Metal Cutting

Intro to EDM 100

This class introduces the process, components and machines of electric discharge machining.

  • Difficulty Beginner

  • Format Online

  • Number of Lessons 16

  • Language English


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Course Outline
  • Objectives
  • What Is EDM?
  • Metal Cutting vs. EDM
  • Advantages of EDM
  • Disadvantages of EDM
  • Steps of the EDM Process
  • How EDM Cuts Metal
  • EDM Components
  • Sinker EDMs
  • Wire EDMs
  • Types of Electrode Materials
  • Types of Dielectric Fluids
  • Flushing Methods
  • EDM Applications
  • Advances in EDM
  • Summary
  • Define EDM.
  • Distinguish between traditional metal cutting and EDM.
  • Describe the advantages of EDM.
  • Describe the disadvantages of EDM.
  • Identidy the steps of the EDM process.
  • Describe EDM metal removal.
  • Identify the components of an EDM machine.
  • Describe a sinker EDM.
  • Describe a wire EDM.
  • Identify the correct electrode material for different EDM processes.
  • Describe the function of dielectric fluids.
  • Describe the importance of dielectric fluid flushing.
  • List common EDM applications.
  • Describe advances in EDM technology.
Vocabulary Term


A machine with a long, continuous cutting blade with serrated teeth that is looped around two or more wheels. The wheels continuously spin the blade during operation.


An alloy of copper and zinc. Brass offers a balance of electrical and thermal conductivity and strength. Most EDM wire is made of brass.


A rough edge remaining on material, such as metal, after it has been machined. EDM processes do not leave burrs on the part edges.


A device that stores an electric charge. EDMs require capacitors to generate the electric current used for machining.


A common cutting tool material used to make both indexable inserts and solid cutting tools. Carbide is very hard and difficult to machine by traditional methods.


A manufacturing process that pours a liquid material into a hollow mold until the material cools into a solidified shape.


A hard, brittle material consisting of compounds formed by metallic and nonmetallic elements. Most ceramics do not conduct electricity.


An unwanted piece of metal that is removed from a workpiece. Traditional machining methods form chips when a tool physically cuts metal.


The rigid, vertical support section of the machine that suspends components and tools over the workpiece.

computer numerical control

The use of computers, programs, and precise motors to automatically control tool movement and carry out sequences of machining operations.


A reddish metal that is very ductile, thermally and electrically conductive, and corrosive resistant. Copper is a common material for EDM electrodes.

deionized water

Water that does not contain any dissolved solids. Deionized water is used as a dielectric fluid for wire EDM machines.

die set

An assembly of two hard, wear-resistant metal plates with matching patterns that are used to shape and form metal parts. Die sets open and close during operation.

dielectric fluid

A fluid that does not conduct an electric current under normal circumstances. For EDM, the dielectric fluid insulates and cools the electrode and workpiece, conveys the spark, and flushes away the removed metal.

electrical discharge machining

A widely used nontraditional machining process that removes metal through the repeated sparking of an electrical current. During machining, the workpiece and an electrode are immersed in a dielectric fluid.

electrically conductive

Able to effectively convey an electric current with low resistance.


A device used to convey an electric current, which can either leave or enter the electrode. EDM machines generate an electric spark between an electrode and the workpiece.

finishing operation

A machining operation used to improve surface finish and bring the part to its final size.


A manufacturing process that forms parts by shearing, stretching, bending, or compressing metal. Forming processes do not create chips.

gap contamination

The presence of unwanted particles between the electrode and workpiece that can disrupt the machining process and damage the part or tool components.


A black, soft form of carbon that conducts electricity and is easily machined. Graphite is the most common EDM electrode material due to its excellent wear resistance during machining.


The use of an abrasive to wear away material from the surface of a workpiece. Most grinding is performed with abrasive wheels.


The ability of a material to resist penetration and scratching.


A type of mineral oil used as a dielectric fluid for EDM machines.


The overall direction of the pattern created by the production process. EDM processes do not create a lay on the workpiece surface.

melting point

The temperature necessary to change a solid to a liquid.


The shorter term for micrometer, which is 0.000001 meter, or approximately 0.000039 inch.

mineral oil

A type of oil manufactured from petroleum and natural minerals. Mineral oil is used as a dielectric fluid for sinker EDMs.

nontraditional machining

The use of a variety of chemical, thermal, and electrical processes to machine metal workpieces. EDM is a nontraditional machining process.

no-wear EDM

An EDM machining process that reverses the direction of current to reduce tool wear. No-wear EDM requires copper electrodes.

off time

The period during an EDM cycle when no spark exists between the electrode and workpiece. Metal is cooled and flushed away during the off time.

on time

The period during an EDM cycle when an electrical spark exists between the electrode and workpiece. Metal is melted and vaporized during the on time.


The difference between the size of the electrode and the size of the cavity created during machining.

recast layer

The surface layer created by an EDM process that is composed of redeposited bits of metal. The recast layer is very thin, and it can be removed by finishing operations.

sinker EDM

A type of EDM machine with a column that suspends an electrode over the workpiece. Sinker EDMs can use electrodes with a variety of shapes, and they are commonly used to machine internal holes and recesses.

spark gap

The smallest space that exists between the electrode and workpiece where the spark occurs.

stainless steel

A type of steel that contains more than 15% chromium and exhibits excellent corrosion resistance.


A metal consisting of iron and up to 2.11% carbon, usually with small amounts of trace elements. Steel is sold in various grades, and it is the most common metal in manufacturing.

synthetic fluid

A fluid that is artificially manufactured by combining a variety of different substances.


An angled, gradually narrowing feature on a part.

tool steel

A specialized type of alloy steel that exhibits excellent strength, toughness, and wear resistance. Tool steels are used in cutting tools, punches, and other industrial tooling.


A gray metal that is very strong at elevated temperatures and is a key alloy for many cutting tools. Tungsten is relatively expensive.


To transform a material into a gas through the application of heat.

vertical milling machine

A basic type of milling machine whose spindle is mounted in a column perpendicular to the floor, and whose worktable rests on an adjustable knee.

wear resistance

The ability of a material to resist the gradual wearing away caused by abrasion and friction.

wire EDM

A type of EDM machine with a thin electrode wire that is spun between two reels during machining. These machines are commonly used to machine contours, sharp corners, and tapers either internally or externally.


The machine component that supports the workpiece and any workholding devices during machining.


A bluish white metal that is corrosive resistant and has a relatively low melting point. Zinc is occasionally used as a coating for EDM wire.