What Is Water Jet Machining?
Water jet machining is one of the modern machining processes which is used to machine different types of workpieces ranging from plastics to metals. As the name suggests in water jet machining, the force created by a water jet is used to remove material from the workpiece or sometimes cut the workpiece into two parts.
For machining softer materials such as plastics and fibers, simple mechanism is used. But when it comes to harder materials such as metals, water alone cannot provide satisfactory results. Hence Abrasive particles are mixed with the water jet to perform the cutting action. This process is known as Abrasive water jet machining.
History of Water Jet Machining
In the 18th century erosion of land, using high-pressure water was quite common for mining purposes. In 1933 a company in Wisconsin patented the first paper for cutting using water jets. Carl Johnson and Durox International in Luxembourg developed water jet machining for cutting plastics in the year 1956. With time there were developments made and modern technologies made water jet machining suitable for hard materials like metals. Nowadays water jets are pressurized to about 5000 bars with a stream of 0.051mm thin.
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Construction of Water Jet Machining
In Water Jet machining, the water reservoir is connected to the hydraulic pump which is used to increase pressure. The hydraulic pump is then connected to the intensifier. The first supply from the intensifier is connected to the accumulator and the second supply is connected to the mixing chamber via a pressure control valve and flow control valve. The mixing chamber is connected to two supply lines, one for high-pressure water and the other for Abrasive particles. The mixing chamber is directly connected to the nozzle where the pressure energy is converted into kinetic energy. Water from the nozzle is collected by the drain system which in turn is connected to the supply reservoir via the pump.
NOTE: The only difference between Water Jet Machining and Abrasive Water Jet Machining is the absence of Abrasive particles. The remaining construction of the setup is exactly similar.
Important Parts of Water Jet Machining
The basic elements involved in a water jet machining setup are as follows:
A water reservoir is used to store water which is to be used for the machining process. The reservoir is generally situated somewhat above the whole setup. This ensures a continuous and uninterrupted flow of water.
A hydraulic pump is used to transfer water from the reservoir and supply it further at a pressure of about 5 bars. The hydraulic pump is provided with a pressure gauge to measure the pressure of water being passed.
Hydraulic intensifier is the main part of a water jet machining setup. This is responsible for increasing the pressure of water from 5 bars to 3000-5000 bars. Hydraulic intensifiers are a set of three concentric cylinders that use the weight of inlet water to increase the pressure of outlet water.
An accumulator is a tank that stores high-pressure water used for machining. It supplies water whenever there is a pressure drop and more high-pressure water is needed. The accumulator is an important element as it helps in the smooth running of the water jet machining process.
There are two valves used in the process of water jet machining. They are as follows:
- Pressure control valve – A pressure control valve is used to control the pressure as well as the direction of the water.
- Flow regulator valve or Flow control valve – It is used to regulate the flow of water. If more water is supplied then the valve will be closed.
Abrasive Storage Tank
Abrasive particles are very important while working with hard materials. The commonly used Abrasive particles are aluminum oxides, sand, garnet, glass particles, etc. The Abrasive storage tank of a water jet machine is used to store the Abrasive particles.
The mixing chamber in water jet machining is the volume where high-pressure water is mixed with the abrasive particles.
The nozzle is the part of a water jet machining setup that converts the pressure energy of water to kinetic energy. A nozzle of a water jet machine has a decreasing area of cross-section and hence can increase the kinetic energy of water. The nozzle of a water jet machine is made of ruby or diamond so that no cutting action should take place at the nozzle end.
The drain system collects the water after machining and sends it back to the reservoir tank. The drain system of a water jet is connected to a pump which helps in the transfer of water to the supply tank.
How Water Jet Machining works?
Water jet machining works on the principle of erosion of the area on which the high-velocity water jet strikes. In the process, first, the pressure of water is increased to a few thousand bars and then the pressure energy is converted into kinetic energy of the water jet. This kinetic energy in the form of a high-velocity water stream is enough to remove material from the surface of the workpiece or penetrate the workpiece resulting in a cutting action.
Let us understand the working of water jet machining step-by-step:
- Water from the reservoir first enters the hydraulic pump.
