Do you feel that your laser cutter's power is decreasing? Perhaps it's not cutting as deeply anymore, or a smoky edge appears along your cut. In this case, it's very possible that your laser's lens needs cleaning. You can do this yourself, with your user manual and our tutorial.
Why is a clean lens important?
We've just given the first reason why a clean lens is important for laser cutters. Your laser cutter's power decreases if the lens is dirty. And that affects its performance. So, for the best results, a clean lens is important.
Another reason to regularly check and possibly clean the lens is that it can get warm when it's dirty. If the lens gets too hot, it can break due to heat stress.
Dirt on the lens affects your laser cutter's performance. Scratches also lead to reduced performance and heat stress. If you see scratches on your lens, replacement is the next step. This is difficult to prevent, but with regular maintenance, you can keep the lens in good condition longer.
Your laser cutter will simply last longer if you maintain it well. Every laser cutter requires a certain level of maintenance to perform optimally. Cleaning the lens is an integral part of that.
How does your laser cutter's lens get dirty?
Dust particles land on the lens during laser cutting, and you cannot prevent this. Some laser cutters have so-called windows that protect the lens and laser from contamination. These windows reduce a bit of laser power, and when they get dirty, they reduce even more. Windows are cheaper to replace than a full lens. For laser cutters where optimal power isn't strictly necessary, these are ideal aids for protecting the lens from dirt. The windows themselves must, of course, be cleaned for best performance.
How do you clean your laser cutter's lens?
Every laser cutter is different. For example, cleaning a diode lens (see below) is different from cleaning a CO₂ laser cutter's lens. We always recommend reading your laser cutter's user manual thoroughly first. It should also state how to remove the lens from the machine.
The following step-by-step plan tells you how to clean a ZnSe (zinc selenide) lens from a CO₂ laser.
1. Preparation: what do you need?
Before you remove the lens from the machine, prepare the area where you will clean the lens. Make sure you have a table with enough space.
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Place a lens tissue or paper without ink on the table to create a soft surface and prevent damaging the lens when you lay it down.
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For cleaning, you will need compressed air, cleaning wipes, acetone or alcohol, and cotton swabs.
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Finally, grab a pair of latex or nitrile gloves. It's important that these do not contain powder or oil. These protect your fingers from the toxic zinc selenide of the lens and protect the coatings and lens itself from scratches.
All the necessary supplies for cleaning a lens are included in the Laser Lens Cleaning Kit.
2. Clean the lens with compressed air
Remove the lens holder from your laser cutter, sit down at your table, and remove the lens itself. The lens looks like a round disk of yellowish glass with one flat and one convex side. Only touch the lens by its sides and never on the flat surfaces.
We recommend first blowing the lens clean with compressed air. Do not use your breath, as you will blow moisture particles over the lens and make it even dirtier. You remove the initial dust with compressed air.
The flat side is likely the dirtiest, as it faces downwards in your laser cutter and thus collects all dust particles. Make sure you don't blow too hard and clean both sides of the lens. Also, immediately check the lens for scratches.
Because not every workshop has a compressor, the Lasersheets Cleaning Kit includes a blower bulb. This also provides clean air for blowing away dust particles on a lens.
3. Cleaning with alcohol
Place the lens flat on the table, lay a wipe over it, and put a few drops of alcohol or acetone on it. Then gently drag the wipe across the lens. This is a better technique than first dripping alcohol or acetone onto the wipe or lens and then wiping the lens clean. It prevents scratches. Repeat this on the other side of the lens until no more dirt comes off.
4. Removing stubborn dirt with a cotton swab
Your laser cutter's lens is already much cleaner, but it's possible that some dirt has remained. You remove this with a cotton swab. Place a drop of alcohol or acetone on the lens and use the cotton swab to gently clean it. Start in the center and make straight movements across the lens.
Don't press too hard and make gentle movements. If dirt is visible on the cotton swab, repeat this step with a new swab until it picks up no more dirt. Repeat for the other side.
Note: if you use acetone to clean your lens? Then only use cotton swabs with a wooden or cardboard handle, because plastic reacts to acetone.
5. Reinserting the lens
Only touch the lens by its side and place it back into the holder. The flat side then goes downwards. Attach the holder in your laser cutter, and it's ready for use again. It's always good to perform a test run, so you're sure the lens is working correctly again for your next project.
What not to do
During the cleaning of a laser cutter's lens, there are a few things you absolutely should not do.
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Blowing on it to remove dust; always use clean compressed air.
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Touching the flat sides of the lens; only hold it by its sides, even when wearing gloves.
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Rough cleaning with circular movements; apply hardly any pressure to the lens and clean with small back-and-forth movements. If the alcohol leaves streaks, you're pressing too hard.
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Using plastic cotton swabs with acetone; with acetone, only choose wooden or cardboard cotton swabs.
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Ignoring your laser cutter's user manual; if the cleaning process is explained differently in your user manual, then your user manual takes precedence.
Cleaning diode lenses
The steps above are for cleaning lenses in CO₂ laser cutters. With diode lasers, the lens cannot be removed from its housing, and the procedure is slightly different (read: easier).
First, read the user manual thoroughly and follow the steps below.
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Remove the lens plus housing from your laser cutter.
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First, clean the dust on the outside of the housing and in the lens head with a wipe soaked in alcohol.
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Pre-clean the lens with compressed air.
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Use a cotton swab with alcohol to clean the inside of the lens. Optionally, remove some cotton first so the swab fits better into the opening.
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Repeat until the cotton swab comes out clean from the lens holder.
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Dry afterwards with a dry cotton swab.
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Clean again with compressed air, and your lens is clean.
When in doubt, consult the specialists
Once you know how to clean your laser cutter's lens, you'll easily do it again next time. But if you have doubts, it's better to first be sure you're doing it correctly. Cleaning each laser cutter is slightly different. A scratch on the lens means it has to be replaced. That can be a costly affair for many laser cutters.
When in doubt, always consult your user manual first. It should specify how best to maintain your laser cutter, how to remove the lens, and so on. This is the definitive document to trust.
Our specialists also have ample experience cleaning lenses. So, contact us if you have doubts and need advice. We can then immediately discuss your next project and the beautiful Lasersheets materials with which you can once again create something beautiful.
