Water jet cutting: aspects to consider before investing

Posted on 03/08/2022 in Guide & Tips

Water jet cutting: aspects to consider before investing

 


Waterjet cutting solves many problems. These are often related to the variety of materials that can easily be cut. Waterjet cutting is often chosen because of its flexibility and responsiveness to its users. It also has many advantages for the production process.

What can a waterjet cutting machine do to improve different phases of production?


Water jet cutting is used to increase component production.

It is important to mention that waterjet cutting technology can improve productivity and precision in the cutting of materials. This makes possible the production of chamfers and also of cutting components or sets in three dimensions.

 As a result, assembly times can be significantly reduced as well as deburring and machining component removal.

Why? Because the precision of the cut limits the surface finish and machining removal, which can be costly. Water jets also negate the limitations of quenching or deburring, which are common in plasma cutting, oxy cutting, and laser cutting.

Water jet cutting machines are a great alternative to milling machines, especially for roughing near the finished surface.

Another practical use of water jet cutting is to prepare for welding. A water jet machine can make a chamfer with great precision It also allows for deep penetration of a weld bead in the material so that it does not create a "central" but a "peripheral" weld.


Abrasive: A balance must be found

Theoretically, the kinetic energy calculation is a key element in calculating the best balance between water jet pump pressure adjustment and abrasive dosing. Its theorem defines kinetic energy (KE). KE = 0.5x mv2 (m denotes the mass, v the speed or velocity).

Let's take an example: If a car (2 tons) strikes a truck (38 tons), the main parameter will be mass. This will override speed (130 km/h for the car, 90 km/h for the truck).

The phenomenon is very similar for water jets. The projected mass, which is the amount of abrasive, as well as the square of jet velocity dependent on pressure, are all important.

Each material and thickness have an "ideal energy velocity." This energy velocity can be controlled by speed (pressure) and proper dosing of abrasives. After this aspect is understood, the abrasive/pressure balance must be adjusted to match the machine's advanced speed.

We could also increase the pressure to play on the square velocity (see kinetic energy). The cutting would be quicker, but excessive pressure would cause more damage to the pipes, connectors, and joints. This would result in higher maintenance costs. Additionally, beyond a certain pressure, the jet's speed doesn't allow for the proper mix of grains. The projected mass drops also decrease the jet's energy, which in turn reduces its effectiveness.

It is important to balance the pressure required to make the process reliable, not too costly, and the number of abrasives that must be projected with the same amount of water. This will ensure you maintain a certain speed and consistency with your machine's speed.

The best ratio between the abrasive & the quantity of water is in the range 1-7." With a 0.25 nozzle at 3500 bar pressure, the water flow rate is 1.74 liters/minute or 1740g. 250g would be the required abrasive. This allows for water / abrasive dosages that penetrate while maintaining decent jet speed. 

This theoretical value is not accurate as the material and thickness of the material will affect the energy's absorption. Every level of absorption must correspond to projected energy. The jet's energy is fully controlled, so all that is left is to adjust the speed ratio to achieve the best result. Motors are required to operate the abrasive. 

Waterjet cutting machines equipped with electronic control and a step motor to dose the abrasive can be used to dose the material almost to the gram. This allows for the calculation of the energy projected onto the component to ensure that the machine is well managed and controlled.


Reduced workforce using a water jet cutter machine

A series of automated cutting programs can increase the productivity of the machine. The machine can produce for many hours without the assistance of an operator. This solution involves creating and launching multiple programs with different thicknesses and materials.

Before the machine operator launches the production sequence, he or she installs the materials to be cut on the water jet table. The machine checks each program to ensure that it is consistent in thickness before starting the appropriate program.


Last, but not least - waterjet cutting machines are more efficient.

They could cut potentially inaccessible areas

Safety sensors are generally installed around the machine. This area is not accessible by the operator, which prevents him from operating concurrently, such as unloading components or loading them.

This system has the advantage of allowing you to load and unload the machine while it cuts. It also meets safety standards and protects the operator. Operators will no longer need to wait until the end of a program in order to gain access to components. Instead, they can take advantage of the machine's peripheral protection.

A larger cutting surface (larger cutting tables) is necessary to improve the production of waterjet cutting machines. This is directly related to the order of programs and the concurrent operation time. It is possible to achieve a wide production range. The operator's tasks during production (therefore concurrent operation time) are also possible.

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