Wire EDM Machine Operation Chapter 8
Copyright November, 98 Page 8-2 Sodick Inc.
Maximum Taper Angle
The maximum taper angle per side can be calculated for a particular workpiece thickness.
To determine the maximum taper angle that can be cut at a given thickness, use the
following calculation (angle must never exceed 30°).
Max Angle = TAN
–1
[U axis travel per side / [part thickness + .800]]
The models A320D or A530D have .980” of U axis travel per side.
The models AP350 or AP500 have 1.380” of U axis travel per side.
Do you want to cut the die with the top of the die up or down? For most applications,
it is best to cut the die with the top of the die up. It makes it easier to measure the size of
the die while it is still on the table of the machine. However, you must also be concerned
with getting the slug out after the first roughing pass! If the wire diameter is very small,
and the taper angle is very large, it may be impossible (for large dies) to remove the slug
from the top after the first roughing passes. If you multiply the tangent of the taper angle
times thickness of the part you are machining, you can easily tell if the slug can be
machined from the top of the die. If the value you calculate is SMALLER than the wire
diameter you are using, you will be able to remove the slug from the top. If not, you
might want to turn the die over and machine with the top of the die face down on the
table top (for large dies), rather than face the necessity of moving X and/or Y to remove it
from the bottom. Note: removing it from the top would be mandatory if the die filled the
work area.
Now that you know some of the considerations to be concerned with, lets look at some
recommended methods of machining dies with taper.
TAPERING TO THE TOP OF THE DIE (NO DIE LAND)
This is the easiest way to machine a die. With this method, you only need one program
that will rough and finish the entire die. When programming, you specify the taper
direction (left or right) and the taper angle correctly. Of course, you must also give
consideration to your offsets, based on whether the punch or the die requires the
clearance (to allow the punch to fit properly into the die).
MACHINING A DIE WITH A LAND
There is a question as to whether it is smarter to machine the die land first and then the
taper angle, or whether it is smarter to machine the taper angle first and then the land.
Much of this is based on personal preference. Depending on the taper angle and thickness
of the die land, we recommend that you run the taper angle first and then machine the
land. However, this may not be possible if the taper angle or die land thickness is too
large.
We recommend this because the total cycle time to machine the die would be
dramatically reduced with this method. If you machine the die land first, the entire shape
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