Machining parameters for an intelligent machining system for composite laminates

Composite laminates exhibit very high in-plane strengths but are plagued by delamination damage when subjected to machining. This is due to their poor transverse strengths and low delamination fracture toughness. In drilling, delamination is initiated when the thrust force exceeds a threshold value, particularly at the critical entry and exit locations of the drill bit. To minimize damage, therefore, it is important to monitor process variables s uch as the machining forces and the position of the tool relative to the wo rkpiece. The availability of a suitable model coupled with an intelligent c ontrol scheme would be a large advancement in the machining of composite la minates. This paper explores the development of such models for machining o f composites and for coupling the models to intelligent control strategies. Using a machining center, a series of drilling experiments were conducted on carbon fiber-reinforced composite laminates to determine key process par ameters for various cutting conditions. An intelligent machining scheme is proposed as the basis for the design of a new machine tool. (C) 1999 Publis hed by Elsevier Science Ltd. All rights reserved.