Wire EDM Machine Operation Chapter 1
Copyright November, 98 Page 1-3 Sodick Inc.
FLUSHING
This is the flow of water that surrounds the wire during the EDM process. The same
flushing nozzles are mounted (one around the upper wire guide and the other around the
lower wire guide) on machines without AWT. If you have an AWT, the upper flushing
nozzle screws onto the upper head. Set the upper flushing nozzle between .005 to .010
inch above the top of the part. The lower flushing nozzle fits onto the lower head and
slides up to about .005" inch below the table automatically when the flushing is turned
on. This is considered to be perfect flushing conditions. The standard flush nozzle is 6mm
I.D. and can be used to a maximum taper angle of 12°. The 10mm nozzle is for taper
angles up to 20°, and the 12mm nozzle is for larger angles.
Flushing is one of the most important factors that contribute to the EDM process. This is
because the small particles created by the EDM process MUST be removed from the
work area, otherwise double burning of these particles will occur and the insulation
properties of the dielectric are eliminated resulting in unstable cutting. Submerge
machining improves the efficiency of the flushing and creates thermal stability and makes
for a cleaner atmosphere for the operator. You will find that the better the flushing, the
faster and more stable the EDM process will occur and wire breakage will decrease.
During rough cutting, you usually want high flushing pressure (T84 code) to remove the
particles. During skim cuts, you want low flushing pressure (T85 code) to avoid having
the pressure of the flushing deflect the wire. NOTE: If the machine is a non AWT, the
flushing may remain on when the control stops at an M00 or M01.
When you enter the cut from the edge of a workpiece or when machining close to an
internal shape, a portion of flushing is being dispersed by the wall of the part itself. When
the wire is not surrounded on both sides of the wire by about .25" of material the flushing
is not perfect and the cut may become unstable and the power may have to be reduced.
Flushing mode can be programmed as part of the NC program (T84 high or T85 low) and
the operator can take control of the flushing flow by adjusting the two flow valves near
the front of the machine or the low and high flush potentiometers below the resistivity
meter.
WIRE SPEED
Wire speed is the rate at which the wire passes through the workpiece and is controlled
by the speed of the pinch rollers above the wire disposal bin. You should use a faster wire
speed for roughing and a slower wire speed for finishing. When roughing, the wire will
usually be under a great deal of power and stress as we try to melt the material away as
quickly as possible. This also results in pitting on the wire and reduction of the wire
diameter you can reduce wire breakage by increasing the wire speed.
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