The vast majority of gas lasers in use today are CO2 lasers operating at the 10.6µm wavelength where there are literally hundreds of thousands of lasers working every day for laser marking, laser engraving and laser cutting applications.
In recent years some of the main laser technology manufacturers have introduced a more specialised version of their 10.6µm lasers modified to operate specifically at the 9.3µm wavelength.
Some materials, such as Polyethylene terephthalate (PET) for example, can be laser marked at the 10.6µm wavelength but will react better at the slightly shorter 9.3µm wavelength.
PET is a thermoplastic best known as a material to manufacture synthetic fabrics for clothing (commonly known as polyester) and it is also used to manufacture bottles containing drinking water, carbonated pops, fruit juices and other beverages.
In the case of a beverage bottle the vessel must be marked with coding such as date of manufacture, date of expiration (use by date) as well as other variables such as product type and batch numbers. Laser marking is a great technology for this process as a laser engraved code can be applied directly to the PET vessel so that it is wear resistant, fast, cheap, difficult to alter/counterfeit and eco-friendly to produce as there are no inks involved.
Using a 10.6µm laser marking machine to mark PET directly creates a clean, glossy mark with some material ablation. When filled with liquids that are highly transparent, such as water for example, the 10.6µm laser engraved code can be low in contrast and therefore hard to read.
When the bottle is filled with a carbonated beverage the engraved (ablated) area can cause a weak spot that in some cases can cause the vessel to fail and the liquid escape, wasting the product completely. This is an increasing problem as bottling plants move towards thinner walled vessels to aid in lowering material use and product cost/weight.
Using the same laser marking machine but at the 9.3µm wavelength creates a different material reaction where the laser marking is frosted in appearance without any ablation taking place, thereby increasing the contrast and readability of the mark no matter what the contents are and reducing the risk for failures of the vessel near to zero.
PET is also used in some specialist applications. For example, it can be combined with PVC to make a film used for the hologram on a credit card. Here, a specifically configured laser cutting machine at the 9.3µm wavelength can kiss-cut the surface film without piercing its backing film with a far cleaner edge and less adverse heat reaction than a similar machine would produce with a 10.6µm laser. Therefore, using the 9.3µm laser for this laser cutting process increases output quality while simultaneously reducing waste through rejected parts.
At Lotus Laser Systems we manufacture a wide range laser marking and engraving solutions ideally configured for laser cutting, laser marking and laser engraving all types of materials. Our experts would be happy to recommend which configuration best suits your application.
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