Waterjet cutting - any material can be used! Cut with water.

Waterjet cutting of metal is a technology that the machine-building and metal-rolling industries cannot do without.

Sometimes it is impossible to achieve the required cut quality even through plasma cutting, which is why equipment for cutting using a waterjet is used.

Waterjet cutting of metal was first used by an American aircraft manufacturing company, which subsequently presented evidence that this technology is the best option for processing steel and other refractory metals.

Since that time, the water-abrasive method has not ceased to be in demand in various production areas. Today, machines whose purpose is to process steel, pipes, etc. with a waterjet are very popular.

Equipment used for cutting metal using waterjet is indispensable when working with thick-walled workpieces. Only these machines are capable of providing high quality steel cutting lines during pipe laying.

After grinding the working area of ​​a 200 mm metal sheet, there is no scale or burrs on the surface of the steel cutting line.

Ideal cut quality combined with gentle temperature conditions are not all the advantages that water-abrasive technology has.

The high cost of installations is compensated by savings on fasteners and components, which are not needed even when working with thin-walled workpieces.

The absence of smoke and dust, as well as other unpleasant factors, is another of the many advantages of waterjet cutting.

In addition, there is no need to replace a worn cutting tool and control the sharpness of the cutter, since, in fact, it is absent.

Instead, the function of a cutting tool is performed by a stream of water in combination with abrasive components.

The process of initial and finishing waterjet processing of a cut is performed in one stage.

At the same time, the speed of the work process proceeds without slowdown, the cutting speed does not decrease, even if it is necessary to process thick-walled elements, as, for example, when laying pipes.

The universal characteristics of metal cutting machines allow simultaneous processing of different materials on one installation - it can be plastic, glass, rubber or a multi-layer product.

Waterjet installations for cutting metal are safe to use and can therefore be used in factories with a possible risk of explosion.

Operating principle and application of waterjet machines

Machines for processing metal with waterjet are universal in use, because their capabilities do not end with cutting rolled metal. The operating principle of water-abrasive units can be seen in the video.

The technology is based on a specially designed system for supplying water under high pressure to the surface being treated.

An auxiliary component of the liquid is an abrasive that is added to the water. Typically, microparticles of sand are used as an abrasive additive.

Water and grains of sand are simultaneously fed into the mixer from separate tanks, where they are thoroughly mixed. As a result, the resulting suspension under pressure enters the nozzle of the installation.

Then a working water-abrasive tool, in the form of an intense jet with certain parameters, is directed at the workpiece and cuts it.

In this case, the speed of waterjet cutting can only be compared with the speed of a plasma cutter, but the quality of a cut made by this method can only correspond to the quality of laser cutting.

The rapid development of modern technologies has made it possible to improve machines by expanding their operational capabilities. Due to this, their scope of use has increased.

Today, water-abrasive equipment makes it possible to:

• Carry out non-standard cutting of any material, while the changing angle of the cut does not negatively affect the quality. The work process, carried out at any angle of inclination, makes it possible to obtain completely finished workpieces at the output and not subject them to finishing;
• Cut parts of the most complex geometric shapes using numerical software. In this case, processing is completely automatic and does not require human intervention. The equipment is controlled by a specially defined computer program. Waterjet cutting (for example, pipe processing) allows you to make the desired circle without permissible errors;
• Machines for processing metal (pipes) with waterjet, used in rolled metal, make it possible to cut the maximum thickness of different metals, as shown in the video. Thus, processing of a workpiece made of medium-carbon steel can be carried out using material with a maximum thickness of 200 mm. The maximum thickness of titanium material can be 15-17 mm; high-strength alloys can have a thickness of 12 mm. But the thickness of the copper billet reaches only 5 mm;
• Waterjet technology has also found its application in the field of art. The equipment makes it possible to produce a variety of design and decoration items; most often, the processing of figures occurs using CNC.

Features of operating CNC machines

Waterjet equipment with computer program control is one of the opportunities to expand the scope of use of machines, increase work efficiency and at the same time increase productivity.

More details can be gleaned from the information provided below and the video story.

CNC machines are used to produce blanks from steel, aluminum, copper and other types of metals.

The strict cutting accuracy provided by CNC water-abrasive equipment has virtually no deviations from the assigned tasks.

Program-controlled waterjet units provide the following advantages:

• CNC-equipped machines operate in accordance with a given program. In this case, each workpiece is processed using individual software. With its help, the jet pressure, the composition of the working cutting suspension and other parameters are automatically selected;
• If on non-CNC machines the selection of the cutting jet can be chosen incorrectly, then in this situation this point is excluded. The equipment independently controls the quality of the cut, then automatically adjusts the mode used;
• Metal processing using software also provides the ability to make holes of the desired diameter;
• As you can judge from the video material, upon completion of the waterjet process, a completely finished part emerges from the workpiece, which does not need to be subjected to grinding or additional processing at the cut points.

Manual machines for water-abrasive cutting of metal

Since some of the work still has to be done with your own hands, the convenience and comfort of using such equipment is far from ideal.

But this also has its advantages, consisting of several simple factors, which in some sense can become decisive when choosing equipment:

• Equipment without software is several times cheaper than CNC machines;
• Processing using a manual waterjet machine is accessible to a person without special education;
• Manual installations are distinguished by simple controls and a small set of functions, which you can set up yourself;
• At the same time, the equipment is provided with all the necessary technical properties that make it possible to obtain workpieces with simple geometric shapes;
• Smooth, high-quality cuts, the ability to cut at an angle, cut material and obtain simple figures with strict geometric shapes - all these functions can be used on any materials, including steel, glass and copper. As an example, work can be done to lay pipes.

You can see the process of setting up a manual machine with your own hands and its actions in the video in the section.

Details about consumables for waterjet machines

All that is required to restore the full operation of waterjet machines for cutting metal is to regularly update consumables and worn-out elements, because the machines fail over time.

The consumption of abrasive, even on machines with software, sometimes exceeds 300 g per minute, since when working with a material of maximum thickness, the figure increases.

Microparticles of natural garnet sand are used as an abrasive, which is capable of cutting viscous and refractory workpieces. The size of a microsand grain can be up to 600 microns.

