Using Robotics to Go From CAD to Path
Robots are typically programmed to replay paths taught using
point-to-point methods. Traditional CNC processing is done by off-line
processing. Both methods have their advantages, however robots have
proven to be more cost effective in terms of flexibility, repeatability,
and with new functions offer improved accuracy. To maximize these
robotic advantages, we need tools that transform an off-line CAD model
into a robot program. These tools have been developed to maximize
uptime, throughput, and workcell utilization. Workcell utilization
efficiencies have many benefits — especially that you aren't
spending additional capital, wasting workcell uptime, or damaging
expensive equipment in order to create process paths all while capitalizing
on the efficient off-line environment used in traditional CNC processing.
State of the art robotic technology is used to produce small
part runs and quick product changes to achieve production flexibility.
Used in various applications, industrial robotics have proven cost
effective, and efficient in order to handle the most complex job ~
especially in materials joining and cutting applications. Where traditional
CNC equipment was accurate, industrial robots provide for increased
accuracy especially considering automatic calibration techniques used
in conjunction with off-line programming. Their flexible design allows
for simple product changeovers and short runs as well as utilizing
the benefits of multi-arm systems when necessary.
Robot to CNC Comparison
||FANUC Robotics Intelligent Robot
||Fixed equipment, linear with some rotary capabilities, but limited
to specific process such as cutting, milling, etc.
||Articulate, flexible 6 degrees of freedom; ideal
for continuous path processes with complete tool orientation control and part
||Articulate, flexible 6
degrees of freedom; ideal for continuous path processes with complete tool
orientation control and part accessibility. Flexible to accommodate product/tool
||Inherently accurate but with high cost and specific process design.
||Flexible design, high value, limited accuracy and off-line performance.
||Flexible design, high value, highly accurate,
efficient off-line performance; Incorporates benefits of CNC through automatic
calibration and off-line programming.
||Off-line with no touch-up through intelligent
||CMM setup and tool shift
||Teach TCP value manually; difficult to maintain.
||Inherent software tools used to setup and maintain
||Limited to specific process (cutting, milling, etc.)
||Flexible, requires setting and scaling application process and point
to point teaching of path. Flexibility through experienced operator only.
||Flexible, automatic setting and scaling application
process data and automatic point to point teaching of path. Flexibility with
||Specific design for singular process.
||Flexible design but requires application and program development.
||Flexible, multi process with many advantages
||Medium, requires tool changer, pallets, etc.
||Low system utilization. Requires program touchup and maintenance. Equipment
must be individually scaled and settings are not repeatable.
||High system utilization. Multi-Arm robot system
capabilities. Off-line programming and transfer to the accurate real robot
which offers maximum cell utilization. Software options offer unattended program
Off-line program creation offers maximum cell up-time when the
mathematical model of the cell is similar to the actual cell. If you
use good setup principals to set up the off-line robot system, the
workcell will prove accurate which saves time and money. Programs
can be generated either off-line or manually. PC file services can
be used to transfer weld parameters, TPP, subroutines, etc., perform
scheduled backups, and compare files. Data management is accomplished
efficiently. The same principals apply to cell cloning and part program
Some things to consider during cell design:
Robot and work cell layout
Robot EOAT (Weld Torch)
Weld Power supply setting
Standardized cell and tooling I/O
Off-line data management
PC off-line programming tools can be used with the inherently
accurate virtual robot controller. Tools are available that will simplify
program creation, accurately set work and travel angles, optimize
weld points, provide automatic coordinated motion, incorporate feature
creation that links weld paths to part geometry, and includes job
creation which links features to make a complete weld program.
Cell I/O mapping
Quick Change tooling — Designs can incorporate
quick change and increased flexibility must consider tooling mount,
other utilities such as Pneumatic, Electrical, and Signal; automatic
tool identification, and Integral crane or hoist
Virtual model Calibration jig
Common main line program
Common welding jobs
Common maintenance programs
Calibrate Your System
System calibration is critical for workcell creation, tool cloning
and off-line programming. Standard calibration functions require no
special PC software or high accuracy machined fixtures. Automatic
Calibration software programs can be used to set up the tool center
point (TCP), calibrate the robot, positioners, calibrate the robot
to positioner or locator, calibrate the robot to fixture tool, and
calibrate to the Weld Power Source. Calibration can also be performed
at the cell level when you have multiple fixtures in the same cell,
when fixtures change while in production, multiple “identical”
cells, are transitioning from integration to production sites, or
if the cell was programmed off-line.
Easy Fixture Changes in Production
After your program is created, you can use program transfer
tools to transfer the program to other robots without touchup.
From Multi-Station Tables to Easy Path Transfer
Powerful software tools can be used to transfer
and touch up programs automatically in workcells where you have multiple
fixtures in the same cell, multiple “identical” cells
(“cloning”), and fixures changing in production. Effective
ROBOGUIDE tools also exist to transition programs from integration
to production sites, and when off-line teaching is required.
ROBOGUIDE Import and Export
A welding program and system can be easily set up using 3-D
CAD model of parts. A welding path can be specified by clicking the
line on the CAD model. It is generated with the designation of torch
angle, travel angle by an operator. Create the welding path by defining
the coordinate in the center of the section of each welding portion.
The welding program is generated after verifying the robot stroke
limits and the interference between robots and work pieces.
Off-line Program Layout to Actual Cell Layout
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