Advanced Machining Processes

Abstract

Advanced machining processes are the material-removing processes different from conventional machining processes, in which a well-guided wedge-shaped tool removes the material in the form of chips by producing contact stresses. There are a variety of ways in which material is removed using these processes. One method is producing stresses in the workpiece by different means but not with a well-guided wedge-shaped tool. There are several processes in this category, e.g., ultrasonic machining, water jet machining, and abrasive jet machining. Another method is utilizing the thermal effect to melt or vaporize the material. This is accomplished by laser beam machining, electron beam machining, and electrical discharge machining. Ion beam machining bombards ions instead of electrons as in electron beam machining. It is principally different from electron beam machining in the sense that in the former, the material removal mainly takes place by sputtering and not by melting or vaporization. Chemical and electrochemical machining processes provide very good surface finish by making use of principles of chemistry. Combination of two or more processes is also in vogue. One such process is chemical–mechanical polishing, which removes the material by the combined action of chemical process and stresses caused by polishing. Advanced machining processes have become popular and economical and are finding their use in industries.

Glossary

Abrasives

These are particles used to polish or clean hard surface by rubbing or grinding

Advanced machining processes

These are the material removal processes different from the conventional machining in which a wedge-shaped tool removes the material by physical contact with the workpiece

Bingham plastic fluid

Bingham plastic is a non-Newtonian viscoplastic fluid that behaves as a rigid body at low stresses but flows at higher stresses

Carbonyl iron particles (CIP)

Carbonyl iron is 99.5% purity iron particles

Coherent beam

A coherent beam is having wave sources with constant phase difference and same frequency

Cutting Tool

Cutting tool in machining operation is used for removing material from the workpiece using shear deformation. Cutting tool may be single-point or multipoint based on the number of cutting edges

Deburring

The unwanted piece of material that remains stuck to workpiece after grinding, drilling, milling, and turning processes, etc., is called burrs. The removal of burrs by some process is called deburring

Dielectric medium

Dielectric materials are insulating material or a very poor conductor of electric current. While placed in an electric field, no current flows through them. Dielectric material can be polarized by an applied electric field

Electrical spark

Electric spark is an abrupt electrical discharge that occurs when a sufficiently high electric field generates an ionized, electrically conductive channel through a normally insulating medium like air or gas

Electrolysis

It is a process of chemical decomposition by passing an electric current through a liquid

Electrolyte

An electrolyte is a solution that dissociates into ions and acquires electricity conducting capacity

Honeycomb structure

Honeycomb structures are available in nature or can be fabricated having in the form of a honeycomb

Laser

The full form of laser is light amplification by stimulated emission of radiation. Laser devices emit a coherent and monochromatic beam of light

Machining

Machining refers to removal of material from workpiece for making a product

Magnetorheological fluid

MR fluid is a smart material whose rheological behavior changes rapidly but it can be controlled easily in the presence of an applied magnetic field

Mesh size of abrasive

Mesh is a measurement of particle size often used in determining the particle-size distribution of a granular material. Mesh size or sieve size is defined as the number of openings in one square inch of a screen. The higher the mesh number, the smaller the screen opening, and the smaller the particle that will pass through

Photoresist

Photoresist is a light-sensitive material used in photolithography and photoengraving while making patterned coating on a surface

Piezoelectric Transducer

This type of transducer works on the basis of piezoelectric effect, derived from Greek word piezen, i.e., to squeeze or press. When mechanical stress or forces are applied to a piezoelectric material like quartz crystal, it produces electrical charges on its surface

Plasma

Plasma is an ionized gas consisting of positive ions and free electrons and is often called the fourth state of matter after solid, liquids, and gases

Rheology

Rheology is the study of the deformation and flow of matter under applied forces

Sputtering

During sputtering, atoms or molecules are ejected from a workpiece material due to the bombardment ion beam

Standoff distance (SOD)

The distance between the nozzle tip and workpiece surface is called standoff distance in abrasive jet machining

Surface roughness

Surface roughness refers to small local deviations of a real surface from an ideally perfect flat surface

Transducer

A transducer is a device that converts one form of energy into another form

Ultrasonic frequency

The term ultrasonic refers to frequency above audible sound frequency of human ear, generally over 20 kHz

Viscoelastic medium

It is a material exhibiting both viscous and elastic property while undergoing deformation. Viscous materials generally resist shear flow and exhibit time-dependent strain. The elastic materials strain when stretched and quickly return to their original state once the stress is removed.