In addition to abrasive, waterjet technology cannot do without water, which is pre-prepared and goes through filters.

If you use liquid without a special preparation system, the quality of the cut will significantly decrease.

The parts of waterjet equipment that most often need to be replaced are the abrasive suspension supply system, nozzle and guide tubes.

As well as sealing elements of the pumping station, without which there will not be the required pressure in the system.

The thematic video in our article will supplement the above information.

Such widespread processes of plasma-arc separation of materials have their limitations. For example, an electric arc is very unstable: when working with metals of high electrical conductivity (copper, brass), the operation in many cases is characterized by melting of the side edges. The presence of gases - by-products of plasma cutting - forces additional measures to be taken to protect the environmental protection of the cutting site. Plasma cutting of dielectric materials (glass, stone, etc.) is generally impossible. In such situations, there is no alternative to waterjet cutting processes. The most popular among this group of methods is waterjet cutting.

The essence of the method and options for its practical implementation

The separation of materials during hydraulic cutting occurs due to the impact of a narrowly directed flow of liquid—water—high pressure on the interface surface. In this case, to intensify the process, a fine abrasive medium can be simultaneously supplied to the technological zone (most often, various types of sand are used for this purpose). Combining, these two flows form an extremely rigid jet, the pressure in which (due to the increased speed of movement) locally exceeds the tensile strength of the material being cut. If you move the tool head, in which all the above-described mechanical processes occur, along a certain trajectory, then you can obtain very complex contour configurations with the required quality and accuracy.

Waterjet cutting of metal using water is usually performed with the following performance characteristics:

1. Pressure - 2000...5000 atm (smaller values ​​​​for softer, predominantly thin-sheet materials).
2. Water flow speed – up to 1000…1200 m/s.
3. Abrasive consumption – up to 50 g/s
4. The average size of an abrasive particle in plan is 100...600 microns (with an increase in this parameter, the accuracy of separation of materials decreases).
5. Water consumption – up to 4 l/min.
6. Waterjet treatment is carried out in the following sequence. The material to be cut is placed in a bath filled with water and fixed in three coordinates relative to the tool head. This can be done with your own hands using a non-automated installation, or on CNC equipment using a pre-set program for separating the material.

Next, the tool head is immersed in the bath, after which an intensive supply of water is turned on at the corresponding speed and pressure values. The liquid, passing through the cutter nozzle, mixes there with the tangentially supplied abrasive flow. Both jets are mixed and directed through a hole in the lower end of the nozzle to the surface of the material being separated. Manually or programmatically, the nozzle is brought closer together, as a result of which the resulting jet pressure increases sharply, producing dimensional destruction of the edges.

Particles of material are drawn into the resulting gap, after which, losing their speed, they fall to the bottom of the bath, from where they are pumped out by a special pump provided by the design of the working unit. During the pumping process, abrasive fractions are separated from water, followed by filtration and drying. Due to the sufficient capacity of the water tanks, waterjet cutting can be carried out continuously and at increased jet speeds.

The equipment bath in which waterjet processing is performed performs two functions:

• Reduces the noise level when cutting (up to 78...80 dB versus 130...140 dB in the case of processing outside the water environment);
• Reduces the energy and speed of the water jet.

Technological capabilities of the method

The technology under consideration is most effective in the following cases:

1. For dielectric materials, as well as conductive products made of non-ferrous metals and copper-based alloys. This is explained by the fact that the electrical conductivity parameters of copper alloys do not allow the use of an electric arc or laser for cutting.
2. If it is necessary to separate parts of very large thickness - up to 250...300 mm: in this case, during plasma-arc cutting, edge melting always occurs.
3. To ensure proper accuracy of the interface: with the correct selection of the mode, the edge roughness is within the range of Ra 0.5...Ra 1.25, which significantly exceeds the capabilities of any other high-energy method.
4. If warping of the finished product is unacceptable, which is inevitable with any of the thermal cutting technology options.

Waterjet cutting of metal has its limitations, so the technology is developed taking into account the following capabilities, in particular, in terms of thickness:

• For non-ferrous metals and alloys, as well as stainless steel – no more than 120...150 mm;
• For carbon fiber reinforced plastics and composite materials – no more than 150…200 mm;
• For artificial and natural stone (marble, granite, basalt, etc.) - no more than 270...300 mm.

When developing the technology, it should be taken into account that conductive materials of relatively small thickness (up to 5...10 mm) are cut poorly by the jet produced by the working unit: a noticeable energy consumption has an effect, with a performance comparable to plasma-arc or laser processing. However, this does not mean that the technology in question is not applicable for separating thin plates or sheets: in this case, the abrasive flow is turned off and separation is carried out directly with a water jet. As a result, the surface does not heat up, which eliminates scaling, high-temperature melting of the interface and other disadvantages characteristic of all technologies for thermal separation of materials.

Waterjet cutting equipment

A waterjet cutting machine is a complex and energy-intensive equipment containing the following components:

1. A tool head equipped with the function of rotating the cutter at a certain angle, which allows processing surfaces of complex configurations at a given speed.
2. A pumping unit for pumping water with a filtration system.
3. Compressor station for supplying abrasive fractions under pressure.
4. A work table with a three-coordinate positioning device (for small equipment, this work is performed by the installation operator himself).
5. A bath with water, which is structurally connected to the equipment frame.
6. Working containers for water and abrasive.
7. CNC control device, or remote control for manual positioning of the workpiece with your own hands.

The most popular are waterjet cutting machines from the Italian company WaterJet Corp. Inc., which produces console and portal equipment. The first is intended for cutting relatively small-sized products, the second, characterized by increased accuracy and rigidity, is suitable for processed products of greater thickness.

WaterJet Corp. Inc produces not only the power plants themselves, but also pumping equipment for them. The running portal of the company's devices is equipped with automated positioning, and allows the simultaneous separation of materials that differ not only in their chemical composition, but also in thickness - a quality that is impossible in principle for thermal cutting equipment.

