Page 224 - Orlicky's Material Requirements Planning

CHAPTER 11 Product Definition 203

FIGURE 11-3
Period
Regular update
logic following 1 2
release of order Regular
for item A. Logic
Schedule Receipts 20
Part A On Hand

Planned-Order Releases 0

Gross Requirements 0
Allocated 20

Part B Schedule Receipts
On Hand 2 –18 –18
Planned-Order Releases 18

Gross Requirements 18
Allocated
Part C
Schedule Receipts
On Hand 30 12 12

lot-for-lot ordering are assumed, but these can be specified for some regular subassem-
blies also.) Once this step is carried out, regular processing logic applies, causing the
records to be updated and their status data aligned correctly.
The phantom BOM technique, as pointed out earlier, applies primarily to net-
change MRP systems. In regenerative systems, the question of posting or not posting
transactions to phantom records to cover assembly activities is not crucial because a
planned-order release does not update component gross requirements data. Hence the
problem of rebalancing (realigning) the planned-order and gross requirements data of the
three records does not arise. Following the planned-order release of the transient sub-
assembly’s parent, the next requirements planning run will wash out both the gross
requirement and the planned-order release for the transient subassembly.
The objective of not having to report phantom transactions still remains, however, and
it can be achieved by again specifying lead time as zero, lot-for-lot ordering, and coding the
inventory record of the transient subassembly so that notices for planned-order releases are
either suppressed or flagged to be disregarded. The MRP system will function correctly.