170 likes | 443 Views
A TOOL FOR OPTIMISING FACILITIES DESIGN FOR CAPITAL GOODS COMPANIES. Christian Hicks Email: Chris.Hicks@ncl.ac.uk University of Newcastle, England. http://www.staff.ncl.ac.uk/chris.hicks/presentations/presin.htm. Capital Goods Companies. Products and processes usually complex.
E N D
A TOOL FOR OPTIMISING FACILITIES DESIGN FOR CAPITAL GOODS COMPANIES Christian Hicks Email: Chris.Hicks@ncl.ac.uk University of Newcastle, England. http://www.staff.ncl.ac.uk/chris.hicks/presentations/presin.htm
Capital Goods Companies • Products and processes usually complex. • Typical products include steam turbines for power generation, oil rigs and bespoke cranes. • Production facilities include jobbing, batch, flow and assembly systems. • Customised to meet individual customer requirements. • Engineered-to-order. • Low volume, ‘lumpy’, erratic demand.
Block plans show the relative positioning of resources. Plans may be evaluated in terms of static measures e.g. total distance travelled by components. Problems may be classified as: Green field – designer free to select processes, machines, transport, layout, building and infrastructure; Brown field – existing situation imposes many constraints. Facilities Design Problems
Based upon an analogy with biological evolution in which the fitness of an individual determines its ability to survive and reproduce. Uses GAs to create sequences of machines or ‘chromosomes’. Applies a placement algorithm to generate layouts. Evaluates layouts in terms of total direct or rectilinear distance to determine ‘fitness’. The probability of ‘survival’ of a chromosome to the next generation is a function of its ‘fitness’ Genetic Algorithm Tool
Heavy engineering job shop. 52 Machine tools. 3408 complex components. 734 part types. Complex product structures. Total distance travelled: Directdistance 232Km; Rectilinear distance 642Km. Case Study
Total rectilinear distance travelled vs. generation (brown field)
Total rectilinear distance travelled vs. generation (green field)
Resultant green field layout Note that brown field constraints, such as walls have been ignored.
Significant body of research relating to facilities layout, particularly for job and flow shops, but much of the research is related to small problems. Capital goods companies utilise flow, cellular, jobbing and assembly systems. Job shops incorporate most capital intensive plant and produce the highest value, longest lead-time items. GA tool generated layout reduces total rectilinear distance travelled by 25% for the brown field case. Conclusions
Future Work • The GA layout generation tool is embedded within a large sophisticated simulation model. • Dynamic layout evaluation criteria can be used. • The integration with a GA scheduling tool provides a mechanism for simultaneously ‘optimising’ layout and schedules with respect to static and dynamic performance criteria.