This article takes an in depth look at water jet cutting.
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Water jet cutting is a manufacturing process that employs high-pressure jets of water, generated by pressurizing pumps, to deliver a supersonic stream for cutting and shaping various materials. Water in water jet cutting is pressurized up to 392 MPa and directed through a small precision nozzle. Upon exiting the nozzle, the water reaches speeds three times faster than the speed of sound.
Pure water jet cutting, which uses only water as its medium, is designed for soft materials such as wood, plastics, foam, paper, and rubber. When an abrasive is added to the water stream, the cutting process becomes more aggressive, enabling it to cut through hard materials like titanium, stainless steel, aluminum, glass, ceramic, and concrete.
The water jet cutting process can be carried out in various ways, with most methods incorporating an abrasive into the water to facilitate cutting through the workpiece. This versatile manufacturing technique can cut, shape, and design a workpiece to meet precise specifications.
The shaping method used in water jet cutting offers several advantages over other cutting processes like plasma or laser cutting. Water jet cutting provides superior accuracy, can handle complex designs, and is suitable for thermally sensitive surfaces. The abrasive, akin to sandpaper, erodes the material being cut without heating it or altering its temper. As a result, the cut edges are clean and ready for welding without the need for additional processing.
Kerf width refers to the material removed during a cutting process. Traditionally, this term described the material removed by a saw blade. In the context of a water jet cutter, kerf width denotes the width of the water stream, typically 0.04 inches or smaller. The inside corners cut by water jet cutting have a radius matching the stream's width. Several factors influence the kerf, including material thickness, type of material, cutting quality, and the characteristics of the waterjet nozzle.
The size of the kerf is a crucial design factor that must be considered when determining the dimensions of the final product. For instance, if the kerf is 0.042 inches, the dimensions of the final part need to be adjusted to account for the cutting width. Otherwise, the final part will be 0.042 inches off.
The initial cut made by a water jet cutter, known as the pierce, is wider than the usual kerf. This first step in the water jet cutting process can be executed in various ways, including stationary, linear, circular, and low-pressure methods. The choice of piercing method depends on the material being cut and the amount of scrap produced.
Tapering in water jet cutting refers to the difference in kerf width at the top and bottom of the cut. This process creates a V-shaped taper because the stream loses energy as it cuts deeper into the material, removing more material at the top than at the bottom.
Slow cutting speeds can result in a reverse taper, where the kerf width is wider at the bottom of the cut. This occurs because more material is removed at the bottom than at the top. A reverse taper is often observed when cutting soft, pliable materials.
Barrel tapers occur when the cut is widest in the middle and narrower at both the top and bottom, typically when cutting extremely thick materials.
For many cutting applications, tapering is not a significant issue and can even be advantageous for certain tasks. However, in precision tooling where cut pieces must fit together accurately, tapering can pose a problem and should be carefully considered.
Water can be pressurized using various methods, such as linear intensifiers and rotary direct drive pumps. Both types of pumps incorporate a motor, water filters, control systems, and sensors to ensure optimal performance.
Linear intensifier pumps operate using pressurized hydraulic oil at 3,000 psi. A low-pressure oil pushes against a piston with a face area 20 times larger than that of the high-pressure plunger, which acts on the water. This difference in size intensifies the pressure on the high-pressure plunger by 20 times, resulting in a final pressure of 60,000 psi.
A direct drive rotary pump operates without hydraulic oil. Instead, it uses an electric motor to rotate a crank that drives pistons to generate water pressure. These pumps typically feature 30 hp motors and an inlet that supplies water directly to the pump.
The pressurized water from the pump is transported through high-pressure tubing to the cutting head. This tubing, known for its excellent yield and tensile strength, features an exceptionally smooth interior surface. It is made from cold-worked stainless steel or thermoplastic pressure hose, available in sizes ranging from 0.25 inches to 0.563 inches, and comes in various lengths to accommodate different water jet cutter designs.
The pressurized water exits through the orifice of the cutting head, which is made of diamond, ruby, or sapphire with a hole smaller than the tip of a pin. As the water flows through this tiny orifice, its velocity dramatically increases to over 90,000 psi or 2,500 mph. The effectiveness of the cutting process is closely linked to the power supplied by the cutting head. With proper use, a precision tooling cutting head can last between 500 to 1,000 hours.
The image below shows two types of cutting heads: one for water-only cutting and another for water with abrasive. The distinction between the two is evident in the red tube, which is used to transport the abrasive material to mix with the water stream.
