Unconventional Machining Process: Types, Working, Uses

Hello, everyone. Today, we’ll delve into comprehensive details regarding unconventional machining processes, including their types, components, operational procedures, applications, advantages, disadvantages, and more.

Unconventional machining processes find extensive application in materials that are hard and brittle, such as tungsten carbide, high-speed steels, stainless steels, ceramics, etc. These materials are challenging to process using conventional machining methods.

Read also: Types of Cutting Tool Materials and Their Properties

The preceding post has already addressed various conventional machining processes like lathe machines, planer machines, milling machines, drilling machines, slotting machines, shaper machines, and more.

Table of Contents

What is Unconventional Machining Process?

An unconventional machining process refers to a specialized category of manufacturing techniques where there is no direct contact between the tool and the workpiece. Instead of traditional mechanical cutting, unconventional machining processes utilize various forms of energy, such as mechanical, electrical, or chemical, to remove material from a workpiece.

These processes are particularly valuable when working with hard, brittle materials that are challenging to machine using conventional methods. Unconventional machining often involves technologies like electrical discharge machining (EDM), laser machining, ultrasonic machining, and others. The absence of direct tool-to-workpiece contact allows for precision machining of intricate shapes and materials that may be difficult to handle through traditional means.

So, If I continue to pronounce these names, then don’t get confused.

Advantages of unconventional machining process 

  1. It has good accuracy.
  2. It provides a good surface.
  3. Complex shapes can be made easily. 
  4. It has longer tool life. 
  5. The rate of metal removal is high.

Disadvantage of unconventional machining process 

  1. The cost of this process is high.
  2. It requires skilled operators.
  3. Its setup is difficult.

Classification of Unconventional Machining Process

Different types of energy are used in this machining process to remove metal. 
Because of which on the basis of energy use
the unconventional machining process can be classified into four categories:
  • Mechanical Energy Based
  • Electrical Energy-Based
  • Chemical and Electrochemical Energy Based 
  • Thermal Energy-Based

Mechanical Energy Based

In this method, mechanical energy is employed for the removal of undesired materials, as seen in processes such as abrasive jet machining, water jet machining, ultrasonic machining, etc.

Electrical Energy-Based

In this procedure, unwanted material is removed using an electrical spark, as observed in processes such as electrical discharge machining, wire cut electrical discharge machining, etc.

Chemical and Electrochemical Energy Based 

In this machining technique, chemical energy is harnessed to eliminate undesired materials, as demonstrated in processes such as photochemical machining, electrochemical machining, electrochemical grinding, etc.

Thermal Energy-Based

In this machining process, heat is applied to eliminate undesired material, as demonstrated in techniques such as plasma beam machining, laser beam machining, etc.

Types of Unconventional Machining Process

Various unconventional machining processes, employing diverse energy sources, are explored in the following discussion:

  • Abrasive Jet Machining
  • Ultrasonic Machining
  • Electrochemical Machining (ECM
  • Electrical Discharge Machining (EDM)
  • Electron Beam Machining 
  • Laser Beam Machining
  • Electrochemical Grinding

Abrasive Jet Machining

Abrasive jet machining is a process based on mechanical energy and is primarily employed for machining hard metals.

Read also: Manufacturing Process of Steel: 6 Methods of Making Steel

In this machining process, a focused stream of abrasive particles, such as aluminum oxide, silicon carbide, diamond powder, glass particles, etc., is directed to impact a section of the workpiece at high velocity.

These high-velocity abrasive particles effectively cut the metal into small pieces.

Refer to the figure for a detailed description of the abrasive jet machining process and its working procedure outlined below.

Unconventional Machining Process
Abrasive Jet Machining

Working Procedure of Abrasive Jet Machining

  1. In abrasive jet machining, initially, air or gases such as nitrogen or carbon dioxide are compressed using a gas compressor, thereby increasing the gas’s density and pressure.
  2. The compressed gas is then directed to a filtration unit, where dust and other suspended particles are removed. Subsequently, the purified gas undergoes moisture absorption in a dryer.
  3. Following this, the clean and dry gas proceeds to the mixing chamber, where abrasive particles are introduced via an abrasive feeder.
  4. These abrasive particles typically have a size ranging from 10 to 50 micrometers.
  5. The high-pressure abrasive particles, along with the gas (pressurized at approximately 850 kPa), are directed to the nozzle, whose diameter falls within the range of 0.18 to 0.80 mm.
  6. At the nozzle, the pressure energy is converted into kinetic energy, resulting in abrasive particles attaining velocities ranging from about 150 to 300 m/s.
  7. Maintaining a distance of approximately 2 mm between the nozzle (made of tungsten) and the workpiece, the high-velocity abrasive particles impact the workpiece.
  8. Through a combination of micro-cutting action and brittle fractures of the work material, these particles efficiently remove material from the workpiece.

