When
to EDM by Geometry?
|
When
|
Why
|
| Very
thin walls |
No
contact, no force, no deformation. |
| Internal
radii equal to or less than 1/32 inch parallel to tool
axis |
Radius
is as small as the spark gap. Generally, tool is
not rotated.
|
| High
ratios of cavity depth to width, for example: slots and
ribs |
No
force means very thin, long electrodes can be used.
|
| Non-round
cavities/openings |
Electrodes
do not have to rotate.
|
| Intermittent
cuts |
Stress
free.
|
| Very
small parts (fits in a 0.25-inch cube) |
Easy
to fixture since no stress or vibration is involved. |
| Recessed
cuts |
Cutting
tools can not reach cutting area or generate desired
shape. |
| Requires
special/unique cutting tools |
Electrodes
often less costly than special cutting tools. Electrode
is easy to machine, unlike carbide. Wire is available
standard. |
| Capable
of high tolerance machining |
Can
EDM conductive material of any hardness. |
| Different
geometry at top and bottom |
Wire
EDM cuts ruled surfaces with a simpler program and machine
than milling. |
| Complex
shapes |
Easier
to program because you are using a tool of constant dimension
instead of a variety of different diameter milling cutters. |
| Requires
multiple component assemblies |
Use
taper or recess or depth: diameter capability to make
it one piece. |
| Angled
cuts |
Ability
to 3-D orbit in space. |
When
to EDM by Material?
|
When
|
Why
|
| Hardness
above Rc 38: hardened steel, Stellite, tungsten carbide |
EDM
vaporizes material rather than cutting it. |
| Toughness:
Inconel, Monel, Hastelloy, Nitralloy, Waspaloy, Nimonic,
Udimet |
EDM
is non-contact, therefore no adhesion of work piece
to tool.
|
| Tends
to leave tough burrs when machined conventionally |
Vaporized
material is flushed away leaving no burr.
|
| Frail/fragile
(can't take stress of machining) |
No
contact, no force.
|
| Expensive
material |
Lower
chip/work piece mass ratio. Slugs from Wire EDM may
be reusable whereas chips from conventional machining
are recyclable at best.
|
| Certain
explosive or flammable materials |
EDM
takes place under water. |
| Materials
with hazardous dust particles |
Particles
are flushed away to the filter. Reduced risk of fumes. |
