Electrical Discharge Machining (EDM) is a process that uses electrical discharges emitted from an electrode to erode an electrically conductive material. As a result, it is possible to erode or “burn” the reverse shape of the electrode into the workpiece.
Author(s): Ben Fleming
Publisher: Fleming
Year: 2011
Language: English
City: Fayetteville
Tags: EDM, Pulse, machining, electrical discharge machining
Table of Contents
Chapter 1
Introduction 1-1
I am in a Quandary 1-1
What do you Want in an EDM 1-2
It is More than a Power Supply 1-2
Some Inspiration 1-3
Chapter 2
A Little EDM History 2-1
Chapter 3
Overview of Mechanical & Electrical Components 3-1
Mechanical 3-1 Electrical 3-2
Chapter 4
The Power Supply 4-1
The Power Circuit 4-2
The Timer 4-2
Control and Motor Driver Circuit 4-3
How Does a Window Comparator Work? 4-4
Conditions at Startup 4-4
Short-Circuit Condition 4-4
What to Do When the Current Stops Flowing 4-5
The Peak Detector 4-5
Manual Up/Down and Dither Circuit 4-6
Chapter 5
Building the Power Supply 5-1
Soldering Tips 5-1
Construction Notes 5-2
Power-Supply Housing 5-3
Case Stiffeners 5-4
Front Panel & Power-Supply Layout 5-6
Power-Supply Layout 5-5
Major Components and Mounting 5-6
Wiring the High-Voltage Section 5-7
Power-Resistor Sizing and Mounting 5-8
Finish High-Voltage Wiring 5-11
PCB Location & Heat Sink Selection 5-12
Wiring the PCB 5-12
VII
EDS Issues 5-12 PCB-to-Panel Connections 5-13
Chapter 6
The Servo 6-1
DC Gear Motor vs. Stepper 6-2
Servo Motor Selection for the Ram 6-2
The Lead Screw 6-3
Removing Shaft Endplay 6-3
Attaching the Lead Screw to the Gearmotor Shaft 6-3
Pin Method 6-3
Glue Method 6-4
The Slide 6-5
Slide Assembly 6-6
Final Slide Adjustment 6-6
Mounting Arm 6-7
Mounting Stud 6-7
Construction of the Head Bracket 6-8
Front Cover 6-10
The Finished Head 6-10
Head Wiring Options 6-11
Wiring the Head to the Power Supply 6-11
ON/OFF Motor Control 6-12
ON, OFF and UP limit Switch 6-12
ON, OFF, UP and DOWN Limit Switch 6-12
ON, OFF, UP, DOWN Limit and Depth-Control Switch 6-13
Chapter 7
Indexing 7-1
Indexer Chuck Overview 7-2
Indexer Chuck with no Metal Insert 7-2
Metal-Inserted Indexer Chuck 7-4
The Metal Insert 7-4
Misc. Indexer Chuck Photos 7-5
Electrode Manufacturing Fixture Block 7-6
Electrode Holders 7-7
The Squaring Tool 7-8
VIII
Chapter 8
Depth Control 8-1
Chapter 9
Finish the Job 9-1
Building a Dedicated, or Add-on, EDM 9-1
Overview of the Work Tank and XY Movement 9-1
The Sherline Conversion 9-2
XY Tables and Selection 9-2
Chapter 10
Dielectric & Filter Selection 10-1
How Flammable is the Dielectric? 10-2
Dielectric & Materials Compatibility 10-2
Filters 10-3
Automotive Spin-on Filters 10-3
Automotive Filter Mounts/Filters 10-4
Diesel Filters 10-4
Water Filters 10-4
Filter Bags/Prefilter 10-4
5-Gallon Bucket Bags 10-5
Chapter 11
Tank & Pump Selection 11-1
Other Storage/Work Tank Options 11-1
Pump Selection 11-3
The Pump Dilemma 11-4
Submergible Pump 11-4
Non-submergible Pump Options 11-5
Chapter 12
The Back Slide 12-1
Frame Work Overview 12-2
Back Slide Rail 12-2
CRS WAYS 12-3
Tubular Frame Option 12-3
Wood Deck Option 12-4
Final Assembly of the Slide and WAYS 12-6
IX
Chapter 13
Tank Assembly 13-1
Work Tank Support and Mounting Feet 13-1
Work Plate 13-2
Plumbing the Tanks 13-3
Dielectric Flow Control 13-5
Other Valve Options 13-6
Flexible Flushing Line 13-6
Variable-Speed Motor 13-7
Work Tank Dielectric Level Control 13-7
Pre-filter (Bag Filter) 13-7
Chapter 14
The Spark 14-1
What Happens in the Gap? 14-1
Duty Cycle 14-3
Frequency of the Spark 14-4
Metal Removal Rates 14-4
DC Arcing 14-5
Chapter 15
Electrodes 15-1
Factors Contributing to Reduced Electrode Wear 15-1
Electrode Polarity 15-2
Volumetric Wear 15-3
End Wear 15-3
Corner Wear 15-3
Electrode Wear Test 15-3
Overcut 15-4
Recast Layer 15-4
Electrode Materials 15-5
Metallic Electrodes in General 15-5
Brass 15-5
Copper 15-6
Copper/Silver Tungsten 15-6
Graphite Electrodes 15-7
Copper Graphite 15-8
Graphite Machining Tips 15-8
Suppliers of EDM Graphite 15-9
X
Chapter 16
Flushing 16-1
EDM Flush Fittings 16-1
Jet Flushing 16-2
Through-electrode Pressure Flushing 16-2
Sealed Flush 16-3
Pot Flushing 16-3
Suction Flushing 16-4
Trepanning 16-4
Chapter 17
Your First Burn 17-1
Chapter 18
Jewelry Manufacturing and EDM Tips 18-1
Using Tokens and Coins as an Electrode 18-1
Using a Copper Earring as an Electrode 18-2
Pressed Arbor 18-3
Glued Arbor 18-3
Glued-together Electrodes 18-3
Upside Down and Sideways 18-3
Carbide Insert Tool Holder 18-3
Multiple Electrode Burns 18-4
Broken Screw and Bolt Removal Techniques 18-4
Chapter 19
Glossary 19-1
Chapter 20
Reference Materials 20-1
Parts List 21-1
Electronic 21-1
Non-Electronic 21-3
