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To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Chapter 15 Chapter 15
Resource Resource PlanningPlanning
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Material Requirements Planning
• Materials requirements planning (MRP) is a means for determining the number of parts, components, and materials needed to produce a product
• MRP provides time scheduling information specifying when each of the materials, parts, and components should be ordered or produced
• Dependent demand drives MRP• It is most valuable in industries where a number of
products are made in batches using the same productive equipment.
• The theme of MRP is “getting the right materials to the right place at the right time”.
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Demand PatternsDemand Patterns
| | | | | | | | | |1 5 10
Day
2000 —
1500 —
1000 —
500 —
0
Bic
ycle
s
Rim
sR
ims
2000 —
1500 —
1000 —
500 —
0
| | | | | | | | | |1 5 10
Day
Figure 15.2(a) (b)
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Demand PatternsDemand Patterns
| | | | | | | | | |1 5 10
Day
2000 —
1500 —
1000 —
500 —
0
Bic
ycle
s
Reorder point
Figure 15.2
Rim
sR
ims
2000 —
1500 —
1000 —
500 —
0
| | | | | | | | | |1 5 10
Day(a) (b)
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Demand PatternsDemand Patterns2000 —
1500 —
1000 —
500 —
0
Rim
sR
ims
2000 —
1500 —
1000 —
500 —
0
| | | | | | | | | |1 5 10
Day
| | | | | | | | | |1 5 10
Day
Order1000 onday 3
Bic
ycle
s
Reorder point
(a) (b)
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Demand PatternsDemand Patterns2000 —
1500 —
1000 —
500 —
0
| | | | | | | | | |1 5 10
Day
Order1000 onday 3
Bic
ycle
s
Reorder point
(a) (b)
Rim
sR
ims
2000 —
1500 —
1000 —
500 —
0
| | | | | | | | | |1 5 10
Day
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Demand PatternsDemand Patterns
(a) (b)
2000 —
1500 —
1000 —
500 —
0
| | | | | | | | | |1 5 10
Day
Order1000 onday 3
Order1000 onday 8
Bic
ycle
s
Reorder point
2000 —
1500 —
1000 —
500 —
0
Rim
sR
ims
| | | | | | | | | |1 5 10
Day
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Demand PatternsDemand Patterns
(a) (b)
2000 —
1500 —
1000 —
500 —
0
| | | | | | | | | |1 5 10
Day
Order1000 onday 3
Order1000 onday 8
Bic
ycle
s
Reorder point
2000 —
1500 —
1000 —
500 —
0
Rim
sR
ims
| | | | | | | | | |1 5 10
Day
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Demand PatternsDemand Patterns2000 —
1500 —
1000 —
500 —
0
Rim
sR
ims
2000 —
1500 —
1000 —
500 —
0
| | | | | | | | | |1 5 10
Day(a) (b)
| | | | | | | | | |1 5 10
Day
Order1000 onday 3
Order1000 onday 8
Bic
ycle
s
Reorder point
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Material Requirements Material Requirements Plan InputsPlan Inputs
Figure 15.4
Bills ofmaterials
Engineeringand process
designs
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Material Requirements Material Requirements Plan InputsPlan Inputs
Bills ofmaterials
Engineeringand process
designs
Othersources
of demand
Authorizedmaster production
schedule
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Material Requirements Material Requirements Plan InputsPlan Inputs
Inventorytransactions
Inventoryrecords
Bills ofmaterials
Engineeringand process
designs
Othersources
of demand
Authorizedmaster production
schedule
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Material Requirements Material Requirements Plan ExplosionPlan Explosion
Inventorytransactions
Inventoryrecords
Bills ofmaterials
Engineeringand process
designs
MRPMRPexplosionexplosion
Othersources
of demand
Authorizedmaster production
schedule
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Material Requirements Material Requirements Plan OutputPlan Output
Inventorytransactions
Inventoryrecords
Bills ofmaterials
Engineeringand process
designs
Materialrequirements
plan
MRPMRPexplosionexplosion
Othersources
of demand
Authorizedmaster production
schedule
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Bill of Materials (BOM)
• Indicates all the raw materials, components, subassemblies, and assemblies required to produce an item
• A structured list of all components, parts, and materials of an item
• Shows way a finished product or parent item is put together from individual components
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Bill of MaterialsBill of Materials
Figure 15.5
Seat cushion
Seat-frame boards
Front legs A
Ladder-back chair
Back legs
Leg supports
Back slats
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Bill of MaterialsBill of Materials
Figure 15.5
Back slats Seat cushion
