In this article we’ll learn in-depth about Non-Traditional Machining, how it works, Types in detail, its applications, benefits and so much more in detail.
What is a Non-traditional Machining Process?
Traditional methods of machining involve operations such as drilling, boring, cutting, milling, etc with the help of traditional tools having a cutting edge. With the increase in the technology and evolution of time, these conventional methods of machining became outdated, though these methods are the basis of the machining process.
When a component is manufactured with the help of modern technology and without the use of traditional methods then the machining process is known as the non-traditional machining process. the non-traditional machining process is also known as non-conventional machining and modern machining process.
Requirement of the Non-traditional Machining Process:
Though the initial cost of a non-traditional machining plant is high the cost of maintenance is comparatively low as compared to traditional plants.
Non-traditional machining processes are the replacement to the conventional machining processes. As they give better results and have higher accuracy.
The efficiency of the non-traditional machining process is much higher than the traditional machining processes. Hence making the non-traditional machining process a requirement during modern days.
It becomes very difficult to machine hard materials such as tungsten and uranium using traditional methods. This can be easily done using modern machining processes.
Non-traditional machining Types:
The following different types are:
- Electro Discharge machining (EDM)
- Electron beam machining (EBM)
- Plasma arc machining (PAM)
- Laser beam machining (LBM)
- Ultrasonic machining (USM)
- Abrasive jet machining (AJM)
#1. Electro-discharge machining (EDM):
Electro-discharge machining or EDM is one of the most commonly used non-traditional methods of machining. it is also known as spark erosion and spark machining. This method is generally used for machining hard materials. The material discharge is controlled by proper energy variation and time of spark.
An EDM setup consists of a DC supply of 50V-450V. the tool and the workpiece are kept in a dielectric medium. The workpiece is connected to the positive terminal hence acts as an anode while the tool is connected to the negative terminal and serves as the cathode.
There is a small gap between the tool and the workpiece. The workpiece must be a conductor of electricity. Rack and pinion arrangement is provided for the movement of the tool perpendicular to the workpiece. The gearbox is used for the movement of the rack and pinion. A capacitor is used for controlling the gear movements.
Working of EDM: When a voltage of 50V-450V is applied to the circuit, the electrons from the tool start flowing towards the workpiece through the dielectric medium. This causes the gap to be ionized due to the electric charge.
As a result of which there is a sudden drop in the resistance which in turn is responsible for the spark to be produced. This spark gives rise to a very high temperature (about 10000oC), this temperature is sufficient enough to melt any metal. The melted metal is then carried out with a flowing dielectric medium. Machining speed is calculated in terms of the volume of metal removed per minute.
Note: Materials such as copper, graphite, brass are used as tools because they are good conductors of electricity and are available easily.
The dielectric medium used can be kerosene oil or paraffin oil, to carry away the waste material and also serves as coolants.
#2. Electron Beam Machining (EBM):
Electron beam machining is the process of machining in which an electron beam is used for removing the metal from the workpiece. The workpiece is placed in a vacuum chamber. An electron beam is focused on the workpiece with the help of an electron gun. As the electron strikes the surface of the workpiece the temperature of the contact point is increased. This results in the removal of a small amount of metal in the form of vapors.
The process is carried out in a vacuum chamber in which there is an electron gun consisting of a tungsten filament that serves as a cathode. A DC power supply is connected to the anode and cathode of the setup. A diaphragm is to narrows the path of the electron beam produced by the electron gun. Focusing lenses and deflector coils are used to focus the beam on the workpiece. The workpiece, in the end, is kept on the worktable.
Working of EBM: A potential difference of 50kV to150kV is applied between the anode and the cathode. The tungsten filament is heated up to 2500oC due to the applied voltage. Because of high temperature, the filaments release electrons which are directed by anode and tungsten diaphragm.
These electrons then reach towards the focusing lenses where it is focused on the workpiece. The deflector then directs the focused electron beam to the desired place on the workpiece. There is an increase in the temperature at the contact point of the electron beam and workpiece. This results in the removal of metal in the form of vapors.
