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All you need to know about WaterJet Cutting

This article was originally published by IQS Directory. Read original article.

This article takes an in depth look at water jet cutting. You will learn more about topics such as:


  • What is water jet cutting?

  • The water jet cutting process

  • Types of water jet cutting cuts

  • Types of water jet cutting

  • Uses for water jet cutting

  • Water jet cutting machines

  • And much more…


Chapter One

What is Water Jet Cutting?

Water jet cutting is a manufacturing process that uses high pressure jets of water provided by pressurizing pumps that deliver a supersonic stream of water to cut and shape various types of materials. The water in water jet cutting is pressurized to 392 MPa and projected using a small precision nozzle. As the water leaves the nozzle, it reaches speeds that are three times the speed of sound.




Pure water jet cutting with water as its medium is designed for soft materials such as wood, plastics, and rubber. When an abrasive is added to the water stream, such as titanium, stainless steel, aluminum, glass, ceramic material, and concrete, cutting becomes more aggressive and capable of cutting hard metals.


Chapter Two

How Water Jet Cutting Works

The water jet cutting process can be completed in several different ways. The majority of the methods have an abrasive blended into the water to blast particles from the workpiece. It is a very versatile manufacturing process that can be used to cut, shape, and design a workpiece to meet exact specifications.

The shaping method used for water jet cutting has several advantages over other cutting processes, such as plasma or laser. Water jet cutting has better accuracy, can cut complex designs, and is able to cut thermally sensitive surfaces.


The Process of Water Jet Cutting

Measuring Kerf Width

Kerf width relates to the material being removed as a part of a cutting process. The term was originally used to refer to the material removed by the cutting of a saw blade. In the case of a water jet cutter, it refers to the width of the stream, which is normally 0.04 inch or smaller. The inside corners cut by water jet cutting have a radius that matches the width of the stream. The kerf depends on a variety of factors, which include material thickness, type of material, cutting quality, and the nature of the waterjet nozzle.

The size of the kerf is an important design factor that has to be accounted for when determining the dimensions of the final product. If the kerf is 0.042 inches, the dimensions of the final part have to be adjusted to account for the cutting width or the final part will be 0.042 inch off.




Initial Water Jet Piercing

The first cut made by a water jet cutter is referred to as the pierce, which is wider than the normal kerf. The initiation of the pierce is the first step in the water jet cutting process. It can be completed in several different ways with stationary, linear, circular, and low pressure being the most common methods. Which of the piercing methods is used is dependent on the material to be cut and the amount of scrap produced.





Tapering in Kerf Width

Tapering in water jet cutting refers to the kerf width at the top of the cut and its width at the bottom. Water jet cuts have a V-shaped taper, which is generated because the stream loses some of its energy as it cuts deeper into the material, with more material being removed at the top than at the bottom.

Slow cutting speeds produce a reverse taper where the kerf width is wider at the bottom, which is caused by removing more material at the bottom of the cut. The reverse taper can be seen when cutting soft, pliable materials.

Barrel tapers are created when the cut is widest in the middle of the cut, which occurs when cutting extremely thick materials.

For most cutting, tapering does not matter and can be used as a benefit for certain jobs. In the case of precision tooling where cut pieces must fit together accurately, tapering can be a problem and needs to be taken into consideration.





Pressurizing the Water

Several methods are used to pressurize the water, including linear intensifiers and rotary direct drive pumps. The two types of pumps have a motor, water filters, control systems, and sensors.

Linear intensifier pumps use pressurized hydraulic oil at a pressure of 3000 psi. Low pressure oil pushes against a piston that has a face area that is 20 times larger than that of the high pressure plunger that pushes against the water. Since the size of the low pressure pump is 20 times larger than that of the high pressure one, the pressure on the larger plunger is intensified 20 times, yielding a pressure of 60,000 psi.




A direct drive rotary pump does not include hydraulic oil. It has an electric motor that rotates a crank that drives pistons that generate the water pressure. Direct drive pumps have 30 hp motors with an inlet that supplies water to the pump.




