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Independent Demand Inventory Types. Cycle Stock Safety Stock Anticipation Pipeline. P. P. Periodic Review Systems. T. On-hand inventory. Time. P. P. Periodic Review Systems. T. Q 1. On-hand inventory. Order placed. Time. P. P. Periodic Review Systems. T. Q 1.
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Independent Demand Inventory Types • Cycle Stock • Safety Stock • Anticipation • Pipeline
P P Periodic Review Systems T On-hand inventory Time
P P Periodic Review Systems T Q1 On-hand inventory Order placed Time
P P Periodic Review Systems T Q1 On-hand inventory Order placed L Time
P P Periodic Review Systems T Order received Q1 On-hand inventory Order placed L Time
P P Periodic Review Systems T Order received Order received Q3 Q1 Q2 On-hand inventory Order placed Order placed L L L Time
L L L P P Protection interval Periodic Review Systems T IP IP Order received Order received Q3 Q1 OH OH Q2 IP1 IP3 IP2 On-hand inventory Order placed Order placed Time
T IP IP Order received Order received Qt = T - IPt IP = OH + SR - BO Q3 Q1 OH OH Q2 IP1 IP3 IP2 T = 400 BO = 5 OH = 0 SR = 0 On-hand inventory Order placed Order placed Q = 400 - (-5) = 405 L L L Time P P Protection interval Periodic Review Systems
T IP IP Order received Order received Qt = T - IPt IP = OH + SR - BO Q3 Q1 OH OH Q2 IP1 IP3 IP2 T = 400 BO = 5 OH = 0 SR = 0 On-hand inventory Order placed Order placed Q = 400 - (-5) = 405 L L L Time P P Protection interval Periodic Review Systems T = Average demand during protection interval + zsP+L st= 15 units L = 3 weeks cycle/service level = 80%
T IP IP Order received Order received Qt = T - IPt IP = OH + SR - BO Q3 Q1 OH OH Q2 IP1 IP3 IP2 T = 400 BO = 5 OH = 0 SR = 0 On-hand inventory Order placed Order placed sP+L = 15 13 = 54 units Q = 400 - (-5) = 405 L L L Time P P Protection interval Periodic Review Systems T = Average demand during protection interval + zsP+L st= 15 units L = 3 weeks cycle/service level = 80% D = (40 units/week)(52 weeks) = 2080 units EOQ D P = = 10 weeks
T IP IP Order received Order received Qt = T - IPt IP = OH + SR - BO Q3 Q1 OH OH Q2 IP1 IP3 IP2 T = 400 BO = 5 OH = 0 SR = 0 On-hand inventory Order placed Order placed sP+L = 15 13 = 54 units Q = 400 - (-5) = 405 L L L Time P P Protection interval Periodic Review Systems T = Average demand during protection interval + zsP+L st= 15 units L = 3 weeks cycle/service level = 80% D = (40 units/week)(52 weeks) = 2080 units EOQ D P = = 10 weeks T = (40 units/week)(13 weeks) + 0.84(54 units) = 565 units
L L L P P Protection interval Periodic Review Systems T IP IP Order received Order received Q3 Q1 OH OH Q2 IP1 IP3 IP2 On-hand inventory Order placed Order placed Time
Continuous Review Fixed lot sizes lower safety stock Periodic Review orders placed at fixed intervals can combine multiple items inventory only needs to be known when order is due Comparison of Continuous (Q, R) and Periodic (T, P) Inventory Systems