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Master Production Scheduling

Master Production Scheduling. Chapter 6. Master Production Schedule. A master production schedule (MPS) is a production plan ( anticipated build schedule ) for an individual product, a customer order, or a product option and common parts Make-to-stock: finished product

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Master Production Scheduling

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  1. Master Production Scheduling Chapter 6

  2. Master Production Schedule • A master production schedule (MPS) is a production plan (anticipated build schedule) for an individual product, a customer order, or a product option and common parts • Make-to-stock: finished product • Make-to-order: customer order • Assemble-to-order: product option and common parts

  3. MPC System

  4. Master Production Scheduling • Effective MPS provides the basis for: • Making customer delivery promises • Utilizing plant capacity effectively • Attaining firm’s strategic objectives (from production plan) • Resolving trade-offs between production and marketing

  5. MPS Activities • Operational level—processing MPS transactions, maintaining MPS records and reports, having a periodic review and update cycle (“rolling through time”), responding to exception conditions, and measuring effectiveness of schedules • Daily basis—marketing and production coordinate through order promising (shipment date for a customer order)

  6. MPS Techniques—Time-Phased Record • Record (by periods) • Forecast • Available: projected inventory balance at the endof the period. [available from prior period + MPS – forecast] • MPS: quantity and time of completion of production • On hand: beginning inventory for the first period.

  7. MPS Techniques—Time-Phased Record • Strategies: • Leveling: MPS constant. Excess inventory to meet future forecasts • Chase: MPS matches forecast. No inventory except safety stock • Mixed (hybrid): lot-sizing approach that falls between the two strategies. Inventory for future periods called cycle stock

  8. MPS Techniques—Rolling through Time • MPS is periodically updated—changes in forecast, orders, production, etc., may require adjustments for future periods • One “pointer” would be negative available balances • A counter-balancing force would be feasibility of change

  9. MPS Techniques—Order Promising • Available-to-promise: deduct existing booked orders from available inventory. (See Figures 6.8, 6.9, 6.10) • Time-phased MPS record convention—use the greater of forecasts or booked orders to calculate available inventory balance. • Accurate order promising helps a firm to reduce inventory by using buffer delivery promise dates instead.

  10. MPS Techniques—Consuming the Forecast • Forecast estimates versus actual booked orders. • Negative Available—need a MPS lot (if feasible). • ATP calculated by using only actual orders and scheduled production. • Use both available and ATP rows for MPS planning: negative available quantities represents a “potential” problem, but a negative ATP is a real problem.

  11. BOM Structuring for the MPS • BOM—engineering document specifying subordinate components. • Single-level BOM. • Indented BOM. • Assemble-to-order may represent almost unlimited number of end items (options multiply), leading to other BOM options for MPS planning.

  12. Modular Bill of Materials • Establish the MPS at option or module level. BOM links options/modules to components but not to end items. Not Buildable. • MPS can be stated in fewer units. • Hill-Rom example (p. 231): 160 end item possibilities, but only 19 time-phased MPS records needed. • Customer order—a unique end item.

  13. Planning Bill of Materials • Planning Bill: Created expressly for forecasting and master scheduling • Unique configuration, not buildable • Store in BOM file • Revise with engineering changes • Phantom Bill: A bill for a subassembly whose components are consumed during the assembly of its parents

  14. Super Bill of Materials • Super bill: describes the options or modules that make up an average end item. • Is used as the MPS unit: the plan would be to build per the average option proportions. • Adds complexity to order entry (ATP logic must be applied to each option in the order).

  15. Final Assembly Schedule (FAS) • States exact set of end products to be produced over give time period (final assembly lead time). • MPS—anticipated build schedule; FAS is actual build schedule. In assemble-to-order MPS stated in super bills and options, FAS stated in end items per customer order. • Hill-Rom example, Figures 6.16-6.19.

  16. Master Production Scheduler (Master Planner) • Consolidate all sources of requirements –forecasts, customer orders, interplant orders, service parts orders, etc. • Carefully evaluate MPS changes to see effect on material and capacity plans. (Resolving competing demands.) • Issue production and assembly orders.

  17. Master Production Scheduler (Master Planner) • Understand trade-offs between customer needs and MPC system objectives. • Resolve conflict on production requirements among functions. • Report performance and problems to top management.

  18. MPS Stability • Firm planned orders—quantity, timing are set by the master planner, not adjusted automatically by the software. • Frozen time periods—no changes in the stated time periods are possible. • Time fencing—specify periods in which differing types of changes are possible (e.g., ice, slush, water zones)

  19. Managing the MPS and Data Base • MPS Data Base • Maintain data integrity • Define clear functional responsibilities • Proper control of changes to BOM • Have a realistic MPS; do not overstate the MPS

  20. Managing the MPS and Data Base • Stability and proper buffering • Force the sum of the MPS’s to equal the production plan. • Measures: • Output/period (dollars or units) vs. the MPS or the budget. • Customer service (hitting order acknowledgement or promise dates).

  21. Concluding Principles • The MPS should reflect the company’s approach to the business environment in which it operates. • The MPS is one part of an MPC system—the other parts need to be in place as well for a fully effective MPS system. • Time-phased MPS records should incorporate useful features of standard MRP record processing.

  22. Concluding Principles • Customer order promising activities must be closely coupled to the MPS. • Available-to-promise information should be provided to both the master planner and the sales department. • A final assembly schedule (FAS) should be used to convert an anticipated build schedule (MPS) into an actual build schedule.

  23. Concluding Principles • The master planner must keep the sum of the parts (MPS) equal to the whole (production plan). • The MPS activities must be clearly defined in an organization. • Firm planned orders can be used in the MPS. • Stability should be designed into the MPS. • The MPS should be evaluated with a formal performance measurement system.

  24. Chapter 6 Assignments • Problems 6.4, and 6.12 a & b, and 6.14 • Due Tuesday, Sept. 24 • Use Excel to do Problems 6.4 & 6.14

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