarios, the component requirements are reduced by updating a withdrawal quantity, as described above.

              While the withdrawal quantity is updated proportionally to the requirement quantity for 'standard' components, it is required for discontinuation components to update the withdrawal quantity proportionally to the original discontinuation quantity. Regarding this, for discontinuation components, the withdrawal quantity can exceed the current requirement quantity of the component.

              This logic of quantity update is required, so that it is at any time possible to determine the open original quantity for the part to be discontinued in following material requirements plannings. During the planning of the part to be discontinued, this quantity is used to determine whether this quantity can be covered with the stock of the part to be discontinued or whether it must be redirected to the follow-up material.

              In the planning of the part to be discontinued, the requirements planning performs a redirection of the requirement quantity with the amount of the quantity already withdrawn.

              Example

              The assumption is a planned order for material A with a quantity of 10 PC and the following component requirements:

                                   Reqmt quantity  Original quantity

           Component          B0:     10 PC           10 PC

           Part to be discont. C1:      3 PC           10 PC

           Follow-up material  C2:      7 PC           10 PC

           Part to be discont. D1:      0 PC           10 PC

           Follow-up material  D2:     10 PC           10 PC

              Component B0 is a 'standard' component without discontinued part, components C1 and C2 describe an active partial discontinuation, a complete redirection to follow-up material D2 is already carried out for part to be discontinued D1.

              After the implementation of this note, in a partial backflush of the order with the amount of 5 PC, the following goods issue quantities are determined for the components with regard to the current redirection relationship:

                                     GI quantity

           Component           B0:      5 PC

           Part to be discont. C1:      3 PC

           Follow-up material  C2:      2 PC

           Part to be discont. D1:      0 PC

           Follow-up material  D2:      5 PC

              On the other hand, the update of withdrawal quantities for the components updates the full withdrawal part onto the parts to be discontinued:

                                   Req. qty  Withd. qty  Open Req. qty

           Component          B0: 10 PC       5 PC          5 PC

           Part to be discont. C1:  3 PC       5 PC          0 PC

           Follow-up material  C2:  7 PC       2 PC          5 PC

           Part to be discont. D1:  0 PC       5 PC          0 PC

           Follow-up material  D2: 10 PC       5 PC          5 PC

              A subsequent material requirements planning for the parts to be discontinued redirects back with the amount of the withdrawal quantities and correspondingly adjusts the requirement and withdrawal quantities for follow-up materials:

                                   Req. qty  Withd. qty  Open Req. qty

           Component          B0: 10 PC       5 PC         5 PC

           Part to be discont. C1:  5 PC       5 PC         0 PC

           Follow-up material  C2:  5 PC       0 PC         5 PC

           Part to be discont. D1:  5 PC       5 PC         0 PC

           Follow-up material  D2:  5 PC       0 PC         5 PC

              The described system behavior regarding withdrawal quantities of parts to be discontinued and follow-up materials corresponds to the desired system design and the requirements of material requirements planning, planned order processing and backflush for these quantities.

    2. Problems for the determination of goods issue quantities
      a) Backflush without planned order reference

              In the backflush without planned order reference, the component quantities to be withdrawn are determined via a BOM explosion.

              Due to the BOM explosion, here the full requirement quantity is always set on the part to be discontinued. In the further backflush processing, the system then checks for the discontinuation component if the GI quantity determined this way can still be covered by the stock of the part to be discontinued. If this is not the case, the determined GI quantity is partially or completely redirected to the follow-up material.

              Within this processing, problems regarding the incorrect redirection of GI quantities or the useless generation of postprocessing records are not known.

      b) Backflush with planned order reference

              In a backflush with planned order reference, the component quantities to be withdrawn are determined from the referenced planned orders by a proportional quantity adjustment of the components. The current discontinuation relationships are taken into account in this calculation. Thus, in principle all situations, in which the current redirection relationship does not match the current stock situation, are critical:

    • Inactive simple discontinuation

                    In an inactive simple discontinuation, the corresponding discontinuation component in the planned order does not include any discontinuation information. It is neither recognizable as part to be discontinued nor is information available on the effective-out date and follow-up material.

                    In this respect, the goods issue posting with planned order reference always tries to withdraw the inactive simple discontinuation regardless of the component stock. If the available stock is not sufficient to cover the determined GI quantity, no redirection on the follow-up material is carried out. Instead, the system generates a postprocessing record for the part to be discontinued.

    • Inactive group discontinuation

                    In the inactive group discontinuation, all information on the discontinuation and follow-up components is already included in the planned order. Because the discontinuation is not yet active, the proportional quantity adjustment always moves the complete GI quantity onto the main part to be discontinued.

                    In the further backflush processing, the system then checks for the main part to be discontinued if the determined GI quantity can still be covered with the stock of the part to be discontinued. If this is not the case, the determined GI quantity is partially or completely redirected to the follow-up material.

    • Active simple discontinuation

                    In the active simple discontinuation, the GI quantities to be posted are determined with regard to the current relationship of the requirement quantities of the part to be discontinued and the follow-up material.

                    Here, the system does not check if corresponding stock is still existing on the part to be discontinued. Regarding this it is assumed that, after a simple discontinuation has been activated, the stock of the part to be discontinued is used up and subsequently all requirements of all planned orders are redirected. For this reason, the stock check is not carried out in case of an already activated discontinuation due to performance reasons.

                    Since the current discontinuation relationship in the planned order is based on the stock situation of the last planning and this stock situation can deviate from the current stock situation, it may happen that follow-up materials are withdrawn although stock is still available on the part to be discontinued. It is also possible in an active partial discontinuation, that the system generates postprocessing records for the part to be discontinued if the stock available on the part to be discontinued is no longer sufficient.

    • Active group discontinuation

                    The same statements as for the active simple discontinuation apply to the active group discontinuation. The calculation of GI quantities to be posted considers the current redirection relationships in the planned order. However, no check is carried out on stocks currently available for the main part to be discontinued.

                    With regard to this it may happen, that follow-up materials are withdrawn by a corresponding GI posting although stock still exists on the main part to be discontinued. It is also possible in an active partial discontinuation, that the system generates postprocessing records for the main part to be discontinued if the stock available on this component is no longer sufficient.

              Regarding the described scenarios, the usage of a group discontinuation even in very simple discontinuation scenarios seems to have clear advantages in comparison to simple discontinuation, because in this case the discontinuation property is already checked in the inactive discontinuation.

              On the other hand, the described problems after the discontinuation activation are classified as minor in both scenarios. In this respect it is assumed that the problems are generally put into perspective in the course of time and that the described generation of postprocessing records for discontinuation components is only performed in very rare cases.

Affected Releases
Software Component Release From Release To Release And subsequent
SAP_APPL46C46C46C
SAP_APPL470470470

Correction delivered in Support Package
Support Packages Release Package Name
SAP_APPL46CSAPKH46C46
SAP_APPL470SAPKH47017

Related Notes
772498MFBF/MF70: Separate backflush and alternative items
513874Discontinued part in the planned order (explanatory note)