Flexible Management of Product Structure and System Configuration

1. Flexible Management of Product Structure and System Configuration 99/01/21 이 기 창

2. Contents • Paper1 • An extended bill of material for selecting production alternatives in a multi-routeing environment • Paper2 • Design of components and manufacturing systems for agile manufacturing • Future Research • Reference

3. An extended bill of material model for selecting production alternatives in a multi-routeing environment K. Kogan Dep. Of Industrial Engineering, Tel-Aviv University, Israel IJPR, 1994, Vol.32, No.3, 657-667

4. Introduction • Alternative BOM (Extended or Multi BOM) • another solution for meeting changing demand instead of MPS modification • optimal BOM that can be identified among all alternative BOMs • modular BOM based on common parts that have similar BOMs • Component type • desirable component : to be exhausted by BOM • undesirable component : to be excluded from any BOM • red component : to be checked between required and available quantity • Problem definition • to get optimal BOM having minimum direct/indirect cost • to get every alternative BOM

5. Hypergraph model • Definition of hypergraph (Berge1989) • Given a finite set X={x1, x2, …, xn}, A hypergraph on X is a family H=(E1, E2, …, Em) of subsets of X such that • 1) • 2) • vertices : x1, x2, …, xn • edges : E1, E2, …, Em • Example for hypergraph

6. Hypergraph model for multi-BOM • Background • Hypergraph has been used for the data scheme in RDB(Owrengo 1988, Maier 1983) and in hypertext DB(Tompa 1989) • Reason • The main feature of multi-BOM is a number of multi-relation between product and subproducts. • Directed hypergraph for multi-BOM • Z : set of components, ZC : a subset of Z • D1(Z) : set of all subsets of Z • Hypergraph H=(ZC, E) is directed if any hyperedge e=(z1,z2,…zk) in E is an ordered set of nodes, that is z1>zi.

7. Example of the multi-BOM

8. Optimal direct search method • Operations on hyperedges and hypernodes • Forward traversing operation(FT) • Given one hypernodes subset ZEJ, return a new set of all hypernodes subsets ZEJ+1 • Backward traversing operation(BT) • Inverse of FT operation • Hyperedge selection operation(HS) • Decalre hyperedge having minimum cost as optimal • Route split operation(RS) • For a red component, if required volume is greater than available, this operation takes one route and returns two. • After one route consume all available quantity, this red component becomes undesirable one.

9. Optimal direct search method • Basic procedure • Culling procedure • Implement forward chaining strategy by cyclically invoking the FT operation • Provides the reduction of the entire components set Z to the restricted set ZC determined by ZE0, …, ZEK • Optimizing procedure • Implement backward chaining strategy by cyclically invoking the BT operation • Decision about the optimal hyperedge is made via HS operation • Planning procedure • Provides the single optimal solution for an order and executes MRP calculation • Controls red components and applies RS operation

10. Example of optimal directed search • Cost information • ZD=ZR={ }, ZUND={z14, z16} • Step 1. Culling procedure • ZE0={(z1)}; ZE1={(z2, z3, z4, z5), (z2, z3, z4, z6)}; ZE2={(z7), (z8), (z9), (z10, z12), (z11, z12)}; ZE3={(z13, z14), (z13, z15), (z13, z16)} • Step2. Optimizing procedure • Optimal costs of noes z10=1.22, z3=1.00, z5=1.64, z1=1.88 • ZE3={(z13, z15)}; ZE2={(z9), (z11, z12)}; ZE1={(z2, z3, z4, z5)}; ZE0={(z1)} • Step3. Planning procedure • {(z1)} {(z2, z3, z4, z5)} {(z9), (z11, z12)} Z2 1.00 Z4 30.00 Z6 2.00 Z7 0.07 Z8 0.20 Z9 0.05 Z11 1.20 Z12 10.00 Z13 15.00 Z14 1.00 Z15 0.50 Z16 0.70

11. Optimal BOM for the example

12. Directed search method • Difference with optimal directed search method • concentrates on the set of all feasible routes • requires a vastly greater memory and time consumption • Operations on hyperedges and hypernodes • similar to optimal directed search method • excludes HS operation and include balancing edge operation(BE) • BE operation : given an edge, returns hyperedge covering this edge • Additional definition • Basic graph : a graph which may include up to all possible binary relations among components • Basic tree : feasible basic graph

13. Directed search method • Basic procedures • Basic tree synthesis • BT and FT operations • completion procedure • complements edges of basic trees by BE operation • Example of directed search method • Step 1 • Basic tree synthesis procedure • T0={(z1, z5), (z5, z10), (z10, z15)}; T1={(z1, z5), (z5, z11)}; T2={(z1, z6)} • Step 2 • Completion procedure • T0={(z1, z5, z2, z4), (z5, z10, z12), (z10, z15, z13)}; • T1={(z1, z5, z2, z3, z4), (z5, z11, z12)}

14. 3 basic tree of the example

15. Conclusion • Modeling and searching for optimal solutions in multi-BOM is implemented by hypergraph. • Closed-loop MRP system may extend its function to design multi-BOM. • Tradeoff between several BOMs per order at lower material cost and one BOM per order at higher material cost should be investigated.

