Grinding, lapping, polishing, EDM,

laser cut, water jest, etc.

Aluminum oxide, silicon carbide, diamond, and cubic boron

nitride (CBN) are four commonly used abrasive materials for the

surface of the grinding wheels.

Grinding is an abrasive machining process that uses

a grinding wheel as the cutting tool.

A basic overview of Outside Diameter

Cylindrical Grinding. The Curved Arrows refer to

direction of rotation

A basic overview of Internal Diameter

Cylindrical Grinding. The Curved Arrows refer to

direction of rotation

Surface grinding is used to

produce a smooth finish on flat

surfaces. It is a widely

used abrasive machining process

in which a spinning wheel

covered in rough particles

(grinding wheel) cuts chips of

metallic or nonmetallic substance

from a workpiece, making a face

of it flat or smooth. The typical

precision of a surface grinder

depends on the type and usage,

however ±0.002 mm (±0.0001 in)

should be achievable on most

surface grinders.

The machine consists of a table that traverses both longitudinally

and across the face of the wheel. The longitudinal feed is usually

powered by hydraulics, as may the cross feed, however any

mixture of hand, electrical or hydraulic may be used depending

on the ultimate usage of the machine (i.e., production,

workshop, cost). The grinding wheel rotates in the spindle head

and is also adjustable for height, by any of the methods

described previously. Modern surface grinders are semi-

automated, depth of cut and spark-out may be preset as to the

number of passes and, once set up, the machining process

requires very little operator intervention.

Depending on the workpiece material, the work is generally held

by the use of a magnetic chuck. This may be either an

electromagnetic chuck, or a manually operated, permanent

magnet type chuck; both types are shown in the first image.

Types of surface grinders:

Horizontal-spindle (peripheral) surface grinders

The periphery (flat edge) of the wheel is in contact with the workpiece,

producing the flat surface. Peripheral grinding is used in high-precision

work on simple flat surfaces; tapers or angled surfaces; slots and

profiles.

Vertical-spindle (wheel-face) grinders

The face of a wheel (cup, cylinder, disc, or segmental wheel) is used on

the flat surface. Wheel-face grinding is often used for fast material

removal, but some machines can accomplish high-precision work. The

workpiece is held on a reciprocating table, which can be varied

according to the task, or a rotary-table machine, with continuous or

indexed rotation. Indexing allows loading or unloading one station

while grinding operations are being performed on another.

Outside Diameter Cylindrical Grinding

Internal Diameter Cylindrical Grinding

A schematic of the centerless grinding process.

Centerless grinding process

Honing or to "Hone"is an abrasive machining process that

produces a precision surface on a metal workpiece by

scrubbing an abrasive stone against it along a controlled path.

Honing is primarily used to improve the geometric form of a

surface, but may also improve the surface texture.

Typical applications are the finishing of cylinders for internal

combustion engines, air bearing spindle and gears. There are

many types of hones but all consist of one or more abrasive

stones that are held under pressure against the surface they

are working on.

In terms of sharpening knives,

a honing steel does not actually

hone knives, but simply realigns

the metal along the edge.

Superabrasives and hone head for cylinders.

Lapping is a machinng process, in which two surfaces are

rubbed together with an abrasive between them, by hand

movement or by way of a machine.

Polishing is the process of creating a smooth and shiny

surface by rubbing it or using a chemical action, leaving a

surface with a significant specular reflection.

Electrical discharge machining (EDM), sometimes colloquially also

referred to as spark machining, spark eroding, burning, die

sinking, wire burning or wire erosion, is a manufacturing process

whereby a desired shape is obtained using electrical discharges

(sparks). Material is removed from the workpiece by a series of

rapidly recurring current discharges between two electrodes,

separated by a dielectric liquide and subject to an electric voltage.

One of the electrodes is called the tool-electrode, or simply the

"tool" or "electrode", while the other is called the workpiece-

electrode, or "workpiece".

Wire-cut EDM

The wire-cut type of machine arose in the 1960s for the purpose

of making tools (dies) from hardened steel. The tool electrode in

wire EDM is simply a wire. To avoid the erosion of material from

the wire causing it to break, the wire is wound between two

spools so that the active part of the wire is constantly changing.

The earliest (NC) machines were conversions of punched-tape

vertical milling machines. The first commercially available NC

machine built as a wire-cut EDM machine was manufactured in

the USSR in 1967. Machines that could optically follow lines on a

master drawing were developed in the 1960s at Andrew

Engineering Company for milling and grinding machines. Master

drawings were later produced by (CNC) plotters for greater

accuracy. A wire-cut EDM machine using the CNC drawing plotter

and optical line follower techniques was produced in 1974.

Dulebohn later used the same plotter CNC program to directly

control the EDM machine, and the first CNC EDM machine was

produced in 1976[

A water jet cutter, also known as a water jet or waterjet, is an

industrial tool capable of cutting a wide variety of materials using

a very high-pressure jet of water, or a mixture of water and

an abrasive substance. The term abrasivejet refers specifically to

the use of a mixture of water and abrasive to cut hard materials

such as metal or granite, while the terms pure

waterjet and water-only cutting refer to waterjet cutting without

the use of added abrasives, often used for softer materials such

as wood or rubber

A diagram of a water jet cutter. #1:

high-pressure water inlet. #2: jewel

(ruby or diamond). #3: abrasive

(garnet). #4: mixing tube. #5:

guard. #6: cutting water jet. #7: cut

material

A 5-Axis Waterjet Cutting Head

Laser cutting is a technology that uses a laser to cut materials,

and is typically used for industrial manufacturing applications, but

is also starting to be used by schools, small businesses, and

hobbyists. Laser cutting works by directing the output of a high-

power laser most commonly through optics. The laser optics

and CNC (computer numerical control) are used to direct the

material or the laser beam generated. A typical commercial laser

for cutting materials would involve a motion control system to

follow a CNC or G-code of the pattern to be cut onto the material.

The focused laser beam directed at the material, which then

either melts, burns, vaporizes away, or is blown away by a jet of

gas, leaving an edge with a high-quality surface finish. Industrial

laser cutters are used to cut flat-sheet material as well as

structural and piping materials.

Diagram of a laser cutter

There are two main types of lasers used in laser cutting.

The CO2 laser is suited for cutting, boring, and

engraving. The neodymium (Nd) and neodymium

yttrium-aluminium-garnet (Nd-YAG lasers are identical

in style and differ only in application. Nd is used for

boring and where high energy but low repetition are

required. The Nd-YAG laser is used where very high

power is needed and for boring and engraving. Both

CO2 and Nd/ Nd-YAG lasers can be used for welding.

Plasma cutting is a process that is used to cut steel and

other metals of different thicknesses (or sometimes other

materials) using a plasma torch. In this process, a gas

(oxygen, air, inert and others dependant on material) is

blown at high speed out of a nozzle; at the same time an

electrical arc is formed through that gas from the nozzle to

the surface being cut, turning some of that gas to plasma.

The plasma is hot enough to melt the metal being cut and

moves fast enough to blow molten metal away from the cut.

Thank You for Your Attention