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How to Laser Engrave Soft Products

by Scott Cunningham
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How to Laser Engrave Soft Products Laser marking or engraving glass, ceramics, plastics or other soft materials can pose a catch-22: Opt for more delicate marking methods to increase quality, and you end up sacrificing speed.

Let me explain. If you’ve ever tried to mark these types of materials with a CO2, fiber, or diode-pumped laser marking machine, you probably noticed poor mark quality. These lasers have long wavelengths and may not react well with more sensitive materials.

So, to achieve more precise marks, you switch to a shorter wavelength laser. But, as these are often less powerful machines, you end up decreasing marking speed.

What’s the best method to laser mark soft products for part identification or traceability? Is there a way to have the best of both worlds?

In this blog, we’ll look at why a higher wattage 532 nm wavelength industrial laser marking machine could be the way to go when you need quality as well as speed. Plus, learn which marking technology will deliver the best marks on widely used soft materials, including silicone, thin plastics or metals, and even glass or ceramic.
 
 

When to Opt for a 532 nm Wavelength Laser

If you’re working with a soft material, a 532 nm wavelength green laser might be your best option. However, we don’t recommend running out and purchasing one just yet. There are many considerations that go into choosing the best laser marking technology in addition to material, like application and mark type.
 

What is Laser Wavelength?

A simple definition of laser wavelength, which is measured in nanometers (nm), is the amount of energy or light a laser produces. Different types of laser emit different wavelengths. The shorter the wavelength, the more concentrated the energy. The greater the energy, the more light that material will absorb.

Greater absorption = Better quality mark

Shorter wavelength lasers, including green and UV lasers, are generally recommended for laser marking soft materials. They offer a higher absorption rate than infrared lasers (like your fiber and CO2 lasers) and are less likely to burn the surrounding material because they produce less heat. This is why this category of lasers are also referred to as “cold lasers.”
 
Shortest Wavelength 180 – 400 nm Ultraviolet (UV) Light
Moderate Wavelength 400 – 740 nm Visible (VIS) Light
Longest Wavelength 700 nm – 1 mm Infrared (IR) Light

 


For instance, laser marking machines in the infrared category, such as CO2, fiber, or diode-pumped technologies, are capable of creating high quality permanent marks on a wide variety of materials, from metals to plastics. However, these same machines can alter or even burn some heat-sensitive materials. This is because the laser energy is not fully absorbed, allowing too much light to pass through without interacting with (or, as we say, marking) the material.

You’re left with indecipherable logos, unreadable barcodes, or damaged parts – none of which is effective for part identification or traceability, not to mention overall equipment effectiveness (OEE).



Why does this happen?

A laser is essentially concentrated light, and each material absorbs light energy differently. As the laser comes in contact with a material, it is changing the surface –and sometimes even chemical compound – of that material. How it changes depends on the type of laser application.

For example, carbon migration occurs during the heating of metal or metal alloys, causing the metal to chemically bond with traces of carbon molecules at or near the part’s surface, creating a dark – sometimes even black – permanent mark. Laser etching or engraving is an application that requires deep laser marks for long-lasting barcodes, serial numbers, or logos on a wide variety of part materials.

An experienced laser marking equipment provider will ask you thorough questions about your processes and requirements to determine which laser marking system you need.

While we’re on the topic of marking speed, we’ll examine the difference between two types of lasers you may be considering for your soft marking application.
 

Choosing a Cold Laser: Green Laser Marking vs. UV Laser Marking


If you’re considering an alternative to infrared laser marking systems, you’ve probably done your research on UV as well green marking lasers. These technologies are similar in that they are both used for marking soft products. But there are also some important differences to consider when you're making a final decision. 

UV lasers are often used for intricate, precise marks on the micro level. Their focused wavelengths allow for a high beam intensity and miniscule spot size.

Both green and UV lasers emit less energy than infrared lasers. However, when your infrared laser is not marking effectively, in my experience, a green laser is the next logical step.

Why?

Achieving clean, readable marks on soft products requires less power. That’s a given. So, we need to compromise somewhere.

Take a typical fiber laser, which operates at a 1064 nm wavelength. Green lasers operate at half that wavelength, or 532 nm. Most UV lasers emit even less power, about 355 nm or one-third that of fiber lasers.

As a result, a green laser gives you more power than a UV laser yet is still delicate enough to mark a wide variety of soft products. You get a high quality mark without significantly decreasing your marking speed. Think of it as that Goldilocks-like quality of not too rough or too slow, but just right.
 

Why Wattage Matters


We’ve talked a lot about laser wavelength so far, but another key determinant of how fast a machine can mark is power output.

While laser wavelength is a measurement of light energy, watts (W) is the unit of measurement for laser power output. For example, a typical industrial fiber laser marking machine will run anywhere from 10W to 100W of output power. They deliver high speeds and deep, permanent marks.

Most green marking lasers on the market today only deliver about 4W to 6W of power output. In general, that translates to relatively slower speeds and shallower marks.

How can you get the speed and quality you need? Don’t give up on green lasers just yet because, as they say, necessity is the mother of invention.

 

What can a Green Laser Machine Mark?


Do you have a material that you think is un-markable because it is too thin or delicate for "traditional" laser marking machines?

Green lasers not only offer more delicate marking but are also surprisingly versatile. Create readable traceability, branding, and identification marks on an expanse of materials, from soft plastics and thin metals to glass and ceramic.  



SMARTmark Green Laser marking machine samples

Green lasers have become more common among medical device manufacturers. In recent years, the medical industry has had to take extra precautions when marking surgical equipment, trays, tubing, and other common products. This is because of new FDA standards that require unique identifiers (UDIs) and "hygienic marking" for both patient safety and speed of recalls.

 

A Better Way to Go Green


Okay, we've covered a lot today, so let's quickly recap:
  • To mark soft materials without damage or readibility issues, manufacturers need to use a laser with a shorter wavelength. These types of lasers create less heat, which is why they're also called "cold lasers."
  • Two popular cold lasers used for marking and engraving are green and UV lasers. Both options are capable of creating quality marks on delicate products, but green lasers provide more output power. More output power (measured in watts) translates to faster marking speeds. 
  • However, most green lasers on the market only offer 4-6W of output power. That's relatively slow if you're currently using a CO2, fiber, or diode-pumped laser marking machine. 
Thankfully, there's a better option. 

Take a look at a green laser marking machine capable of reaching a maximum power output of 20W, more than three times that of other green laser marking technologies. If you're interested in learning whether a green laser is the right choice for your material or application, take advantage of our sample marking. It's a free service performed in our labs by experts that allows you to be certain you're getting the right mark every time. 

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