Pure water jet cutters are the original type of water jet cutting tools. They are preferred because they produce less moisture on the workpiece compared to contact methods, and they create a thin, precise stream ideal for detailed geometries with minimal material loss. Pure water jet cutters use a cutting head with a jewel, though rubies are not suitable for use with pure water. The water stream travels at Mach 2 for 40,000 psi and Mach 3 for 60,000 psi.
In an abrasive water jet cutting system, an abrasive material is introduced into the cutting head, where it is mixed with the water stream. This addition sharpens the stream, enhancing its cutting effectiveness. Abrasive water jet cutters can handle a wide range of materials, regardless of their hardness or thickness, making them versatile for various applications.
An abrasive water jet cutter accelerates abrasive material along with the water stream to erode the surface of the material being cut. It is 1,000 times more powerful than a pure water jet cutter. The larger diameter stream can cut materials up to ten inches thick without generating heat or causing mechanical stress.
Although cutting, in essence, involves severing material with a cutting tool, water jet cutting operates similarly to a band saw but with more precision. Modern manufacturing, however, involves far more complex and advanced cutting processes than the traditional band saw method.
Water jet cutting machines can be programmed for a diverse range of cuts, tailored to specific application needs. They can perform traditional single cuts as well as more complex multi-axis cuts, including 2, 3, 4, and 5-axis configurations.
One-dimensional water jet cuts are straightforward, involving a single pass of the workpiece through the cutting mechanism. These are the simplest cuts, typically used for trimming. During the process, the operator feeds the workpiece into the cutting tool, while debris and water are collected on the other side. A variation of this method is the slitter, which cuts pieces to specific widths. One dimensional cutters can operate with either pure water or water mixed with an abrasive.
Two-dimensional cutting involves using PC or CNC programming to control the process. These machines are equipped with a servo motor and closed-loop feedback systems to manage positioning and cutting velocity. The catcher tanks are water-filled and have slats to support the workpiece. Additionally, the Z-axis of an XY two-dimensional cutting machine adjusts the height of the cutting device to accommodate variations in the thickness of the workpiece.
Two-dimensional cutting is ideal for quickly and efficiently cutting various materials and parts, making it suitable for applications requiring speed and precision.
Three-dimensional cutting utilizes the X axis (left to right), Y axis (front to back), and Z axis (up and down) to achieve precise cuts. In this process, the workpiece stays stationary while the cutting tool moves along these three planes. This method is commonly used to produce complex mechanical components.
Four-dimensional cutting involves the XYZ axes for traditional three-dimensional movement, plus an additional rotary motion around the X axis, known as the A axis. This setup allows for cutting on multiple sides of a workpiece, including creating holes or openings. The A axis enables the automatic flipping of the workpiece, allowing the waterjet to access and cut from both sides.
A 5-axis system offers exceptional power and flexibility by allowing the workpiece to be manipulated along five different axes simultaneously. It combines traditional XYZ linear movements with rotational movements around these axes, specifically the A, B, and C axes, which enable 180° rotations around the X, Y, and Z axes, respectively. This advanced setup facilitates the fabrication of highly complex and intricate solid components.
Five-axis machining demands extensive CNC programming to manage the complex rotary movements involved. Its primary advantage is the capability to work on all five sides of a single workpiece in one operation. This method is particularly valuable for producing components with intricate details and high precision.
The principle of water jet cutting is straightforward, relying on pressure, velocity, and an abrasive. While the core concept is simple, its applications are diverse and highly specialized. Various techniques have been developed to address specific requirements across different industries and materials.
Water jet cutting can be categorized into two main types: pure water and abrasive water jet cutting. Each of these categories can be further subdivided based on specific factors, including the material being cut, the desired precision, and the complexity of the cut.
Abrasive flow machining (AFM) is used for interior surface finishing, particularly for deburring and honing parts that are difficult to reach with traditional methods. By using a mixture of water and abrasive, AFM effectively erodes raised surfaces inside a workpiece, similar to the action of a grinder or sandpaper, to remove unwanted particles and achieve a smooth finish.
The abrasive jet machining process is a key aspect of abrasive water jet cutting. It involves a high-pressure stream of water mixed with abrasive particles that blast and erode the workpiece, removing particulate matter, burrs, and other materials. This technique uses extremely fine particles applied at high velocity and is particularly effective for cutting and shaping brittle, thin, and hard materials. Abrasive jet machining excels in creating intricate shapes and achieving smooth, even edges.