High Pressure Tubing

The pressurized water from the pump travels through high pressure tubing to the cutting head. High pressure tubing has excellent yield and tensile strength with an exceptionally smooth interior surface. It is produced from cold worked stainless steel or thermoplastic pressure hose in sizes from 0.25 inches up to 0.563 inches and comes in a wide variety of lengths to fit the design of the water jet cutter.




Water Jet Cutting Head

The pressurized water passes through the orifice of the cutting head, which is a diamond, ruby, or sapphire with a hole smaller than the point of a pin. As the water passes through, its velocity radically increases to over 90,000 psi or 2500 mph. The cutting process is directly affected by the power provided by the cutting head. A precision tooling cutting head, when used properly, can last from 500 to 1000 hours.

The image below has an example of two cutting heads, which are water only and water with abrasive. The difference between the two types can be seen in the red tube carrying the abrasive to the water stream.




Pure Water Jet Cutters

Pure water jet cutters are the original form of water jet cutting tool. They are used due to the fact that they create less moisture on the surface of the workpiece than is created by touching it. They have a thin stream that cuts excellent detailed geometries with limited material loss. The construction of a pure water jet cutter has a jewel with rubies being excluded and unsuitable for work with pure water. The stream travels at Mach 2 for 40,000 psi and Mach 3 for 60,000 psi.




Abrasive Water Jet Cutting System

In the abrasive water jet cutting system, an abrasive material is fed into the cutting head, where it is mixed appropriately with the water stream. The introduction of an abrasive makes the stream sharper and creates more effective cutting. The addition of an abrasive makes a water jet cutter capable of cutting anything regardless of its hardness or thickness.

With an abrasive water jet cutter, the stream accelerates the abrasive material that erodes away the surface of the material being cut. An abrasive water jet cutter is 1000 times more powerful than a pure water jet cutter. The stream is larger in diameter and capable of cutting materials that are ten inches thick without creating heat or mechanical stress.



Chapter Three

Types of Water Jet Cuts

In many ways, the cutting process, regardless of the method, is very straightforward where a piece of material is severed using a cutting tool. As can be expected, this is also true of water jet cutting, which can perform cuts much like a band saw. The process of cutting in modern manufacturing is far more complex, complicated, and advanced than that which resembles the old band saw.

Water jet cutting machines can be programmed to perform a wide variety of cuts depending on the needs of the application. They are capable of performing traditional single cuts and 2, 3, 4, and 5 axis cuts.

Types of Water Jet Cuts

One Dimensional

One dimensional water jet cuts are stationary cuts performed in one pass of the workpiece through the water jet cutting mechanism. They are the simplest form of cut and used for trimming. The operator feeds the workpiece into the cutting tool while the debris and water are caught on the other side. A variation of the one dimensional cutter is a slitter that cuts pieces to specific widths. One dimensional cutters can be pure water or water with an abrasive.

Two Dimensional - XY

Two dimensional cutting requires the use of PC or CNC programming. They have a servo motor with closed loop feedback to control positioning and cutting velocity. Catcher tanks are water filled and have slats to support the workpiece. The Z portion of an XY two dimensional cutting machine controls the height of the cutting device to adapt to the variations in the thicknesses of the workpiece.

Two dimensional cutting is ideal for rapid and fast cutting of different materials and parts.

Three Dimensional XYZ

Three dimensional cutting involves the use of the X axis that moves left to right, the Y axis that moves front to back, and the Z axis that moves up and down. In the three axis process, the workpiece remains stationary while the cutting tool moves along the three planes. It is a process used to produce mechanical components.

The image below is a diagram of the XYZ axis process.

Four Dimensional - XYZA

In four dimensional cutting, the workpiece is processed by the three axis of XYZ but includes a fourth dimensional rotary motion around the X axis. The cutting along the A axis allows the workpiece to be cut along the B axis. It is an excellent method for cutting in the sides of a workpiece of holes or other openings. The addition of the A axis offers the option of automatically flipping the workpiece to allow the waterjet to remove material from both sides of the workpiece.

