Ultimate Guide to Water Jet Machining Process: Advantages & Features 2022

Water jet processing is one of the “removal processing” that cuts metal with jets of water. It is used for the precision cutting of various workpieces such as urethane and glass that are easily deformed, including cutting automobile bodies and bumpers. By mixing abrasives with water, it is possible to process hard-to-cut materials such as titanium, which is difficult to cut and to cut thick plates.

This article explains the benefits of water jet processing, as well as “abrasive water jet”, which is a mixture of abrasives.

Since it does not use cutting oil and does not generate dust, it is attracting attention as an environmentally friendly process!

What kind of processing is waterjet?

A waterjet cutting machine is cutting parts

Waterjet cutting is a processing method that cuts metal with jets of water. Using the same principle as the high-pressure washer used in car washes, water is sprayed at high pressure to cut metal.

High processing energy can be generated by pushing out water compressed to 300-600MPa from a small diameter nozzle of φ0.1mm.

The jetting speed of water reaches three times the speed of sound, and any material can be used as long as the work can is wet.

A “water jet machine” is used for processing, and 3D processing by NC control and complex processing by 5-axis control is possible. Adjusting the water pressure can be applied to various processes such as deburring, polishing, and cleaning.

The principle of waterjet metal processing technology

This method of cutting metals appeared in the middle of the last century. Initially, pure water was used, but after a few years, engineers decided to add abrasive sand to the jet, which greatly increased the cutting properties.

The essence of this technology is to act on the material with a jet of water under strong pressure. Today this technology is one of the most dynamically developing and is considered one of the best cutting methods.

Waterjet metal cutting is in no way inferior in quality to plasma; laser or mechanical cutting, in addition, such a jet is a tool that is not subject to wear. The jet diameter used is different, depending on the type of material. Usually, it is 0.5-1.5 mm. Due to the small diameter, material waste is very small.

An important advantage of this technology can be called the fact that cutting can be started from any point of the product.

Any waterjet cutting machine works like this:

1. High power pumps create 3800 to 6200 bar water pressure inside the self-centering cutting head.
2. A thin jet of water is formed in the nozzle, which, under high pressure, at a speed higher than the speed of sound, is fed into the mixer.
3. Water is supplied to the mixer of the apparatus from the nozzle, and the abrasive material is supplied from a special hopper for the abrasive.
4. After mixing, water and abrasive form a cutting jet, which is applied to the material being cut.

The cutting table is cantilevered or gantry and has a specially designed frame for optimum stability and freedom from distortion and vibration at high speeds.
The cutting process is controlled by specialized software, various versions of which allow cutting of any shape, depending on the capabilities of the cutting head.

The main advantages of waterjet cutting

Cold cut: Waterjet cutting is a “cold” process, as it does not require additional heat input. Water and abrasive are involved in the cutting process, the heating of the cut material remains insignificant, and there are no thermal and mechanical deformations.

Also, the advantage of a “cold” cut is the absence of burrs, warping, and scale, therefore, the resulting products, due to the high quality of the cut, do not require preliminary preparation before subsequent operations (for example, painting or welding).

Also, the process of cold cutting as whole increases productivity, since when installing workpieces, they do not need to be fixed and cooled before the next technological process.

High cutting accuracy (± 0.1 mm): The combination of high pressure and a small cutting area allows you to achieve the desired result without additional operations.

Waterjet cutting is actively used when it is necessary to obtain a high-quality cut, for example, to obtain precise geometric shapes. Also, waterjet cutting can be used for a wide variety of materials and non-standard types of surfaces.

High versatility in application: Waterjet cutting is used in a wide range of applications, from mass production of sheet metal parts to three-dimensional marble carving, and is one of the most versatile cutting systems today.

The allowable thickness for cut steels is 300 mm. The introduction of 5-axis cutting heads has led to rapid growth in waterjet cutting: when cutting flat parts, the head can make continuous cuts, move around the workpiece, and also make bevel cuts in the range of ±55 ^°.

Features of water jet machining

Since water jet machining uses water, it has various advantages that other machining methods do not have.

1. Not affected by heat

Since “water” is used, there is no heat generation compared to cutting and laser processing.

Therefore, the processing accuracy is high, and it is possible to process materials that are vulnerable to heat.

2. The machining force can be adjusted

Since “water” is used, the force applied to processing can be adjusted by adjusting the water pressure.

Therefore, it is possible to process soft materials such as rubber and urethane, as well as printed circuit boards.

3. Low cost

Because it uses “water”, it is easy to maintain and the running cost is low.

4. Eco-friendly

Since “water” is used, dust is not generated during processing. In addition, ” coolant “, which is used in large amounts in cutting, is not required.

Principle of water jet machining

Water jet processing is divided into “water jet processing” which uses only water and “abrasive water jet processing” which mixes abrasives with water.

This is a processing method that cuts the workpiece only by high-pressure jetting of water. It is suitable for cutting soft materials such as urethane, wood, and resin.

Due to its high environmental friendliness, it is widely used not only in metal processing sites but also in food processing and medical industries.

Abrasive water jet machining

Abrasive water jet machining

This is a processing method in which an abrasive is mixed with water to cut the workpiece.

Abrasives are sucked in by the negative pressure of high-pressure water and sprayed as a mixed liquid from the nozzle.

It has a high cutting capacity and is suitable for cutting difficult-to-process materials such as titanium and ceramics as well as metals. It is also used in the processing of automotive parts and new materials for aircraft. For water jet processing, NC-controlled water jet processing machines called “water jet machines are used.

Configuration of water jet machine

• Ultra high-pressure water generator
• processing nozzle
• Abrasive supply device

Ultra high-pressure water generator

This is a pump that emits super high pressure of 300 to 600 MPa.

Processing nozzle

It is made of materials such as cemented carbide and diamond to prevent wear from the jet.

• For water jet processing, use a nozzle with a diameter of about 0.1 to 0.3 mm.
• In abrasive water jet processing, use a nozzle of about φ1mm

Abrasive supply device

Equipment for mixing abrasives with water in abrasive water jet processing.

Summary

In this article, we explained the benefits of water jet processing and various methods of mixing abrasives. Water jet machining is attracting attention as a machining method that is friendly to the environment because it does not use cutting oil, and is friendly to workers as it does not generate dust. In addition to metal processing, it is also used for rescue activities in the event of a disaster because it is non-flammable.