16. Design of components and manufacturing systems for agile manufacturing G.H. Lee Dep. of Industrial Engineering, Soongsil University, Korea IJPR., 1998, Vol.36, No.4, 1023-1044

17. Introduction • Agile manufacturing system • short life cycle, low volume, increased variety • simple, flexible, reconfigurable, responsive to market change • rapid introduction of new and modified products • Focus of this paper • manufacturing lead time reduction • dynamic reconfiguration of manufacturing systems

18. Design for short manufacturing lead time • Related literature • design rules aiming at the reduction of production costs • Hundal(1993), Sur(1978) • design rules for improved schedulability • Kusiak and Hee(1994) • design for automated assembly rules • Boothroyd(1991), Laszcz(1984) • Design for agility rule • “Design an assembly so that precedence constraints for subassemblies are ordered from the shortest maximum machining time to the longest.”

19. Assembly sequence and Gantt chart (initial)

20. Assembly sequence and Gantt chart (agility rule)

21. Manufacturing system reconfigurations • Related literature • relocating m/c’s at a minimum cost : Cohners(1984) • adapting to a variety of products : Makino(1994) • 2 types reconfigurable system • statically reconfigurable system • the concept of building blocks that are easily moved • dynamically reconfigurable system • limited reconfigurability such as conveyors • Factors to be considered • material handling costs, m/c relocation costs, retooling costs, lost revenue

22. Reconfiguration condition • If the following inequality is true, system i should be reconfigured to system j. : set of components to be produced in system j : material handling cost of component r in system i : material handling cost in the best configuration of manufacturing system k for component r : machine relocation costs from system i to system j : lost revenue when machines are relocated

23. Solution procedure • QAP(quadratic assignment problem) • manufacturing system reconfiguration problem • NP-complete • Algorithm Step 0 : Begin with production stage and corresponding configuration Step 1 : Configure system Step 2 : Evaluate configured system at this stage Step 3 : Until all stages are considered, go to step 1. • Configuration is done by heuristic method by Connolly(1990), etc. • M/C relocation rule • Use bi-directional material handling carriers. • Minimize the number of location constraints imposed on machines. • Relocate machine tools with the lowest relocation cost.

24. Example (cost information) Material handling cost Machine arrangement cost

25. Example (component information)

26. Example (initial & final configuration) Initial configuration Final configuration

27. Conclusion • Design rule applied at design stage reduces the manufacturing lead time. • Manufacturing system reconfiguration based on production plan may bring advantages such as reduction of complex material flow, reduction of the number of material handling devices, reduction of time and cost to handle material, etc. • Standard machine relocation costs and time is not available yet. • Design rules for reconfigurable hardware, software, shopfloor are necessary.

28. Future research • BOM management in an integrated manner • Engineering BOM conversion • BOM design for manufacturability such as scheduling, modularizing, etc. • Capacity planning that contains BOM policy • Manufacturing BOM evaluation and improvement based on the information of material flow and shop floor status • Manufacturing system design • General design methodology • Relationship between design and operating strategy

29. Reference • Hundal, M.S., 1993, Rules and models for low-cost design. In Design for manufacturability, New York, ASME, 21, 75-84 • Berge , C., 1989, Hypergraphs, North-Holland Mathematical Library. • Owrengo, M, 1988, Query translation based on hypergraph models, Comuter Journal, 31, 2, 155-164 • Tompa, F.W., 1989, A data model for flexible hypertext database systems, ACM Transactions on Information Systems, 7, 1, 85-100 • Sur, N.P, 1978, On an axiomatic approach to manufacturing and manufacturing systems, Journal of Engineering for Industry, 100, 127-130 • Kusiak, A, and Lee, G.H., 1997, Design of parts and manufacturing systems for reliability and maintainability, The International Journal of Advanced Manufacturing Technology, 13, 67-76

30. Reference • Laszcz, J.F., 1984, Product design for robotics and automatic assembly, Proceedings of Robots 8 Conference, 1, pp.6.1-6.22 • Boothroyd, G., 1991, Assembly automation and product design, New York, Marcel Dekker. • Cohners, 1984, Flexible assembly a boon or short production runs. In Automated Assembly, Dearborn, MI:SME, pp.184-190 • Makino, H., 1994, New developments in assembly systems, Annals of the CIRP, 43, 501-522.