Chinese-English Bilingual Teaching For Logistics & Supply Chain Management

1. Chinese-English Bilingual Teaching ForLogistics & Supply Chain Management Chapter 7. Stock Control 余毅艺 Anniesyql@hotmail.com Office:8314B

2. Ch.7 Stock Control • Stock Classification 库存的分类 • Stock Identification 库存辨认 • Forecast 库存预测

3. Stock control is the determination and regulation of which items are kept in stock and what quantities of each are stocked without stock excess or stock deficiencies. • The aim. • a high level of stock. • stockholding costs.

4. The range and depth of stockholdings is determined by an assessment of the following factors. • The nature of demand • Degree of protection against stock-outs • Purchasing costs • Holding costs • Lead-time

5. 1. Stock classification • 80/20 in such cases 80% of the items in stock typically make up only 20% of the total stock value, while the remaining 20% of (high-value) items account for 80% of the total stock value. • 这一法则是由意大利经济学家帕累托在十九世纪末期提出的,应该说这一法则具有普遍的适用性。

6. 1. Stock classification • ABC groups • Category A items –10% of items by volume account for 70% of value; • Category B items – 20% of volume accounts for 20% of value; • Category C items – 70% of volume accounts for 10% by values.

7. 1. Stock classification • The stock control policy for the categories might be as follows: • Class A –close control and checked once a month; • Class B –medium control and checked every three months; • Class C –minimum control with free issue

8. 2. Stock identification • Stock consists of many different types of individual items. • The easiest way to identify an item is by name or word description. • The problem is that different people may describe the same item using different words. • This can result in duplication of the same item with consequent higher than necessary stockholding levels

9. 2. Stock identification • The development of a coding system follows a series of stages. • Identification of each item by function and need. • Specification of each item. • Classification into groups and sub-groups. • Application of code.

10. 2. Stock identification • Classification into groups and sub-groups could be made on any of the following bases. • Nature of material • End use of material • Location on stores • Source of supply • End user customer

11. 2. Stock identification • 所谓零件分类编码系统 • 目前，世界上大约有100多种零件分类编码系统。 • OPITZ系统(德)、MNTPOФAHOB(前苏联)、BRISCH系统(英)、KK-3系统(日)、CODE系统(美)、MICLASS系统(荷)等。 • OPITZ系统

12. 2. Stock identification • In theBrischsystem there are 2 parts to the code. The ‘surname’ comes first and provides the broad item classification. • Surname ： • 1st figure = main classification 主族分类 • 2nd figure = sub-group 子组 of main classification • 3rd figure = item classification 项目分类

13. 2. Stock identification • The ‘forename’ which follows describes each item in detail e.g. • Forename: • 4th figure = length • 5th figure = diameter • 6th figure = type of head • 7th figure =surface finish

14. 2. Stock identification • So 100- 5648 could mean: • 1 = bought out parts, 0 = fasteners and fixings扣件和装备, 0 = nuts and bolts 螺母螺栓 • 5 = 2cm, 6 = 10mm, 4 = hex RD hex (六角，radial direction 径向), 8 = zinc coated

15. 2. Stock identification • The coding details of all stock items are normally maintained in a list or catalogue called the stores vocabulary. • This facilitates stock rationalization, whereby stock codes can be analyzed and any duplicate stock can be easily highlighted. • As well as codifying items into unique part numbers, inventory can also be broken down into generic constituent areas.

16. 2. Stock identification • Categorization of stock may also be used for accounting or analytical reasons. • Maintenance stock • Project stock • Insurance stock • Strategic stock

17. 3. Forecast • An effective stock control system involves decisions on: • how much stock to hold using forecasts of usage and replenishment; • how much to order——order quantity; • when to order for stock——timing of orders.

18. 3. Forecast • Each item stocked, decisions on how much should be held are made on the basis of demand forecasting. • Forecast comparisons use sales data and production data from the bill of materials. • 它是MRP的重要文件，几乎所有的管理部门都要到它。它能详细表列出装配结构中的零件状态及装配组件或零件中包含的参数。

19. 3. Forecast --- (1) EOQ • 经济订货批量 EOQ = • annual usage (商品年需求量/使用量) • acquisition cost per order (每次订货成本) • stockholding cost per unit (单位商品年保管费/库存费/单位库存维持成本)

20. 3. Forecast 库存预测--- (1) EOQ • EOQ example • 经济订货批量EOQ = • So order quantity is 37. = 37 units

21. 3. Forecast ---(2)safety stock • This is the ‘lead-time’（提前期） which includes things like: • time to identify then authorize replenishment • time to establish supplier contact and complete paperwork • time for the supplier to obtain or produce the goods • time to have the goods delivered • time for goods inwards/receiving and quality checking time.

22. 3. Forecast ---(2)safety stock • Safety stock (or buffer stock) • A fixed quantity • A given day’s worth • A quantity calculated statistically based on usage and supply factors

23. 3. Forecast ---(3)ROL • Re-order levels are used to trigger consideration of stock reordering action. • It is a stock level at which new stock must be ordered if replenishment is to arrive before a stockout occurs, provided demand remains as predicted.

24. Understanding Inventory • The inventory policy is affected by: • Demand Characteristics • Lead Time • Number of Products • Objectives • Promote service level • Minimize costs • Cost Structure

25. Cost Structure • Order costs (acquisition/administration costs ) • Fixed • Variable • Holding Costs (stockholding costs ) • Insurance • Maintenance and Handling • Taxes • Opportunity Costs • Obsolescence

26. Inventory Order Size Avg. Inven Time EOQ: A View of Inventory* Note: • No Stockouts • Order when no inventory • Order Size determines policy

27. EOQ: Calculating Total Cost* • Purchase Cost Constant • Holding Cost: (Avg. Inven) * (Holding Cost) • Ordering (Setup Cost):Number of Orders * Order Cost • Goal: Find the Order Quantity that Minimizes These Costs

28. Total Cost Holding Cost Order Cost EOQ EOQ:Total Cost*

29. EOQ: Optimal Order Quantity* • Optimal Quantity = (2*Demand*Setup Cost)/holding cost • Setup Cost 采购/(生产)准备成本

30. 经济订货批量（EOQ）模型 • 经济定货批量(Economic Order Quantity,EOQ)的假设条件。 • 需求已知且常量； • 一次订货量无限制； • 采购、运输无价格折扣； • 订货提前期已知且常量； ... • 经济订货批量（EOQ）模型的目标 • 经济订货量是一种决策模型，在一系列假设的基础上计算订货的最优数量。经济订货批量平衡了订购和持有存货的变动成本。

31. EQQ（定量订货法 Stationary） • 经济采购/订货量（Economic order quantity，EQQ）定义：使采购成本及存货持有成本加总值最小的采购量。适用于需求及成本都很稳定的情况。 • 模型假设： • 每次订货的订货量相同， • 订货提前期固定， • 需求率固定不变。

32. 经济订货批量计算公式如下： 2DS Q*= Ci 式中：Q*——经济订货批量 D——商品年需求量 S——每次订货成本 Ci——单位商品年保管费 EQQ（定量订货法 Stationary） 实际演练

33. 2×16000×40 2 EQQ（定量订货法 Stationary） 例：某仓库某种商品年需求量为16000箱，单位商品年保管费2元，每次订货成本为40元，求经济订货批量Q*。 Q*= =800箱

34. Q & A !