Intensifiers are used to dramatically increase the pressure of pure water, allowing it to shape and form soft materials without leaving behind water residue. Hydraulic pumps play a crucial role in this process, converting the force of the water into mechanical energy to achieve the required high pressure.
A significant advancement in high-pressure water jet cutting was the introduction of corundum elements in the cutting head, including varieties such as rubies and sapphires. Corundum is renowned for its hardness, toughness, and stability, being resistant to acids and the second hardest mineral on Earth.
CNC water jet cutting utilizes high-pressure water in a programmable manner to perform multiple operations in a single pass. It is particularly useful for materials that are sensitive to high-temperature processes. CNC water jet machines can handle various operations such as cutting, forming, deburring, reaming, and honing, making them ideal for tasks requiring precision and minimal thermal impact.
Most CNC water jet cutting machines operate on three axes: X (left to right), Y (front to back), and Z (up and down). Recent advancements include five-axis models that add rotational capabilities. The A axis allows rotation around the X axis, and the B axis provides rotation around the Y axis, offering greater flexibility and precision in cutting complex shapes.
The water jet cutting process has become popular for its precision and quick turnaround times. Its high-quality results and performance make it the preferred cutting method in industries that demand precise and accurate tolerances.
Since its inception in the 1950s and subsequent improvements in the 1970s, water jet cutting has steadily become a crucial component in industrial operations. Its widespread use is largely due to the absence of heat in the cutting process, which offers significant advantages.
In the aerospace industry, where complex and precise components are crucial, water jet cutting is indispensable. The strict tolerance requirements leave no room for error, making water jet cutting essential for producing everything from jet engines to custom-designed control panels.
Abrasive water jet cutting is employed in the aerospace industry to cut metals such as steel, brass, Inconel, and aluminum. This process is utilized for components like wing sections, turbine blades, brake parts, and landing gear, with the ability to cut materials up to eight inches thick.
A significant advantage of water jet cutting in the automotive industry is its compatibility with robotic systems. Pure water jet cutting is utilized for shaping interior components such as carpets, insulation, and head linings. This method minimizes material waste and reduces the need for extensive cleanup.
Water jet cutting avoids heat-affected zones (HAZ), does not produce noxious fumes, and minimizes stress on the workpiece. It creates smooth, burr-free surfaces, eliminating the need for secondary finishing.
In medicine, water jet cutting technology is being explored as a replacement for traditional surgical tools. High-pressure spiral water is used to crush and aspirate liver parenchymal cells during tumor treatment. This method is preferred because it avoids heat that could damage surrounding organs and reduces the risk of bleeding. By adjusting the pressure and flow rate, it is possible to dissect human tissue with less trauma, bleeding, and postoperative complications.
Similar to its use in medicine, water jet cutting is highly effective for glass due to its precision and adaptability. The process allows for detailed modifications and adjustments to the cutting stream, which is crucial for working with delicate glass materials. By avoiding damage to the glass's internal structure, water jet cutting ensures smooth and efficient cuts. Its omnidirectional stream can handle any shape, form, or configuration with pinpoint accuracy, making it ideal for cutting holes, notches, and intricate designs without causing distortions.
Industrial processes often generate unwanted materials, and storage tanks and conduits can accumulate flakes, scales, and rust over time. While highly caustic cleaners can be effective, they may not always be suitable for every situation. High-pressure water jet cutting provides a safe and efficient alternative, using its high-speed, pulsating blast to remove and clean industrial equipment, storage units, and piping without the need for harsh chemicals.
The energy generated by a water jet cutter far exceeds the energy required to remove scales, coatings, or contaminants from a surface. This makes it an exceptionally safe and efficient cold cutting method for industrial cleaning. Its high efficiency and speed minimize downtime and prevent work stoppages, making it a valuable tool for maintaining industrial equipment and surfaces.
Water jet cutting of food is a USDA-approved method that offers both productivity and sanitary benefits. Like its industrial applications, water jet cutting in the food industry is valued for its precision and effectiveness in portion control. It is capable of cutting meat, fish, poultry, pastries, and frozen foods into precise and uniform shapes.
The key feature of water jet cutting for foods is the use of pure, clean water, which is central to its operation. The high-speed operation of water jet cutters enables efficient and rapid processing of food products.
