What is waterjet cutting of metal
A sheet metal workpiece is placed on the work surface. It is cut to the desired format. Cutting areas are exposed to water with abrasive particles added. These substances interact with the surface, destroying it. It is necessary to maintain a certain pressure, a pressure which provides the necessary velocity of liquid and solid particles. The task of the equipment in this technology is to separate the part from the whole. The power of the machine is great, but the ability is limited by the density of the alloy and its thickness.
The production range of waterjet cutting machines ranges from small, conventional CNC metalworking machines and compact ones with a 2 by 4 meter sheet metal table design to huge lines that can work like rolling mills. But according to the principle of the device any machine for metal cutting with water has:
- housing in the form of a water bath, which serves as a trap for waterjet, absorbing its energy,
- clarifiers and filters required for water treatment and sedimentation of spent abrasive particles,
- coordinate table with servomotors for moving the cutting head,
- high pressure pump unit with piping,
- operator panel based on industrial computer.
modern machines with CNC and drives for cutting head travel enable material processing according to 2D, 2,5D and 3D technologies, i.e. with high accuracy perform fine art cutting in several planes and edge processing at any angle. The possibilities of making 3D parts with waterjet cutting are well demonstrated in the video.
Operating principle and materials to be cut
Cutting metal is done with a water jet that has an abrasive added and then runs it through the nozzle. Pressure of 200-600 atmospheres allows to cut many materials. Work can be done at any angle, you just need to change the angle of the nozzle.
In this case it is possible to cut effectively:
- metals (ferrous and nonferrous) and their alloys;
- Stone products made of marble and granite;
- steel (stainless steel, heat-resistant, alloyed);
- armored, ordinary and composite glass;
- Ceramic products (concrete, tiles, ceramic, ceramic granite)
Cutting of very hard materials is done with water and special minerals sand. Soft materials (rubber, plastic, cardboard) can be cut only with water without any additives.
Advantages of water-jet machines
Effective work with all materials: non-permeable, brittle, ductile, composite materials, no high temperatures in the area of cutting (maximum. 90ºC), so it saves construction of the material, less production waste due to precision cutting with a narrow part of the cut (only 1 mm), the edge of the finished product is smooth, no need for further processing, the thickness of the cut sheet is from 150 to 300 mm, no dust and poisonous compounds harmful to human health appear, to increase productivity, it is possible to cut simultaneously several.
This technology has serious differences from all other methods of separation of sheet metal. When using this method, the surface of the metal being processed is not subjected to pressure and mechanical effects of another type. Due to this, there is no friction in the cutting zone and, accordingly, no heating of the tool or workpiece surface, which positively affects the quality of machining and greatly expands the area of application of this technology.
Most often abrasive cutting with water is used to separate sheet metal, but in recent years this method is increasingly used to process other materials, which include:
- natural stones (granite, marble, etc.).);
- Ceramic tiles, sheet glass;
- carbon and stainless steel, titanium and other metals;
- reinforced concrete structures;
- Various plastics and rubber.
The use of waterjet technology minimizes material consumption, which is an important advantage. In addition, cutting with an abrasive and water is the only possible way of cutting metal in companies with high fire and explosion risks.
Use of water-jet cutting machines and working principle
Waterjet metal cutting devices are versatile in use, as their capabilities do not end at cutting metal products. The technology is based on a specially designed system of high-pressure water supply to the surface to be treated.
An additional fluid element is the abrasive added to the water. As a rule, microparticles of sand are used as an abrasive additive. Water and sand pass simultaneously into the mixer from separate containers where they are mixed thoroughly. The resulting mixture is then fed into the nozzle of the machine at high pressure.
Then, a working water-abrasive torch, in the form of a strong jet with certain characteristics, is fed onto the workpiece and cuts it.
In this case, the speed of waterjet cutting can be compared only with the speed of plasma cutting, but the quality of the cut made by this method corresponds only to the quality of the laser cutting.
Today, water-abrasive machines allow:
- Cut out products of any geometric shape by means of numerical programming. In this case the processing is fully automated and does not require an operator. The machine is controlled by a specially installed computer program. Waterjet cutting of pipes makes it possible to make the required circle without any errors;
- Making irregular cuts in any material, whereby the varying slope of the cut does not negatively affect the quality. The work process, which is carried out at any inclination, allows you to get a completely finished product at the output and not to subject it to finishing processing;
- Abrasive waterjet method found its application in the field of art. The equipment makes it possible to make various decorations and design objects, as a rule, the processing of figures is done with the help of CNC;
- Hydro-abrasive machining installations used in metal products allow you to cut the maximum thickness of any metal, this can be seen in the video. Thus, the processing of medium-carbon metal products can take place using material with a maximum thickness of 20 cm. The greatest thickness of the titanium alloy is 16-18 mm; high-strength metals can be 11 mm thick. But the thickness of the copper product reaches only 6 mm.