Seat-frame boards
Leg supports
Front legs
Back legs A
Ladder-back chairJ (4)
Seat-frameboards
C (1)Seat
subassembly
D (2)Frontlegs
B (1)Ladder-backsubassembly
E (4)Leg
supports
AALadder-backLadder-back
chairchair
I (1)Seat
cushion
H (1)Seat
frame
G (4)Backslats
F (2)Backlegs
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Master Production Schedule
• Based on actual customer orders and predicted demand
• Indicates when each ordered item will be produced
• Time-phased plan specifying how many and when the firm plans to build each end item
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Master Production ScheduleMaster Production Schedule
200
Ladder-back chair
Kitchen chair
Desk chair
1 2
April May
670670
3 4 5 6 7 8
200
150
120
200
150
200
120
Aggregate production plan for chair family
670670
Figure 15.6
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Inventory Record• Detailed information regarding the quantity of
each item, on hand, on order committed to use in various time periods
• MRP system using inventory master file to determine the quantity available for use in a given period
• If sufficient items are not available, the system includes the item on the planned order release report
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Inventory RecordInventory Record Figure 15.11
Item: CDescription: Seat subassembly
Lot Size: 230 unitsLead Time: 2 weeks
Gross requirements 150150
1
230230
00
2
00
00
3
00
120120
4
00
5
00
150150
6
00
120120
7
00
8
00Scheduled receipts
Projected on-hand inventory
Planned receipts
Planned order releases
37
Week
0000
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Inventory RecordInventory RecordItem: CDescription: Seat subassembly
Lot Size: 230 unitsLead Time: 2 weeks
Gross requirements 150150
1
230230
00
2
00
00
3
00
120120
4
00
5
00
150150
6
00
120120
7
00
8
00Scheduled receipts
Projected on-hand inventory
Planned receipts
Planned order releases
37
Week
0000
Explanation:Gross requirements are the total demand for the two chairs. Projected on-hand inventory in week 1 is 37 + 230 – 150
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Inventory RecordInventory RecordItem: CDescription: Seat subassembly
Lot Size: 230 unitsLead Time: 2 weeks
Gross requirements 150150
1
230230
117117
00
2
00
00
3
00
120120
4
00
5
00
150150
6
00
120120
7
00
8
00Scheduled receipts
Projected on-hand inventory
Planned receipts
Planned order releases
37
Week
0000
Explanation:Gross requirements are the total demand for the two chairs. Projected on-hand inventory in week 1 is 37 + 230 – 150 = 117 units.
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Inventory RecordInventory RecordItem: CDescription: Seat subassembly
Lot Size: 230 unitsLead Time: 2 weeks
Gross requirements 150150
1
230230
117117
00
2
00
00
3
00
120120
4
00
5
00
150150
6
00
120120
7
00
8
00Scheduled receipts
Projected on-hand inventory
Planned receipts
Planned order releases
37
Week
0000
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Inventory RecordInventory RecordItem: CDescription: Seat subassembly
Lot Size: 230 unitsLead Time: 2 weeks
Gross requirements 150150
1
230230
117117
00
2
00
00
3
00
120120
4
00
5
00
150150
6
00
120120
7
00
8
00Scheduled receipts
Projected on-hand inventory
Planned receipts
Planned order releases
37
Week
0000
Projected on-hand inventory balance at end of week t
Inventory on hand at end of week t - 1
Gross requirements
in week t
Scheduled or planned receipts in
week t
= + –
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Inventory RecordInventory RecordItem: CDescription: Seat subassembly
Lot Size: 230 unitsLead Time: 2 weeks
Gross requirements 150150
1
230230
117117
00
2
00
00
3
00
120120
4
00
5
00
150150
6
00
120120
7
00
8
00Scheduled receipts
Projected on-hand inventory
Planned receipts
Planned order releases
37
Week
0000
117117 117117 – – 33 – – 33 ––153153 ––273273 ––273273
Projected on-hand inventory balance at end of week t
Inventory on hand at end of week t - 1
Gross requirements
in week t
Scheduled or planned receipts in
week t
= + –
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Item: CDescription: Seat subassembly
Lot Size: 230 unitsLead Time: 2 weeks
Gross requirements 150150
1
230230
117117
00
2
00
00
3
00
120120
4
00
5
00
150150
6
00
120120
7
00
8
00Scheduled receipts
Projected on-hand inventory
Planned receipts
Planned order releases
37
Week
0000
117117 117117 ––33 – – 33 ––153153 – – 273273 – – 273273
Planned OrdersPlanned OrdersExplanation:Without a new order in week 4, there will be a shortage of three units: 117 + 0 + 0 – 120 = – 3 units.
