Lot sizing

13-1

MRP & ERP

MPS, RCCP, MRP, CRP, & ERP

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MRP & ERP

MANUFACTURING RESOURCE PLANNING
Aggregate Forecast Aggregate Production Plan

Core MRP

Detailed Forecast

Master Production Schedule

Rough-Cut Capacity Planning

Material Requirements Planning

Capacity Requirements Planning

Purchasing

Dispatching

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MRP & ERP

Aggregate Versus DetailedForecasts (Review)
• Use aggregate forecasts for planning medium-range overall production levels.
– High long-range forecast accuracy – Detail not needed for planning long-range resource use (labor, inventory, etc.)

• Use detailed forecasts for initial detailed shortrange Master Production Schedule (MPS)
– Detailed forecasts reasonably accurate for this time frame – Need product-specific detailfor MPS

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MRP & ERP

MPS

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MRP & ERP

From The Aggregate Plan To The MPS
• Suppose that Export TVs, Inc. has the following production plan for the next six months:
Month TVS J F M A M J 12,000 12,000 15,000 15,000 15,000 18,000

• If they make three models, the MPS for January might look like:
MPS 31" 33" 36" 1-Jan 8-Jan 15-Jan 22-Jan 2,000 1,000 0 1,000 1,000 1,000 02,000 0 1,000 3,000 0

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MRP & ERP

Figure 14-4

Planning Horizon

Assembly
Subassembly

Fabrication
Procurement

1

2

3

4

5

6

7

8

9

10

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MRP & ERP

The Master Production Schedule
• An MPS starts with a forecast and a beginning inventory balance
Product X Period Forecast Projected Available Balance Net Requirements MPS Planned OrderRelease Product Y Period Forecast Projected Available Balance Net Requirements MPS Planned Order Release 1 5 20 2 10 3 8 4 5 5 6 6 8

1 7 12

2 2

3 10

4 13

5 5

6 5

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MRP & ERP

The Master Production Schedule
• Inventory is projected forward until a shortage, or “net requirement,” occurs
Product X Period Forecast Projected Available Balance Net Requirements MPS Planned OrderRelease Product Y Period Forecast Projected Available Balance Net Requirements MPS Planned Order Release 1 5 15 2 10 5 3 8 3 4 5 5 6 6 8

20

1 7 12

2 2

3 10

4 13

5 5

6 5

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MRP & ERP

The Master Production Schedule
• Production is scheduled to be completed (the MPS is a planned finish time) to cover the shortfall
Product X Period Forecast Projected AvailableBalance Net Requirements MPS Planned Order Release Product Y Period Forecast Projected Available Balance Net Requirements MPS Planned Order Release 1 5 15 2 10 5 3 8 5 3 8 4 5 5 6 6 8

20

1 7 12

2 2

3 10

4 13

5 5

6 5

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MRP & ERP

The Master Production Schedule
• A planned start time – the “planned order release” is determined based on lead time (here it is one period)Product X Period Forecast Projected Available Balance Net Requirements MPS Planned Order Release Product Y Period Forecast Projected Available Balance Net Requirements MPS Planned Order Release 1 5 15 2 10 5 3 8 5 3 8 4 5 5 6 6 8

20

8

1 7 12

2 2

3 10

4 13

5 5

6 5

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MRP & ERP

The Master Production Schedule
• The process continues until the product isscheduled
Product X Period Forecast Projected Available Balance Net Requirements MPS Planned Order Release Product Y Period Forecast Projected Available Balance Net Requirements MPS Planned Order Release 1 5 15 2 10 5 3 8 5 3 8 4 5 0 5 6 8 6 14 6 8 0

20

8

14

1 7 12

2 2

3 10

4 13

5 5

6 5

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MRP & ERP

The Master Production Schedule
• The other product is scheduledthe same way
Product X Period Forecast Projected Available Balance Net Requirements MPS Planned Order Release Product Y Period Forecast Projected Available Balance Net Requirements MPS Planned Order Release

20

1 5 15

2 10 5

3 8 5 3 8

4 5 0

5 6 8 6 14

6 8 0

8

14

12

1 7 5

2 2 3

3 10 13 7 20

4 13 0

5 5 5 5 10

6 5 0

20

10

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MRP & ERP...