Quản lý tồn kho là gì

Quản lý tồn kho là gì ? tồn kho quản lý là quá trình kinh doanh ra mức độ tồn kho tổ chức để đạt được dịch vụ khách hàng cao

ear —— ~ aim

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Agenda

® 1 What Is Inventory Management

® 2 Two forms of Demand

® 3 Inventory and Supply Chain

Management

® 4 Inventory and Quality Management

® 5 Inventory Control system

® 6 Economic Order Quantity (EOQ)

Models

1 What is Inventory management

?

® Inventory management is the process

of trading off the level of inventory

held to achieve high customer service levels with the cost of holding

inventory, including capital tied up In Inventory, variable storage costs and obsolescence

® [he purpose of Inventory

Management:

ohow many units to order

owhen to order

2 Two forms of Demand

© Cars, appliances, computers, and

houses are examples of independent demand inventory

3 lnventory and Supply Chain

Management

® Bullwhip effect

odemand information is distorted as It

moves away from the end-use

customer

ohigher safety stock inventories to are stored to compensate

® Seasonal or cyclical demand

® Inventory provides independence from vendors

® Take advantage of price discounts

® Inventory provides independence

between stages and avoids work stop-

pages

4 Inventory and Quality

Management

® Customers usually perceive quality

service as availability of goods they

want when they want them

® Inventory must be sufficient to provide high-quality customer service in Total Quality Management (TQM)

5 Inventory Control System

® Continuous system (fixed-order-

quantity)

© constant amount ordered when inventory declines to

predetermined level

® Periodic system (fixed-time-period)

© order placed for variable amount after fixed passage of time

6 Economic Order Quantity

(EQOQ) Models

® EOQ

© Optimal order quantity that will minimize total Inventory costs

® Basic EOQ model

® Production quantity model

Assumptions of EOQ Model:

® Demand is known with certainty and Is

constant over time

® No shortages are allowed

® Lead time for the receipt of orders is

constant

® Order quantity is received all at once

EOQ Cost Model

EOQ Cost model

Proving equality of costs at optimal point

EOO Cost Model

Production Quantity Model

® An inventory system in which an order is

received gradually, as inventory Is

simultaneously being depleted

® AKA non-instantaneous receipt model

© assumption that Q Is received all at once Is relaxed

® p - daily rate at which an order Is received

over time, a.k.a production rate

® d - daily rate at which inventory is demanded

Production Quantity Model

Orders eceipt receipt

receipt period P P

Production Quantity Model

p = production rate d= demandrate

Maximum inventory level = Q- > d

Production Quantity Model Example

Quantity Discounts Model

Quantity Discount example

TC= -=~*~2 + PD=$194,105

Reorder Example

Demand = 10,000 yards/year

Store open 311 days/year

Daily demand = 10,000 / 311 = 32.154 yards/day

Lead time = L = 10 days

R = d*L = (32.154)(10) = 321.54 yards

© probability that the inventory

available during lead time will meet demand

Variable Demand with a Reorder

Reorder Point with a Safety

Reorder Point With Variable Demand

R=dL+ ZO , 1

where

d = average daily demand

L = lead time

Oo, = the standard deviation of daily demand

Z = number of standard deviations

corresponding to the service level probability

zơ,ÏL = safety stock

Reorder Point for a Service

Reorder Point for Variable

Demand

The carpet store wants a reorder point with a 95%

service level and a 5% stockout probability

d =30 yards per day

L =10 days

Gc, =5 yards per day

Fora 95% service level, z= 1.65

R=dL+ Z Gy II Safety stock =Z ogy

= 30(10) + (1.65)(6)(-(Tö) = (1.65)(5)(-/10)

= 326.1 yards = 26.1 yards

Order Quantity for a Periodic

qd =average demand rate

t, =the fixed time between orders

[ =lead time

G, = Standard deviation of demand

ZO, Ý +f =safety stock

J =inventory level

Fixed-Period Model with Variable Demand

z = 1.65 (for a 95% service level)

Q =dff, + L) +zo„^Íf,+L -I

= (6)(60 + 5) + (1.65)(1.2)^/60 + 5 - 8

= 397.96 bottles