Waterjet cutting is a cold cutting technology. With the help of a waterjet, the material is separated without thermal influence. Either filtered water is used or an abrasive agent (e.g. sand) is added.
Waterjet cutting history
The water breaks through whole mountain ranges, single drops hollow out massive rocks. In nature, the power and hardness of water has stood out for thousands of years. Technology has been exploiting this power since the beginning of the 20th century, first for digging gravel and clay, and in the 1930s for mining ore and coal using a high-pressure waterjet. In the 1960s, the aircraft manufacturer Boeing finally provided the decisive impetus for using the waterjet as a cutting technology. In 1971 the first machine for waterjet cutting was eventually produced..
Advantages of waterjet cutting
- High quality of the cut edges
- No thermal influence
- Suitable for a wide range of materials
A high-pressure pump ensures that the waterjet in a modern cutting machine is compressed to up to 6,000 bar and then forced through a nozzle. As a result, the jet reaches outlet speeds of up to 1,000 m/s. Compared to air, this is approximately three times the speed of sound. For high material thicknesses, an abrasive such as sand is added for waterjet cutting. Since only natural materials such as water and sand are used in this cutting technology, neither toxic gases nor vapours are produced.
Components processed with waterjet
With pure water or additional abbrasives
Three variants of this waterjet technology are used on the CNC machines. Pure water cutting, abrasive cutting or micro waterjet cutting is used for different materials and thicknesses. Abrasive cutting is most frequently used in the field of waterjet cutting, as it provides good results with low and high material thicknesses. Pure waterjet cutting, on the other hand, is mainly used for soft and thin materials, while micro waterjet cutting is used for the most precise applications.
Pure waterjet cutting
Clean water cutting or pure water cutting is primarily used for cutting soft and thin materials, such as leather, foam, rubber, paper or textiles. This cutting technology uses exclusively the jet energy of water. The biggest problems are jet trailing and angle errors. Jet trailing occurs when the cutting at the point of entry is faster than at the point of exit, i.e. energy is lost when cutting the material. Due to the decreasing energy level of the waterjet, the angle error also occurs. Both phenomena can result in inaccuracies in the cutting process. To counteract this, the cutting speed can be reduced. Thus, in pure water cutting, the cutting performance remains limited for hard materials (steel, granite) and higher thicknesses.
Abrasive cutting is used for high-quality separation of thicker materials. It is characterized by the fact that in comparison to pure water cutting, a cutting agent, a so-called abrasive – such as garnet sand or corundum – is added to the waterjet. Only by adding the abrasive materials, also known as abrasives, higher cutting speeds for stronger materials and higher cutting qualities can be achieved. This waterjet technology is used to cut aluminium, copper, stainless steel, granite or marble, for example. To enable abrasive cutting, the cutting head must be equipped with a special focusing nozzle and an abrasive mixing chamber, in contrast to pure water cutting. The high speed of the waterjet creates a negative pressure and thus draws the abrasive into the mixing chamber. The water-sand mixture is then bundled into a jet in an abrasive focusing nozzle.
Micro waterjet cutting
With micro waterjet cutting, positional accuracies of 1 μm are achieved. In addition, the angle error is hardly existent with this form of waterjet cutting. The high accuracy is achieved by an extremely fine-grained cutting medium (abrasive) and a smaller diameter of the waterjet. This results in an extremely high reproducibility of the components. With waterjet cutting in the micro range, even conductive or highly heat-sensitive materials can be processed. For optimum results, constant temperatures in the processing room and in the cutting basin are a prerequisite in addition to a precise and stable portal cutting system.
This waterjet technology can be used to cut a wide variety of materials and material composites – without the material being heated. Since the temperatures in the cutting zone are around 60 to 80 °C, this cutting method is considered a cold cutting process. Waterjet cutting is used where no structural changes on the cutting edges are desired. It is also possible to cut any contours and to start and end at any point on the material surface.
The disadvantage of this waterjet technology: the cutting quality suffers with increasing cutting speed. In addition, waterjet cutting in the field of metalworking is considered quite expensive and relatively slow compared to other cutting methods. The cutting range for waterjet cutting is between 0.5 and 300 mm, depending on the power of the high-pressure pump and the material.
Where is waterjet cutting used?
Waterjet cutting is used particularly frequently in the processing of plastics, metal, leather and stone. Waterjet cutting systems are perfect for the extremely precise processing of all metals, stones, bullet-proof glass, ceramics, plastics, foam and many other materials.
A modern waterjet cutting machine also offers a range of technology options for bevel cutting, drilling, tapping and countersinking and also allows the integration of supports for plasma cutting.