Application of Abrasive Jet Machining

  1. It is used in the drilling and cutting of hard metals. 
  2. It is used for machining brittle and heat sensitive materials like glass, mica, ceramic, sapphire, quartz, etc. 
  3. It is used for manufacturing electronic components. 

Advantages of Abrasive Jet Machining

  1. High surface finish. 
  2. It can machine heat sensitive material.
  3. It is free from vibration.  
  4. The initial cost is low compared to other non-traditional procedures. 
  5. Thin sections can be made easily.

Disadvantages of Abrasive Jet Machining 

  1. Low metal removal rate. 
  2. Nozzle life is limited, so it needs to be replaced frequently. 
  3. The abrasive particle cannot be reused in this process. 
  4. This machine can not use for a soft and ductile material.

Ultrasonic Machining

Ultrasonic machining is a non-conventional machining process that relies on mechanical energy and is specifically employed for machining hard and brittle materials.

In ultrasonic machining, ultrasonic waves are transformed into mechanical vibrations using the magnetostrictive effect. The ultrasonic machine generates frequencies ranging from 20,000 to 30,000 Hz.

This cost-effective process is widely utilized in various industries for metal cutting due to its advantages of low heat generation and efficient machining.

Refer to the figure for a comprehensive description of the ultrasonic machining process and its working procedure outlined below.

Ultrasonic Machining
Ultrasonic Machining

Working Procedure of Ultrasonic Machining

  1. Initially, a low-frequency electric current is sourced from the power supply.
  2. This low-frequency current undergoes conversion into a high-frequency current through specific electrical equipment.
  3. The resultant high-frequency current then traverses the transducer, which transforms the high-frequency electric signal into high-frequency mechanical vibration.
  4. This mechanical vibration is further transmitted through the booster, where it undergoes amplification before being directed to the horn.
  5. The horn, also known as a tool holder, conveys this amplified vibration to the tool, causing it to vibrate at an ultrasonic frequency.
  6. To facilitate the machining process, an abrasive gun is employed to supply an abrasive slurry (e.g., aluminum oxide, silicon carbide, boron carbide, diamond dust, etc.).
  7. The mixture of abrasive slurry and water is delivered between the tool and the workpiece.
  8. As the tool vibrates, the abrasive slurry synchronously vibrates at this high frequency, effectively engaging the workpiece and imparting a metallic appearance to it.

Application of Ultrasonic Machining

  1. It is used to produce fine holes. 
  2. It is the best suited machine for hard and brittle materials. 
  3. With the help of this, a cavity or hole is easily made in the dies.

Advantages of Ultrasonic Machining

  1. The workpiece is free from any stress after machining.  
  2. Extremely hard and brittle materials can be easily removed.
  3. Excellent accuracy and surface finishing are achieved. 
  4. Operational cost is very low. 
  5. This process is environmentally friendly as it takes place without any chemical reactions and heating. 
  6. It is suitable for both conducting and non-conducting materials.

Disadvantages of Ultrasonic Machining 

  1. In this, the metal removal rate is low and can not be used for large machining operations.
  2. The initial cost and initial cost of the equipment are very high. 
  3. The power consumption is quite high. 
  4. The slurry may need to be changed frequently.
  5. Equipment life is short.

Electrochemical Machining (ECM

Electrochemical machining is a non-conventional machining process based on electrochemistry, where metals are removed through electrochemical dissolution—a process that stands in contrast to electroplating.

Operating on Faraday’s law of electrolysis, the tool is connected to the negative terminal (functioning as the cathode) of the battery, while the workpiece is connected to the positive terminal (serving as the anode) of the battery. Both are positioned at a distance within an electrolyte solution.

Upon supplying a DC current (ranging from 3 to 30V) to the electrode, the metal starts to move away from the workpiece.

Refer to the figure for a comprehensive depiction of the electrochemical machining process and its working procedure detailed below.

Electrochemical Machining
Electrochemical Machining

Working Procedure of Electrochemical Machining

  1. In ECMNaCI is usually in water as an electrolyte. 
  2. The tool is connected to the negative terminal, and the workpiece is connected to the positive terminal. 
  3. When current passes through the electrodes, the anode or workpiece and the cathode or tool reaction occurred >
  4. NaCI = (Na+)  +  (CI-
  5. H20 =( H +)  + ( OH-)
  6. Positive ions move towards the tool and negative ions towards the workpiece. 
  7. Thus the hydrogen ion moves towards the tool.  
  8. As hydrogen reaches the tool, it takes some electrons from it and turns into a gas. This gas goes into the environment.

