Analysis and structuring of process planning logic for CNC machining: An education and training perspective

Programming of computer numerical control (CNC) machining centres using computer aided manufacturing (CAM) software is efficient provided that machining operations and their sequence has been correctly determined by the user. Such decisions, however, are a largely matter of experience. If the user is inexperienced, then Computer Aided Process Planning systems may be employed, but these are usually legacy systems. Thus, normally some prior knowledge has to be induced to the inexperienced user in the form of structured knowledge or rules. After studying a representative number of parts, creating and validating process plans and feeding them to a CAM system some baseline knowledge has been created and structured into rules. Training the user towards applying these rules, or even creation of custom rules is based on part analysis according to a basic reasoning. This is best implemented by advance-organisers of the schematic type regarding part form, process identification, work-holding and setup sequencing, whilst creation of steps or instructions for guiding the process plan generation flow is effected according to the Structure of the Observed Learning Outcome paradigm. The method has been applied to a sizeable audience and preliminary statistical and qualitative evidence on its effectiveness is presented.