Laser Cutting Sheet Metal With Protective Film: 4 Key Points!

Author: Molly

Jun. 16, 2025

Laser Cutting Sheet Metal With Protective Film: 4 Key Points!

Bubbles may form under the film if cutting gas escapes between the sheet and the film during cutting. The risks are as follows:

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  • a large bubble catching on the laser head and dragging the sheet away, resulting in uncontrolled movements and consequently significant damage.
  • damage to the head and lens.

In 90% of cases, bubbling occurs during the drilling phase.

The risk of bubbling is amplified when the cuts are very close together. For example, small holes that are very close together. The gas pressure is concentrated on a very small surface and bubbles appear. There is also a strong risk of bubbling when the holes are less than 5mm apart. In this case, vaporisation must be carried out to avoid bubbling, i.e., burning the film before the cutting and, more specifically, the drilling phase. ‘Pre-drilling’ is available on most machines and can be done in the same operation as drilling, without significantly impacting productivity.

When the distance between the holes is greater, the holes are made in an area where the film is intact. There is therefore less risk of bubbles.
 

Protective film on sheet metal impacts the production process. Yet, suppliers standardise films, at the cost of optimising the cutting process. However, when the volumes are high enough, or if the film is applied in-house, then the manufacturer can choose a more suitable film.

When choosing the film, it’s important to find a balance between high adhesion to limit bubbles and low adhesion to make the film easier to remove.

A) With this in mind, there are several aspects to consider when choosing a film :

? the cutting technology: fibre laser source or CO2 laser
A fibre laser’s wavelength is ten times shorter than that of a CO2 laser and is not absorbed by the plastic. Thus, using a film designed for CO2 laser would create a very uneven cut if used with a fibre laser source. In fact, films specifically for fibre laser cutting have built-in absorbers.

? the material: stainless steel, aluminium, pre-lacquered,  etc.

Stainless steel/aluminium: Some materials are highly thermally conductive, e.g., aluminium, copper, etc. In this case, the heat spreads when cutting and can melt the film. The sheet protection for these materials therefore must be adapted, with a higher level of thermal resistance than a film for stainless steel, for example.

Pre-lacquered steel: Cutting pre-lacquered steel can be problematic if the lacquer used is not designed for good laser wave absorption. Even if there are specific films, the lacquer must be adapted, in particular with specific additives.

Double-sided: Double-sided protection can cause a small amount of burring during cutting, because the film on the table side retains the material. It is therefore recommended to use thin films, which reduce, or even eliminate, quality problems.

? Thickness of the sheet metal used
Depending on the thickness, the pressure of the cutting gas is different and therefore does not require the same level of adhesion. As a result, a film designed for thin sheet metal will result in a lot of bubbling if used on thick sheet metal.

? Material finishes: brushed, glossy, scotch-brite, etc.
Adhesion depends on the surface and the film products are adapted to each surface. It is therefore important to take the finish of the material into account when choosing a film.

B) Quality control: how to ensure that the film is suitable and properly applied?

Suggested reading:
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Contact us to discuss your requirements of Laser Protection Film. Our experienced sales team can help you identify the options that best suit your needs.


? Specific colour codes and markings enable the operator to identify the type of film for visual inspection. Brice Lequette – Novacel explains: "The protective film for a CO2 laser is black on the glue side and white on the outside, whereas for a fibre laser it is black on the glue side and grey on the outside.”

? It is important to properly apply the film, especially by limiting its elongation. This is because plastic is a shape memory material that will return to its original size if elongated. Elongation reduces adhesion and the film will therefore be less resistant to gas pressure, leading to an increased risk of bubbling.

A quick test can be carried out to check that the film has been properly applied:

  • peel off a strip of film from the sheet,
  • wait a minute,
  • compare the length of the removed film to the area where it was stuck. The difference should not be more than 1%.


A few visual clues can also alert to any issues, such as small application defects like bubbles, etc.

? The sheet metal should not be cut for 48 hours after applying the film.
 

Laser safety window and window film - LA Hobby Guy

Laser safety window and window film

  • Quote

Post by Nzelinsky » Mon Jan 02, 12:31 am

So I am in the planning stages of building myself an safety/exhaust enclosure for my new foxalien reizer mega which I upgraded with a genmitsu 10W compressed spot diode. I already have the exhaust portion sorted out as currently its running with a hood over my laser and doing a fairly decent job of venting the smoke.

What is currently my dilemma is for the enclosure I would like to have at least one decent size viewing window on top of the enclosure. My laser is 400x800mm working area. I found a manufactured enclosure that would work made for the extended Xtool but they are charging over $400 for that and Im working with the budget comparable to somebody who has basically zero income... So i have only maybe $100 bucks for the enclosure to spend if I can find somebody to lend me the $100.

I was going to use some acrylic and get the darkest window tint film available, or 2 way mirror film perhaps I imagined might do the job. However in the interest of not losing my eyesight further research has led me to some companies that sell laser safety windows and laser safety window film. Does anybody on here have any experience with these films or windows that can help me understand which color and density/type of window/film to purchase? And is there any reasonably priced suppliers that you can direct me towards?

Any suggestions or relevant experience would be magnificently appreciated.

Thanks Nick- Genmitsu 10 watt compressed spot diode running on Foxalien reizer mega 400x800mm (lightburn all the way)

Re: Laser safety window and window film

  • Quote

Post by LaserRK » Mon Jan 02, 5:01 am

IMO it is max save for scattered radiation (auto translation?)
I'm using orange 2c04
should absorb scattered radiation but no direct beam.
Blue Dot on White paper should disapear behind this window Qidi X-Max
Neje 3 Max - A - ~10Watt
Superslicer -> OctoPrint,

Lightburn, Fusion360

Re: Laser safety window and window film

  • Quote

Post by AceWickwire » Mon Jan 02, 8:36 am

My name is Ken. Now have a Roly Lasermatic Mk2 30w (started with an xTool D1 10w laser). Have been using a laser for a couple years now. Have been a woodworker for a number of years.

Re: Laser safety window and window film

  • Quote

Post by michvhf » Mon Jan 02, 9:26 pm

The company is the world’s best Laser Cutting Protection Film Supplier supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.

You can also try https://noirlaser.com/lasershields Vince - aka Vinny aka Vince Nobucks
LightBurn, Omtech 40W CO2 (not the stock controller), Aufero with LaserTree 80 watt (10 optical) laser, 30 Watt MOPA from LasersOnly.

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