Advanced Waterjet Technology for Machining Curved and Layered Structures

Abstract Considerable advancements in waterjet technology take advantage of its inherent merits as a versatile machine tool have been achieved in recent years. Such advancements include, but are not limited to, process automation, machining precision, multimode machining of most materials from macro to micro scales, and cost effectiveness with fast turnaround. In particular, waterjet as a cold cutting tool does not introduce heat-affected zones (HAZ) and preserves the integrity of parent materials. As such, for heat-sensitive materials, its cutting speed is over ten times faster than those of thermal-based tools, such as solid-state lasers, electric discharge machining (EDM), and plasmas cutting. Although waterjet is basically a 2D machined tool, novel multi-axis accessories were developed to enable 3D machining and for machining on workpieces with 3D geometry. For composites, waterjet unlike mechanical routers is capable of minimizing or mitigating tearing and fraying. CNC hard tools that are in direct contact with highly abrasive composite matrix often experience rapid wearing while the heat generated by machining processes induces thermal damage to the composite. This is a nonissue for waterjet as it is a noncontact tool. The only issue for machining composites with waterjet was the damage caused by large stagnating pressure developed inside blind holes during the initial piercing operation (before breakthrough). Considerable effort was made to understand and resolve the waterjet piercing damage issue. For extremely precise parts, waterjet can serve advantageously as a near-net shaping tool; the parts can then be finished by light trimming with proper precision tools. Since the bulk of the material is removed by waterjet, the operating lives of the precision tools can be greatly extended. This paper presents a collection of waterjet-machined samples to demonstrate many benefits by applying waterjet for multimode machining of curved and layered structures.