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Item: CDescription: Seat subassembly
Lot Size: 230 unitsLead Time: 2 weeks
Gross requirements 150150
1
230230
117117
00
2
00
00
3
00
120120
4
00
5
00
150150
6
00
120120
7
00
8
00Scheduled receipts
Projected on-hand inventory
Planned receipts
Planned order releases
37
Week
0000
117117 117117
Planned OrdersPlanned Orders
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Item: CDescription: Seat subassembly
Lot Size: 230 unitsLead Time: 2 weeks
Gross requirements 150150
1
230230
117117
00
2
00
00
3
00
120120
4
00
5
00
150150
6
00
120120
7
00
8
00Scheduled receipts
Projected on-hand inventory
Planned receipts
Planned order releases
37
Week
0000
117117 117117 227227
230230
Planned OrdersPlanned OrdersExplanation:Adding the planned receipt brings the balance to 117 + 0 + 230230 – 120 = 227 units.
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Item: CDescription: Seat subassembly
Lot Size: 230 unitsLead Time: 2 weeks
Gross requirements 150150
1
230230
117117
00
2
00
00
3
00
120120
4
00
5
00
150150
6
00
120120
7
00
8
00Scheduled receipts
Projected on-hand inventory
Planned receipts
Planned order releases
37
Week
0000
117117 117117 227227
230230
Planned OrdersPlanned OrdersExplanation:Adding the planned receipt brings the balance to 117 + 0 + 230230 – 120 = 227 units.
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Item: CDescription: Seat subassembly
Lot Size: 230 unitsLead Time: 2 weeks
Gross requirements 150150
1
230230
117117
00
2
00
00
3
00
120120
4
00
5
00
150150
6
00
120120
7
00
8
00Scheduled receipts
Projected on-hand inventory
Planned receipts
Planned order releases
37
Week
0000
117117 117117 227227
230230
230230
Planned OrdersPlanned OrdersExplanation:Offsetting for a two-week lead time puts the corresponding planned order release back to week 2.
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Item: CDescription: Seat subassembly
Lot Size: 230 unitsLead Time: 2 weeks
Gross requirements 150150
1
230230
117117
00
2
00
00
3
00
120120
4
00
5
00
150150
6
00
120120
7
00
8
00Scheduled receipts
Projected on-hand inventory
Planned receipts
Planned order releases
37
Week
0000
117117 117117 227227
230230
230230
Planned OrdersPlanned OrdersExplanation:Offsetting for a two-week lead time puts the corresponding planned order release back to week 2.
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Item: CDescription: Seat subassembly
Lot Size: 230 unitsLead Time: 2 weeks
Gross requirements 150150
1
230230
117117
00
2
00
00
3
00
120120
4
00
5
00
150150
6
00
120120
7
00
8
00Scheduled receipts
Projected on-hand inventory
Planned receipts
Planned order releases
37
Week
0000
117117 117117 227227
230230
230230
227227 7777 ––4343
Planned OrdersPlanned OrdersExplanation:The first planned order lasts until week 7, when projected inventory would drop to – 43.
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Item: CDescription: Seat subassembly
Lot Size: 230 unitsLead Time: 2 weeks
Gross requirements 150150
1
230230
117117
00
2
00
00
3
00
120120
4
00
5
00
150150
6
00
120120
7
00
8
00Scheduled receipts
Projected on-hand inventory
Planned receipts
Planned order releases
37
Week
0000
117117 117117 227227
230230
230230
227227 7777
230230
Planned OrdersPlanned OrdersExplanation:Adding the second planned receipt brings the balance to 77 + 0 + 230230 – 120 = 187.