The meaning of hydro-abrasive method consists in supplying a thin water jet mixed with small abrasive particles (electrocorundum grains, silicon carbide, garnet sand, etc.) to the machined object.). the water is pumped up to extremely high pressure (1000 to 6000 atmospheres) then it passes through a nozzle with extremely high speed (from 900 m/s) and washes the particles of material out of the cutting zone.
Cutting speed depends on the shape, size, weight and hardness of the abrasive particles, the impact angle as well as the physical and technical properties of the material to be cut. This method allows a wide variety of materials to be processed: glass, plastic, metal, stone, composite compounds, rubber, wood, etc. The range of thicknesses which can be controlled by waterjet cutting is quite wide. from 0,1 to 300 mm and even more. 3D-cutting of workpieces is possible thanks to the swiveling working head. The basic principles of the technology at
Abrasive waterjet cutting process
The actual waterjet cutting process consists of four phases.
- The phase that creates the curved frontal cutting surface. The focused waterjet cuts a narrow slot in the workpiece. the jet is gradually introduced into the workpiece and moves along the workpiece at a constant cutting speed.
- Phase The beginning of the step (precipice) formation. The angle between the jet and the cutting surface gradually increases.
- Phase Completion of the step (precipice), moving it downwards. Layer removal only occurs over a small portion of the cutting face.
- Phase Restoration of the initial state. The step is “pressed” into the workpiece fairly quickly. As the step shifts downward, an even cutting surface is formed again. the initial cutting condition is restored.
The process described above is cyclic.
Water only acts as a carrier in the waterjet cutting process. Cutting is caused by the removal (shearing) of a certain amount of material layers, which is caused by the impact of the solid particles of the abrasive. Presence of abrasive in the jet increases its machining capabilities, enables cutting of metal.
The most common abrasives are quartz sand, garnet abrasive, olivine, silicon carbide and electrocorundum. The widespread use of the above abrasive materials is due to their relative cheapness, hardness and high cutting properties. For example, garnet abrasive is hard and heavy; because of this, it is actually stable throughout the cycle of use. This makes it possible to obtain a high quality cut with a certain depth of roughness, depending on the size of the grain and the cutting speed. Based on its high viscosity, such abrasive can be repeatedly reused. Domestic companies mainly use quartz sand.
As with any kind of material processing, the most favorable conditions for mastering the process of abrasive waterjet cutting can be achieved by selecting its optimal technological parameters: working fluid pressure, shape and diameter of the hole of water and abrasive nozzles, the amount of abrasive, fed the distance from the nozzle to the cutting surface, the rate of feed, the quality of the cutting surface. The analysis of these parameters requires a detailed study and is essential for the research of this technology.
Advantages of the method
Bearing in mind that this type of machine is more expensive than easier counterparts. But the initial cost is compensated by the price of consumables, fasteners and optional components. Another advantage of working with hydraulics. even during long hours of work, there is no smokescreen, no dust flying in all directions. In addition, there is no need to monitor how sharp the cutting tool is, periodically replace it and buy additional equipment for sharpening.
At the same time, waterjet method of metal cutting allows you to maintain high production speed due to the rapid processing of metal workpieces. Cutting speed remains the same even when processing thick-walled blanks. It is possible to process not only metal, but also glass, rubber, plastic and other multi-layer workpieces with the help of waterjet machine.
Advantages of the method of cutting metal with a waterjet
Equipment used to cut metal using waterjet is indispensable when working with thick-walled blanks. Only these machines can deliver a high quality steel cut line when laying pipes.
No dross or burrs on the steel cutting line after machining a 200 mm sheet metal section.
Perfect cut quality combined with gentle temperature conditions are not all the advantages of water-abrasive technology.
High system costs are compensated by savings in fixtures and assemblies, which are not necessary even for thin-wall materials.
Absence of smoke plume and dust and other nuisances is another of the many advantages of water-abrasive cutting.
In addition, there is no need to replace worn-out cutting tools and control the sharpness of the cutter, because, in fact, it is absent.
Instead, a jet of water combined with abrasive components serves as the cutting tool.
The process of initial and final waterjet cutting is performed in one step.
And the cutting speed is slow, without slowing down, even when cutting thick-walled material, such as pipe-laying projects.
The universal characteristics of metal cutting machines allow for simultaneous processing of different materials. it can be plastic, glass, rubber, or multi-layer products.
IMPORTANT: Metal cutting technology with a torch
Waterjet cutting machines are characterized by operational safety, so they can be used in factories with a probable risk of explosion.