Lecture 28: Supply Chain Scheduling 2

1. Lecture 28: Supply Chain Scheduling 2 © J. Christopher Beck 2005

2. Outline • Discrete Manufacturing vs Continuous Manufacturing • What Difference Does It Make? • A Typical Framework for Supply Chain Optimization • Medium Term Planning • Short Term Scheduling • Information System Issues © J. Christopher Beck 2005

3. Supply Chain Scheduling © J. Christopher Beck 2005

4. Discrete vs. Continuous Manufacturing • Continuous (process) production • Main inventory/products are finely divisible • Steel, shampoo, paper • Discrete production • Main inventory/products are individually countable • Cars, computers, consumer electronics • Scheduling problems are different © J. Christopher Beck 2005

5. Continuous:1. Main Processing • Raw materials aretransformed to intermediate products • Machines have high start-up/shutdown costs and • High changeover costs • Often fixed batch sizes • Usually run 24/7 © J. Christopher Beck 2005

7. Continuous:2. Finishing • Products of mainprocesses are “specialized” • Cut, bent, extruded, painted, printed, … • Often these are commodities • Many clients • Mix of make-to-stock, make-to-order • Due dates, sequence dependent changeovers, and inventory management are important © J. Christopher Beck 2005

8. Discrete:1. Primary Conversion • Like finishing in continuous • Stamping, bending, cutting • Process is generally pretty simple • Output is often a part • Car body part, computer case, … • Schedule is often integrated with downstream processes © J. Christopher Beck 2005

9. Discrete:2. Main Production • Many differentoperations of many tools • 100 step process for semiconductors! • Machines are very expensive • Often organized like a job shop • Each order has its own route, quantity, due date • Sequence dependent changeovers © J. Christopher Beck 2005

10. Discrete:3. Assembly • Put together parts • Machines are cheap but material handling is important • Assembly lines • cars or consumer electronics • Due dates, changeovers, sequencing, … © J. Christopher Beck 2005

11. Table 8.1 © J. Christopher Beck 2005

12. Table 8.2 © J. Christopher Beck 2005

13. Supply Chain Decomposition © J. Christopher Beck 2005

14. Medium-term Aggregation • Time abstraction • 1 unit = 1 day or 1 week • Product abstraction • Work at product “family” level • e.g., Tuborg beer, not 6-pack, 12, 24, keg, … • Cost/job/capacity abstraction • Average processing times • Sequence dependencies ignored • Factory treated as a single resource © J. Christopher Beck 2005

15. Medium-term Planning Results • Daily or weekly • Demand for product families at each facility • Inventory levels • Transportation requirements • No detailed scheduling has been done! © J. Christopher Beck 2005

16. Medium-term Constrains Short-term © J. Christopher Beck 2005

17. Medium-term Decouples Short-term © J. Christopher Beck 2005

18. Short-term Scheduling Uses More Precise Data • Time in minutes or seconds • Horizon ≈ week, 2 weeks • Jobs and resources are detailed • Set-up time/cost are taken into account • Products not just product families • Demand for each product is represented © J. Christopher Beck 2005

19. Problem • Short term schedule solution may not exist! • Why? • May require feedback of information to the medium-term and a resolve • Carlsberg takes 10-12 hours for a medium-term solve … © J. Christopher Beck 2005

20. Feedback Mechanism Needed © J. Christopher Beck 2005

21. Information Infrastructure Requirements © J. Christopher Beck 2005