Computer Aided Process Planning, Strategy, and Models in the Aircraft Industry

Abstract

Unlike computer aided design (CAD) and computer aided manufacturing (CAM) systems which have been used in industry for a long time, computer aided process planning (CAPP) systems are yet to be transferred from research laboratories to industry. Aircraft industries are trying to improve their performance by developing CAPP software, and the present study contributes to this effort. Aircraft parts are specific mainly because of their complex geometry, which generates many accessibility problems, and their thin shells, which generate machining deformation and vibration problems. New CAPP approaches have been specified and developed for aircraft structural parts. Machining features are defined as machining faces. The part is split up into a set of machining faces with accessibility, adjacency, and rigidity properties. New set-up strategies are defined. These highlight three particular features in the machining of such parts: the categorization, which is a strict guide as to how the part should be machined; the best-fit blank orientation relative to the part; and the potential machining directions of the part which are the main elements for decision making.

Enhanced functions supporting process planning for aircraft structural parts

“…The function we present below is very dedicated to the machining of aircraft structural parts, meaning that it is the first step to support a specific planning activity, nonusual in programming for other components such as automotive or mould parts [Cap,06]. Indeed, structural aircraft parts are made from slab stock in two setups (front-side/back-side) on a five-axis machine tool with no intervening operations.…”

“…Indeed, the next step for the planner is to set the position of the part ensuring that the limited motions of rotational axes do not forbid the access to any of the selected machining directions. [Cap,05] proposed several other methods to set the stock orientation of for aircraft structural parts, one of which was to compute the stock of minimal volume. They also proposed a visibility-based method and an algorithm for positioning the part on the machine-tool and accessibility checking [Cap,04].…”

“…[Cap,05] proposed several other methods to set the stock orientation of for aircraft structural parts, one of which was to compute the stock of minimal volume. They also proposed a visibility-based method and an algorithm for positioning the part on the machine-tool and accessibility checking [Cap,04]. Their usage is currently questioned in industry and will serve as a future function proposition for our process planning generation help system.…”

An ant colony approach to operation sequencing optimization in process planning

“…2,3 Based on the information, an instruction set should be prepared in the form of process plan, which includes the sequence, machines as well as tools to be used; cutting conditions for the individual processes and so on. 4–6 For a part with complex structures and numerous features, process planning is well known as a complicated decision-making process involving selecting machining operations for every feature and sequencing the aggregate of all the operations considering precedence constraints, choosing available manufacturing resources, determining setup plans, machining parameters and so on. 7–9 All the activities should be considered comprehensively to get an optimal plan so that total machining time or production cost could be sharply decreased and manufacturing efficiency could be greatly increased.…”

Definition and recognition of rib features in aircraft structural part

“…(3) Currently, for the aircraft industry, commercial CAM tools do not have efficient process planning function to assist NC programming. Aircraft structural parts are challenging because their complex geometry generates accessing problems, and the deformation and vibration problems caused by their thin shells (Capponi et al 2006). However, the related process knowledge and experience are implicit and owned by engineers.…”