Lecture 28 Supply Chain Scheduling 2 J Christopher

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

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

Supply Chain Scheduling © J. Christopher Beck 2005 3

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

Continuous: 1. Main Processing n n n Raw materials are transformed 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 5

© J. Christopher Beck 2005 6

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

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

Discrete: 2. Main Production n Many different operations of many tools n n n 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 9

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

Table 8. 1 Segment Process Horizon Clock Speed Differentiation Continuous: Main Planning Long-medium Low Very low Continuous: Finishing Planning/ scheduling Medium-short Medium/ High Medium/low Discrete: Conversion Planning/ scheduling Medium-short Medium Very low Discrete: Main Planning/ scheduling Medium-short Medium/low Discrete: Assembly Scheduling Short High © J. Christopher Beck 2005 11

Table 8. 2 Segment Optimization Problem Solution Technique Continuous: Main Lot-sizing, cyclic scheduling MIP Continuous: Finishing Single machine, parallel machine Batch scheduling, inventory control, dispatch rules Discrete: Conversion Single machine, parallel machine Batch scheduling, dispatch rules, CP Discrete: Main Flow shop, job shop IP, CP, shifting bottleneck, LS Discrete: Assembly line Grouping, spacing, sequencing techniques, CP, LS 12 © J. Christopher Beck 2005

Supply Chain Decomposition Mediumterm planning Shortterm scheduling Stage 1 © J. Christopher Beck 2005 Stage 2 Stage 3 Stage 4 13

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

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

Medium-term Constrains Short -term Mediumterm planning Shortterm scheduling Stage 1 © J. Christopher Beck 2005 Stage 2 Stage 3 Stage 4 16

Medium-term Decouples Short -term Mediumterm planning Shortterm scheduling Stage 1 © J. Christopher Beck 2005 Stage 2 Stage 3 Stage 4 17

Short-term Scheduling Uses More Precise Data n n n 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 n Demand for each product is represented © J. Christopher Beck 2005 18

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

Feedback Mechanism Needed Mediumterm planning Shortterm scheduling Stage 1 © J. Christopher Beck 2005 Stage 2 Stage 3 Stage 4 20

Information Infrastructure Requirements Mediumterm planning Shortterm scheduling Stage 1 © J. Christopher Beck 2005 Stage 2 Stage 3 Stage 4 21