Five Dimensional - XYZAB

The power and convenience of a 5 axis system allows the workpiece to be manipulated on five sides at one time. The workpiece is still moved along the XYZ axis. Additional movements are rotational ones around the XYZ axis where the A, B, and C axes perform 180o rotations around the X, Y, and Z axes. The use of this type of cutting allows for the fabrication of extremely complex solid components.

The process of five axis machining requires a great deal of CNC programming preparation to account for the multiple rotary movements. Its major benefit is the ability to work one workpiece on five sides in a single operation. Five axis machining is beneficial for producing components with intricacies and details with exacting precision.


Chapter Four

Types of Water Jet Cutting

The concept of water jet cutting is rather simple and involves pressure, velocity, and an abrasive. Though the process is not complicated, how it is applied varies widely. The many variations have been developed to meet the exact specifications for different applications.

The types of water jet cutting are divided between pure water and pure water with an abrasive. From these two classifications, the process is further divided according to several factors.


Water Jet Cutting Types

Abrasive Flow Machining (AFM)

Abrasive flow machining is an interior surface finishing. The use of AFM is necessary for deburring and honing of the interior of parts that traditional deburring methods cannot reach. As the water and abrasive make contact with raised surfaces on the interior of a workpiece, it erodes the surface removing the unwanted particles much like a grinder or sandpaper.



Abrasive Jet Machining

The abrasive jet machining process is the essence of abrasive water jet cutting and includes a high pressure stream of water with an abrasive. It blasts and erodes the workpiece to remove particulate matter, burrs, and materials. As is common with abrasive water jet cutting, the particles used for cutting are extremely fine and applied at high velocity. It is a process that is used to cut and shape brittle, thin, and hard materials. Abrasive jet machining is used to cut intricate shapes and form smooth, even edges.



High Pressure Water Cutting

Through the use of intensifiers, the pressure of pure water is radically increased such that it can shape and form soft materials without leaving a water residue. The intensification of the water flow is created by hydraulic pumps that harness the force of the water and change it into mechanical energy.

A major advancement in high pressure water jet cutting occurred by introducing corundum elements in the cutting head, which are varieties of rubies and sapphires. Corundum is very hard, tough, and stable. It is unaffected by acids and is the second hardest mineral on earth.


CNC Water Jet Cutting

CNC water jet cutting employs the same methods of high pressure water but is programmed to do multiple operations during one pass. The main use of CNC water jet cutting is in situations where the material to be shaped and cut is sensitive to high temperature processes. Some of the cycles a CNC water jet cutting machine passes through are cutting, forming, deburring, reaming, and honing, which are operations that are best suited for the water jet cutting process.

The majority of CNC water jet cutting machines are three axes and perform functions along the X, Y, and Z axis where the X axis moves left to right, the Y moves front to back, and the Z moves up and down. A recent addition to CNC water jet cutting machines is the five axes model that has a rotation around the X axis called the A axis and a rotation around the Y axis referred to as the B axis.



Chapter Five

Uses for Water Jet Cutting

The water jet cutting process has gained popularity due to its precision and fast turnaround times. The quality and performance of water jet cutting have made it the preferred cutting method for several industries, especially those that require precise and highly accurate tolerances.

Since its inception in the 1950s and the improvements in the 1970s, water jet cutting has been steadily becoming an essential part of industrial operations. The simple fact that there isn’t any heat involved is sufficient reason for its wide use.

Water Jet Cutting Uses

Water Jet Cutting in the Aerospace Industry

All components for aerospace require complex and accurate precision. The dictates of aerospace do not allow for any type of error. It is for this single reason that water jet cutting is an essential part of aerospace part production from the manufacturing of jet engines to custom designed control panels.

Abrasive water jet cutting is used in the aerospace industry for cutting steel, brass, Inconel, and aluminum. The metals cut by the process are used for wing sections, turbine blades, brake components, and landing gear and are used to cut forms that are eight inches thick.



Auto Industry

A key factor regarding the use of water jet cutting in the auto industry is its ability to be integrated into robotic systems. Both methods of water jet cutting are used with pure water jet cutting being used to shape interior carpets, insulation, and head linings. Pure water jet cutting produces minimal material waste and undoes cleanup.

