Robot Offline Programming and Simulation: Program the Next Job Without Stopping This One
The hidden cost of a robotic welding cell is programming time. Every hour spent teaching points with a pendant is an hour the robot isn't welding. For a shop running small batches and many part numbers, that can wipe out most of the robot's productivity. Offline programming (OLP) moves that work from the shop floor to a PC.
Teach pendant versus offline programming
Teach pendant programming means jogging the robot to every point by hand and recording it. It's direct and needs no extra software, but the robot sits idle the whole time, and complex parts can take a day or more.
Offline programming means building the program in a 3D simulation of the cell. The programmer imports the CAD model of the part, picks the weld seams, sets the torch angles and weld parameters, and lets the software generate the robot path. The program is checked for reach, collisions and axis limits in simulation, then sent to the robot.
Where offline programming saves the most
High-mix, low-volume work. New part numbers can be programmed while the robot is busy on current jobs.
Large or complex parts. Hundreds of welds on a frame or chassis are much faster to define from CAD than to teach point by point.
Multi-axis cells. Coordinating a robot with positioners and tracks is hard by hand and much easier in simulation.
Quoting. Simulated cycle times let you quote robot-welded jobs with confidence before the first part is made.
New cell design. Simulation proves reach, layout and cycle time before any equipment is bought.
What simulation checks before a program runs
Reach. Can the torch get to every weld at the right angle?
Collisions. Does the robot, torch, cable or positioner hit the part, the fixture or itself?
Singularities and axis limits. Will any joint wind up or flip mid-weld?
Cycle time. How long does the whole program take, including positioner moves?
Weld sequence. Is the order of welds sensible for distortion control?
The limits of offline programming
A simulation is only as accurate as the model behind it. Real parts are cut, bent and tacked with tolerances, and fixtures are never exactly where the CAD says. That gap is closed in two ways:
Calibration. The robot's tool centre point and the positions of the fixture and positioner are measured in the real cell and matched to the simulation.
Sensing. Touch sensing or laser seam finding locates each joint on the real part and shifts the program to suit. See our post on arc weld seam tracking for how this works.
With both in place, offline programs typically need only light touch-up on the first part, rather than a full re-teach.
Getting started
OLP pays off fastest when you have accurate CAD models for your parts, a repeatable fixture for each part family, and someone in-house who understands welding as well as software. It doesn't need to be a full-time role; many shops have a welder or supervisor run the OLP station a few hours a week.
How DPAC helps
DPAC Robotics & Automation uses simulation from the first concept of every robotic welding and palletising cell we design. We prove reach, layout and cycle time before build, and we can set up an offline programming workflow for your existing cell, including post-processing, cell calibration and training for your team.
Spending too long teaching the robot? Talk to us about bringing programming off the floor and onto a PC
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