Waterjet cutting in many cases is considered the only way to obtain spatial details. For example, only with the technology considered is it possible to perform separation practically without heating the workpiece (the maximum increase in edge temperature is 600 °C, and even less when processing in a water tank). Such equipment can be used to separate thick sheet glass, ceramics, and hard alloys - materials that are very sensitive to elevated temperatures. The good quality of the final result eliminates the need for subsequent transitions, and the very small jet thickness - up to 0.8 mm - minimizes material loss. High pressures created in the separation zone do not cause the appearance of residual stresses in the workpiece, and contribute to a subsequent increase in its operational durability.

Every year, metallurgical enterprises around the world smelt hundreds of thousands of tons of steel. Increased demands on cut quality have led to the emergence of new processing technologies. Especially considering that many alloys are quite hard. The most advanced technologies are laser and water cutting of metal (water jet). We will consider the essence of the latter in detail in this article.

First tests

Back in the 30s of the 20th century, American and Soviet scientists were puzzled by this issue. The impetus was that it was necessary to achieve high accuracy and speed of work. The first developments began in the 50s of the 20th century by engineers from the USA and the USSR. In 1979, they began to use sand, which was added to a stream of water, and the concept of “waterjet” appeared. The key requirements are high pressure and speed of water supply to the surface being treated.

Already in 1983, serial production of equipment for waterjet cutting (WJC) was launched. In fact, even today it is one of the most ideal tools for cutting, since it has no wear and it is possible to regulate the diameter of the jet. This method can work with sheet thicknesses up to 300 mm. This led to the fact that metal cutting with water began to be actively used in aircraft construction, mechanical engineering, stone processing and the production of armored vehicles and the space industry.

Operating principle and technology description

It is based on the principle of erosion processing. It consists in the fact that a jet of water under high pressure with abrasive particles is applied to the metal being processed. As a result, particles of the metal being processed are separated. Various parameters such as speed and depth are adjusted using the jet diameter and size, as well as the abrasive flow rate.

The main component of the system is the high pressure pump (4,000 bar). It compresses the water and delivers it to a special water nozzle, behind which there is a mixing chamber. There the pomegranate sand and water are mixed. Then the mixture enters a diamond or carbide nozzle, which has a diameter of up to 1.2 mm. From it, at a speed of more than 1,000 m/s, the waterjet falls directly onto the metal being processed. This is how metal cutting with water occurs, and now we move on.

About the features of GAR

High cutting properties can be achieved due to the presence of high-strength abrasive. In this case, a stable flow is ensured only if the garnet sand particles do not exceed 30% of the jet cross-section. Water, for the most part, performs exclusively a transport function. The size of the abrasive also depends on the requirements for the quality of the cut. The lower they are, the larger particles can be used.

When cutting metal with water, it is extremely important to select the optimal abrasive hardness. The indicator depends on the material being processed. The harder it is, the harder the sand is used. It is recommended not to use abrasives with a hardness less than 6.5 on the Mohs scale. At the same time, it is worth paying attention to the wear of the nozzle. The harder the sand, the faster it wears out. Therefore, at this stage it is extremely important to carry out theoretical calculations and only then begin work.

Cutting metal with a jet of water: advantages

The key advantage of this method is that it allows you to achieve high quality cuts, that is, obtain the necessary roughness after processing. In addition, it is worth highlighting the following advantages:

• the possibility of a fire or explosion during processing is eliminated;
• environmentally friendly process (no gases are formed during cutting);
• alloyed additives in the processed metal do not burn out;
• possibility of processing metal up to 30 cm thick;
• low temperature in the cutting zone (90 degrees Celsius);
• high efficiency due to the absence of idling of the cutting head.

As you can see, cutting metal with water under pressure has a number of advantages over other methods. It is environmentally friendly, safe and effective. Modern machines even allow processing several sheets at once in one stroke, if the thickness allows it. In general, GAR is developing more and more every year, and therefore the characteristics are significantly improving.

Briefly about the disadvantages

But this system cannot be ideal. Therefore, there are some disadvantages here. Firstly, due to the high speed of supply of water with abrasive and serious pressure, the process is quite noisy; it is advisable to only wear earplugs near it. Secondly, the low processing speed of thin sheet steel. But this is when compared with laser and plasma technologies. In addition, the cutting head wears out quite quickly. This in turn leads to high operating costs. Therefore, any machine for cutting metal with water must be regularly maintained and faulty or worn-out mechanisms must be replaced. Otherwise, work efficiency and cut quality will gradually decrease.

Equipment in industry

Modern machines for professional use allow processing stainless steel up to 20 centimeters thick. In this case, the strength indicators and group of metals are not important. The small jet diameter (1 mm) allows cutting to a very high tolerance. If an industrial machine is used, then it becomes possible to process stone and other hard rocks, such as marble, etc.

Currently, this is one of the most effective and popular glass cutting methods. GAR works with both thin crystal and bulletproof glass with micron accuracy. Today, GAR machines are used for the production of gaskets and the processing of foam materials such as rubber and plastic. But to achieve optimal results, it is necessary to use modern electronic systems and various scanners.

About the design features

To achieve the required result, industry uses exclusively CNC machines. Therefore, the process is almost completely controlled by electronics. A professional machine includes various systems. For example, controlling the optimal clearance. This system provides the best distance between the cutting head and the metal being processed for the greatest accuracy in the cut location. A material scanning sensor is also used. It is needed to scan the metal for irregularities. The readings are transmitted to the CNC, as a result of which the gap changes.

To automate the process, an abrasive supply control sensor is introduced into the system. It regulates the amount of pomegranate sand. In addition, such a system stops operation if foreign elements (burlap, coarse particles) enter the high-pressure pump. All this must work as one, and only in this situation can optimal results be achieved. A modern industrial machine costs a lot of money and therefore requires regular maintenance. If this is not done, it may fail completely.

DIY metal cutting with water

It is quite logical that no one will purchase industrial CNC equipment for single use. In this case, so-called manual machines are very helpful. They do not have software control, so all cutting parameters are set by the operator. Actually, the quality of the cut depends entirely on the qualifications of the specialist. With the proper approach, you can achieve results no worse than with professional equipment. Manual machines still have their advantages. They consist in the low cost of equipment and the ability to produce a workpiece of the desired geometric shape at a certain angle on your own. But to do this, it is advisable to completely understand the controls, and then cutting metal with water will be a completely simple task.