Water jet cutting does not have heat affected zones (HAZ), generates noxious fumes, or creates stress on the workpiece but produces smooth burr free surfaces that eliminate the need for secondary finishing.


Water Jet Cutting in Medicine

In medicine, water jet cutting technology is being used to replace surgical cutting tools. The high pressure spiral water crushes and sucks liver parenchymal cells in the treatment of tumors. It is selected to perform these functions since it does not produce heat that would damage other organs and minimizes the chance of bleeding. Changing the pressure and flow rate makes it possible to dissect human tissue with less trauma, bleeding, and postoperative problems.


Cutting of Glass

Much like the medical field, water jet cutting of glass is used due to the ability to modify, adjust, and change the cutting stream. Cutting glass is a very delicate process that requires precision tools to avoid puncturing or breaking the glass. The ability of water jet cutting to cut glass without damaging the glass’ internal structure leads to smooth and efficient cutting. The omnidirectional stream can cut any shape, form, configuration, or workpiece down to the finest detail. The high pressured stream creates pinpoint accuracy, making it capable of cutting holes, notches, and structures without distortions.



Water Jet Cutting in Industrial Cleaning

Various industrial processes produce unwanted materials during the performance of the process. Additionally, industrial storage tanks and conduits require cleaning due to the accumulation of flakes, scales, and rust. Though highly caustic cleaners can remove built up matter, they may not be applicable for all circumstances. The high speed, pulsating blast from a high pressure water jet cutting device can safely remove and clean industrial equipment, storage units, and piping.

The energy produced by a water jet cutter is much higher than the energy necessary for scales, coatings, or contaminants to adhere to a contaminated surface. It is an exceptionally safe, cold cutting method for industrial cleaning. A key factor for its use is its efficiency and speed, eliminating down time and work stoppage.



Food Industry Cutting

Water jet cutting of food is a United States Department of Agriculture (USDA) approved method of cutting that provides productive and sanitary benefits. Much like other industrial uses of water jet cutting, the food industry depends on water jet cutting for its precision and assistance with portion control. A water jet cutter is capable of cutting meat, fish, poultry, pastries, and frozen foods to precise and perfect shapes.

The key feature for water jet cutting of foods is the pure clean water that is central to its operation. The speed at which water jet cutters operate allows for efficient and rapid processing of food products.



Water Jet Cutting Electronics

A major issue in the production of electronics is cost. Manufacturers are constantly searching for ways to reduce costs while increasing efficiency. The cost effectiveness and efficiency of water jet cutting have made it an essential part of electronics production. The process can be used for cutting circuit boards whether the board is populated or empty. It is also an effective method for stripping wires without the worry of damaging the wire.


Water Jet Cutting Fiberglass

Safety is the key issue with fiberglass handling, which requires precision, efficiency, and accuracy. Water jet cutting is capable of shaping and forming fiberglass without the creation of dust or waste. Cuts are made quickly to the precise dimensions of the application.

There are few limitations on the rigidity of the fiberglass being cut whether it is for shaping insulation or for shaping and forming of boats. Fiberglass is delivered in precision cut shapes, which are formed using water jet cutting.


Chapter Six

Types of Water Jet Cutting Machines

Water jet cutting machines have the water jet cutting process attached to a large controllable mechanism, including a high pressure pump, controller, catch tank, an X Y movement system, and abrasive or pure water nozzle. A key component to a water jet cutting machine is motion control that serves the multiple functions of controlling the motion of the cutter and providing a method for holding the workpiece in place.

There are several types, sizes, designs, and processes used to produce water jet cutting machines. Many of the different varieties have CNC controllers that further enhance the cutting process and its precision.


Water Jet Cutting Machine Types

Computer Numerical Control (CNC)

A very common part of modern manufacturing is the computer numerical control (CNC) machine that can be programmed to perform multiple tasks in one pass over a workpiece. The use of CNC programming for water jet cutting has been widely used for many years and is a combination of the finest cutting process with precision control.