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Item: CDescription: Seat subassembly
Lot Size: 230 unitsLead Time: 2 weeks
Gross requirements 150150
1
230230
117117
00
2
00
00
3
00
120120
4
00
5
00
150150
6
00
120120
7
00
8
00Scheduled receipts
Projected on-hand inventory
Planned receipts
Planned order releases
37
Week
0000
117117 117117 227227
230230
230230
227227 7777
230230
Planned OrdersPlanned OrdersExplanation:Adding the second planned receipt brings the balance to 77 + 0 + 230230 – 120 = 187.
187187
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Item: CDescription: Seat subassembly
Lot Size: 230 unitsLead Time: 2 weeks
Gross requirements 150150
1
230230
117117
00
2
00
00
3
00
120120
4
00
5
00
150150
6
00
120120
7
00
8
00Scheduled receipts
Projected on-hand inventory
Planned receipts
Planned order releases
37
Week
0000
117117 117117 227227
230230
230230
227227 7777
230230
187187
230230
Planned OrdersPlanned OrdersExplanation:The corresponding planned order release is for week 5.
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Planned OrdersPlanned OrdersItem: CDescription: Seat subassembly
Lot Size: 230 unitsLead Time: 2 weeks
Gross requirements 150150
1
230230
117117
00
2
00
00
3
00
120120
4
00
5
00
150150
6
00
120120
7
00
8
00Scheduled receipts
Projected on-hand inventory
Planned receipts
Planned order releases
37
Week
0000
117117 117117 227227
230230
230230
227227 7777
230230
187187
230230
187187
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Additional MRP Scheduling Terminology
• Gross Requirements-total requirements for a component or end product
• Scheduled receipts-when a purchase or product order that has already been placed will be available
• Planned order release-how many and when to produce to meet gross requirements
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Lot Sizing in MRP Programs
• Lot-for-lot (L4L) (producing as much as required)
• Fixed order quantity (ordering same quantity each time an order is issued)
• Periodic order quantity (allows a different order quantity for each order issued, but tends to issue the order at predetermined time intervals such as every two weeks)
• Economic order quantity (EOQ)
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Lot-Sizing Rule ComparisonLot-Sizing Rule Comparison The FOQ rule generates high average The FOQ rule generates high average
inventory because it creates remnants.inventory because it creates remnants.
The POQ rule reduces The POQ rule reduces average on-hand inventory average on-hand inventory because it does a better because it does a better job of matching order job of matching order quantity to requirements.quantity to requirements.
The L4L rule minimizes The L4L rule minimizes inventory investment inventory investment but maximizes the number of orders placed.but maximizes the number of orders placed.
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
MRP OutputsMRP Outputs
Figure 15.16
MRP MRP explosionexplosion
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
MRP OutputsMRP Outputs
Material requirements plan
Action notices Releasing new orders Adjusting due dates
Priority reports Dispatch lists Supplier schedules
Capacity reports Capacity requirements planning Finite capacity scheduling Input-output control
MRP MRP explosionexplosion
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
MRP OutputsMRP Outputs
Material requirements plan
Action notices Releasing new orders Adjusting due dates
Priority reports Dispatch lists Supplier schedules
Capacity reports Capacity requirements planning Finite capacity scheduling Input-output control
MRP MRP explosionexplosion
Routings and time
standards
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
MRP OutputsMRP Outputs
Material requirements plan
Action notices Releasing new orders Adjusting due dates
Priority reports Dispatch lists Supplier schedules
Capacity reports Capacity requirements planning Finite capacity scheduling Input-output control
MRP MRP explosionexplosion
Manufacturing resources plan
Performance reports
Routings and time
standards