Application of Electrochemical Machining

  1. ECM is used in the machining of disc or turbine rotor blades. 
  2. It can be used to slot very thin walled collets. 
  3. The ECM is used to generate the internal profile of the internal cam. 
  4. ECM is also used in the Production of satellite rings and connecting rods, machining of gears and long profiles, etc.

Advantages of Electrochemical Machining

  1. It can machine very complex surfaces. 
  2. A single tool can be used for machining a large number of workpieces.
  3. Metal machining does not depend on the strength of the tool and the hardness of the tool. 
  4. ECM provides a very high surface area.

Disadvantages of Electrochemical Machining

  1. High initial cost of the machine. 
  2. The design and tooling system is complex. 
  3. The fatigue property of the machined surface may be reduced.  
  4. Nonconducive materials cannot be machined. 
  5. Blind holes cannot be machined through ECM.

Electrical Discharge Machining (EDM)

This machining process employs an electric spark for metal cutting.

The sparks generated during this process generate heat, facilitating metal removal through erosion and evaporation.

Conducted in dielectric fluid, this non-traditional machining process necessitates both the workpiece and the tool to be made of conductive materials.

Refer to the figure for a detailed description of the electrical discharge machining process and its working procedure outlined below.

Electrical Discharge Machining
Electrical Discharge Machining

Working Procedure of Electrical Discharge Machining

To initiate the electrical discharge machining process, both the workpiece and the tool are submerged in dielectric fluid, crucial for controlling the arc discharge. Maintaining a minimal gap of approximately 0.5 mm between the workpiece and the tool, a high-frequency current is directed to the electrode, sparking the creation of an arc between the two.

As a result of erosion and the evaporation of ions, metal begins to dislodge from the workpiece. To prevent a short circuit, chips and suspended particles are constantly removed from the gap between the workpiece and the tool. This uninterrupted removal is made possible by the continuous supply of dielectric fluid.

Application of Electrical Discharge Machining 

  1. It is specially used for master die makers. 
  2. Finished products
  3. Long aspect hole

Advantages of Electrical Discharge Machining 

  1. Every conductive material can be cut by this process.
  2. A complex dies sections and complex shapes can be produced with precision.
  3. This process is independent of burrs.
  4. Thin sections can be easily formed without deforming any parts.
  5. Pieces of hard workpieces can be easily cut.  

Disadvantages of Electrical Discharge Machining

  1. In this machining process, the equipment wears out more. 
  2. Good electrical conductors can only be made by EDM.

Electron Beam Machining

It is a non-traditional machining process based on thermo-electric energy that operates without the use of tools.

This machining process relies on the fundamental principle of transforming the kinetic energy of electrons into heat energy. When high-speed electrons impact a section of the workpiece, they convert their kinetic energy into heat energy.

The generated heat energy causes the material on the surface of the workpiece to evaporate. To prevent energy loss, this process is conducted in a vacuum, as electron collisions with air particles can deplete their energy before reaching the material. It is primarily employed for drilling holes of various shapes.

Refer to the figure for a detailed depiction of the electron beam machining process and its working procedure outlined below.

Electron Beam Machining
Electron Beam Machining

Working Procedure of Electron Beam Machining

To commence the electron beam machining process, the electron gun generates high-velocity electron particles. These electrons advance towards the anode, positioned after the cathode tube.

Subsequently, an intensely focused electron beam traverses magnetic lenses, forming a series of lenses dedicated to assimilating converging electrons while absorbing divergent and low-energy electrons. This arrangement ensures a high-quality electron beam.

The electron beam then proceeds through electromagnetic lenses and a deflecting coil, which concentrates the electron beam onto a specific spot. At this juncture, the highly intense electron beam impacts a section of the workpiece, where the kinetic energy of electrons transforms into thermal energy.

The resultant high temperature, generated through this conversion process, causes the material to melt and vaporize, leading to material removal (cutting). The entire process is conducted within a vacuum chamber to prevent collisions between electrons and air particles, preserving their kinetic energy.

Application of Electron Beam Machining

This technique is employed to create extremely small holes ranging from 100 micrometers to 2 millimeters. It finds application in the fabrication of holes in diesel injection nozzles. Furthermore, it is utilized within the aerospace industry for crafting turbine blades intended for supersonic engines and in the production processes related to nuclear reactors.

