CHARACTERISTICS OF SURFACES MACHINED WITH ABRASIVE-WATERJETS

The general characteristics of surfaces machined with abrasive-waterjets (AWJs) are discussed in terms of surface texture and surface integrity. Data are presented from several studies involving different machining operations, including cutting, milling, turning, and drilling, and various advanced materials. The effects of AWJ parameters on surface texture effects, such as waviness, kerf taper, and burr height, in thin sheet metals typically used in the aerospace industry are presented and discussed. Other surface texture parameters, including surface finish and lay, are also addressed for selected machining applications such as milling and turning. Abrasive particle size is found to be the dominant parameter affecting the surface finish. The surface integrity effects are defined as particle deposition, delamination, gouging, microstructural changes, cracking, chipping, work hardening, and heat-affected zones. Particle deposition occurs in the machining of ductile materials, but deposited particles can easily be removed by cleaning. Minor work hardening may result but can be totally eliminated if the dominant material removal mechanism is the cutting wear mode, which prevails under certain jet and traverse conditions. Thus, although the machining of advanced materials with AWJs may result in minor but controllable surface texture effects, it does not generally affect the integrity of the material.