Let's sum it up

Currently, the most popular processing method is cutting metal with water. The pressure in this case is very high, which should not be forgotten. Failure to comply with safety precautions can lead to dire consequences. Please also note that it is not possible to make such equipment yourself. This is due to the fact that the parts must be of very high quality.

A manual machine is most optimal for home use. It does not cost as much money as an industrial one, but at the same time it has flexible settings and allows the owner to make a very high-quality cut. It is quite possible that in the near future cutting metal under water will improve and even here it will be possible to apply such a principle as GAR.

Almost no metal rolling and mechanical engineering enterprise can do without equipment for cutting sheet metal. Often high demands are placed on the quality of the cut, which makes it impossible to use traditional equipment: guillotines and plasma cutting.

Waterjet cutting of metal with water has been used since the 60s of the last century. For the first time, a US aircraft manufacturing company officially began to use metal cutting using the waterjet method. Later, the company officially announced that this method is optimal for cutting metal and other high-strength materials.

Since then, the waterjet processing method has become widespread. Is water-abrasive cutting limited to rolled metal only or does it have a wider scope of application? What are the advantages and disadvantages of metal cutting using waterjet technology?

Scope of application of waterjet cutting

The most common is water-abrasive cutting of metal with a jet of water, but the equipment is also used for cutting the following materials:

1. Marble, granite, stone and other rocks.
2. Glass, ceramics.
3. Steels and metals, including: titanium, stainless steel.
4. Reinforced concrete.
5. Plastic, textolite, ebonite and paronite plates, rubber.

At the same time, when cutting, it is possible to achieve a minimum consumption of building materials, components, etc. In enterprises with increased fire and explosion hazards, waterjet machines are the only possible equipment that meets the requirements for the work.

Working principle of waterjet cutting

• Water is supplied from a special reservoir under pressure to the mixer.
• At the same time, an abrasive mixture, usually consisting of small sand particles, is sent into the mixer.
• After mixing with the abrasive, the water is supplied to the nozzle for cutting the metal with an abrasive water jet.
• A thin stream is directed onto the surface of the material being processed and cuts it.

This operating principle allows you to significantly increase the speed of metal processing and the quality of its cutting. The only consumable that will need to be replaced is the abrasive powder itself. You will need to add abrasive powder to special containers from time to time.

The speed of waterjet cutting of metal can be compared with that of automatic plasma machines. But the quality of work can only be compared with cutting with a laser.

Waterjet cutting equipment

The same principle is used for industrial purposes. To do this, you simply need to increase the water pressure several times when cutting metal, and also control the direction of the resulting water jet. This is done as follows:

In addition to the main components of the equipment, when choosing a machine for cutting metal with water, you need to pay attention to the availability of additional options for working on the machine. The extended functionality of the device allows you to perform figure cutting if necessary.

Waterjet cutting capabilities

Thanks to modern technologies and improvements to machines, it has been possible to expand their functionality and scope of application.

Recently, waterjet cutting of pipes has become widespread. Thanks to special machines for cutting pipes, it is possible to obtain a perfectly evenly cut circle without deviations.

CNC waterjet machines

Thanks to CNC machines, it is possible to produce precise parts with minimal deviation from specified dimensions, which is almost impossible to achieve with traditional cutting methods. The operating principle of CNC waterjet equipment is as follows:

Machines for waterjet cutting of small parts with numerical control may differ in functionality and main purpose. Before purchasing a CNC machine for cutting small-format parts, you need to pay attention to the scope of application and recommendations related to operation.

Manual waterjet cutting

• Lower cost - compared to CNC machines, such an installation will cost approximately 1.5 times less.
• There is no need for specialized education. Manual waterjet equipment for cutting iron has simple controls and a minimum number of functions. This allows you to carry out all the necessary operations when processing parts of simple geometric shapes.
• General functionality remains unchanged. Smooth cutting, as well as cutting material at an angle, cutting out simple geometric shapes and cutting material can be done using conventional equipment. Waterjet cutting of aluminum, copper, steel, glass and other materials is also possible using such equipment.

The use of manual installations is limited by their low functionality. Complex geometric shapes, the use of the machine in artistic cutting, and where high precision and a high-quality final result are required, you will need to purchase CNC equipment.

Consumables for waterjet cutting

• Abrasive for cutting metal on a waterjet machine. Even in the most economical CNC installations, the consumption of abrasive powder is about 300-350 g. per minute In this case, the thickness of the material being processed can slightly increase the consumption coefficient. For work, fine sand made from natural garnet material is used. Garnet sand has high strength characteristics and is even used for cutting refractory and malleable materials. In this case, the size of abrasive sand grains should be no more than 600 microns.
• Water - in addition to abrasive powder, cutting will require the use of water that has undergone a preparation and filtration procedure. Liquid with impurities significantly affects the quality of the cut, so the use of water treatment systems is not only desirable, but also a mandatory requirement.

In addition to these two main consumables, processing materials will also require electricity, sufficient air and regular replacement of wear parts.

• The abrasive mixture supply system most often needs to be replaced. Installation of a new nozzle will be required every 50 hours of operation, a guide tube 100 hours. Interestingly, as these parts wear out, abrasive garnet sand for waterjet cutting will expand the diameter of these units and, as a result, increase the thickness of the cut from 1 to 1.5 mm. Which is significant, especially when it comes to expensive materials.
• Gaskets and seals of the pumping station. These components are also considered consumable parts that wear out quite quickly and require constant replacement. Maintaining pressure in the system depends on the seals. And the first sign that you need to pay attention to is a drop in operating pressure at the same production parameters.

You can find offers to purchase abrasive material at a low price, made not from garnet, but from other sedimentary rocks. The use of low-quality abrasives significantly reduces productivity and increases wear on machine parts.