Note: Vacuum setup is used so that the electron beam should not get scattered by air particles. And the electrons should travel easily from the electron gun to the workpiece. The velocity of electrons is 0.66times of the velocity of light.
#3. Plasma Arc Machining (PAM):
Plasma arc machining is a low-cost process of machining that uses plasma for cutting the workpiece. When the gases are heated above 5500oC they are partially ionized. They form a mixture of positively charged particles, neutral particles, and negatively charged particles, this mixture of partially ionized gas is called plasma. This plasma is then used for the cutting purpose and the process is called plasma arc cutting.
It consists of a DC power supply whose positive terminal is connected to the nozzle (anode) and the negative terminal is connected to the electrode present in the torch. The electrode is generally made of tungsten with insulation provided on the top. A water-cooling system is provided in a few cases to absorb the heat produced at the nozzle end.
Working on plasma arc machining is quite simple. As soon as a potential difference is created between anode and cathode the electrode gets heated up, this results in increased temperature of the gases present in the chamber. As soon as the gases are ionized the beam of plasma is focused with the help of the arc. The focused beam of plasma increases the temperature at the point of contact on the workpiece. This melts the metal which is then removed away.
Note:- Different types of gases are used for cutting different metals. For example, for cutting aluminum nitrogen, nitrogen-hydrogen and argon-hydrogen can be used.
#4. Laser beam machining (LBM):
One of the well-known methods of non-traditional machining is laser beam machining. Laser stands for light amplification by stimulated emission of radiation. A laser beam when properly focused is projected on the workpiece it increases the temperature at the point of contact. The temperature obtained is more than the melting point which evaporates the metal at the surface.
The main functional part of an LBM setup is a xenon flash lamp which is situated in a casing that is highly reflecting. The laser rod consists of one totally reflecting mirror and one partially reflecting mirror facing each other. One of the commonly used lasers is a ruby laser. A power source with a timer to produce light in the form of a flash. A convex lens is used to focus the divergent light rays.
Working of LBM: The flashlights are radiated from the lamp and are focused on the laser rod. These light rays are reflected in the tube and are excited. A slightly divergent ray of light is allowed to leave from the tube through the partially divergent mirror.
These slightly divergent rays are then focused and concentrated on the workpiece with the help of a convex lens. As the ray of laser strikes the workpiece it increases the temperature at the point of contact. This increase in temperature results in the removal of metal in the form of vapor.
Note: it is important to wear safety glasses while watching a laser cutting process as it can damage the eyes of the viewer.
#5. Ultrasonic machining (USM):
The term ultrasonic machining refers to the involvement of vibration above 20kHz which is more than the upper audible limit of the human ears. These vibrations are used for machining purposes.
A USM setup consists of an ultrasonic oscillator which is used for the current supply. The oscillator is connected to an ultrasonic transducer which converts electrical signals to mechanical vibrations. A transducer is connected to the tool holder and the tool is attached to the holder. Abrasive slurry is forced on the workpiece which removes the waste material in the form of chips.
Working of Ultrasonic Machining: Alternating current from the oscillator reaches the transducer where it is converted to mechanical vibrations in order of 20kHz to 40kHz. A feed mechanism is used to move the tool arrangement in a vertical direction. The cutting action is performed by the vibration of the cutting tool on the workpiece. The slurry on the other hand is used to remove the waste products in the form of chips.
#6. Abrasive jet machining (AJM):
Abrasive jet machining is the process of machining in which the cutting operation is done using a mixture of grained particles (10-40 microns) with air or some other gas. The mixture is directed to the workpiece in the form of a stream. The velocity of the fine particle mixture varies from 200 to 400 m/sec. the metal is removed from the workpiece with the action of erosion. This happens due to the force of impact with which the mixture hits the workpiece.
The setup of an abrasive jet machining consists of a mixing chamber in which the fine-grained abrasive particles are filled with the help of a hopper. A regulator to control the vibration is situated below the hopper. A gas supply pipe is situated along with a filter and a pressure gauge for the supply of gas into the chamber. A filter is used to remove the impurities from the gas and a pressure gauge is used to check the pressure. The outlet system consists of another pressure gauge along with a control valve. There is a nozzle situated at the end of the outlet pipe which directs the fine mixture over the workpiece.
