High level inventory management

High level inventory management

It seems that around about 1880 there was a change in manufacturing practise from companies with relatively homogeneous lines of products to vertically integrated companies with unprecedented diversity in processes and products. Those companies (especially in metalworking) attempted to achieve success through economies of scale - the gains of jointly producing two or more products in one facility. The managers now needed information on the effect of product mix decisions on overall profits and therefore needed accurate product cost information. A variety of attempts to achieve this were unsuccessful due to the huge overhead of the information processing of the time. However, the burgeoning need for financial reporting after 1900 created unavoidable pressure for financial accounting of stock and the management need to cost manage products became overshadowed. In particular it was the need for audited accounts that sealed the fate of managerial cost accounting. The dominance of financial reporting accounting over management accounting remains to this day with few exceptions and the financial reporting definitions of 'cost' have distorted effective management 'cost' accounting since that time. This is particularly true of inventory.
Hence high level financial inventory has these two basic formulas which relate to the accounting period:
Cost of beginning inventory at the start of the period + inventory purchases within the period + cost of production within the period = cost of goods sold
Cost of goods - cost of ending inventory at the end of the period = cost of goods sold
The benefit of these formulae is that the first absorbs all overheads of production and raw material costs in to a value of inventory for reporting. The second formula then creates the new start point for the next period and gives a figure to be subtracted from sales price to determine some form of sales margin figure.
Manufacturing management is more interested in inventory turnover ratio or average days to sell inventory since it tells them something about relative inventory levels.
Inventory turn over ratio (also known as inventory turns) = cost of goods sold/Average Inventory=Cost of Goods Sold/((Beginning Inventory+Ending Inventory)/2)
and its inverse
Average Days to Sell Inventory=Number of Days a Year/Inventory Turn Over Ratio=365 days a year/Inventory Turn Over Ratio
This ratio estimates how many times the inventory turns over a year. This number tells us how much cash/goods are tied up waiting for the process and is a critical measure of process reliability and effectiveness. So a factory with two inventory turns has six months stock on hand which generally not a good figure (depending upon industry) whereas a factory that moves from six turns to twelve turns has probably improved effectiveness by 100%. This improvement will have some negative results in the financial reporting since the 'value' now stored in the factory as inventory is reduced.
Whilst the simplicity of these accounting measures of inventory are very useful they are in the end fraught with the danger of their own assumptions. There are in fact so many things which can vary hidden under this appearance of simplicity that a variety of 'adjusting' assumptions may be used. These include:
Specific Identification
Weighted Average Cost
Moving-Average Cost
FIFO, and LIFO.

Logistics

Logistics or distribution

The logistics chain includes the owners (wholesalers and retailers), manufacturers' agents, and transportation channels that an item passes through between initial manufacture and final purchase by a consumer. At each stage, goods belong (as assets) to the seller until the buyer accepts them. Distribution includes four components:
Manufacturers' agents: Distributors who hold and transport a consignment of finished goods for manufacturers without ever owning it. Accountants refer to manufacturers' agents' inventory as "matériel" in order to differentiate it from goods for sale.
Transportation: The movement of goods between owners, or between locations of a given owner. The seller owns goods in transit until the buyer accepts them. Sellers or buyers may transport goods but most transportation providers act as the agent of the owner of the goods.
Wholesaling: Distributors who buy goods from manufacturers and other suppliers (farmers, fishermen, etc.) for re-sale work in the wholesale industry. A wholesaler's inventory consists of all the products in its warehouse that it has purchased from manufacturers or other suppliers. A produce-wholesaler (or distributor) may buy from distributors in other parts of the world or from local farmers. Food distributors wish to sell their inventory to grocery stores, other distributors, or possibly to consumers.
Retailing: A retailer's inventory of goods for sale consists of all the products on its shelves that it has purchased from manufacturers or wholesalers. The store attempts to sell its inventory (soup, bolts, sweaters, or other goods) to consumers

Inventory examples

While accountants often discuss inventory in terms of goods for sale, organizations - manufacturers, service-providers and not-for-profits - also have inventories (fixtures, furniture, supplies, ...) that they do not intend to sell. Manufacturers', distributors', and wholesalers' inventory tends to cluster in warehouses. Retailers' inventory may exist in a warehouse or in a shop or store accessible to customers. Inventories not intended for sale to customers or to clients may be held in any premises an organization uses. Stock ties up cash and if uncontrolled it will be impossible to know the actual level of stocks and therefore impossible to control them.
Whilst the reasons for holding stock are covered earlier, most Manufacturing organizations usually divide their "goods for sale" inventory into:
Raw materials - materials and components scheduled for use in making a product.
Work in process, WIP - materials and components that have begun their transformation to finished goods.
Finished goods - goods ready for sale to customers.
Goods for resale - returned goods that are salable.
Spare parts

Business

Business inventory

The reasons for keeping stock

There are three basic reasons for keeping an inventory:

Time - The time lags present in the supply chain, from supplier to user at every stage, requires that you maintain certain amount of inventory to use in this "lead time"
Uncertainty - Inventories are maintained as buffers to meet uncertainties in demand, supply and movements of goods.
Economies of scale - Ideal condition of "one unit at a time at a place where user needs it, when he needs it" principle tends to incur lots of costs in terms of logistics. So Bulk buying, movement and storing brings in economies of scale, thus inventory.
All these stock reasons can apply to any owner or product stage.

Buffer stock is held in individual workstations against the possibility that the upstream workstation may be a little delayed in long setup or change-over time. This stock is then used while that change-over is happening. This stock can be eliminated by tools like SMED.
These classifications apply along the whole Supply chain not just within a facility or plant.

Where these stocks contain the same or similar items it is often the work practice to hold all these stocks mixed together before or after the sub-process to which they relate. This 'reduces' costs. Because they are mixed-up together there is no visual reminder to operators of the adjacent sub-processes or line management of the stock which is due to a particular cause and should be a particular individual's responsibility with inevitable consequences. Some plants have centralized stock holding across sub-processes which makes the situation even more acute.

Special terms used in dealing with inventory
Stock Keeping Unit (SKU) is a unique combination of all the components that are assembled into the purchasable item. Therefore any change in the packaging or product is a new SKU. This level of detailed specification assists in managing inventory.
Stockout means running out of the inventory of an SKU.
"New old stock" (sometimes abbreviated NOS) is a term used in business to refer to merchandise being offered for sale which was manufactured long ago but that has never been used. Such merchandise may not be produced any more, and the new old stock may represent the only market source of a particular item at the present time