The main use of CNC water jet cutting is in situations where the material to be shaped and cut is sensitive to high temperature processes. Some of the cycles of a CNC water jet cutting machine include cutting, forming, deburring, reaming, and honing, which are operations that are best suited for the water jet cutting process

A CNC water jet cutting machine has all of the properties and characteristics associated with water jet cutting. The machines used for CNC water jet cutting are normally flatbed machines with CNC programming connected to the machine’s components. CNC water jet cutting machines are flexible and versatile enough to be customized to fit any production need.


Flatbed Water Jet Cutting Machines

Flatbed water jet cutting machines have a working table that allows for the cutting of large pieces. The flatbed design permits easy access to the table for loading and unloading of materials. A main feature of flatbed water jet cutting machines is their ability to collect the water from the cutting process as well as any waste matter. Water jet cutting flatbed machines are used for their low cost, ability to cut any type of material, and the absence of heat. Parts for water jet cutting keep their heat treatment when placed in the cutting process, which removes the need for heat treatment after being cut.



Computer Numerical Control (CNC)

A very common part of modern manufacturing is the CNC machine that can be programmed to perform multiple tasks in one pass over a workpiece. The use of CNC programming for water jet cutting has been widely used for many years and is a combination of the finest cutting process with precision control.

A CNC water jet cutting machine has all of the properties and characteristics associated with water jet cutting. The machines used for CNC water jet cutting are normally flatbed machines with CNC programming connected to the machine’s components. CNC water jet cutting machines are flexible and versatile enough to be customized to fit any production need.


Portable Water Jet Cutting

Portable water jet cutting machines are a low cost, environmentally safe, and flexible cutting method for cleaning contaminated surfaces, removing burrs, and cutting off the rust. They are suitable for use in dangerous and hazardous conditions, such as the oil industry, construction tunnels, and pipelines. Portable water jet cutting machines have all of the features of high pressure water and velocity and can cut any type of material.

The two types of portable water jet cutting machines are differentiated by how they insert the abrasive into the water stream. One method is to supply the abrasive at the time it is released through the nozzle. The second less effective type is to premix the abrasive with the water before it gets pressurized.




Chapter Seven

Products Made Using Water Jet Cutting

There is an endless list of products, parts, components, and materials shaped and machined using water jet cutting. From highly precision parts for aerospace to decorative ornaments for the home, water jet cutting is relied on to produce precision cuts and precise dimensional accuracy.

The list below contains a few examples of items that have been produced using water jet cutting. Included in the many uses of water jet cutting is the placement of logos on final products and on the surface of hard materials.


Water Jet Cut Products

Wooden Electric Guitar

Using a CAD drawing, the outline of a guitar body is placed on the workpiece. The piece of wood is fed into the water jet cutter. Since water jet cutting does not place a load on the workpiece, it is capable of cutting delicate wood without damaging the grain.


Making Gears

A common product that is manufactured using water jet cutting is gears due to the precision and accuracy they require.


Using Water Jet Cutting on Cams

Cams can easily be made using water jet cutting. All that needs to be determined is the desired shape. Once the CAD rendering is loaded, the water jet cutting machine quickly and easily cuts it.


Producing Chains

Chains produced using water jet cutting are designed to handle heavy loads of several tons. The links are produced using water jet cutting and assembled into chains to lift exceptionally heavy loads.


Creating Name Plates

Water jet cutting is used to create permanent name plates out of heavy metals. The process is used to produce name plates, signage, and company logos. The main reasons for using water jet cutting are due to its precision, removal of the need for finishing, and the smooth edges and finish.



Water Jet Cutting Rubber

Water jet cutting of rubber is far easier than any other cutting method and can cut any thickness. It is able to cut through rubber back metals to streamline the manufacturing process. Water jet cutting does not require special tooling or dies and completes rubber cutting with precision, speed, and optimization of materials.

A unique feature of the water jet cutting of rubber is stack cutting, where several workpieces are piled on top of each other and cut with one pass.



The six items listed above are an extremely small sampling of the products, parts, components, and materials that are fabricated by water jet cutting. With the many advancements in technology and cutting techniques, water jet cutting has become essential for efficient and streamlined industrial operations.


Chapter Eight

Advantages of Water Jet Cutting

There are innumerable methods for cutting, shaping, and forming of industrial products that are capable of performing numerous cuts in a variety of dimensions. Each of those methods has one significant disadvantage, which is the amount of heat they produce during the cutting process. Even the shearing process produces friction during cutting that creates heat.

