Waterjet Cutting Page

Waterjet & Abrasive Waterjet Cutting

The waterjet cutting process uses a low volume, very thin stream of ultra high pressure water for cutting high precision parts. This thin stream of water leaves the cutting head at over twice the speed of sound, and when a small amount of abrasive is added to the stream it is able to cut virtually any material. Waterjet cutters are able to cut soft materials such as rubber at very fast rates and with a quick change in cutting heads, thicker materials such as 4" stainless steel can also be cut to to part accuracies < 0.004". Waterjet cutting offers many unique abilities over other CNC methods such as laser or plasma. These features include the ability to cut virtually any material to thicknesses over 6" and the lack of heat hardening being imparted to the cut materials.

When evaluating the waterjet cutting process it is important to consider the following:

Waterjet Cutting Vs. Laser & Plasma

High Pressure Pump Technologies

Pump Sizing Requirements

High Pressure & Abrasive Plumbing

Waterjet Environmental Requirements

A simple diagram of an abrasive cutting head is shown to the right.

(1) Incoming High Pressure Water

(2) Orifice (Typical ID From 0.006" To 0.020")

(3) Incoming Abrasive/Garnet (Up To 1.5 Pounds Per Minute)

(4) Mixing Tube (Typical ID From 0.020" To 0.050")

(5) Exiting Abrasive Stream

The waterjet cutting process operates by supplying up to 60,000 PSI water through a plumbing system to the cutting head. Inside the cutting head, a sapphire or diamond orifice restricts the high pressure water flow to a diameter ranging from 0.004" to 0.025". This focused stream of supersonic water is capable of cutting rubber, soft plastics, food, insulation, synthetic turf, carpet and many other soft materials. As most of these materials are so easily cut, a large number of waterjet systems purchased for cutting soft materials are configured with two or more cutting heads, thereby greatly increasing the production capability of the machine.

Harder materials can be cut when an abrasive powder, such as garnet, is mixed in with the stream of water. To aid in this process, the abrasive cutting head incorporates a mixing chamber below the orifice. The flow of high pressure water through this chamber creates a venturi effect, which in turn draws the garnet powder into the stream. This abrasive enriched waterjet stream is then re-focused by a mixing tube which typically has an internal diameter between 0.020" to 0.050". The exiting abrasive stream produces a kerf width that is roughly the same size as the mixing tube ID and is ideal for cutting aluminum, steel, titanium, granite, marble, composites, wood, glass and many other materials.

The abrasive usage is typically between 0.5 pound per minute to 1.5 pounds per minute, depending on the orifice/mixing tube combination, garnet mesh size and the application's requirements.

Abrasive Waterjet Cutting Head

CNC Machines Waterjet Cutting

Waterjet Cutting Examples

Abrasive Application

3" Aluminum

Abrasive waterjet cutting offers several advantages for processing metals.

1) Can Cut Virtually Any Metal

2) No Heat Affected Zone To Damage Tapping Tools

3) Able To Cut Metals Over 6" Thick

4) Part Accuracies < 0.004"

Abrasive Application

2 CM Granite

Abrasive waterjet cutting offers several advantages for processing stone.

1) Small Radius Corners

2) Able To Cut Stone Over 6" Thick

3) Consistent Cutting With No Dulling Of The Tool

4) Part Accuracies < 0.004"

Non-Abrasive Application

3/8" Rubber

Waterjet cutting performs extremely well for rubber cutting and gasket applications where high speed cutting of complex shapes is required. Cutting speeds can exceed 600 IPM for 3/8" thick medium density rubber.

Non-Abrasive Application

Foam Backed Synthetic Turf

Waterjet cutting is increasingly being used is for cutting logos and complex shapes from synthetic turf and carpet materials. Production rates can be more than double the rates from conventional ultrasonic systems. CNC Machines International continues to be a pioneer in this application.