A major concern in electronics manufacturing is cost, as manufacturers strive to reduce expenses while boosting efficiency. Water jet cutting has become essential in this sector due to its cost-effectiveness and efficiency. It can cut circuit boards, whether populated or empty, and is also effective for stripping wires without causing damage.
Safety is a primary concern when handling fiberglass, which demands precision and efficiency. Water jet cutting addresses these needs by shaping and forming fiberglass without producing dust or waste. The process delivers cuts quickly and to the exact dimensions required for the application.
Water jet cutting handles fiberglass with minimal limitations on rigidity, making it suitable for applications ranging from shaping insulation to forming boat components. The precision of water jet cutting ensures that fiberglass is delivered in accurately cut shapes, meeting exact specifications for various uses.
Water jet cutting machines feature a comprehensive setup that includes a high-pressure pump, controller, catch tank, an XY movement system, and either an abrasive or pure water nozzle. A crucial element of these machines is the motion control system, which not only directs the movement of the cutter but also securely holds the workpiece in place during the cutting process.
Water jet cutting machines come in various types, sizes, designs, and processes. Many of these machines are equipped with CNC controllers, which significantly enhance the precision and capabilities of the cutting process.
A staple in modern manufacturing is the computer numerical control (CNC) machine, which can be programmed to perform multiple tasks in a single pass over a workpiece. The integration of CNC programming with water jet cutting has been widely adopted for years, combining precision control with advanced cutting capabilities.
CNC water jet cutting is primarily used for materials sensitive to high temperature processes. It excels in tasks such as cutting, forming, deburring, reaming, and honing, which are well-suited to the water jet cutting method.
A CNC water jet cutting machine incorporates all the features of traditional water jet cutting. Typically, these machines are flatbed setups equipped with CNC programming that interfaces with the machine’s components. Their flexibility and versatility allow them to be customized to meet various production requirements.
Flatbed water jet cutting machines feature a large working table designed for cutting sizable pieces. This design facilitates easy loading and unloading of materials. A key advantage of flatbed machines is their ability to collect water and waste from the cutting process. These machines are valued for their cost-effectiveness, ability to cut various materials, and lack of heat generation. As a result, parts retain their heat treatment throughout the cutting process, eliminating the need for post-cutting heat treatment.
CNC machines are integral to modern manufacturing, enabling the programming of multiple tasks to be performed in a single pass over a workpiece. The integration of CNC programming with water jet cutting has been established for many years, combining advanced cutting techniques with precise control to achieve exceptional results.
A CNC water jet cutting machine incorporates all the features of traditional water jet cutting but is enhanced with CNC programming. Typically designed as flatbed machines, these CNC water jet cutters offer the flexibility and versatility needed to adapt to various production requirements, making them customizable to meet specific manufacturing needs.
Portable water jet cutting machines offer a cost-effective, environmentally friendly, and adaptable solution for tasks such as cleaning contaminated surfaces, removing burrs, and cutting off rust. Designed for use in hazardous conditions like the oil industry, construction tunnels, and pipelines, these machines deliver high-pressure water and velocity, making them capable of cutting through any type of material.
Portable water jet cutting machines can be classified into two types based on how the abrasive is introduced into the water stream. The first type inserts the abrasive directly into the water stream at the nozzle, providing a more effective cutting action. The second type premixes the abrasive with the water before it is pressurized, which is generally less effective.
Water jet cutting is employed to shape and machine a vast array of products, parts, components, and materials. From precision parts for the aerospace industry to intricate decorative ornaments for the home, water jet cutting is valued for its ability to deliver precise cuts and maintain dimensional accuracy across a wide range of applications.
The list below highlights just a few examples of items produced using water jet cutting. This versatile process is used not only for crafting various products but also for applying logos and designs on both final products and the surfaces of hard materials.
Using a CAD drawing, the outline of a guitar body is marked on the workpiece. The piece of wood is then fed into the water jet cutter. Because water jet cutting does not apply significant pressure to the workpiece, it can cut delicate wood without damaging the grain.
Gears are commonly manufactured using water jet cutting because the process provides the precision and accuracy needed for their complex shapes and tight tolerances.
Water jet cutting is well-suited for manufacturing cams, as it allows for precise shaping based on the desired design. By loading the CAD rendering into the machine, the water jet cutter can quickly and accurately produce the cam with the specified shape.
Chains produced with water jet cutting are designed to handle extremely heavy loads, often several tons. The links are precisely cut using water jet technology and then assembled into chains capable of lifting exceptionally heavy weights.
