CO2 lasers are widely used in packaging and printing, where applications include perforating, scribing, marking, engraving and kiss cutting. Ventilation holes are made in plastic film for packaging fresh produce, lines are scribed to make easy-tear openings in plastic pouches, information is marked on boxes, bottles, labels and cans, printing plates are engraved and easy-peel stickers are produced by laser scoring.
Laser perforating – keeping food fresher for longer
With volumes of waste around the world increasing year on year, keeping food fresher for longer is a key priority for many food manufacturers. Modified atmosphere packaging (MAP) technology uses laser-perforated holes to regulate the levels of oxygen, carbon dioxide, nitrogen and other gases inside the pack, maintaining the freshness and extending the shelf life of the fruit and vegetables inside. In turn, that gives consumers more time to enjoy fresh food, ultimately reducing wastage.
For this application, lasers in Luxinar’s SR series are the most suitable. They can be used to perforate holes at regular intervals across the packaging film in accordance with the respiration rate of the produce inside. This IP66-rated hard sealed CO2 laser is integrated in the packaging machinery, where hole size can be monitored continuously and adjusted on the fly, so the film can be perforated accurately and reliably. In this way, the colour, taste and nutrient content in food is preserved, mould growth is inhibited and the shelf life is increased in a controlled and predictable manner.
MULTISCAN CO2 lasers from Luxinar can be used to create easy opening pouches and sachets for various food products. The laser is used to selectively weaken the packaging material, enabling it to tear easily along the scribed line. As the laser does not cut through the packaging film, the pouch remains airtight until opened by the consumer.
Marking a range of packaging
MULTISCAN VS and MULTISCAN HE laser systems are available in three wavelengths, to suit different packaging films. The process is fast and highly flexible; the same laser could be used to scribe, mark and perforate the packaging as required. The non-contact nature of the process means there is no downtime due to tool wear or breakage.
The laser marking process is quick, clean, and reliable. Marks are indelible and tamper-proof, and consumable costs are effectively non-existent once the laser coder is installed. This makes laser coding an attractive alternative to traditional ink-based technologies.
Solutions for high-speed marking and coding
Food labelling legislation is becoming more stringent and there is pressure on the industry to mark lot numbers, batch codes and “best before” dates on products. This information must be frequently updated as it is applied to each item. Lasers are now a popular choice for food packaging companies for a number of reasons that include the diversity of the material they can mark and the longevity of the inscription compared to the alternative inkjet printing method. The MULTISCAN VS is popular among customers seeking this application.
Beverage markets - from marking PET and glass bottles, to labels
Beverage marking systems must be able to operate in hostile environments, and to withstand regular washing down in order to comply with hygiene legislation. The IP66-rated MULTISCAN HE is currently the only high-speed CO2 laser marking system able to meet the demands of the world’s fastest labelling systems. This highly versatile system can mark alphanumeric text, QR codes, data matrix and complex graphics onto a variety of surfaces, including paper labels, plastic bottles, painted metal cans and hot glass bottles.
Lasers in the printing industry
Solutions for flexography
The OEM 45iX has become a best seller for Luxinar due to its versatility and the ease with which it can be integrated into existing production lines. Its short optical pulse with high peak power improves edge quality and minimises the heat affected zone. The power stability of 1% ensures a high level of process repeatability, making it an attractive solution. This makes the OEM 45iX the ideal candidate for direct laser engraving on flexo printing plates.
As a general rule, the desired speed of a laser source is proportional to the power level required. Therefore, for a more delicate product, or if a cost-sensitive solution is required, a laser from the SR series could be a better option.
Solutions for digital printing
CO2 laser-based machine tools are well-established across many industries and have become the tool of choice for both narrow and wide web applications. Laser processing provides flexibility, with extremely accurate control of cut depth, high repeatability and consistency but without the need to change tools, unlike the mechanical alternatives.All Luxinar’s CO2 laser sources, but particularly the SCX 35 and the SR series, allow companies to design modular machines to process a range of plastics and paper using the appropriate wavelength. The laser source can be easily integrated into existing production lines, coupled with a galvo-based system, a cutting head or a combination of both.
Lasers offer flexibility and stability for kiss cutting labels
In the packaging and label markets, mechanical (or die) cutting is well suited for high volume, standard products. Innovation is a key differentiator and companies try to devise new ways to package their products. This trend in innovation means that packaging labels are changing in shape and size on a regular basis, and new materials are being used, so the packaging industry needs flexible tools. The laser provides this flexibility.
Labels are made up of different materials such as paper, plastics or a combination of both. These materials absorb light in a different way. In a market where paper labels are the dominant products, 10.6µm lasers will be preferred over other wavelengths. A 10.6µm wavelength laser will also offer 10% more power than a 10.25µm wavelength laser. On the other hand, if the labels are mainly made of a combination of plastics (PP, PET, etc.), a 10.25µm wavelength will be preferred. Some OEMs will favour the µm wavelength in order to offer greater cutting flexibility to their customers.
Another key factor is the stability of the laser. Label stocks are made up of 3 layers: the carrier or base material, the bonding agent and the “sticker” itself. To produce a label, manufacturers use a kiss cutting process: the laser has to cut the sticker and the bonding agent without damaging the carrier material.
For a given label shape when cutting paper, the laser is normally used at a high duty cycle whereas when cutting PP the laser is used at a lower duty cycle. Having a stable laser throughout the power range allows a producer to control the depth of cutting and therefore the quality of the label.
To find out more about the uses of lasers in packaging, see Packaging.