High Speed Machining Precision Tooling - Indobiz.biz

Figure 1. The transform part
zero software feature was
designed to minimize steps.
Figure 2. Workpiece surface contact point + tool vector
EXAMPLE: G01 X10.Y10.Z10. I0.5J0.5K0.707106
would be equivalent to: G01 X10.Y10.Z10.B45.C45
Benefits of Tool
Vector Input feature:
• Program is machine
independent
• Control software computes
machine angles and
positions
• Simplifi es post-processor
1.
2.
3.
4.
Create a Rotary Position
data block
Set the Transform Part
Zero fi eld to YES
Insert a Transform Plane
Reference Point data
block
Specify the distance to
shift the part zero relative
to the original setup
Redundancy in Posting a Five-Axis
Program
Each time you refi xture, you have to waste
valuable time re-entering the distance
from part zero to the center lines of
rotation and then repost the program. If
your control has a software feature such
as tool center point management, you
only have to post the program once and
machine the part—no matter where it is
in relation to the center lines of rotation
on the machine.
Tool center point management solves
the problem for CAM software. The CAM
programmer generates the toolpath
based on the part model’s zero location.
Therefore, you can post the program
independent of where the stock is
fi xtured on the table—a substantial time
saver for a fi ve-axis part.
Complex and Diffi cult Post Processors
CAM systems generally use tool vectors
to generate the toolpath. To make
programs independent of the machine’s
rotary confi guration and to simplify the
post processor, there is a tool vector
input control software feature for fi veaxis
machining centers (see Figure 2).
This feature lets you specify the tool tip
location relative to the workpiece and
the tool axis vector instead of using
address letters to specify the B and C
axes angles. Executing the program is
much faster because the post doesn’t
need the machine confi guration and the
centerline of the rotary axes.
Marks on the Part
Simultaneous fi ve-axis toolpaths can
result in odd looping rotary moves
that leave marks on the part when the
program is interpolated by the machine’s
control. One solution is a feature called
toolpath linearization, which is specifi c to
fi ve-axis, G-code programs. It eliminates
the many line segments in the form of
XYZBC moves that a CAM system uses
to create a smooth part.
With toolpath linearization, the tool tip
and tool vector can be interpolated
between tool positions with respect to
the workpiece even with the tool and
Fig 3ab – with toolpath linearization, the tool tip and tool
vector can be interpolated between tool positions with
respect to the workpiece even with the tool and part
rotating inside the machine
part rotating inside the machine (see
Figures 3ab).
Reposting to Adjust for Tool Wear on
3-D Surfaces
For 3-D surfaces, you cut off of the tool
centerline to get a better surface fi nish.
Because you have to adjust the tool
diameter for wear, you are sometimes
forced to repost the program. A software
feature called 3-D tool compensation
eliminates the need to repost the part
program because the control’s software
compensates for the tool geometry (see
Figure 4 for visual explanation).
Summary
In this competitive environment with
skilled labor shortages and demanding
schedules for complex parts, investing
in machine tools with the latest
technology is the most effi cient way to
see measurable productivity gains.
Figure 4. Workpiece surface contact point + contact point
surface normal + tool vector
EXAMPLE: M128 3D Tool Geometry Compensation
G41.2D_ R_G00 X0.Y0.Z0. U0.V0.W1. I0.J0.K1.
G01 X10.Y10.Z10. U0.V0.W1. I0.5J0.5K0.707106 F1000
XYZ = Surface contact point
UVW = Surface normal at contact point
IJK = Tool vector
3-D tool geometry compensation.
indometalworking news Vol. 2 / 2008 27