Advantages of waterjet cutting

1. No surface heating. During the processing of the workpiece, all heat generated is instantly removed under the influence of water. Due to the absence of metal cutting elements, the heat generated from friction is negligible. Minimal heat generation ensures precise cutting of materials that can be deformed under high temperatures.
2. Functionality - the advantages of waterjet cutting of metal are difficult to list, but one of the most important is that with the help of a GAR machine you can cut the most complex shapes of workpieces. It also becomes possible to produce a complex profile with any required radius, shapes and contours.
3. No additional work - after cutting out the required part, there is no need for subsequent grinding and processing of the cut area. A slight roughness is almost invisible to the naked eye.
4. Manufacturability of the cutting process - the machine is completely universal; if necessary, it can be used for drilling. It is possible to perform the operation regardless of atmospheric and other conditions. Hand-held units can be used to cut material even underwater or at depths of up to several hundred meters. At the same time, 2-3 units can be powered simultaneously from one high-pressure pump.
5. Cost-effective compared to plasma processing of material - the advantages of water-abrasive cutting are obvious. The cutting speed can reach 30000 mm/min. Moreover, this does not affect the quality of the cut. If we consider that only 0.5-1 mm of material is lost when cutting, as well as the accuracy and full compliance of the finished product with the specified dimensions, the high profitability of the GAR installation becomes obvious.
6. Safety - the machines can be installed even in production areas with a high risk of explosion, when producing flammable materials. The absence of surface heating, the possibility of sparks and other characteristics make the use of water-abrasive machines as convenient and safe as possible.
7. Possibility of cutting thick-walled materials. It is possible to process steel sheets up to 3 cm, as well as reinforced concrete blocks with a thickness of up to 10 cm.
8. The versatility of the machines - one installation allows you to simultaneously process steel, plastic, rubber, fabric, etc. and, if necessary, you can cut multi-layer workpieces consisting of several materials.

CNC machines are considered the most functional, but the lack of qualified personnel explains why manual cutting with GAR is in higher demand.

Disadvantages of waterjet cutting

• The appearance of taper is especially noticeable when processing thick-walled steel and other refractory metals. As a result, the end of the workpiece is not cut straight, but in the form of a funnel. Taper is usually eliminated by using an additional automation and taper control device.
• Same speed for both thick and thin materials. This significantly affects the profitability of the equipment. The issue is solved by folding sheets in layers to simultaneously cut several pieces at once.

Otherwise, the use of GAR is convenient, practical and cost-effective. Equipment for cutting with water and abrasive powder helps solve important problems associated with poor-quality processing of parts, as well as reduce the time required for production. Consumables are fully compensated by the efficiency of this equipment.

The continuous expansion of the range of structural metal, non-metal and composite materials used in industry and construction requires new technologies for their processing. One of these technologies is cutting with a high-speed water jet under high pressure - water jet cutting.

The possibility of using a jet of liquid under ultra-high pressure as a cutting tool for processing various materials was first described in the USSR. This happened in 1957. But this method of processing materials was patented only four years later, and not in the Union, but in the USA.

Natural tool

The tool for water-jet cutting of materials is a specially formed jet of liquid emanating from a special nozzle with a diameter of 0.08-0.5 mm at a supersonic speed (1000 or more m/s) and providing a working pressure on the workpiece of 400 MPa or more. Since the distance from the nozzle end to the surface of the material is several millimeters, the jet pressure exceeds the tensile strength of the material - due to this, cutting is carried out.

There are two methods of water jet cutting of materials:

• water cutting, or waterjet cutting;
• waterjet cutting (water plus abrasive) - abrasive waterjet cutting.

The presence of abrasive in the jet increases its technological capabilities - a liquid-abrasive suspension can be used to cut hard and difficult-to-cut materials of considerable thickness.

The modes of waterjet cutting, carried out by both methods, can be expanded by supplying a coolant to the jet head, which promotes the formation of ice flakes in the jet, which give it abrasive properties.

When waterjet cutting, the angle of attack is also taken into account - the angle between the direction of the jet and the surface being processed. Maximum cutting ability and process productivity are achieved at an attack angle of 90°.

Materials and applications

Using water jet cutting, almost all materials can be processed: paper and cardboard, fabrics, leather and rubber, glass and ceramics, granite and marble, concrete and reinforced concrete, all types of polymer materials, including composite, foil and metallized plastics, all types of metals and alloys, including difficult-to-cut ones - stainless and heat-resistant steels, hard and titanium alloys.

Abroad, the range of industries in which water-jet cutting technologies are used today is wide. First of all, these are: the space industry and rocketry, the defense industry, aviation, shipbuilding, automobile and instrument engineering, electrical engineering and microelectronics, light industry (including leather and footwear) and food industry, construction, medicine.

Water-jet cutting is especially often used to carry out the following technological operations (this is not a complete list):

• in the defense industry - recycling of obsolete weapons (cutting missile casings, military equipment, ships and submarines), cutting shell casings and washing out explosives;
• in the electronics industry - cutting electronic circuit boards (the use of water-jet cutting made it possible to achieve a cut size of up to 0.1 mm and ensure the absence of dust, as well as solve the problem of material delamination), removing flash from microcircuit cases;
• in the automotive industry - cutting false ceilings, carpets, dashboards, plastic bumpers, etc.;
• in construction - cutting concrete structures for their subsequent dismantling, clearing seams, etc. Water jet cutting is often used to produce complex contours in marble and granite (a narrow cut makes it possible to create inlays when making decor);
• in the food industry - cutting deep-frozen products, various dense foods, chocolate.

Advantages and disadvantages

The main advantages of water jetting are as follows.

1. Leveling thermal effects. The heat generated during the cutting process is carried away almost instantly by the water. As a result, there is no noticeable increase in temperature in the workpiece. This characteristic is decisive when processing materials that are particularly sensitive to heat. Low force (1-100 N) and temperature (+60...+90°C) in the cutting zone eliminate deformation of the workpiece, melting and burning of the material in the adjacent area. Note that no technology other than waterjet cutting can ensure the absence of thermal effects on the metal near the cut.