- The hydraulic pump increases the pressure of water to around 5 bars and sends it to the intensifier.
- The intensifier increases the pressure from 5 bars to 3000 to 5000 bars and sends it to the mixing chamber and accumulator.
- Accumulator provides a high-pressure water supply to the mixing chamber whenever needed.
- After passing through the intensifier water needs to go through the pressure control valve where pressure is controlled.
- After passing through the control valve it reaches the flow control valve, where the flow of water is checked.
- In this way, high-pressure water reaches the mixing chamber where it is mixed with abrasive particles.
- The high-pressure water is then converted to a high-velocity flow of water. This stream of water and abrasives strikes the workpiece.
- Material removal takes place due to the erosion of material from the surface of the workpiece.
- The waste water is removed through the drain and is supplied to the reservoir with the help of a pump.
- The water supply is stopped and the finished product is removed.
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Applications Of Water Jet Machining
The applications of Water Jet Machining are as follows:
- Water jet machining is widely used in aerospace industries for machining cabin panels, engine components, trimming of turbine blades, etc. This process is used because of the requirement of high accuracy during machining.
- Normal water jet machining is also used in textile industries for cutting soft and thin materials with high accuracy and without the generation of heat.
- Very large setups of Abrasive water jet machining are used for cutting rocks through the principle of erosion by a pressurized stream of water and abrasive particles.
- Very few machining processes are capable of cutting fragile materials like glass. One of these machining includes water jet machining which is also used for machining different glass products such as mirrors.
- Water jet machining is also used in automobile industries for machining different automotive parts. This is due to the minimum wastage of material during the machining process.
Advantages Of Water Jet Machining
There are several advantages of Water Jet Machining such as:
- Accuracy – The accuracy of finished products obtained by water jet machining is quite high. A tolerance of about 0.12mm can be obtained using water jet machining.
- Complex structures – The stream of water produced in water jet machining can in the order of a*0.01mm. This gives an advantage while manufacturing complex structures and detailed products.
- Clean process – Water jet machining is a clean process as it is dust-free and waste materials are washed out through Drain. This provides a better surface finish of the workpiece.
- Low cost of running – The cost of running a water jet machining setup is low. This is due to the absence of moving parts. There are no electrodes or cutting tools used and water used in the process can be reused. This factor also helps in reducing the cost of running.
- No heat generation – Heat generation in a water jet machining process is negligible. Due to no heat generation, there are no thermal cracks produced in the workpiece. This results in a better quality product.
- Adaptability – A water jet machining setup can be used for hard materials like metals as well as soft materials like plastics and fibers. Machining soft materials are not possible using traditional machining methods as the heat produced would burn soft materials.
- Eco-friendly – Water jet machining is an eco-friendly process as there are no pollutants produced in the process. Waste management is also easy in the case of water jet machining.
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Disadvantages Of Water Jet Machining
Also, there are some disadvantages of using Water Jet Machining which are as follows:
- Material thickness – One of the major disadvantages of water jet machining is that it cannot cut very thick materials.
- High initial cost – The initial cost of a water jet machining setup is high. This is due to various pressure-increasing parts. The nozzle used is made of ruby or diamond which is also very costly.
- Corrosion – It is obvious that when we machine a workpiece using water jet machining, the metal surface may get corroded due to moisture. This is one of the drawbacks of water jet machining as Corrosion may result in decreased strength of the workpiece.
- Low productivity – The time taken to machine a given workpiece using water jet machining is more when compared to traditional machining methods. This results in low output or lower productivity of the machining plant.
Video on Water Jet Machining
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In conclusion, water jet machining is an innovative and highly efficient method of cutting and shaping various materials. Its use of high-pressure water streams mixed with an abrasive material offers a unique advantage over traditional cutting methods. Water jet machines are capable of cutting through thick materials with ease, providing precise cuts without causing any heat-affected zones or material distortion. This makes it an ideal choice for industries such as aerospace, automotive, and construction. Water jet machining is also environmentally friendly as it does not produce harmful waste materials. Overall, the benefits of water jet machining make it a valuable asset in any manufacturing process, and it is a technology that is here to stay.
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- Feature Image : Techni Waterjet
- Video : engineering world