The concept of waterjet cutting is quite simple. Here’s how it works:
1. Generate Pressure
An ultrahigh-pressure pump generates a stream of water with pressure rated at 94,000 psi (6,480 bar).
To put it into perspective, a fire hose contains a pressure of 390 to 1,200 psi (20 to 84 bar).
2. Convert Pressure into Velocity
This pressure is converted into velocity via a tiny diamond orifice (0.381mm diameter), creating a stream as small as a human hair which can cut soft materials.
3. Introduce Garnet
To increase cutting power by 1,000 times, garnet is pulled into the supersonic waterjet stream.
Water and garnet exit the cutting head at nearly four times the speed of sound, capable of cutting steel over one foot thick.
Pure & Abrasive Waterjet
There are two types of waterjet: pure and abrasive. Combined, these two technologies can cut virtually any material, any shape, at any thickness.
Pure waterjet cuts soft materials like gasket, foam, plastic, paper, disposable diapers, insulation, cement board, automotive interiors, carpet, food.
Abrasive waterjet is similar to a pure waterjet, except that after the pure waterjet is created, garnet abrasive is pulled into the head via a venturi vacuum, mixed with the water, and then the resulting abrasive waterjet stream can cut hard materials like metal, ceramic, stone, glass and composite.
Waterjets cut with stream velocity.
How do you get velocity? With ultrahigh-pressure water.
Ordinary tap water is filtered and fed into a waterjet pump rated to pressures of 94,000 psi (6400 bar). The pressurized water runs to the cutting head safely contained within the plumbing to maintain pressure. At the cutting head, the water then passes through the diamond orifice and the supersonic waterjet stream is created.
All the pressure is exchanged for velocity when the water passes out of the diamond orifice. The higher the pressure, the higher the stream velocity.
Waterjet vs. Other Technologies
|Process||Secondary Processing||Materials||Thickness||Part Accuracy (Overall Tolerances)||Capital Investment||Machine Setup|
|Waterjet||Erosion using high speed liquid sandpaper||Usually none. Waterjet is a cold-cutting process that leaves a satin smooth edge||Virtually any material||Up to 24 inches, virtually any material. Z-axis constraint is only limit to thickness||Up to +/- 0.025mm (Typically 0.25mm though)||£45,000 – £350,000+||Same setup for all materials|
Using a high temperature ionised gas arc
|Typically yes. Slag grinding for removal of HAZ (heat affected zone) & flattening to eliminate distortion from heat. Assist gas used impacts depth of HAZ||Primarily steel, stainless steel and aluminum||Up to 2–3 inches, depending on the material||Up to +/-0.25mm (Typically lower though)||£45,000 – £250,000+||Different setup for different jobs|
|Laser||Melting using a concentrated laser light beam||Sometimes yes. Removal of oxidised edge and HAZ. Gases used impact depth of HAZ||A variety of materials, but primarily steel, stainless steel and aluminum||Generally 1 inch or less, depending on the material||Up to +/-0.025mm (Typically 0.2mm)||£155,000 – £800,000+||Different gases and parameters for different jobs|
|EDM||Erosion using an electrical discharge||Usually none. Very shallow HAZ imparted||Conductive materials||Generally 12 inches or less||Up to +/-0.025mm||£80,000 – £300,000+||Different wire types for different jobs|
With waterjet, you get a satin smooth edge right off the table. With other cutting technologies there’s often secondary processing required to get that same satin smooth edge that waterjet produces.
Cut Speed Range
There are clear benefits to each cutting method below, waterjet in comparison with laser, plasma, and edm is an incredibly versatile process that allows you to cut thick or thin materials with ease. With waterjet, you get a satin smooth edge right off of the table – no secondary processing required.