A rule based system for printed wiring assembly process planning

Abstract

A prototype computer-aided process planning (CAPP) system, PWA_Planner (printed wiring assemblies planner), is presented. PWA_Planner is a rule based system for preparing assembly plans for the manufacture of PWAs via automatic component mounting machines, PWA_Planner uses a forward planning procedure, starts from a design blueprint and a bare printed wiring board (PWBrpar; components are mounted on the board until the completed PWA is reached. The final assembly plan includes a component assignment diagnostic file, a process plan, and automatic mounting machine program files. PWA_Planner utilizes a computer-aided design (CAD) representation of the PWA and automatic component mounting machine descriptions to prepare the assembly plans. The assembly plans eliminate interference between components and mounting heads, utilize preferred component mounting paths, and consider the order in which automatic mounting machines assemble the PWA. PWA_Planner is written in PROLOG. Board descriptions, parts information, blueprint description, and components specifications are represented as facts. The capabilities of automatic mounting machines, mounting sequence, and interference checking method are written as rules. A forward-chaining control logic is used. It can be used to provide feedback to PWA designers on the producibility of the design and to generate good assembly process plans. The current version of PWA_Planner does not have optimizing scheme built-in. This paper demonstrates a sound application of artificial intelligence in manufacturing.