2. Versatility of processing. The abrasive liquid jet is particularly effective when machining many difficult-to-cut materials, such as titanium alloys, various types of high-strength ceramics and steels, as well as composite materials. When waterjet cutting of the latter does not create breaks in the structure of the material, which, thus, retains its original properties. It is with the help of a jet of water that various sandwich structures are cut. Waterjet systems are capable of cutting metals up to 300 mm thick, stone and concrete - up to 1000 mm. At the same time, a fairly high processing accuracy is achieved - 0.1 mm when cutting metals up to 100 mm thick.

3. Ability to reproduce complex contours and profiles. High jetting can produce very complex shapes or bevels at any angle. In its technical capabilities, a liquid jet approaches an ideal point tool, which makes it possible to process a complex profile with any radius of curvature, since the cutting width is 0.1-3.0 mm.

When cutting a fragile material - glass - waterjet processing allows you to create shapes and contours that are unique to other technologies; Although waterjet technology is inferior to diamond when making straight glass cuts, no other technology allows complex contours to be obtained directly during the cutting process.

4. Good surface quality. It is possible to obtain a finishing surface with a roughness Ra of 0.5-1.5 microns, i.e. in many cases there is no need for additional processing.

5. Manufacturability of the process. The cutting tool (water jet or water plus abrasive) does not need to be sharpened; the impact load on the product is minimal, there is no backlash on the cutting tool, since there is no direct contact between the product and the tool; various operations (for example, drilling and cutting) can be performed with the same tool; low tangential force on the part allows in some cases to do without clamping this part; there is the possibility of cutting at a distance of about 200 meters from the pump, as well as the possibility of cutting from one high-pressure pump simultaneously with two or more cutting heads on one table or several heads on different tables; cutting can be carried out at heights and at depths of up to several hundred meters, including under water.

6. Economical process. Cutting speed is high. (Cutting speeds for various materials depend on many factors; the average values ​​of these speeds for various materials are shown in the table). The cut can begin at any point on the workpiece and there is no need to first make a hole. The small cutting width allows you to save scarce materials when cutting them. The average water consumption in an abrasive-liquid cutting device is low - about 3-4 l/min, despite high operating pressures (400 MPa or more).

7. Process automation. It is quite easy to use computer control systems, optical tracking devices and full-scale six-axis robots.

8. Availability. The use of relatively inexpensive components such as water and, for example, quartz sand as an abrasive makes the process accessible.

9. Security. Since there is no heat accumulated during abrasive fluid blasting, the process is explosion and fire safe. There is no radiation or danger of slag or fine particles flying out. Airborne dust is virtually eliminated. The noise level ranges from 85-95 dB.

The disadvantages of hydraulic cutting technology include: design difficulties that arise when creating high fluid pressure, the rather low durability of the nozzle and the complexity of its manufacture.

Factors hindering the practical implementation of water jet technology in enterprises are:

• high energy intensity compared to a number of other types of cutting;
• discrepancy between actual characteristics and declared ones (for example, lower jet speed, which does not allow cutting certain materials);
• Some potential consumers lack the required production scale, which makes the installation of hydraulic cutting equipment unprofitable;
• quite high cost compared to other, for example, electromechanical cutting equipment.

Water jet cutting speed, m/min

Beam or jet?

Water jet cutting is an alternative not only to mechanical cutting, but also to laser, plasma, and ultrasonic cutting, and in some cases, as already mentioned, it is the only possible type of processing.

Currently, waterjet and laser cutting of engineering materials used in similar fields are competing technologies. In both cases, the cutting tool is formed in the machine itself due to the design features of the corresponding units, and then, moving along an energy channel or pipelines, it approaches the unit where the process of its formation is completed. When using both technologies, there is no need to store, sharpen and rearrange the working tool - it is constantly updated due to the continuity of its formation over time.

Without delving into an analysis of the advantages and disadvantages of these technologies, it should be noted that laser radiation is more universal (cutting, marking, hardening, etc.), although the scope of application of a high-speed liquid jet is not limited only to hydraulic cutting (in some cases, a pulsed liquid jet is used for strengthening hard-to-reach surfaces of complex shapes).

A definite advantage of hydrocutting over laser cutting is the absence of a thermally affected area on the edges of processed parts, but this condition is not always decisive. Thus, it has been established that laser cutting of parts made of structural steels of type 20, 30 KhGS, etc. increases their fatigue strength and durability compared to mechanically cut parts.

A natural question arises: are there any recommendations for the use of this or that technology? The experience of manufacturers and users says: yes, they exist.

From the point of view of economic feasibility, the use of water jet technology is most justified when cutting fragile (glass, stone) workpieces with a thickness of 40-100 mm, plywood, wood, composite materials in the entire range of permissible thicknesses, with large volumes of cutting: stainless steel with a sheet thickness of over 6- 10 mm, copper - over 2-3 mm, aluminum alloys - over 5-6 mm.

When contour cutting a thin sheet, laser systems are almost always more effective, since the cost of laser cutting of workpieces with small thickness is much lower than the cost of waterjet cutting.

Ultimately, the areas of application of laser and waterjet cutting technologies in mechanical engineering will be separated by their technological and economic indicators. One thing is indisputable: with the current level of development of mechanical engineering, the volume of use of water jet cutting (in the USA, Europe, Asia-Pacific countries) is constantly increasing.

Main components of hydraulic cutting equipment

The water jet cutting complex includes: high pressure pump; cutting head; coordinate table and cutting head movement drives; high pressure wiring; abrasive supply system (for waterjet cutting); numerical control system. Additionally, the complex can be equipped with: a device to prevent collisions of the cutting head with the workpiece; a system of several cutting heads; mechanical pre-drilling system; a water jet trap that extinguishes its energy and also serves to collect spent abrasive, and a number of others.

Hydraulic cutting equipment has varying degrees of versatility and automation, including being manufactured in the form of robotic complexes.

High pressure pump ensures the creation of a supersonic jet of liquid as a cutting tool. A universal hydraulic circuit diagram has been developed, where a special double-acting or single-acting multiplier is used as a pressure amplifier (Fig. 1). The choice of layout depends on the specific processing conditions (for example, on the permissible pressure drop, required fluid flow), which allows achieving the desired results in both productivity and quality. In addition, standard control, distribution, control and auxiliary hydraulic devices are used.

