Most beginners with little experience in laser welding will often experience a common problem. They cannot help but damage or burn through their protective lenses. It can become incredibly frustrating to damage your protective lenses because they force you to stop working and require you to spend more money to replace them.
Extending the life of your laser welding optics typically requires correct gas flow, air knife settings, torch angles, and daily clean-room habits. Unfortunately, beginners experience protective lens burnout because they don’t understand concepts like air knife setup and laser torch maintenance. Until you understand these concepts, you will have little luck with protective laser welding optics in your fabrication shop.
What Exactly Does the Protective Window Do?
Every handheld laser welder has a protective window, which is a transparent optical component within the head to prevent contamination of the internal lenses. These expensive glass lenses are responsible for shaping and directing the laser beam to focus on one precise location. But if the lenses get dirty, it becomes more difficult to maintain precision in your laser welds.
To prevent this problem from happening, manufacturers design their handheld laser welders with a protective window at the head of the device to block the debris from making contact with the lenses. That way, laser light can shine through while blocking dirt, smoke, and sparks from impacting the lenses.
The Culprit: How Spatter Destroys Your Lenses
When you see flying sparks of liquid metal as you weld, you are seeing spatter in the air. Spatter is the number one destroyer of protective lenses. Even though laser welding doesn’t produce as much spatter as MIG and TIG welding, you must still take precautions anyway. It only takes one droplet of hot liquid metal to land on the protective window for it to become damaged.
At first, a tiny black dot will form on the protective window. Then, as you continue to use the laser welder, the protective window will become increasingly hot until it eventually cracks or shatters inside the device. And even if it doesn’t shatter, the black hot spot on the window can still throw off the laser beam and cause weaker and less precise welds.
The First Line of Defense: Gas Flow and Air Knife Setup
So, what is the best way to stop flying sparks from hitting the protective window? It all comes down to the gas flow and air knife setup.
A handheld laser welder relies on a shielding gas flow to keep air and other environmental gas contaminants away from the molten weld metal to prevent rust. Meanwhile, the shielding gas flow also pushes away harmful fumes, soot, and spatter from the laser welding optics.
In addition, every handheld laser welder comes with a special feature called an air knife. The purpose of the air knife is to blast compressed air across the front of the protective window to blow away heavy sparks and debris from the glass.
However, you have to make sure the air pressure is high enough to blow away the sparks, or else they will damage the lenses. Follow the manufacturer’s recommended air knife setting to blow away incoming debris adequately.
Operator Habits: Why Welding Perfectly Vertical Kills Lenses
You could have perfect air knife settings and still destroy your protective lenses if you don’t hold your handheld laser welder correctly. Beginners make the common mistake of holding their welder straight up in a vertical position, where the head points directly toward the table.
Here is the problem with vertical laser welding. First, it will cause the sparks to travel straight down toward the head of the welder, where the protective lenses reside. Second, if you are welding a clean piece of metal, the laser beam could bounce straight up from the surface back into the welder device, causing it to overheat.
For this reason, you must get in the habit of tilting your wrist at about a 10 to 15-degree angle when using the laser welder. It will ensure the sparks and laser light travel safely away from you and the device.
Environmental Hazards: Dust and Oil in the Shop
Metal fabrication shops are incredibly dirty places. Everything, from the oils from the bandsaws to the dust from the grinders, creates numerous airborne hazards in the environment. That is why it’s imperative to keep the protective cap on the laser welder when you are not using it. Otherwise, debris will accumulate on the protective window and increase the risk of damage to the glass of the lenses.
How to Properly Inspect and Clean Optics without Scratching
Realistically, it is impossible to keep your protective optics clean 100% of the time. There will eventually be a small smudge, fingerprint, or small number of dust particles that make their way to the window.
Daily inspections are the only way to detect these issues. It will require you to inspect the protective lenses under a bright LED light to recognize any minor imperfections. If you notice any smudges or particles on the lenses, you can clean them away with high-purity isopropyl alcohol and optical-grade cleaning swabs.
You only need one drop of alcohol and gentle pressure from the swab to clean the lenses. Do not scrub or use any force, or else you run the risk of scratching the lenses.
A Checklist for Extending Consumable Life
Do you want to maximize the consumable life of your protective window? Here are some tips for extending consumable life:
- Keep the protective cap on the torch when not in use
- Inspect the protective window for dust and debris before turning on the welder
- Conduct regular laser torch maintenance to keep your shop and lenses clean
- Check the regulator to ensure proper shielding gas flow
- Test the air knife to ensure the air flow is active
- Weld at around 10 to 15-degree angles to prevent direct backward spatter
When you make these tasks part of your routine laser torch maintenance, you will extend the life of your protective and internal lenses for a long time. Not only will that save you money in the long run, but you will also be able to produce high-quality welds on a consistent basis.
