First, the role of inventory and the significance of inventory control
1, the concept of inventory
From the whole process of enterprise production and operation activities, inventory refers to the materials reserved by enterprises for production and/or service and for sales. The forms of inventory mainly include: raw materials, auxiliary materials, products in process, finished products and purchased parts.
Inventory is not only the basis for the reasonable existence of production and service system, but also necessary for the reasonable organization of production and service process. It is not only established in theory, but also completely realized in practice, ensuring a higher supply rate with lower inventory cost.
2, the role and classification of inventory
The fundamental purpose of setting up inventory is to ensure that the required quantity is provided for the required materials at the required time and place. At the same time, inventory can also play the following roles; Prevent shortage and improve service level; Save expenses and reduce costs; Ensure the smooth progress of production and sales; Improve production balance and adjust seasonal demand.
3, the significance of inventory control
(1) The role of inventory control
Mainly: under the premise of ensuring the production and operation needs of enterprises, keep the inventory at a reasonable level; Grasp the inventory dynamics, place orders in a timely and appropriate manner to avoid inventory backlog or shortage; Reduce the occupation of inventory space and reduce the total inventory cost; Control the occupation of inventory funds and speed up capital turnover.
(2) Control the inventory reasonably.
Problems caused by excessive inventory: increasing warehouse area and inventory storage cost, thus increasing product cost; Occupy a lot of working capital, resulting in sluggish funds, which not only increases the burden of paying interest, but also affects the time value and opportunity income of funds; Causing tangible and intangible losses of finished products and raw materials; Causes a large number of idle enterprise resources, affecting its rational allocation and optimization; It covers up all kinds of contradictions and problems in the whole process of enterprise production and operation, which is not conducive to improving the management level of enterprises.
Problems caused by too little inventory: the decline of service level, affecting sales profit and corporate reputation; Insufficient supply of raw materials or other materials in the production system, which affects the normal production process; Shorten the ordering interval, increase the ordering times and increase the ordering (production) cost; It affects the balance of production process and the integrity of assembly.
Second, the cost of inventory.
Inventory cost consists of the following items:
1, material cost. Refers to the cost of purchasing or producing materials.
2. Ordering cost, also known as purchasing cost. Used for foreign orders, refers to all expenses incurred in each order or purchase.
3. Operation replacement cost. Also known as process equipment adjustment fee and production preparation fee, it refers to the expenses incurred when the processing object changes (that is, job replacement) under the mass production mode.
4. Inventory storage cost. Also known as storage expenses, it refers to the expenses incurred in storing and keeping inventory materials.
5. Out of stock cost. Refers to the loss caused by inventory shortage in the process of production and operation.
Three. Inventory ABC management method
1, overview
The basic principle of ABC management method classifies and sorts the inventory of enterprises (materials, products in process and finished products) according to their importance, value, amount of capital occupied or consumed, etc. , so as to distinguish between primary and secondary, grasp the key points and adopt different control methods respectively. The key point is to find out the key minority (Class A) and the minor majority (Class B and Class C), and only by focusing on managing the key minority can we get twice the result with half the effort.
ABC management method is applied to inventory control and adopts the control mode of "replenishing inventory". By properly controlling the internal inventory scale, the external random demand can be guaranteed. Therefore, ABC management method is aimed at independent demand inventory items.
2. Basic practices
(1) Collect data.
(2) Sort by value.
(3) Calculation and arrangement.
(4) classification.
3.ABC classification and inventory control mode
(1) Inventory control mode of Class A materials. Class A materials are the focus of inventory control, with fewer varieties and higher prices, which are mostly key and commonly used materials for production (management). For Class A materials, continuous control is generally adopted to check the inventory situation at any time. Once the inventory drops to a certain level (order point), the order must be placed in time. Class A materials are generally ordered on a regular basis, and the quantity of each order is limited to the replenishment target inventory level.
(2) Control mode of Class C materials. Because of the variety of inventory types, low value or low annual consumption, the inventory level of Class C materials can be controlled according to their total inventory. For class C materials, relatively extensive quantitative control methods are generally adopted. You can order a larger order quantity or economic order quantity.
(3) Control mode of Class B materials. The inventory control mode of Class B materials is between Class A and Class C materials, and the general (or conventional) control mode can be adopted to order in batches according to economic orders.
Four. Independent demand and dependent demand
1, independent demand
Independent demand, also known as market demand, refers to the demand for a substance, which has nothing to do with the demand for other things in quantity and time, but only depends on the demand of the market and customers. From the point of view of inventory control, its essential meaning refers to those uncertain needs that are beyond the control of the enterprise itself.
2. Dependent demand
Dependent demand, also known as related demand, refers to the demand for one material, which directly depends on the demand for other materials in quantity and time. From the point of view of inventory control, its essence refers to those deterministic needs that enterprises can control themselves.
3, the demand analysis of the production process
The production process of an enterprise consists of input, transfer and output. If we combine the process of input, transformation and output to analyze independent demand and subordinate demand, we will find that the demand for enterprise output is an independent demand that enterprises themselves cannot meet in recent years. In the production process, once the demand for input parts and conversion parts is determined, the demand and demand time can be determined by forecasting and ordering, so as to determine the demand for raw materials, purchased parts, outsourced parts and others. The demand for semi-finished products and in-process products in the process of processing and transformation is subordinate demand. The quantity and time of its demand can be accurately calculated step by step according to the clear subordinate demand relationship.
However, the demand for raw materials and the demand for work-in-process in the conversion link should be different in inventory control methods. Due to the influence of force majeure factors such as supplier's delivery date, material transportation cycle and material quality, enterprises have little control over these external factors, and some even can't control them at all. Therefore, the inventory management of raw materials in enterprises should be handled according to the inventory control method of independent demand.