With water jet cutting, the workpiece remains cool while being cut accurately and precisely. It is a cold process where the molecular structure does not change, and thermal stress does not occur.


Water Jet Cutting Benefits

Extreme Precision

The precision and accuracy of water jet cutting is unbelievable, with a cutting accuracy between ± 0.003 inch to ± 0.005 inch. Since the cutting speed can be altered mid cut, parts can be cut with multiple edges.


Secondary Finishing

Water jet cutting does not create rough surfaces, burrs, or imperfections, which removes the need for secondary finishing. It produces minimal kerfs and smooth finishes. The smoothness of finishes results from the use of erosion to remove material instead of heat or shearing.


Versatility Advantage

There is a limitless number of uses for water jet cutting since it is capable of cutting any material regardless of its hardness. It cuts materials without altering their mechanical properties or weakening their integrity. For increased efficiency, thin materials can be stacked and cut to increase productivity and further lower costs. Additionally, water jet cutting machines come in a variety of table sizes to match the many sizes of workpieces.


Environmentally Safe

Being green is a factor for every manufacturer and industry. The effects of the efforts to preserve the environment have affected other cutting methods except water jet cutting. Most cutting methods produce waste, particulate matter, and pollutants, which are not produced by water jet cutting.

Water jet cutting does not produce toxic gases, harmful waste materials, or poisonous contaminants. It uses pure water that is augmented with natural abrasive materials. Leftover matter from the process can be discharged without damage to the environment.


Ease of Use

The process of water jet cutting involves using a water pump and cutting tool to produce a high velocity water stream at three times the speed of sound. The same components are used to create any type of cut in any type of material.

This lack of complexity makes water jet cutting a cost effective and economical production method whether the cuts are 2D or 3D objects.


Programming Shape

The programmed shape created by engineering software easily transfers into the controls of the water jet cutting machine. The entered data is used to produce precise positioning, cutting speed, and cutting angle. Once the specifics of the material is entered, the machine rapidly completes the cutting process.


Cost Savings of Water Jet Cutting

Of the many positive attributes of water jet cutting, cost savings is the most significant and prominent. The cost of running a water jet cutting machine is far less than any other cutting process. Added to running cost benefits are fast transition times, the speed of the cutting process, and ease of setup.


Lack of Chemicals

The only fluid used in water jet cutting is water and an abrasive that erodes away the material. The jet stream of water cools any heat that is produced. Warping, distortion, and hardening are not factors, which further minimizes secondary processing. Water jet cutting is safer for workers and operators since it does not produce vapors.


Water Jet Cutting Efficiency

Water jet cutting is the most efficient cutting method due to its power and handling of materials. Much of its efficiency can be seen in recycling the water it uses and the removal of the need for secondary processing. Since it can cut anything, tooling does not have to be changed when moving from one product to the next.


Product Control

Precision water jet cutting offers better control of the cutting process such that workpieces can be cut to the sizes and dimensions that are required. It is a more manageable method compared to cutting with a blade or saw.


Sanitary

Water jet cutting is ideal for the food industry since it does not involve the use of chemicals, cutting tools, or any material that would come in contact with food. Under the present restrictions requiring extreme cleanliness and sanitation, water jet cutting is ideal for food processing cutting with standards that demand zero cross contamination.


Conclusion

  • Water jet cutting is a manufacturing process that uses high pressure jets of water provided by pressurizing pumps that deliver a supersonic stream of water to cut and shape various materials.

  • The water jet cutting process can be completed in several different ways. The majority of the methods have an abrasive blended into the water to blast away material from the workpiece.

  • The concept of water jet cutting is rather simple and involves pressure, velocity, and an abrasive.

  • Water jet cutting machines have the water jet cutting process attached to a large controllable mechanism, including a high pressure pump, controller, catch tank, an X Y movement system, and abrasive or pure water nozzle.

  • The water jet cutting process has gained popularity due to its precision and fast turnaround times.


Thank you IQS Directory for allowing us to share this article.


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