To process large-sized or free-standing products in a factory, port, landfill, or to perform work under water, the high-pressure pump can be mounted on any vehicle - an electric car, a car, a ship. In this case, the liquid jet is supplied to the product, located, as a rule, at some distance from the high-pressure pump, using a flexible hose.

Cutting (jet) head carries out the final formation of a high-pressure thin jet as a cutting tool according to its geometric and energy parameters. The design features of the jet head (the relative position of the parts, the nature of their connection and sealing), influencing the hydrodynamic characteristics and compactness of the generated jet, determine the quality and reliability of its operation.

There are many designs of jet heads for hydrocutting materials, which objectively indicates the variety of operational requirements placed on them and, at the same time, the lack of optimal designs. Let's give the following classification:

• jet heads with improved dynamic characteristics for liquid processing of materials (equipped with special structural elements);
• liquid abrasive jet heads. The most advanced designs are those with free introduction of abrasive into the working fluid stream with minimal disruption of their hydrodynamic characteristics;
• jet heads with a refrigerant supply to cool the flowing liquid. The design includes channels for supplying coolant, which is intended to impart abrasive properties to the working fluid. This allows not only to enhance the cutting capabilities of the jet due to the formation of ice flakes in the jet, but also to increase the wear resistance of the nozzle due to the formation of a frozen layer on its surface;
• combined nozzle heads.

In Fig. Figure 2 shows schematic diagrams of cutting heads for both hydro- and water-abrasive cutting.

By the way, the option of up to four cutting heads operating simultaneously is used in the design of water jet systems produced by almost all of the world's leading equipment manufacturers.

The formation of a supersonic liquid jet as a cutting tool is carried out using nozzles. A universal technique has been developed for analyzing the hydraulic characteristics of nozzles with different internal channel profiles. Theoretical and experimental studies have shown that the most rational internal nozzle profile, which increases the productivity of water jetting of various materials by approximately 20%, is a catenoidal profile.

Usually nozzles are made of artificial stones - sapphire, diamond, corundum. Their durability is 250-500 hours. In Fig. Figure 3 shows the cutting head of the Paser 3 model of the American company Flow International Corporation.

High pressure wiring. High pressure water is supplied from the high pressure pump to the cutting head by a system of fixed and moving pipes. To ensure tight connections during the movement of the portal and the working head, special high-pressure hinges or specially shaped spiral tubes are used.

Abrasive supply system. Two abrasive supply systems are used - a vacuum one, operating on the principle of a spray gun, and one that operates under pressure. The abrasive is poured into a hopper located next to the work table and supplied to the working head through flexible hoses. Powders of hard alloys, carbides, and oxides are usually used as abrasives. The choice of abrasive depends on the type and hardness of the material being cut. Thus, for high-alloy steels and titanium alloys, especially hard garnet particles are used, for glass - the corresponding fractions of ordinary sand, for plastics reinforced with glass or carbon fibers - silicate slag particles.

Manufacturers

The Russian market of equipment for water-jet cutting of materials is capable of satisfying almost any request. The products presented there are from such specialized foreign companies as the American Flow International Corporation (with many branches around the world), the Swedish Water Jet Sweden AB, the Italian Waterjet Corporation, the Czech PTV, as well as such world-famous manufacturers of sheet processing equipment as the Swiss Bystronic concern, a German company Trumpf, allows you to solve almost any problem. However, this segment of the equipment market is developing quite actively, as evidenced by the recent appearance of products from a number of foreign manufacturers, including the following companies: Sato Schneid-systeme (Germany), Aliko (Finland), Trenntec (Germany), ESAB Welding & Cutting Productions (Sweden), Digital Control (France).

Among the manufacturers of hydraulic devices and, first of all, high-pressure pumps, the company Ingersoll Rand (USA) should be noted - the undisputed world leader in products of this class. Naturally, such leading manufacturers of hydraulic cutting equipment, such as Water Jet Sweden AB, use Ingersoll Rand equipment as the main components associated with the creation of the jet flow itself. For example, a high-pressure pump model Strimline series SL IV of this company creates the required water pressure of 4000 bar, which is then converted into kinetic energy of a jet with a speed of 900 m/s using sapphire with a flow section diameter of 0.08-0.5 mm.

The leader of Russian water-jet cutting is the city of Vladimir, where, based on the developments of Vladimir State University, the research laboratory of water-jet cutting and JSC SKTB PO "Vector" have created several models of installations for water-jet cutting.

Industrial installations are produced by CJSC Laser Complexes (Shatura), OJSC Tulamashzavod, OJSC ENIMS (Moscow), and the Belarusian joint venture LLC SPozhitok. Until recently, some specialized water-jet cutting systems were produced by the Institute of Mining (Khabarovsk), the Ukrainian Research and Production Enterprise Indris, Moscow University, and Pellemash JSC, but today nothing is heard about these products. One way or another, there is some choice among domestic products. Although, hand on heart, we must admit that our equipment does not yet reach the best world standards.

Leader

In 1971, the Flow International group produced the world's first water jet cutting unit, and in 1981 developed a method for introducing abrasive into a water jet, which significantly expanded cutting capabilities. According to experts, the company’s machines have the best positioning accuracy (about 0.07-0.08 mm), and, consequently, processing accuracy.

The company's products allow you to solve almost all cutting problems:

• The WMC Waterjet Machining Center system is designed for any 2D cutting, including on an industrial scale. Its main distinguishing feature is the increase in productivity achieved through the patented Quicklift Z axle with built-in sensor and shockproof device;
• For small metal and stone work, the Inregratred Flying Bridge installation was created;
• The compact Bengal unit is designed for waterjet and waterjet cutting and is suitable for laboratory use, tool making and small batch production;
• The Dragon modular three-dimensional cutting system is used for both waterjet cutting of soft materials and waterjet cutting of metal, stone, glass, and composites.