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
MRP OutputsMRP Outputs
Material requirements plan
Action notices Releasing new orders Adjusting due dates
Priority reports Dispatch lists Supplier schedules
Capacity reports Capacity requirements planning Finite capacity scheduling Input-output control
MRP MRP explosionexplosion
Manufacturing resources plan
Performance reportsCost and price data
Routings and time
standards
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
MRP ExplosionMRP ExplosionItem: Seat subassemblyLot size: 230 units
Lead time: 2 weeks
Gross requirements 150150
1
230230
117117
2 3
120120
4 5
150150
6
120120
7 8
Scheduled receipts
Projected on-hand inventory
Planned receipts
Planned order releases
37
Week
117117 117117
0 00 0
00 00 000 00 0
227 227 77 187 187
230230
230230
Figure 15.18
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Item: Seat subassemblyLot size: 230 units
Lead time: 2 weeks
Gross requirements 150150
1 2 3
120120
4 5
150150
6
120120
7 8
Planned receipts
Planned order releases
Week
0 00 0
230
230
230
230
MRP ExplosionMRP Explosion
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Item: Seat subassemblyLot size: 230 units
Lead time: 2 weeks
Gross requirements 150150
1 2 3
120120
4 5
150150
6
120120
7 8
Planned receipts
Planned order releases
Week
0 00 0
230
230
230
230
MRP ExplosionMRP Explosion
Item: Seat framesLot size: 300 units
Lead time: 1 week
Gross requirements
1
00
2 3 4 5 6 7 8
Scheduled receipts
Projected on-hand inventory
Planned receipts
Planned order releases
40
Week
00 00 00300 00 0
Item: Seat cushionLot size: L4L
Lead time: 1 week
Gross requirements
1
00
2 3 4 5 6 7 8
Scheduled receipts
Projected on-hand inventory
Planned receipts
Planned order releases
0
Week
00 00 000 00 0
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Item: Seat subassemblyLot size: 230 units
Lead time: 2 weeks
Gross requirements 150150
1 2 3
120120
4 5
150150
6
120120
7 8
Planned receipts
Planned order releases
Week
0 00 0
230
230
230
230
Item: Seat framesLot size: 300 units
Lead time: 1 week
Gross requirements 00
1
00
2 3 4 5 6 7 8
Scheduled receipts
Projected on-hand inventory
Planned receipts
Planned order releases
40
Week
230
00 00 00300 00 0
Item: Seat cushionLot size: L4L
Lead time: 1 week
Gross requirements 00
1
00
2 3 4 5 6 7 8
Scheduled receipts
Projected on-hand inventory
Planned receipts
Planned order releases
0
Week
230
00 00 000 00 0
Usage quantity: 1 Usage quantity: 1
MRP ExplosionMRP Explosion
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Item: Seat subassemblyLot size: 230 units
Lead time: 2 weeks
Gross requirements 150150
1 2 3
120120
4 5
150150
6
120120
7 8
Planned receipts
Planned order releases
Week
0 00 0
230
230
230
230
Item: Seat framesLot size: 300 units
Lead time: 1 week
Gross requirements 00
1
00
2 3
00
4 5 6 7 8
Scheduled receipts
Projected on-hand inventory
Planned receipts
Planned order releases
40
Week
230 2300
00 00 00300 00 0
Item: Seat cushionLot size: L4L
Lead time: 1 week
Gross requirements 00
1
00
2 3
00
4 5 6 7 8
Scheduled receipts
Projected on-hand inventory
Planned receipts
Planned order releases
0
Week
230 2300
00 00 000 00 0
Usage quantity: 1 Usage quantity: 1
MRP ExplosionMRP Explosion
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Item: Seat subassemblyLot size: 230 units
Lead time: 2 weeks
Gross requirements 150150
1 2 3
120120
4 5
150150
6
120120
7 8
Planned receipts
Planned order releases
Week
0 00 0
230
230
230
230
Item: Seat framesLot size: 300 units
Lead time: 1 week
Gross requirements 00
1
00
4040
2 3
00
4 5
00
6
00
7 8
Scheduled receipts
Projected on-hand inventory
Planned receipts
Planned order releases
40
Week
110110 110110
230 2300 0
00 00 00300 00 0
110 180 180 180 180
300
300
Item: Seat cushionLot size: L4L
Lead time: 1 week
Gross requirements 00
1
00
00
2 3
00
4 5
00
6
00
7 8
Scheduled receipts
Projected on-hand inventory
Planned receipts
Planned order releases
0
Week
00 00
230 2300 0
00 00 000 00 0
0 0 0 0 0
230
230
230
230
MRP ExplosionMRP Explosion
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Item: Seat framesLot size: 300 units
