A waterjet stream acts like a beam when cutting, much like plasma cutting and laser cutting. These types of non-rigid cutting tools have to address the beam flexing and changing within the target material to minimize part cutting errors.
What is taper?
Taper in waterjet cutting is when the entrance width of cut is different than the exit width of cut.
What is stream lag?
Stream lag causes corner damage when the exit point lags behind the entrance point, shown in the bottom of the part below.
Plasma cut parts often exhibit an upside-down V-shaped taper where the width of cut is wider at the bottom. Laser and waterjet exhibit a normal V-shaped taper (more narrow width of cut at the bottom). Plasma, laser and waterjet can all yield stream lag errors when cutting a part.