Water jet cutting is employed to create durable name plates from heavy metals. It is ideal for producing name plates, signage, and company logos due to its precision, elimination of the need for additional finishing, and the smooth, clean edges it provides.
Water jet cutting of rubber is highly efficient and versatile, capable of cutting through any thickness. It streamlines the manufacturing process by cutting through rubber and backing metals without the need for specialized tooling or dies. This method ensures precision, speed, and optimal material use.
A unique feature of water jet cutting rubber is stack cutting, where multiple layers of workpieces are stacked and cut in a single pass. This method increases efficiency and throughput by allowing simultaneous cutting of several pieces at once.
The six items listed above represent just a tiny fraction of the diverse products, parts, components, and materials fabricated using water jet cutting. Thanks to ongoing technological advancements and innovations in cutting techniques, water jet cutting has become a vital tool for efficient and streamlined industrial operations.
There are countless methods for cutting, shaping, and forming industrial products, each capable of performing various cuts and dimensions. However, a significant disadvantage of these methods is the heat generated during the cutting process. Even shearing, for example, produces friction that results in heat.
Water jet cutting maintains the workpiece at a cool temperature during the cutting process, ensuring accuracy and precision. It is a cold cutting method that preserves the molecular structure of the material and prevents thermal stress.
Water jet cutting offers remarkable precision and accuracy, with a tolerance range of ± 0.003 inch to ± 0.005 inch. Additionally, the ability to adjust cutting speed mid-process allows for the creation of parts with multiple edges.
Water jet cutting avoids creating rough surfaces, burrs, or imperfections, eliminating the need for secondary finishing. It produces minimal kerfs and smooth finishes due to its erosion-based material removal process, rather than relying on heat or shearing.
Water jet cutting has limitless applications because it can cut any material, regardless of its hardness, without altering its mechanical properties or weakening its integrity. For enhanced efficiency, thin materials can be stacked and cut simultaneously to boost productivity and reduce costs. Moreover, water jet cutting machines are available in various table sizes to accommodate different workpiece dimensions.
Environmental sustainability is a key concern for manufacturers and industries, and water jet cutting stands out in this regard. Unlike many traditional cutting methods that generate waste, particulate matter, and pollutants, water jet cutting is a cleaner process. It does not produce hazardous byproducts, making it an environmentally friendly choice for cutting and shaping materials.
Water jet cutting is an environmentally friendly process as it generates no toxic gases, harmful waste materials, or poisonous contaminants. It operates using pure water combined with natural abrasive materials. The leftover material from the cutting process can be safely disposed of, minimizing environmental impact.
The process of water jet cutting involves utilizing a water pump and cutting tool to generate a high-velocity water stream, which travels at speeds up to three times the speed of sound. This technology enables precise and versatile cutting across various materials using the same core components.
This simplicity in the water jet cutting process makes it a cost-effective and economical method for producing both 2D and 3D cuts.
The programmed shape from engineering software is seamlessly transferred into the water jet cutting machine's controls. This data dictates precise positioning, cutting speed, and cutting angle. Once the material specifics are entered, the machine efficiently completes the cutting process.
Among the numerous advantages of water jet cutting, cost savings is the most significant and prominent. Running a water jet cutting machine is considerably less expensive compared to other cutting processes. Additionally, the benefits include fast transition times, high cutting speed, and ease of setup.
The only fluids used in water jet cutting are water and an abrasive that erodes the material. The water jet stream cools any heat produced, preventing warping, distortion, and hardening, which minimizes the need for secondary processing. Additionally, water jet cutting is safer for workers and operators, as it does not produce harmful vapors.
Water jet cutting is the most efficient cutting method due to its power and versatility with materials. Its efficiency is highlighted by its ability to recycle the water used and eliminate the need for secondary processing. Additionally, because it can cut through any material, there is no need to change tooling when transitioning from one product to another.
Precision water jet cutting offers superior control over the cutting process, allowing workpieces to be cut to exact sizes and dimensions. This method is more manageable compared to traditional cutting methods like blades or saws, providing greater accuracy and flexibility in production.
Water jet cutting is ideal for the food industry because it avoids the use of chemicals, cutting tools, or any materials that might come into contact with food. Given the stringent cleanliness and sanitation requirements in food processing, water jet cutting meets the standards for zero cross-contamination, ensuring a safe and hygienic cutting process.
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