Lead time: 1 week
Gross requirements
1 2 3 4 5 6 7 8
Planned receipts
Planned order releases
Week
300
300
Item: Seat cushionLot size: L4L
Lead time: 1 week
Gross requirements
1 2 3 4 5 6 7 8
Planned receipts
Planned order releases
Week
230
230
230
230
00 00 00 00230 2300 000 00 00 00230 2300 0
MRP ExplosionMRP Explosion
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Item: Seat framesLot size: 300 units
Lead time: 1 week
Gross requirements
1 2 3 4 5 6 7 8
Planned receipts
Planned order releases
Week
300
300
Item: Seat cushionLot size: L4L
Lead time: 1 week
Gross requirements
1 2 3 4 5 6 7 8
Planned receipts
Planned order releases
Week
230
230
230
230
00 00 00 00230 2300 000 00 00 00230 2300 0
Gross requirements
1
00
2 3 4 5 6 7 8
Scheduled receipts
Planned receipts
Planned order releases
200
Week
00 00 000 00 0
Projected on-hand inventory
Item: Seat-frame boardsLot size: 1500 units
Lead time: 1 week
MRP ExplosionMRP Explosion
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Item: Seat framesLot size: 300 units
Lead time: 1 week
Gross requirements
1 2 3 4 5 6 7 8
Planned receipts
Planned order releases
Week
300
300
Item: Seat cushionLot size: L4L
Lead time: 1 week
Gross requirements
1 2 3 4 5 6 7 8
Planned receipts
Planned order releases
Week
230
230
230
230
00 00 00 00230 2300 000 00 00 00230 2300 0
Gross requirements 00
1
00
2 3
12001200
4 5
00
6
00
7 8
Scheduled receipts
Planned receipts
Planned order releases
200
Week
0 00 0
00 00 000 00 0
Projected on-hand inventory
Item: Seat-frame boardsLot size: 1500 units
Lead time: 1 week
Usage quantity: 4
MRP ExplosionMRP Explosion
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Item: Seat framesLot size: 300 units
Lead time: 1 week
Gross requirements
1 2 3 4 5 6 7 8
Planned receipts
Planned order releases
Week
300
300
Item: Seat cushionLot size: L4L
Lead time: 1 week
Gross requirements
1 2 3 4 5 6 7 8
Planned receipts
Planned order releases
Week
230
230
230
230
00 00 00 00230 2300 000 00 00 00230 2300 0
Gross requirements 00
1
00
200200
2 3
12001200
4 5
00
6
00
7 8
Scheduled receipts
Planned receipts
Planned order releases
200
Week
200200 200200
0 00 0
00 00 000 00 0
500 500 500 500 500
1500
1500
Projected on-hand inventory
Item: Seat-frame boardsLot size: 1500 units
Lead time: 1 week
MRP ExplosionMRP Explosion
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Solved Problem 1Solved Problem 1
Figure 15.21
LT = 2 LT = 3
LT = 3
A
B (3) C (1)
LT = 1
G (1)
LT = 3 LT = 6
LT = 3
LT = 1
D (1)D (1) E (2) F (1)
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Solved Problem 2Solved Problem 2
Figure 15.22
A
B (1) C (2)
D (1)
LT = 2
LT = 1 LT = 2
LT = 3
Inventory Record Data
ITEMDATA CATEGORY B C D
Lot-sizing rule POQ (P=3) L4L FOQ = 500 unitsLead time 1 week 2 weeks 3 weeksScheduled receipts None 200 (week 1) NoneBeginning (on-hand) 20 0 425 inventory
Table 12.1
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Solved Problem 2Solved Problem 2Item: B Lot size: POQ (P = 3)Description: Lead time: 1 week
Gross requirements 100100
1
2020
2 3 4 5 6 7 8
Scheduled receipts
Projected on-hand inventory
Planned receipts
Planned order releases
20
Week
200200 200200
200
0 0 240 60 0
280
9 10
120 180 60
0 0
360
280 360
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Solved Problem 2Solved Problem 2Item: C Lot size: L4LDescription: Lead time: 2 weeks
Gross requirements 200200
1
200200
2 3 4 5 6 7 8
Scheduled receipts
Projected on-hand inventory
Planned receipts
Planned order releases
0
Week
00 00
400
200
0 0 0 0 0
400
9 10
240 360 120
0 0
240 360 120
400 240 360 120
To Accompany Ritzman & Krajewski Foundations of Operations Management, © 2003 Prentice Hall, Inc. All rights reserved.
Solved Problem 2Solved Problem 2Item: D Lot size: FOQ = 500 unitsDescription: Lead time: 3 weeks
Gross requirements 400400
1
425425
2 3 4 5 6 7 8
Scheduled receipts
Projected on-hand inventory
Planned receipts
Planned order releases
425
Week
2525 2525
240
285 425 305
500
9 10
360 120
500
360305 305 305
500 500
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