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Arc-On Time: The Number That Explains Most Cobot Welding Payback
ArmMate
Ask a shop owner how much welding gets done in a day and you usually get an answer in parts. Ask how many minutes the arc was actually lit and the room goes quiet.
That second number, arc-on time, explains most of what a welding cobot does for a shop. It is also the easiest one to measure before you spend anything.
What operator factor means
Operator factor is the share of a shift the arc is actually on. Everything else, fitting, tacking, flipping parts, chipping, grinding, walking for wire, hood up to look, waiting on a crane, is arc off.
The AWS Welding Digest puts the industry standard average operator factor at roughly 10 to 12 percent, with the highest at 20 percent. For a 10 hour day, that is about 60 minutes of arc-on time (AWS Welding Digest, weld setting optimization for collaborative robots).
That is not a knock on welders. It is the nature of manual welding. A skilled person spends most of the day getting the part ready to weld.
Where a cobot changes the math
A cobot does not make your welder faster at fit-up. It changes two things.
The arc runs while the person does something else. Once the cobot is welding, the operator is free to load, unload, inspect or prep the next part. The arc no longer waits on the person, and the person no longer stands at the arc.
Travel speed holds. In the same AWS article, a welding technology supervisor puts manual travel speed at 12 to 20 inches per minute at best, and says a cobot can consistently run at three to four times that speed. Your number will depend on the joint, the process and the procedure, but the direction is clear. A steady torch at a steady speed and distance makes a repeatable bead.
The two station layout
The simplest way to raise operator factor is to give the cobot two places to weld.
- Station A is welding.
- Station B is being unloaded and reloaded by the operator.
- When A finishes, the cobot moves to B. The operator unloads A.
A case study published by the International Federation of Robotics describes exactly this rhythm in a high mix fab shop: operators run one robot, hit start, and load the other while the first one runs, then go back and forth. Two operators typically run two cells each (IFR case study).
The design rule is simple. Loading time on one station should be shorter than weld time on the other. If it is not, the arc waits again and the layout needs another look: a faster clamp, a better fixture, or a split of the weld program.
Program once, run all shift
A taught cobot program makes the same weld on part one and part one hundred. That consistency feeds back into arc-on time: less rework, less grinding of overwelds, fewer parts going back to the bench. AWS also notes that overwelding wastes shielding gas, and that a cobot's consistent control keeps gas use to what each weld needs.
Measure your own operator factor
Before you talk to anyone about automation, measure your baseline for a week.
- Pick one repeat part that a single welder runs.
- Note start and stop time for each part, or use the arc time readout if your power source has one.
- Add up arc-on minutes for the shift.
- Divide by the shift length.
Now you have a real number for that job. Multiply it out. If a cobot cell lets the same welder keep one station lit while loading the other, what does that do to parts per shift?
You do not need our numbers. You need yours.
What a cobot does not fix
- Fit-up problems from cutting or forming. The cobot will weld the gap it was taught.
- A part that needs constant repositioning by hand.
- Jobs that run once and never come back.
Those are worth fixing first. A cobot pays off on the jobs that repeat.
How we scope it
We start with your arc-on number, your parts and your floor space. Welding stations are part of our industrial cobot work, and how it works shows the steps from first visit to a running cell. We work with shops across Orange County.
FAQ
What is a normal operator factor for manual welding?
AWS cites roughly 10 to 12 percent as the industry average, with 20 percent at the high end.
Does a cobot replace the welder?
No. The welder teaches the program, sets the procedure, loads parts and checks quality. The cobot holds the torch for the repeat welds.
How many stations should a first cell have?
Two is a good starting point when loading takes a meaningful share of the weld time.
Book a free site assessment
Measure one job for a week and bring the number. We will walk your floor and tell you honestly whether a cobot changes it. Book a free site assessment at armmate.com/contact, email hello@armmate.com, or call (949) 441-4828. ArmMate, 15642 Sand Canyon Ave #51176, Irvine, CA 92619. https://armmate.com