Advantages of Electron Beam Machining 

It is capable of generating minuscule holes in various shapes. This machining method is versatile, capable of processing materials regardless of their hardness and other mechanical properties. It yields high-quality surface finishes. Additionally, highly reactive materials can be effectively machined as the process takes place under vacuum conditions.

Disadvantages of Electron Beam Machining 

  1. Capital cost is high. 
  2. Require high skill operator. 
  3. The rate of material removal is low.  
  4. Require regular maintenance. 
  5. Producing the perfect vacuum is difficult.

Laser Beam Machining 

Laser beam machining is a thermo-electric energy-based non-traditional machining process that employs a laser beam to heat materials.

In this machining method, metal is extracted from the workpiece’s surface through the process of melting and evaporating metal particles. It is distinguished as a non-traditional machining process wherein no conventional tools are utilized.

This process is applicable to both metallic and non-metallic materials, primarily employed for cutting materials and drilling holes.

Refer to the figure for an in-depth depiction of the laser beam machining process and its working procedure outlined below.

Laser Beam Machining
Laser Beam Machining

Working Procedure of Laser Beam Machining

  1. Initially, laser material, such as CO2 or other gases, is introduced into the laser vacuum (discharge) tube.
  2. Next, the power switch is activated, connecting to the flash lamp. The lamp generates light energy, which excites the electrons within the atom.
  3. The atoms of the laser substance absorb energy from the light produced by the flash lamp, transitioning the atomic orbital electron from a lower energy level to a higher, unstable state.
  4. This energy becomes fully immersed in the laser material. Once the atom accumulates sufficient energy, it continuously emits energy.
  5. The laser light emitted is collected by a focusing lens and directed toward the workpiece.
  6. The laser, now aimed at the workpiece, initiates the process of melting or vaporizing the surface, marking the commencement of the machining process.

Application of Laser Beam Machining 

This technique is applied to create minute holes with a diameter of around 0.005 mm in refractory and ceramic materials. It is utilized for both drilling holes and cutting various materials, including metals and non-metals. Predominantly employed in the aerospace industry, it proves valuable for intricate profiles where traditional tool-based machining is impractical.

Advantages of Laser Beam Machining

This method is capable of drilling and cutting through all types of materials, delivering elevated surface quality in the machining process. Notably, no conventional tools are employed in this method. It enables the precise drilling of micro holes and exhibits effectiveness in cutting very hard materials using laser beam machining. The process allows for the attainment of high accuracy in the final product.

Disadvantages of Laser Beam Machining

  1. High capital and maintenance cost. 
  2. It cannot be used to make blind holes. 
  3. Lasers may lead to a safety hazard.

Electrochemical Grinding

In the electrochemical grinding process, material removal occurs through a combination of both electrochemical and grinding processes.

During the grinding phase, only 10% of the metal is removed, with the remaining 90% being removed through the electrochemical process.

Refer to the figure for a detailed depiction of the electrochemical grinding machine and its working procedure outlined below.

Electrochemical Grinding
Electrochemical Grinding

 

Working Procedure of Electrochemical Grinding

The grinding wheel, constructed with diamond particles, is affixed to the spindle. The spindle, responsible for rotating the grinding wheel, operates at a speed ranging from 900 to 1800 rpm/min.

During the process, the workpiece is connected to the positive terminal, while the tool is connected to the negative terminal. A consistent gap of 2.5 mm is maintained, and the electrolyte flows between this gap. Sodium chloride and sodium nitrate serve as electrolytes, also functioning as coolants. The electrolyte undergoes filtration and recirculation.

Upon supplying power, ions are extracted from the workpiece. Positive ions move towards the grinding wheel, and negative charges are carried away by the electrolyte. The grinding process results in the removal of a certain amount of metal.

Application of Electrochemical Grinding

  1. Used to machine hard and brittle materials.  
  2. Suitable for grinding tungsten carbide tools.  
  3. Used to machine thin components.

Advantages of Electrochemical Grinding

  1. Fast process and high metal removal rate. 
  2. Very hard materials are removed. 

Disadvantages of Electrochemical Grinding

  1. Only suitable for conducting material.
  2. Requires high electrical power.
  3. High investment.
  4. Not suitable for complex shapes.
  5. Electrolytes can cause corrosion.

I hope that I have cleared all your doubts related to the unconventional machining process

If you have any doubts related to this topic then you can ask me through contact us page or directly mail to me.

 

1 thought on “Unconventional Machining Process: Types, Working, Uses”

  1. I quite like reading through a post that will make men and women think.

    Also, thanks for allowing for me to comment!

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