Working of AJM: The gas is supplied from the inlet pipe and the fine-grained particles are supplied from the hopper. The vibrations produced in the chamber due to the vibrating device are used to mix air and finely grained particles. As the pressure inside the chamber is increased the control valve is relieved due to which the fine mixture is allowed to vent out of the nozzle with a high velocity. This causes the removal of metal due erosion effect by the abrasive particles.
Table for comparison between above Nonconventional machining processes:
|PAM||very low||very low||very high|
|LBM||medium||very low||very high|
Advantages of Non-traditional methods of Machining:
High accuracy: Nowadays accuracy is the key concern for industries may it be small-scale or large-scale industries. the products produced by traditional methods of machining are less accurate when compared to the products manufactured by non-traditional methods of machining. Hence high accuracy makes unconventional machining fit for the modern days and acts as a replacement to traditional machining processes.
Less noise: Non-traditional methods of machining play a major role in reducing the noise pollution of the surrounding area, as they are a better replacement for traditional machining methods. Some of the non-traditional machining plants can be situated in residential areas because the process involved is silent.
High production: Modern or unconventional methods of machining promote a high production rate when compared to traditional methods of machining. This is because the working process of non-traditional methods is faster and more accurate than the traditional methods.
Less waste product: Waste product management becomes very difficult while working on traditional machines. The chips produced must be disposed of timely which requires extra effort. But in the case of non-traditional methods of machining, there is either no waste produced or micro waste is produced which is easy to handle and dispose of.
No wear of the tool: There is no contact between the tool and the workpiece in non-traditional methods of machining. This eliminates the risk of tool failure and no wear and tear of the tool take place.
Disadvantages of Non-traditional methods of Machining:
High initial cost: The initial cost of the setup of a non-traditional machining plant is higher when compared to a traditional machining plant, as it has many electronic parts working along with mechanical parts. This makes it unsuitable for small-scale and cottage industries.
High power requirement: The power required to run a non-traditional machining plant is much higher than to run a traditional machining plant. This is because there is no contact between the tool and the workpiece hence more energy is required to machine the tool surface.
Complex mechanism: Unlike the traditional machining methods, non-traditional machining methods are more complex. The operator must be skilled enough to handle the processes involved in non-traditional machining methods. If the plant stops working due to various reasons, a highly skilled professional will be needed to fix it.
Lower metal removal rate: The metal removal rate of non-traditional machining methods is generally low when compared to traditional methods. This makes non-traditional methods unsuitable for products with large dimensions.
Not suitable for soft materials: The cutting action performed by a non-traditional machining method is generally due to a localized increase in the temperature of the workpiece. This makes the process unsuitable for machining soft materials such as rubber or plastic as the workpiece would get burnt.
Applications of Non-traditional methods of Machining:
Here are the following applications:
- Non-traditional machining methods are used for the design of dies as it is used to machine hard surfaces. Many of the hard metals which cannot be machined using traditional methods can be machined by unconventional machining methods.
- Non-traditional methods are also used in automobile industries for drilling very small diameter holes of a nozzle of a fuel injection system. Gears can also be machined using non-traditional machining methods.
- Many of the non-traditional methods of machining are used for machining complex designs on thin metal sheets such as Laser Beam Machining.
- Unconventional machining processes such as Abrasive Jet Machining can be used for machining fragile materials like glass, ceramics, and quartz.
- Machining of a cutting tool can also be done using a non-conventional machining process.
- Modern machining has great importance in aerospace industries, as it is used to manufacture complex parts of an aircraft.
- Electrochemical Machining
- Welding Defects
- Plasma Arc Welding
- Submerged Arc Welding
- Electrical Discharge Machining
- Abrasive Jet Machining
- Ultrasonic Machining
- Submerged Arc Welding Machine
- Laser Beam Machining
- Image: By Saubhik Roy- Design Team Learn Mechanical and Wikipedia.
- Feature Image: Modified by Author
So this is all about Non-conventional Machining, I hope this session was beneficial for you. Do let me know if you have any doubts regarding this topic, I will try to answer your quires within 24 hours!