The company has developed a new hydraulic cutting technology, which, according to the developers, allows increasing cutting speed by almost 300%. The Dynamic Waterjet system, which provides active control of accuracy, is based on a mathematical model used to control the position of the “hand” with the working head. This system automatically eliminates the formation of bevels during cutting and ensures the required accuracy of the part, taking into account the specified tolerances. The system eliminates the need for additional processing after waterjet cutting and reduces machine time for cutting metals and composite materials with a thickness of 1.25-480 mm. In addition, due to increased cutting accuracy, losses of sheet material during cutting are reduced.

Alternative

Despite its recognized leader status, Flow has competitors, and very serious ones.

One of them is the Swedish company Water Jet Sweden AB. As a nozzle, Water Jet uses its own patented cutting head, as well as the use of an Avtoline nozzle from Ingersoll Rand. Currently the most popular machine in the mechanical sector is the NC3015S with a usable table surface of 3010 x 1510 m. A controlled Z axis is standard on all systems. And the installations produced by the company with four and five controlled axes allow for such processing as, for example, cutting grooves with a blunt cone profile.

Having started work as a dealer of Flow, PTV has over time mastered its own (i.e. Czech) production of most of this equipment. First of all, this applies to coordinate tables, which today are designed and manufactured by PTV. In addition, all auxiliary equipment is also designed and manufactured in the Czech Republic. Currently, PTV only purchases high-pressure hydraulic equipment from the US - pumps, accumulators, tubing, etc., which amounts to less than 50% of the total system cost. PTV uses software developed by Czech companies in its installations in combination with control systems from Siemens.

The range of possible cutting speeds (i.e., actually an adjustable range of speeds of movement of the cutting head above the table) on a PTV installation ranges from 1 to 30,000 mm per minute, which makes it possible to perform high-quality and accurate cutting on the same installation of parts of a wide variety of sizes and thickness

The universal installation of the Italian company Waterjet Corporation for waterjet cutting WJ 1630/50 portal type creates a jet pressure of 4130 bar. The cutting head is capable of five-axis machining. Other gantry machines of the company are designed for pipe cutting with a double working area (cutting six-meter pipes is carried out with automatic rotation of the pipe and a back stop), as well as for robotic operations (a machine with two cutting heads and automatic loading and unloading).

Byjet Bystronic waterjet cutting devices have a powerful specialized CNC system that provides automatic selection and optimization of processing parameters when cutting various materials along any contour, automatic control of abrasive supply and water pressure in real time, depending on the configuration of the processed contour, as well as the properties of the material and thickness . Thanks to the use of a special dispenser, Byjet Bystronic systems can use almost any type of abrasive with a grain size from 0.05 to 0.3 mm. The use of a special high-pressure pump control system ensures the absence of water pulsations at the outlet, which allows achieving the best quality of processing.

Potentially

And a few more words about installations that, in our opinion, are of potential interest for domestic manufacturers.

The Quickjet unit, created by Germany's Trenntec, has a rigid welded structure that, combined with hardened and ground guides, provides positioning accuracy of 0.1 mm per 1 m length and repeatability accuracy within 0.05 mm. The Z axis can be adjusted manually over a length of 150 mm. There is a high-pressure pump, an air cooling system, an abrasive tank holding 50 kg, and a device for automatically feeding abrasive into the cutting head. Water consumption - 2.6 l/min at a pressure of 380 MPa.

French Digital Control presents a machine for water jet cutting under pressure of 380 MPa. For soft materials, water jet cutting is used, and for hard materials, water jet cutting is used. Processing area - 1500 x 1000 mm. The machine is equipped with a 22 kW high-pressure pump, a cutting head with an abrasive supply system and a Cyborg 2000 digital control system. The control system has a post-processor for converting files, to enable the preparation of programs outside the machine, to ensure manual or automatic cutting of sheets.

Domestic products

The Hydrocutting Research Laboratory (Vladimir) presents a semi-automatic CNC machine for cutting sheet materials that are difficult to machine (glass, carbon, boron plastics, titanium, ceramics, glass, magnetic and hard alloys), cutting holes of arbitrary shape and parts with complex contours. The machine consists of two modules: the main movement drive - a high-pressure station and the feed drive - a two-axis table. The feed drive is equipped with a CNC system, which ensures precise movement of the table along two mutually perpendicular coordinates and production of holes and parts of various configurations according to a given program.

In addition, the Vladimir laboratory produces a semi-automatic CNC machine for processing non-metallic materials (leather, cardboard, vinyl, rubber, etc.), a semi-automatic machine for removing flash from microcircuit cases, a semi-automatic machine for cleaning drums of duplicating equipment, a four-position machine for cleaning capillary holes tips, double-circuit machine for unloading military equipment.

JSC "Tulamashzavod" presents a technological installation for waterjet cutting, designed for cutting complex-shaped parts up to 150 mm thick from any metals and alloys, cutting non-metallic sheet materials (marble, granite, plastic, cardboard, glass, ceramics) with the following dimensions of the working surface of the table - length up to 4000 mm, width up to 2000 mm.

The working area of ​​processing of the GL-250/5M and GL-400/ZM installations of JSC "Laser Complexes" ranges from 1200 x 800 mm to 6000 x 1500 mm.

JSC ENIMS accepts orders for the manufacture of both individual units of installations for water-jet cutting, and the entire installation as a set.

The price of success

It is not easy to get a definite answer to the question about the cost of such equipment. It all depends on the modification of the model, the configuration, the presence or absence of individual functions, etc., etc. The spread can be quite significant. But in any case, such equipment cannot be cheap. For example, the company representing the interests of the Czech company PTV gives the following figures: from 5 to 10 million rubles per installation. Company representatives claim that with normal system load (an average of 2500-3000 working hours per year), the return on investment (as they say in the USA, “payback time”) will be one and a half to two years. Domestic products are cheaper. In particular, ENIMS OJSC names from 40 to 100 thousand USD. e. (read: dollars or euros). In any case, when making a choice, it is worth considering the information from Water Jet: the operating costs of the NC3015S waterjet cutting system are approximately 0.26 of the same conventional units per minute.

And in conclusion, perhaps, only one thing can be said. According to numerous organizations that analyze the global market for mechanical engineering products, the production of water jet cutting equipment is the fastest growing segment of the machine tool industry.