Cutting Reflective Metals with a Laser

Reflective metals, as their name may suggest, are metals which can reflect back wavelengths that are directed at them. Examples of these metals are copper, brass, and bronze. Some of the most reflective are aluminium, gold and silver, the latter of which can reflect around 95% of visible light.

This poses an obvious problem for the laser cutting process, which involves a laser beam of heat and light. Below we have explained how you can cut metals which are reflective using a fiber laser.

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Aluminium is one of the most reflective metals

Why can there be problems with laser cutting reflective metals?

As mentioned above, a reflective metal can redirect much of what is aimed at it back to the source. Known as ‘flashback’, this can be highly damaging for laser-based cutting machines should their own lasers end up breaking the equipment.

Some laser machines can cost many thousands of pounds and have expensive replacement parts, so this kind of situation clearly needs to be avoided. Gas laser cutting, the most common type of laser-based cutting, was founded in 1964 and remains a common method.

Despite this, it has perhaps the most trouble at cutting metals which are reflective out of any of the other cutting processes. This is because it uses beams of lights and mirrors, giving the beam plenty of places to be reflected back into the laser itself.

While some sought to solve this by placing a non-reflective coating on the metal, the molten metal that is created during the laser cutting process is also reflective itself. This means that this can also damage the laser, regardless of how much non-reflective coating you have used. Gas lasers especially struggle with yellow metals such as copper or brass.

Gas laser cutting struggles working with yellow reflective metals such as brass

Gas laser cutting struggles working with yellow reflective metals such as brass

However, this isn’t to say that gas lasers can’t work with reflective type metals at all, and steps can be taken to complete this process successfully, although there is still the risk of damage. Generally, modern lasers have a failsafe in place by detecting when too much heat is being reflected back into the laser and subsequently shutting it down.

What is the best solution for cutting reflective type metals?

Despite these advancements in technology for gas lasers, it is still not the most efficient method and you are still running the risk of damages. Fiber laser cutting, the most recent advancement in laser-based cutting technology, is the solution to working with reflective metals effectively.

Rather than using mirrors, gases or delicate lenses, this type of technology uses fibre optic cables instead. This means that the reflective nature of the metals pose no risk of damaging the fiber laser in the same way that they would do with a gas or crystal laser.

However, it must be noted that fiber lasers are only really effective on metals that are under 5mm in thickness. Any metals that are above this can still be cut using fiber lasers, but the speed is slowed down and the quality of the cut is lessened. For these circumstances, waterjet laser cutting is generally recommended as the proposed solution.

Reflective type metals are used in many industries around the world, such as the electronics, automotive, aerospace and semiconductor industries, and so it is important that they are cut reliably and with high quality in mind.

Reflective metals cutting in action

Considering the above information, here at SPI Lasers we have chosen to only manufacture fiber lasers. Alongside the advantages it poses over gas and crystal laser cutters, fiber type lasers also have a longer service life, require less maintenance, are safer, and work at much quicker speeds.

To demonstrate the capabilities of our fiber lasers, we have put together some videos of cutting reflective type metals with our lasers.

Tower bridge

Not only did we want to show that our laser cutters can cut reflective metals, we also wanted to demonstrate the intricate and complicated shapes it can create too. So we created a replica model of the iconic Tower Bridge in London.

This is constructed from metals ranging from 1mm thick brass to 10mm thick stainless steel, and cuts at around 5m/min.

Dragon

Another intricate and elegant shape that we wanted to laser cut was a dragon. The project was a complete success, and we managed to make an idea come to life! This was done from a mixture of metals, including brass, copper, aluminium, stainless steel and mild steel. This use of a huge variety of metals demonstrates just how capable our lasers are.

Eagle

Finally, we wanted to create another animal, albeit a slightly less fictional one this time. This came in the form of an eagle. You can see our eagle masterpiece here.

 

Looking for more information on the cutting process?

If you have more questions on the cutting process, or want to know more about how it works, then simply get in contact with us here.

 

Image credits: yuelanliu and Hermann

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