White Powder Contamination: Industrial Laser Service Case Study

Take a little Time to Save a lot of Time (and Money) — Industrial Laser Service Case Study

Most people understand that regular, routine laser maintenance saves money over the long haul. The math supports this, just from an industrial laser service perspective. Servicing industrial lasers – inspecting the optics and mirrors, fine-tuning calibrations, and even doing essential training — lets those CO2 Cincinnati lasers keep humming along.

Laser Maintenance Group (LMG) isn’t just about laser maintenance. We understand the costs in time and money that a struggling laser center can cause in the productivity and quality aspects as well. The indirect cost of sending out poor quality parts or even good parts that are consistently late is hard to quantify. We all agree: Poor quality and late delivery is worse than direct maintenance costs.

What many companies don’t remember is that these complex laser centers eventually require rebuilds. While more costly than routine industrial laser service calls, these rebuilds are essential to keeping these CO2 lasers running at peak efficiency.

Industrial laser service case study scenario — Laser System: Cincinnati CL-7A with a 2KW Rofin-Sinar resonator
High-Level Laser Problem: Instability at High Power
Laser Resonator Internal Optics

Several factors can cause instability at high power. Based on LMG’s experience, if your laser has over 12,000 hours since the last rebuild, chances are it’s a ‘White Powder Contamination’ issue. That is, your resonator optics are being coated with tungsten dust. That disrupts the laser in the beam path as it gets circulated through the gas system. Pictured are two affected internal optics (The silver one is a rear mirror. The yellow one is an output coupler).

Laser Geek-Out: Explanation

CO2 laser white powder contamination is an eventual and normal condition for DC-excited lasers. Laser maintenance won’t prevent this; the material science doesn’t yet exist to avoid this issue.

On all CO2 lasers, the tungsten cathode pins oxidize over time. The problem can be accelerated by vacuum leaks and poor quality laser gas. Both factors contribute to the moisture content inside the system. This allows for the oxidation of the pins. This oxidation then gets distributed throughout the system. Some lands on the internal laser optics and mirrors. As the optics are coated with this dust, laser beam quality and power drop off quickly.

Root Cause Problem:

The tungsten oxide (white powder) contamination has a root cause: The resonator is way past the 12,000 hours where a white powder rebuild should be done. As a result, the tungsten oxide dust coats the optics, deforming the beam shape and lowering the laser’s power.

Short-term routine laser center maintenance solution:
Laser service: White powder contamination can be prevented by laser system rebuilds.
Laser Service Guy Kiser tunes a Rofin-Sinar resonator

Because of this problem, the optics need to be changed at every maintenance interval. Mere cleaning won’t help, since it is usually burned in. The crystal structure of the optic is stressed from absorbing too much laser energy rather than passing it through to the beam delivery. After any of the optics are replaced, we at LMG have to realign them to form a symmetrically-shaped laser beam. (In this photo Laser Service Guy Kiser tunes a Rofin-Sinar resonator.)

Only changing the optics creates what we call a performance spike. The laser runs great for a week or maybe even a month and then starts to slowly fall back to where it was. How fast the laser degrades depends on how severe the contamination is.

Long-term preventative industrial laser service solution:

The Rofin-Sinar resonators on these CO2 Cincinnati lasers should have a white powder rebuild after approximately 12,000 hours of operating time. That may be longer or shorter, as the operating condition of the resonator dictates.

Don’t let anyone tell you your laser is old, and it won’t ever make rated power again. Quite frankly, hearing that upsets me. Why? It means that person either doesn’t know about Cincinnati CO2 lasers and Rofin-Sinar resonators, or doesn’t care. If your 2000 watt resonator cannot make and hold at least 2200 watts, your tech should be embarrassed.

How laser service impacts your manufacturing and your business

At LMG, we’ve seen how the laser’s performance affects the entire plant. If a laser is not performing well, the result can wreak havoc with production schedules. When this happens, the quality of the parts you make is in jeopardy. We also know that corporate accountants are going to complain every time any manufacturing division asks for money, whether it’s to fix the roof or fix a laser.

At LMG we work with our customers to help them prepare for this expense. (In fact, right now we are working with customers to see how the Covid-19 stimulus package funds can be used for this type of industrial laser service and production improvement.) We can usually tell in advance that the performance will degrade to the point something needs to be done in order to keep up with production and quality.

Laser failure bottom line and industrial laser service solution:

What happens if your laser operators have to keep slowing down to cut decent parts? The quality folks are angry. The production leads are frustrated. Your laser operators are stressed out from being gunned down from both sides.

Solution? Let LMG take a look at your laser center and get it back to normal. We know how to make things right, from the various laser parts, to the programming, to the operations. You don’t have to live under this type of pressure, with good laser systems that aren’t functioning at their potential. Learn more about LMG’s Industrial Laser Services, then call us! We will work with you to get your laser back up to where it needs to be, and your team back to normal.


Use the Right Fire Extinguisher Around Laser Systems

To avoid laser system and optics contamination, it’s vital to have the right type of fire extinguishers in your factory. AND you should know which extinguishers to use, when, and why.

Did you know that, although CO2 fire extinquishers cost many times more than typical Class D extinguishers, they are well worth the extra cost? In this video, part of Laser Maintenance Group / Innovative Laser & Design’s Laser Safety series, Scott Kiser explains why he is a firm believer in having several CO2 extinguishers in his shop.

Another way to avoid lens contamination is to use the right kind of fire extinguisher around your laser systems.

CONTACT LMG:
To discuss how LMG can help your business, call 423-593-7206 or email lasersolutions@comcast.net

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Scott Kiser

Scott Kiser is the founder, owner and Chief Technology Consultant at LMG (Laser Maintenance Group) and Innovative Laser & Design. He has more than 20 years of experience operating, maintaining and repairing industrial lasers. He started his career as an electrician, rising to the rank of Petty Officer First Class aboard the USS Spadefish nuclear submarine. Scott and his wife Angela co-own LMG and Innovative Laser & Design. Both industrial laser firms are USA Veteran-owned small business (SBA) companies.