Laser coding technology has revolutionized the way many companies add variable data to their packaging. This technically advanced coding method ensures high-quality, permanent marking and offers versatility and efficiency across various materials and industries.
One of the many advantages of laser coding is that no consumables such as inks or solvents are needed, helping the environment and reducing operating costs – even though the capital cost of the equipment is usually higher than with inkjet printers.
Another key factor is that laser coders require less maintenance than many types of coding equipment.
Laser coders are available in several flavors based on the wavelength of the light that is generated. Just as inkjet printers need different inks for the best results on specific substrates, the success of a laser coder depends on matching the laser light wavelength to the material that needs to be coded.
All lasers installed for packaging or industrial applications should have guarding installed to ensure they meet the laser safety standards. This is particularly important for fiber, UV, and green-wave lasers, where the light can cause permanent eye damage.
CO2 Lasers (10.6 µm, 10.2 µm, and 9.3 µm)
CO2 lasers are the most common type for packaging applications.
As the name suggests, these lasers use a light source that contains CO2 gas to produce the laser light.
CO2 lasers are available in a wide range of output levels, allowing them to be effectively used for coding on low-volume packaging lines and some of the fastest.
10.6 µm CO2 Laser: This is the most common type of CO2 laser and is incredibly versatile. It’s primarily used for coding on paper, cardboard, wood, and glass. Think of a chipboard cereal box with its expiration date and batch number – that’s the work of a 10.6 µm CO2 laser.
10.6 µm lasers are also used for adding variable information to labels, either by removing a layer of ink to show the background color or by utilizing a laser-receptive coating, such as that produced by Datalase.
10.2 µm CO2 Laser: Slightly different in wavelength, the 10.2 µm laser offers better absorption on certain plastics compared to the 10.6 µm variant.
As a result, some laser manufacturers promote their 10.2 µm lasers as a good solution for coding on various plastic films.
9.3 µm CO2 Laser: This laser variant is often employed for adding variable production codes to PET packaging, such as plastic water bottles.
The more common 10.6 µm laser is also often used, but this produces a low contrast mark that can be difficult to see.
The light produced by a 9.3 µm laser causes a foaming effect on the surface of the material, causing a white-looking character with a little more contrast.
9.3 µm CO2 lasers are often found adding production codes to PET water bottles on very high-speed packaging lines.
Fiber Laser (1064 nm)
Fiber lasers are known for their efficiency and high-quality marking on metals and hard plastics. They are ideal for industries where durability and precision are paramount, like automotive and electronics. For instance, a fiber laser can be used to etch serial numbers and QR codes on automotive parts or electronic components, ensuring traceability and compliance with industry standards.
In packaging applications, fiber lasers are often installed on lines where the packaging material is metalized foils and also for metal cans.
While continuous inkjet (CIJ) printers have traditionally been used for these applications, high-speed lasers have been gaining market share due to lower maintenance requirements and no consumable consumption.
UV Lasers (355 nm)
UV lasers can often produce an excellent, high-contrast code on materials that are difficult for other lasers. They use a cold marking process, which means there’s minimal heat impact on the material being marked, making them a good solution for marking perfect thin films (including mono-materials), foils, and delicate plastics.
In the pharmaceutical industry, UV lasers are often used to code on blister packs and vials, ensuring legibility without compromising the integrity of the packaging.
Another application for UV lasers is adding variable text and barcodes to HDPE bottle and caps, where the UV light can produce a very high contrast mark.
UV lasers use a DPSS diode array to produce the laser light with a wavelength of 1064 nm. The beam passes through a frequency tripling crystal which provides the output light at 355 nm.
UV lasers tend to be more expensive than CO2 or fiber lasers and both the laser diodes and crystal need to be changed periodically.
Green Wave Lasers (532 nm)
Green wave lasers are similar to the UV models in that a 1064 nm beam of light from a diode light source is passed through a crystal that changes the wavelength. In this case, the frequency is doubled to give an output of 532 nm.
These green wave lasers offer many of the advantages of a UV laser at a somewhat lower purchase and operating cost. The range of materials that can be coded with a green wave laser is not as diverse as the UV laser, so it is vital that testing is carried out before making any purchase.
Critical Concerns When Purchasing a Laser Coder
Because every substrate to be printed can react differently to laser light, be sure that your prospective laser vendor can test your products to ensure compatibility.
To ensure that the correct power laser is specified, your vendor needs to be able to test (or accurately simulate) their suggested laser operating at (or above) your actual production speed.
This testing will determine not only which wavelength of laser is best for your products but also the power output that will be needed to meet your production speeds.
Safety is crucial when installing a laser coding system, so be sure that your vendor offers suitable guarding for the type of laser you intend to use.
For CO2 lasers, plexiglass guarding is often used, but for fiber, UV and green-wave lasers, you need to ensure the laser is completely enclosed with compatible guarding (often made from stainless steel) that prevents any stray laser light from escaping from the enclosure.
Particle and Fume Extraction
Many laser coding operations produce an amount of smoke, particles or fumes in the marking area.
Discuss with your laser vendor what kind of particle and fume extraction filter system will be needed for your particular project, and be sure to build the costs of this into your budgeting.
The environment where your laser will need to operate will have an impact on the level of environmental protection the laser equipment will need.
Most laser vendors can offer equipment of various IP ratings up to IP68. In some cases, air-conditioning units might be needed to keep the laser cool if installed in hot areas.
Laser coding technology offers a versatile and efficient solution for adding variable data to packaging. Each type of laser – be it CO2, fiber, UV, or green wave – has its unique advantages and is suited for specific materials and applications. By understanding these nuances, businesses can choose the most appropriate laser coding solution to meet their needs, ensuring high-quality, durable, and legible markings on their products that help meet sustainability targets.
There are a number of factors that need to be taken into account when specifying a laser, but if carefully planned, a laser coding installation will give many years of excellent results.