Page 473 - Orlicky's Material Requirements Planning

CHAPTER 26 Demand-Driven Planning 451

FIGURE 26-22
Slippage in Part FPZ schedule.

Order Request Promise
Part Number Profile Start Date ASRLT Date Date Late Quantity Vendor Customer Source
PPH PO-000591 LTM 2/15 75 2/28 2/28 1 SpaceTech Driven by WO-000589, SAA
PPG PO-000590 LTM 1/19 40 2/28 2/28 2 Days 1 Siemens Driven by WO-000589, SAA
PPE PO-000592 LTM 2/13 20 3/05 3/05 1 Sony Driven by WO-000587, SAB
PPF PO-000593 LTM 2/18 15 3/05 3/05 1 SpaceTech Driven by WO-000587, SAB
PPC PO-000594 LTM 2/18 25 3/15 3/15 1 Boeing Driven by WO-000582, SAY
SAA WO-000589 NB 2/28 80 3/05 3/05 2 Days 1 Driven by WO-000587, SAB
PPI PO-000596 LTM 3/03 25 3/28 3/28 1 Raytheon Driven by WO-000588, SAZ
SAB WO-000587 NB 3/05 90 3/15 3/15 2 Days 1 Driven by WO-000585, SAW
PPD PO-000595 LTM 3/09 18 3/27 3/27 1 MicroTech Driven by WO-000583, SAD
PPJ PO-000598 LTM 3/15 20 4/04 4/04 1 SpaceTech Driven by WO-000586, SAC
SAY WO-000582 NB 3/15 45 4/04 4/04 1 Driven by WO-000580, SAE
SAW WO-000582 NB 3/15 102 3/27 3/27 2 Days 1 Driven by WO-000583, SAD
PPK PO-000599 LTM 3/18 20 4/07 4/07 1 Siemens Driven by WO-000584, SAX
PPB PO-000597 LTM 3/20 15 4/04 4/04 1 Sony Driven by WO-000580, SAE
SAD WO-000583 NB 3/27 117 4/11 4/11 2 Days 1 Driven by WO-000581, SAF
SAZ WO-000588 NB 3/28 32 4/04 4/04 1 Driven by WO-000586, SAC
SAE WO-000580 NB 4/04 58 4/17 4/17 1 Driven by WO-000579, FPA
SAC WO-000586 NB 4/04 35 4/07 4/07 1 Driven by WO-000584, SAX
SAX WO-000584 NB 4/07 39 4/11 4/11 1 Driven by WO-000581, SAF
SAF WO-000581 NB 4/11 123 4/17 4/17 2 Days 1 Driven by WO-000579, FPA
PPA PO-000600 LTM 4/12 5 4/17 4/17 1 SpaceTech Driven by WO-000579, FPA
FPZ WO-000579 NB 4/17 136 5/01 5/01 2 Days 1 NASA Driven by Atlantis, line 1, NASA

example of slippage occurring within the ASRLT chain. The promise date of PPG has Downloaded by [ Singapore Polytechnic Library 176.79.113.174] at [06/05/21]. Copyright © McGraw-Hill Global Education Holdings, LLC. Not to be redistributed or modified in any way without permission.
been moved back two days. It is two days late. This will result in a delay to SAA. SAA
lies on the ASRLT chain. The two-day delay of PPG transfers variability from a noncriti-
cal path to a critical path and is pushing the promise date of the end item by two days.
Coding feeding paths into that chain with an LTM designation is one way to gain
better visibility and protection for the ASRLT chain. In many cases, the LTM designation
itself will not prevent slides of those feeding legs from affecting the ASRLT chain, but the
LTM designation notifies the planner about the slide sooner. There is value in this knowl-
edge in order to allow the development of another tactic that will absorb the variation in
BOM legs that affect the ASRLT chain.
Figure 26-23 displays the total length of all legs in the BOM by a large number at the
left termination of the leg. The ASRLT is represented by the shaded boxes and remains
136 days. The longest non-ASRLT path is 101 days (terminating in PPG). This is a differ-
ence of 35 days. This leg can be started a sensible period of time ahead of the late start
date to account for potential delays without changing or redefining the ASRLT chain. A
time buffer can be employed that will absorb potential disruption from a supplier with-
out adding any lead time to the total assembly schedule and better protect the ASRLT. All
activity/legs feeding into the ASRLT chain that are not part of that chain can be buffered
with time. Figure 26-24 is FPZ’s BOM with these time buffers inserted. The shaded rec-
tangular boxes represent the time buffers. The time buffers are an insertion into the lead
time of non-ASRLT legs. The length of each of those legs has been lengthened, and the
release or start dates for items on those paths are adjusted accordingly.