Principle Of Water Jet Machine-
This process works on the basic principle of water erosion. In this process, a high-speed well-concentrated water jet is used to cut the metal.It uses the kinetic energy of water particle to erode metal at the contact surface.The jet speed is almost 600 m/s. It does not generate any environmental hazards. For cutting hard materials, abrasive particles are used in the water jet.These abrasive particles erode metal from the contact surface.
Equipment – Parts Of Abrasive Water Jet Machine-
In the water jet machining process a hydraulic pump is used to pump the water from the storage tank for the machining process. It is connected to an electric motor of about 100 Horsepower.
As the name implies, it is used to increase the water pressure for further process. Hydraulic intensifier accepts water from the pump at a small pressure about 4 bar. The water pressure at the outlet of the intensifier is about 3000-4000 bars.
A hydraulic accumulator is used when a large amount of pressure energy is required for an instant. It used to eliminate pressure fluctuation.It supplies fluid at high pressure when required.
Tubes are used to supply high-pressure water to the nozzle for further cutting process. It increases the kinetic energy of the fluid. Its diameter is about 10-14 mm. It provides flexible movement and does not allow any significant loses.
Flow regulators are used to regulating the flow according to cutting requirement. For high cutting load, high pressurized water is supplied at the high rate.
Abrasive particles are used in abrasive waterjet machining for machine hard material. Generally Aluminium oxide, Silicon carbide etc. used as abrasive particles.
As we know, nozzles are used to convert pressure energy into kinetic energy. This nozzle converts high pressure of water into a high-velocity jet. This high-speed water jet strikes at work surface which is used for machining. There is a possibility of erosion at the orifice of the nozzle due to high-pressure water jet. Therefore high wear resistance material is used for the nozzle.The size of the nozzle is about 0.2 – 0.4 mm. If abrasive waterjet machining is used, abrasive particles mixed in water stream before entering into the nozzle.
Drain and Catcher-
The drain and catcher system is used to remove debris and other machined particle form water. It separates metal particle from water and this water is further sent to the reservoir. It also used to reduce noise associated with WJM.
The working of waterjet machining can be summarized as follows-
- First water is filled in the water reservoir. It provides water for cutting operation.
- A pump sucks water from the water reservoir and sends it to intensifier.
- Intensifier increases the water pressure from 4 bar to 4000 bars. It sends water to an accumulator which store some pressurize water.
- This high-pressure water now sends through tubing system to the nozzle. The water passes through flow regulator valve which regulates the flow.
- Now, this high-pressure water enters into the nozzle. Nozzle converts some pressure energy of water into kinetic energy.
- A high-speed high pressurize water jet is available at the nozzle exit.
- This water jet sends to strike at the work surface. It erodes metal from the contact surface. Thus metal removal takes place.
This is a whole working process of waterjet machining.
- It is used in aerospace industries.
- Abrasive jet machining is used to cut hard metal like stainless steel, titanium, Inconel etc.
- It is used for machining or cutting reinforced plastic.
- Use to cut stone which reduces dust in the environment.
- Used to machining PCB.
Advantages and Disadvantages:
- It does not change mechanical properties of the workpiece. It is useful for machining heat sensitive material.
- It is environment-friendly because it does not form any dust particle and used water as cutting fluid.
- Good surface finish.
- No physical tool is required.
- It can cut both soft and hard material. For machining soft materials, water jet machining is used and for machining hard materials, abrasive water jet machining is used.
- It is ideal process for laser reflective materials where laser beam machining cannot be used.
- Lower cost of machining.
- It cannot be used for machining material which degrades in presence of water.
- Low metal removal rate.
- High initial cost.
- The thick material cannot be machined easily.