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

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.

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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?

Contact us to discuss your requirements of Laser Cutting Protection Film Supplier. 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.
 

Very important! Current fiber technology does not require the same level of maintenance as CO2 technology, but if a machine breaks down, it is imperative to get it back up and running as soon as possible.

CO2 lasers require extensive and time-consuming maintenance. It is not unusual for a service technician to be on site for up to three straight days. CO2 lasers require servicing every 12 months or every 2,000 operating hours. With increasing service life, the overhauls required (for example of the resonator, optical components, and beam path) increase.

In comparison, the maintenance of fiber laser machines is considerably less time and cost intensive. A fiber laser has fewer parts that require maintenance, which translates into real cost and time savings. Thus, the time required for maintenance and inspection of fiber lasers is significantly reduced and usually takes just a few hours.

However, both laser technologies require the service intervals to be adapted in the event of shift operation. Naturally, a laser cutting machine that is in operation 24/7 requires more frequent overhauls. This has an impact on both the maintenance costs and the downtime for servicing.

At the end of the day, the choice of a laser cutting machine should be based not only on the purchase price, but also on the total cost of ownership, calculated over the machine&#;s entire service life. Maintenance and energy costs as well as machine downtime should definitely be factored in. The energy costs, which can make up a considerable portion of the total annual expenses, are significantly lower with fiber lasers.

For all these reasons, potential buyers should obtain information about the availability and supply of spare parts, so their machine can be promptly repaired in the event of a breakdown. They should also clarify whether the supplier has a service technician stationed nearby who speaks their language.

When you use sophisticated, highly complex technologies, you have to reckon with hiccups. A laser cutting machine that is unable to cut because of a single damaged part is simply not an asset for the customer.
 

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