3 ms·
I would like to know how its possible to operate this thing without wearing down the nozzle as fast as you're cutting the workpiece. Is the grit fed down the ce
by crispyambulance 10y ago
I would like to know how its possible to operate this thing without wearing down the nozzle as fast as you're cutting the workpiece. Is the grit fed down the center of a laminar flow of water so it never touches the metal of the nozzle?
- semi-extrinsic 10y agoThe particles in the flow won't hit the nozzle much at all, since the average flow is tangential to the nozzle walls. Even if the flow is highly turbulent inside the nozzle, there is a boundary layer where the velocity becomes zero. However, when the flow impacts a solid object, the particles can't "keep up" with the fluid splashing away due to their inertia, so they hit the solid object at high speed. Particles in turbulent flow are characterised by (among others) the Stokes number [1], which says something about how well the particles follow the flow. This depends e.g. on the particle size, roughness, and the density difference between solid and fluid. I imagine they have tuned the Stokes number to an optimal tradeoff between cutting speed and nozzle/fluid line wear. [1] https://en.wikipedia.org/wiki/Stokes_number https://en.wikipedia.org/wiki/Stokes_number
- Cerium 10y agoThe nozzles do wear and are made of hard but brittle materials. Bumping the nozzle when joging the machine around is an easy 200 USD mistake to make.
- chromaton 10y agoThe waterjet "jewel" is typically diamond, and the nozzle tungsten carbide. Both are very hard, and thus wear slowly. Though they do wear.