Unformatted text preview: tiplicative factor must be applied
when more than one subassembly is required for
each higher level item.
each The Product Structure Diagram
The product structure diagram is a graphical
representation of the relationship between the various
levels of the productive system. It incorporates all of the
information necessary to implement the explosion
calculus. Next slide depicts an end item with two levels of
subassemblies. 5 Typical
Typical Product Structure
Diagram Example 7.1 6 Example 7.1 Example 7.1 Projected Requirement Scheduled Receipts On hand.inv(end of week) Planned order release 7 Lot Sizing
The simplest lot sizing scheme for MRP systems is lotThe
for-llot (abbreviated LFL). This means that requirements
are met on a period by period basis as they arise in the
explosion calculus. However, more cost effective lot
sizing plans are possible. These would require
knowledge of the cost of setting up for production and the
cost of holding each item. This brings to mind the EOQ
formula from Chapter 4, which can be used in this
context. However, there are better methods.
Statement of the Lot Sizing
Assume there is a known set of requirements (r1, r2, . . .
rn) over an n period planning horizon. Both the set up
cost, K, and the holding cost, h, are given. The objective
is to determine production quantities (y1, y2, . . ., yn) to
meet the requirements at minimum cost. The feasibility
condition to assure there are no stockouts in any period
j j ∑ y ≥ ∑r
i i =1 i for 1 ≤ j ≤ n. i =1 8 Lo...
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