In: Mechanical Engineering
WHAT IS INVENTORY?
Inventory is a stock or store of goods or services, kept for use or sale in the future. There are four types of inventory Raw materials & purchased parts Partially completed goods called work in progress (WIP) Finished-goods inventories Goods-in-transit to warehouses or customers (GIT) The motive for inventory: there are three motives for holding inventory, similar to cash. Transaction motive: Economies of scale is achieved when the number of set-ups are reduced or the number of transactions are minimized. Precautionary motive: hedge against uncertainty, including demand uncertainty, supply uncertainty Speculative motive: hedge against price increases in materials or labor
WHAT IS INVENTORY MANAGEMENT?
The objective of inventory is to achieve satisfactory levels of customer service while keeping inventory costs within reasonable bounds. Level of customer service: (1) in-stock (fill) rate (2) number of back orders (3) inventory turnover rate: the ratio of average cost of goods sold to average inventory investment Inventory cost: cost of ordering and carrying trade-of.
ROLE OF INVENTORY MANAGEMENT IN SUPPLY CHAIN:
Managing customer and vendor relationships is a critical aspect
of managing supply chains. In many cases, the collaborative
relationship concept has been considered the essence of supply
chain management. However, a closer examination of supply chain
relationships, particularly those involving product flows, reveals
that the heart of these relationships is inventory movement and
storage. Much of the activity involved in managing relationships is
based on the purchase, transfer, or management of inventory. As
such, inventory plays a critical role in supply chains because it
is a salient focus of supply chains.
Perhaps the most fundamental role that inventory plays in supply
chains is that of facilitating the balancing of demand and supply.
To effectively manage the forward and reverse flows in the supply
chain, firms have to deal with upstream supplier exchanges and
downstream customer demands. This puts an organization in the
position of trying to strike a balance between fulfilling the
demands of customers, which is often difficult to forecast with
precision or accuracy, and maintaining adequate supply of materials
and goods. This balance is often achieved through inventory.
For example, a growing trend is the implementation of sales and
operations planning (S&OP) processes.4 The fundamental purpose
of S&OP is to bring the demand management functions of the firm
(for example, sales forecasting, marketing) together with the
operations functions of the firm (for example, manufacturing,
supply chain, logistics, procurement) and level strategic plans.
This often involves extensive discussions about the firm’s on-hand
inventory, in-transit inventory, and work-in-process. Such
discussions allow the sales and marketing group to adequately plan
for the forthcoming time horizon by gaining a realistic picture of
the inventory levels available for sale. Additionally, the
operations groups are able to get updated and direct sales
forecasting information, which can assist in planning for future
inventory needs. Such information may very well result in shifts in
manufacturing plans or alterations to procurement needs because of
the strategic decision to focus on specific units of inventory
instead of others in the near future.
Another example of balancing through inventory is the use of
point-of-sale5 data for perpetual inventory management in the
retail industry. For many retailers, every “beep” of a cash
register upon scanning of an item’s bar code during checkout
triggers a series of messages that another unit of inventory has
been sold. This information is not only tracked by the retailer but
is also shared with upstream vendors. As items are depleted from
inventory, in some cases, both the retailer and vendor work
collaboratively to determine when reordering is necessary to
replenish the depleted inventory, especially at the distribution
center level. This is a balancing of supply and demand because
demand information is tracked to determine when to best place
replenishment orders based on the time required to get the
inventory to the store location. In essence, inventory decisions
are used to effectively time when supply inflows are needed to
handle demand outflows.