Manufacturing Knowledge Menu
EDM
Manufacturing Services | EDM Manufacturing Equipment
V W Broaching Service V W Broaching Service has provided precision Wire EDM services for the smallest shops to the largest of corporations, V W Broaching has worked on parts for every imaginable industry - biomedical, automotive, home appliances, hand tools, government, consumer goods. www.vwbroaching.com |
|
Electrical Discharge Machining, EDM is one of the
most accurate manufacturing processes available for creating
complex or simple shapes and geometries within parts and
assemblies. EDM works by eroding
material in the path of electrical discharges that form an arc
between an electrode tool and the work piece. EDM
manufacturing is quite affordable and a very desirable
manufacturing process when low counts or high accuracy is
required. Turn around time can be fast and depends on
manufacturer back log.
The EDM system consists of a
shaped tool or wire electrode, and the part. The part is connected
to a power supply. Sometimes to create a potential difference between the
work piece and tool, the work piece is immersed in a dielectric
(electrically nonconducting) fluid which is circulated to flush
away debris.
The cutting pattern is usually
CNC controlled. Many EDM machine electrodes can rotate
about two-three axis allowing for cutting of internal cavities.
This makes EDM a highly capable manufacturing process.
EDM comes in two basic types:
wire and probe (die sinker). Wire EDM is used primarily for shapes
cut shapes through a selected part or assembly. With a wire EDM machine, if a
cutout needs to be created, an initial hole must first be drilled
in the material, then the wire can be fed through the hole to
complete the machining. Sinker (diesinking) EDMs are generally used
for complex geometries where the EDM machine uses a machined
graphite or copper electrode to erode the desired shape into
the part or assembly. Sinker EDM can
cut a hole into the part without having a hole pre-drilled for
the electrode.
Design Considerations
- Relax the surface-finish for
the part, if feasible. This allows the manufacturer to produce
the part with fewer passes, at a higher current level and a
higher metal-removal rate.
- Design or prepare the part such that the
amount of stock removed by EDM is relatively small. Use
traditional machining techniques to remove the bulk of the
stock with the finishing operations performed by EDM. This
significantly reduces the amount of time and cost for each
part.
- The EDM manufacturer should
consider fixtures such that several parts can be stacked and
machined simultaneously or a single part can have several EDM
operations performed simultaneously.
- When existing holes are to be
enlarged or reshaped by EDM, through holes are preferred to
blind holes as they permit easier flow of dielectric fluid past
the area being machined
Dimensional Accuracy (+/- 0.0005
inches per inch)
Feature Profile accuracy of .0003 is
obtainable with cutting path
Features to feature true position of .002 is reasonable and down
to .001 is possible when geometry requires removal and
reattachment of wire.
Surface Finish (microinches)
Features created by EDM have an "orange peal" appearance.
16
Ra is achievable, 64 or higher Ra is typical and less expensive.
Wall Thickness
Min Wall
Thickness (inches): 0.01 (over a 5" inch span)
As always, consult
with EDM vendor for specific capabilities.
Back to Top
© Copyright 2000 - 2008, by Engineers Edge, All rights reserved. Disclaimer |
