乔普拉《供应链管理(第7版英文版)》教学课件CH12
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Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved
The Role of Safety Inventory (1 of 3)
• Safety inventory is carried to satisfy demand that exceeds the amount forecasted – Raising the level of safety inventory increases product availability and thus the margin captured from customer purchases – Raising the level of safety inventory increases inventory holding costs
Supply Chain Management: Strategy, Planning, and Operation
Seventh Edition
Chapter 12
Managing Uncertainty in a Supply Chain Safety Inventory
Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved
2. Order fill rate – Fraction of orders filled from available inventory
3. Cycle service level (CSL) – Fraction of replenishment cycles that end with all customer demand being met – Replenishment cycle – the interval between two successive replenishment deliveries
Learning Objectives (1 of 2)
12.1 Understand the role of safety inventory in a supply chain. 12.2 Identify factors that influence the required level of safety inventory. 12.3 Evaluate the appropriate level of safety inventory for a supply chain. 12.4 Discuss the impact of supply uncertainty on safety inventory.
Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved
Measuring Product Availability
1. Product fill rate (fr) – Fraction of product demand satisfied from product in inventory
2. Periodic review – Inventory status is checked at regular periodic intervals – Order is placed to raise the inventory level to a specified threshold
Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved
Learning Objectives (2 of 2)
12.5 Understand how aggregation helps reduce the required safety inventory in a supply chain. 12.6 Determine the impact of replenishment policies on safety inventory. 12.7 Improve the management of safety inventory in a multiechelon supply chain. 12.8 Identify managerial levers that lower safety inventory without hurting product availability.
Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved
The Role of Safety Inventory (3 of 3)
• Three key questions 1. What is the appropriate level of product availability? 2. How much safety inventory is needed for the desired level of product availability? 3. What actions can be taken to reduce safety inventory without hurting product availability?
Measuring Supply Uncertainty
Lead time (L) is normally distributed with L = Average lead time σL = Standard deviation of lead time
Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved
period Lead time (L) is the gap between when an order is placed and when it is received
Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved
Replenishment Policies
1. Continuous review – Inventory is continuously tracked – Order for a lot size Q is placed when the inventory declines to the reorder point (ROP)
Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved
Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved
Factors Affecting the Level of Safety Inventory
• The desired level of product availability • The uncertainty of demand • The uncertainty of supply • Inventory replenishment policies
Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved
Summary of Learning Objective 2
Safety inventory is influenced by the desired product availability, demand uncertainty, replenishment lead times, and lead time variability. Product availability is measured using the fill rate or cycle service level. Demand uncertainty is measured by the forecast error. For lead time one measures both the mean and the standard deviation. The required safety inventory is also influenced by the inventory policy implemented. Continuous review policies order a fixed quantity after variable replenishment intervals. Periodic review policies order variable quantities after fixed replenishment intervals.
Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved
Measuring Demand Uncertainty
D = Average demand per period σD = Standard deviation of demand (forecast error) per
Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved
Summary of Learning Objective 1
Safety inventory helps a supply chain provide customers with a high level of product availability in spite of supply and demand uncertainty. It is carried just in case demand exceeds the amount forecasted or supply arrives later than expected.
Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved
Determining the Appropriate Level of Safety Inventory (1 of 8)
• Evaluating Safety Inventory Given a Reorder Point Expected demand during lead time = D × L Safety inventory, ss = ROP − D × L
Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved
The Role of Safety Inventory (2 of 3)
Figure 12-1 Inventory Profile with Safety Inventory
Evaluating Demand Distribution over L Periods
L
L
DL Di L
i2 2 ij i j
i 1
i 1Βιβλιοθήκη i> jDL DL L L D
The coefficient of variation
cv /
Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved
The Role of Safety Inventory (1 of 3)
• Safety inventory is carried to satisfy demand that exceeds the amount forecasted – Raising the level of safety inventory increases product availability and thus the margin captured from customer purchases – Raising the level of safety inventory increases inventory holding costs
Supply Chain Management: Strategy, Planning, and Operation
Seventh Edition
Chapter 12
Managing Uncertainty in a Supply Chain Safety Inventory
Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved
2. Order fill rate – Fraction of orders filled from available inventory
3. Cycle service level (CSL) – Fraction of replenishment cycles that end with all customer demand being met – Replenishment cycle – the interval between two successive replenishment deliveries
Learning Objectives (1 of 2)
12.1 Understand the role of safety inventory in a supply chain. 12.2 Identify factors that influence the required level of safety inventory. 12.3 Evaluate the appropriate level of safety inventory for a supply chain. 12.4 Discuss the impact of supply uncertainty on safety inventory.
Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved
Measuring Product Availability
1. Product fill rate (fr) – Fraction of product demand satisfied from product in inventory
2. Periodic review – Inventory status is checked at regular periodic intervals – Order is placed to raise the inventory level to a specified threshold
Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved
Learning Objectives (2 of 2)
12.5 Understand how aggregation helps reduce the required safety inventory in a supply chain. 12.6 Determine the impact of replenishment policies on safety inventory. 12.7 Improve the management of safety inventory in a multiechelon supply chain. 12.8 Identify managerial levers that lower safety inventory without hurting product availability.
Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved
The Role of Safety Inventory (3 of 3)
• Three key questions 1. What is the appropriate level of product availability? 2. How much safety inventory is needed for the desired level of product availability? 3. What actions can be taken to reduce safety inventory without hurting product availability?
Measuring Supply Uncertainty
Lead time (L) is normally distributed with L = Average lead time σL = Standard deviation of lead time
Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved
period Lead time (L) is the gap between when an order is placed and when it is received
Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved
Replenishment Policies
1. Continuous review – Inventory is continuously tracked – Order for a lot size Q is placed when the inventory declines to the reorder point (ROP)
Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved
Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved
Factors Affecting the Level of Safety Inventory
• The desired level of product availability • The uncertainty of demand • The uncertainty of supply • Inventory replenishment policies
Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved
Summary of Learning Objective 2
Safety inventory is influenced by the desired product availability, demand uncertainty, replenishment lead times, and lead time variability. Product availability is measured using the fill rate or cycle service level. Demand uncertainty is measured by the forecast error. For lead time one measures both the mean and the standard deviation. The required safety inventory is also influenced by the inventory policy implemented. Continuous review policies order a fixed quantity after variable replenishment intervals. Periodic review policies order variable quantities after fixed replenishment intervals.
Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved
Measuring Demand Uncertainty
D = Average demand per period σD = Standard deviation of demand (forecast error) per
Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved
Summary of Learning Objective 1
Safety inventory helps a supply chain provide customers with a high level of product availability in spite of supply and demand uncertainty. It is carried just in case demand exceeds the amount forecasted or supply arrives later than expected.
Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved
Determining the Appropriate Level of Safety Inventory (1 of 8)
• Evaluating Safety Inventory Given a Reorder Point Expected demand during lead time = D × L Safety inventory, ss = ROP − D × L
Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved
The Role of Safety Inventory (2 of 3)
Figure 12-1 Inventory Profile with Safety Inventory
Evaluating Demand Distribution over L Periods
L
L
DL Di L
i2 2 ij i j
i 1
i 1Βιβλιοθήκη i> jDL DL L L D
The coefficient of variation
cv /
Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved