Waterjet Basics

This non-traditional application of abrasive waterjet may interest some to whom waterjet machining is an unfamiliar process, so here is a brief primer:

Abrasive waterjet machining can be thought of as a water-driven grinding process. A narrow, high-pressure jet of water carries particles of garnet abrasive at speeds ranging from 1,000 to 2,400 feet per second. This garnet does the cutting. And there are few materials, metal or non-metal, that cannot be cut in this way. In metalworking, abrasive waterjet machining often finds work cutting hard steels, aerospace alloys, and other materials that are difficult to machine through a more conventional, mechanical cutting process. However, waterjet machining also offers other advantages. One is that it's a "cool" process. Because there is no heat-affected zone, waterjet is a candidate for applications where thermal-induced micro-fractures or distortions in the part are unacceptable.

Abrasive waterjet machining - Process

This article uses "waterjet" and "abrasive waterjet" interchangeably, but it's worth noting that the terms are not necessarily synonymous in larger contexts. There is such a thing as pure waterjet cutting used outside the metalworking industry. But in the context of machining metals and other hard materials, "waterjet machining" can be assumed to mean abrasive waterjet machining, with the hard garnet particles added to the jet.



Historically, controlling a waterjet's depth of cut has been difficult. That's why waterjet machining is typically used in applications where depth of cut doesn't matter. These include applications where the jet passes all the way though the workpiece, like slotting, drilling, and machining cut-outs. Machining when the jet does not pass all the way through has traditionally been limited to "artistic" purposes, like etching and labeling.

Waterjet milling does add control over depth of cut. Thanks to this addition, waterjet cutting when the jet does not pass all the way through can be used not just for appearance effects, but also to produce features that are functional.