Waterjet cutting: effective, flexible and precise For a variety of materials and cutting thicknesses of 0,1 - 300 mm.
Waterjet cutting is one of the fastest growing industrial manufacturing processes. Especially the versatile fields of application, ease of use and effectiveness increases convince users of a wide range of different industries to integrate STM water jet cutting systems in their production processes. The technology of water jet cutting allows to cut almost any material. Therefore, STM systems can be found in tool- and mould-making, the automotive, aircraft or aerospace industry, as well as in the stone and tile sector, the metal construction sector and the contract manufacturing.
The technology of waterjet cutting
For the cutting process, water is pressed through a nozzle with a pressure of 4000-6000 bar. Resulting in enormous speeds. The water exits with Mach 2-3 (two to three times the velocity of sound). The advantage is that the workpiece surface remains nearly cold because the cut is immediately cooled by the water. While waterjet cutting, there are no prestructural changes, increased hardness or noxious fumes.
Clean water cutting
The pure water jet cuts soft materials such as foam and rubber. It is also used in the food industry.
The benefits of the pure water cutting:
- Very thin beam (normal range of 0.1 to 0.25 mm)
- Extremely detailed geometry
- Very low material loss by cutting processing
- Simple clamping
Abrasive waterjet cutting
If abrasive (garnet) is added to the water after the water nozzle, hard materials such as glass, metal, composites, etc. can be cut up to a thickness of 300 mm. Generally, it can be said that with the abrasive waterjet it is possible to cut materials to the hardness of the abrasive (Mohs hardness of about 8).
The advantages of abrasive waterjet cutting:
- Extremely versatile process
- No heat affected zones
- No mechanical exposure
- Thin beam (0.5 to 1.3 mm in diameter)
- Hardly or no burrs
The faster a material is cut with the waterjet, the coarser is the cut. In principle, it must be said that by doubling the material thickness, the feed rate is generally reduced by more than half the value.
The faster the cut is made, the narrower the kerf at the waterjet discharge at the bottom edge of the material. The cutting width at the entry point is mostly 1 mm. With “fine cuts“, the kerf at the exit point has a width of approx. 0.8 mm, with “normal cuts“ approx. 0.5 mm and with “centre cuts”, the approximate width is 0.3 mm.
CAUTION – this ratio has the most effect on thin materials. The angle deviation is thus approx. 7° with a “normal cut” of 2 mm stainless steel but only about 1° with 50 mm stainless steel.
What does the cutting quality depend on?
The operating materials in use such as focus and water nozzle are provided by a few suppliers worldwide. Consistently similar output parameters like pressure and amount of water result in a very similar cutting result.
The main difference is, as always, in the detail. In fact the point is how fine-tuned the waterjet cutting system is and how precice it can adjust to the cutting task. In this context the cutting speed is key since it has a big impact on the quality and costs.
The cutting speed does not depend so much on the basic parameters like water pressure and amount of water - which do not vary much among suppliers, the differences lie in a single-digit percentage range - but on the required cutting quality.
A separating cut is 3 times faster than a quality cut and therefore the costs are 3 times lower.