By Tim Heston
Brent Donner has some stories to tell when it comes to CO2 laser cutting machine mainte- nance: dirty optics, burned resonator tubes,
clogged filters, gunk on the gaskets over the cutting head—you name it, he’s seen it. No wonder
the machines aren’t cutting like they used to.
Fiber lasers dominate new laser cutting machine
sales, and from a maintenance perspective, there’s
a good reason for that. Fiber lasers aren’t mainte-nance-free. They still have chillers and a cooling
system, and their cover glasses, which protect the
cutting head optics, still need to be cleaned or replaced. But overall the fiber laser has fewer moving
parts than its older CO2 cousin.
That said, tens of thousands of CO2 laser cutting
machines remain in fabrication operations across
the country. Donner’s own shop, New Ulm, Minn.-based DLC Manufacturing & Fabrication, has a CO2
cutting laser that cuts through extraordinarily thick
plate—1.5 in. (that’s not a typo) and even thicker.
The edges emerge clean and smooth, no deburring
Visit the shop and you’ll find machines that don’t
look their age. His secret is a careful though not terribly complicated maintenance regimen. A beam of
light, combined with a column of assist gas, is the
laser’s cutting tool. A dirty cutting tool doesn’t cut
well, and neither does a beam that passes through
debris and dirt (see Figure 1).
This includes dirt in the beam path between the
resonator and workpiece, the bellows (which at
Donner’s shop are purged with gas from a nitrogen
generator, not liquid nitrogen tanks), and in the path
the water takes from the chiller to cool the system.
It really boils down to a simple concept: Keep it
clean, inside and out. “It’s not rocket science,” Donner said. “You just have to pay attention to details.”
Along with DLC Manufacturing & Fabrication, Donner has another business called Donner Laser Consulting for which he has traveled the country to
bring tired lasers back to life, sometimes to conditions better than they were new.
To start, Donner talks to the laser operator about
his lens changing and cleaning regimen. Does he
blow the cutting head cavity out before inserting
it back into the machine? Some machines have a
blow nozzle on the side just for this purpose. If a
blow nozzle isn’t available, an operator can find an
unused port and put one on.
A common rubber bulb (like a baby snot remover)
sometimes does the trick, though this solution isn’t
ideal. The bulb has a small flap in the back to draw
air into it, which isn’t good if you have dirty shop air.
You may end up blowing dirty shop air right into the
top of the lens.
“This is why I use a little filter to ensure no con-
tamination gets into the head from your blower noz-
zle,” Donner said (see Figure 2). “I bring it every
place I go. If they don’t have a blower on their ma-
chine, I find an unused port [for the nitrogen purge]
and create my own blower nozzle.”
Donner next pulls out the cutting head and checks
several gaskets just above the head assembly. Often
these gaskets have never been wiped clean, but
they need to be.
“In all the shops I’ve visited over the years,” Don-
CO2 laser cutting: Keep it clean, save money
ner said, “no one has known that those gaskets
These gaskets can be the source of myriad cutting
problems. An operator may do a stellar job cleaning
the lens, yet he fails to blow the head cavity clean
before reinserting the cutting head. This introduces
dirt into the system and onto those gaskets. When
the head contacts those dirty gaskets, they drop
specks of dirt onto the newly cleaned cutting lens.
The operator locks the cutting head tight, and the
machine turns on the nitrogen purge gas, which in
turn induces that dirt back up into the bellows—not
a good thing if you want to keep your beam-delivery
Good maintenance requires
a detailed eye and a lot of common sense
These optics, each from a different machine brand,
have seen better days.
After cleaning or changing out a lens, Donner uses a
blow gun with a small filter attached to blow out the
cutting head cavity.
Dirt and debris can enter through holes in the machine’s bellows, and the duct tape shown here won’t