In part two of our common misconceptions series we get into some machine design topics and specific cutting applications. If you haven’t read it, be sure not to miss what I discussed in part one.
What did you say?
I can’t say I’ve heard them all, but I’ve heard a bunch of them: strange misconceptions about waterjets.
It’s not surprising.
After all, we are cutting with a supersonic waterjet stream (often with a garnet sand added to it) and yet it can cut through a foot thick (300 mm) of metal. People say, “No it can’t!” Actually, yes it can.
Today waterjet is one of the fastest growing machine tool processes in the world and has over 30,000 systems installed. But how did it begin? I’ve seen many different claims over the years as to the start of waterjet. There is only one thread – one sequence of events – that I subscribe to, and that is the specific sequence that leads to the commercialization of waterjet for the cutting of soft materials in the 70’s.
Waterjets can be attached to a variety of machines. There are hand-held waterblasting wands with rotating tips used to remove paint; stationary jets used for high-speed tissue paper slitting; single axis systems used for cutting baked goods, fiber cement board or other product moving off of a roll; and still others attached to 7-axis pedestal robots used for trimming automotive interiors. But the most common machine used to hold or move a waterjet (or an abrasive waterjet) is the shapecutting machine tool. These are similar to machines that cut with plasma, laser, or router.
With this machine the material is placed (or held) on a work table and the cutting head is moved in an XY plane over top. Sometimes the head has 5 axes of motion for bevel or 3D cutting. I will use the abrasive waterjet shapecutting system in my example from this point forward.
Let’s start with the basics.
Waterjets are cool. They cut cool – they look cool – and the more you understand how they work and what they can cut the more you appreciate the technology. After 30 years of waterjetting I still marvel at water and sand cutting through super hard materials. It’s just water and abrasive, for goodness sake. How cool is that?!