An integrated design and planning environment for welding - Part 2: Process planning

This paper describes the specification and implementation of aggregate proc ess planning methods for complex welding operations. The methods are implem ented as an aggregate process planning tool, CAPABLE/Welding, which can be used to evaluate the manufacturability of complex fabrications at the early stages of design. The first part of the paper discussed the aggregate prod uct modelling methods, which are object-oriented and feature-based. The agg regate product model provides the necessary abstraction of design data to f acilitate the assessment of early designs. A key planning requirement was t o utilise the aggregate product model by developing process knowledge captu ring and optimisation techniques so that production time and cost can be ca lculated for complex fabrications requiring many welding operations and set -ups. CAPABLE/Welding is a tool usable directly by designers, as it does no t require specialist process knowledge. A range of generic welding process models has been developed and the planning techniques are instantiated with regard to company specific production equipment and factory layout. Altern ative process and machine options are explored and the optimum production m ethod is found using a simulated annealing algorithm. This selects process types, equipment, finds the best welding orientation, number of set-ups and finds the optimum processes and routes for minimum product cost or lead ti me. The resulting plans are presented graphically via a hypertext browser. This combines a graphic display of process time and cost distribution by fe ature with links to the relevant process knowledge. The process planning pr ocedure of a product is used in this paper to illustrate the system functio nality. (C) 2000 Elsevier Science B.V. All rights reserved.