CHAPTER
11: MANUFACTURING & MATERIALS HANDLING
INTRODUCTION
There is extensive literature available on
a variety of inventory management practices, referred to as MRP I (materials
requirement planning), MRP II (manufacturing resources planning), JIT (just-in-time),
and the Japanese concept called Kanban. Although these are related to
production scheduling, only two of them (MRP I and externally oriented JIT) are
true concerns of logistics managers.
KANBAN
·
An
internal production control technique for minimizing the capital invested in
in-process parts inventories
·
Prevent
accumulation of components that are defective
·
Reflects
the deep concern of Japanese management with quality control
·
The cost
savings possible from minimizing rejects
·
Frequently
termed JIT
·
Control by
production manager
MATERIALS
REQUIREMENTS PLANNING (MRP I)
·
The
preparation of a master production schedule for some period into the future
·
The
preparation of a bill of materials for each item to be produced
·
The
explosion of the units on the master
production schedule into a component-by-component requirement schedule, in
terms of both quantities and dates needed
·
The
scheduling of component inventory replenishment according to necessary lead
times and economic order, buying, or shipping quantities to conform with the
requirement schedule rather than average demand over time
MANUFACTURING
RESOURCES PLANNING (MRP II)
·
Embodies
planning issues related plant capacity
·
Not the
direct responsibility of the logistics manager
·
It involve
the interest of logistics management when inputs on production materials
availability are solicited to enable decisions concerning production materials
·
Decision
regarding investment in added production facilities or reduction in plant
capacity are normally made by corporate management
·
The
resulting plant capacity will govern the decisions of the logistics manager
concerning the materials provisioning required to support the projected
production schedule
JUST-IN-TIME
(JIT) SCHEDULING
·
The
Japanese concept of externally oriented JIT is that shipments of materials for
the production lines should arrive
·
The goal
of JIT is to minimize inventories of production materials
·
Recently received
a considerable amount of management attention and emphasis in the United States
QUANTITTIVE
APPLICATIONS TO INVENTORY MANAGEMENT
·
The
elementary methods used for analytical application to inventory management
encompass considerations of cost optimization, essentiality, and confident
based on predictability of demand patterns
·
The following
are confidence based on predictability total inventory costs, economic order
quantities, and inventory levels for consumable and reparable components
TOTAL
INVENTORY COST
·
Inventory-level decisions would be relatively
simple if users organized their requirements so that an equal number of all
items were needed each day and if the time required to schedule, produce, and
transport replenishment stock were known and constant
·
The two
major factors affecting the order quality of a product are the cost of placing
an order and the cost of carrying inventory
·
The cost
of placing an order or setting up a production run is assumed to be constant
regardless of the size of order
ECONOMIC
IMPLICATIONS OF INVENTORY
·
The
economic focus on the inventory manager of a commercial enterprise is the costs
of inventory and the profitability of the inventory policy
INVENTORY
COSTS
·
The
predominant elements of inventory costs are
1.
Order
processing or production setup costs
2.
Investment
costs
3.
Warehousing
costs
4.
Inventory
risk
5.
Stock-out
costs
ORDER
PLACEMENT OR SETUP COSTS
·
Order
placement costs are generated at a distribution center and in thye plant
purchasing activity
·
The
equivalent type of cost in the production process is the cost of setting up a
machine or a production line to produce an items
INVENTORY
INVESTMENT
·
Investment
in an inventory item include the purchase price
·
To this
must be added any costs of transportation to distribution centers where other
inventories may be located for subsequent shipment to customers
·
The most
significant impact of inventory investment takes the form of opportunity costs
WAREHOUSING
COSTS
·
Warehousing
costs, or inventory holding cost, include storage (facilities) cots, property
taxes, and insurance costs, but not the costs of moving goods into and out
of warehouse
·
Unless
capacity limits are being reached, the incremental cost of storing more
inventory may be very small
·
Once
capacity limit reached, the incremental cost could markedly increase
INVENTORY
RISK
·
Costs of
spoilage, damage, obsolescence, and pilferage are difficult to analyze and vary
significantly by type of product
·
Spoilage
or damage can result in the total loss of a product
·
The
reworking of defective products, or the reallocation of a product from one
distribution point to another
·
Inventory
losses from pilferage have two adverse effects
·
Represent
a financial loss
·
The
pilfered goods may continue to be carried in the inventory as phantom assets
and noted as available for sale until the loss is discovered
STOCK-OUT
COSTS
·
Cost easy
to count
·
Hard
stock-out costs that are comparatively easy to assess include the costs
·
It is not
abnormal to find such costs amounting to double or triple the costs for
processing of a routine stock order
·
The soft
costs of stock-outs, which are seldom analyzed and nearly impossible to
measure, are those of lost selling time and profit