Grinding and Non-Conventional Machining Flashcards

Flashcards covering grinding machines, wheel specifications, bonding materials, and non-conventional machining processes (ECM, EDM, PAM, AJM, USM) as described in the lecture notes.

Grinding Machine Types

Includes surface, cylindrical (plain & universal), centreless, internal, tool and cutter, and special machines like thread, gear, and disc.

Grinding Wheel Specifications

Criteria for selection including abrasive material, grain size (grit), grade (hardness), structure (spacing/density), bonding material, and wheel shape/size.

Natural Abrasives

Abrasive grains found in nature such as Sandstone, Emery, Corundum, and Diamond.

Artificial Abrasives

Synthetic grains including Aluminium oxide ($Al_2O_3$), Silicon carbide ($SiC$), Cubic boron nitride ($CBN$), and Synthetic diamond.

Centreless Grinding

A process where the workpiece is supported by a work rest blade and held between a grinding wheel and a regulating wheel instead of centres or chucks.

Regulating Wheel

A control wheel in centreless grinding that governs the rotation and feed of the job.

Loading

A condition where metal chips or swarf get stuck in the pores between abrasive grains, common when grinding soft and ductile materials.

Electro-Chemical Machining (ECM)

A process based on controlled anodic electrochemical dissolution where the workpiece (anode) and tool (cathode) are separated by a flowing electrolyte.

LASER

Light Amplification by Stimulated Emission of Radiation.

Non-conventional Machining

Processes using electrical, chemical, thermal, or mechanical energy to remove material without a conventional sharp cutting tool or chip formation by shear.

Plasma

The fourth state of matter consisting of highly ionized gas with free electrons and ions, formed at temperatures between $5,000$ and $30,000^\circ\text{C}$.

EDM Dielectric Fluids

Fluids such as Kerosene, Deionized (distilled) water, hydrocarbon-based EDM oil, and Transformer oil used in electrical discharge machining.

MEMS

Micro Electro-Mechanical Systems.

Plasma Arc Machining (PAM)

A process using a high-velocity jet of ionized gas at $16,000$ to $33,000^\circ\text{C}$ to melt and blow away workpiece material.

Honing

A low-velocity abrasive finishing process using bonded hones on a rotating and reciprocating spindle to improve hole geometry and finish.

Glazing

A defect where abrasive grains become dull but remain bonded, making the wheel surface smooth and shiny, which increases friction and heat.

Truing

The process of restoring the true geometrical shape and concentricity of a grinding wheel using a diamond-tipped tool.

Dressing

The act of removing dull or loaded abrasive grains to expose new sharp cutting grains and clean the wheel's pores.

Vitrified Bond (V)

A strong, porous, and heat-resistant bond made of clay and feldspar used in approximately $75\%$ of grinding wheels.

Silicate Bond (S)

A binder made of sodium silicate that releases grains easily, suitable for grinding delicate or thin-edged tools.

Shellac Bond (E)

An organic bond used for thin wheels to achieve mirror finishes and for cutting-off operations.

Rubber Bond (R)

An elastic bonding material used for thin cutting-off wheels and centreless regulating wheels.

Resinoid Bond (B)

A synthetic resin bond utilized for high-speed rough grinding and snagging wheels.

Metallic Bond (M)

A bond made of metal powders like bronze or copper used specifically for diamond and $CBN$ wheels.

Electric Discharge Machining (EDM)

Material removal by rapid spark discharges between a tool and workpiece submerged in dielectric fluid, generating temperatures up to $10,000^\circ\text{C}$.

Abrasive Jet Machining (AJM)

A process where a high-velocity mixture of gas and abrasive particles ($150$ to $300\,\text{m/s}$) erodes material from the workpiece surface.

Ultrasonic Machining (USM)

A method using a tool vibrating at $20$ to $40\,\text{kHz}$ to hammer abrasive slurry particles against a workpiece, causing micro-chipping.

Nozzle Tip Distance (NTD)

A process parameter in AJM typically ranging from $0.25$ to $15\,\text{mm}$.