Why CO₂ lasers are ideal for marking glassware

Glassware may be marked for a number of reasons.  Marking may be purely decorative, information may be added for product traceability, or the surface may be altered for technical reasons.  Glass etching is traditionally done using abrasive or caustic substances, or using a hand tool or burr. However, laser marking has emerged as a practical alternative, especially for technical applications. 

For example, pharmaceutical companies use laser coding machines to mark glass containers, syringes and vials. These machines typically utilise the carbon dioxide laser, more commonly abbreviated to CO₂ laser, for a number of reasons. This blog post will examine why CO₂ lasers have risen to  prominence in  in glass marking applications.

What is a CO₂ laser? 

First invented in the early 1960s, the CO₂ laser is still widely used in industry today. The sealed CO₂ laser consists of a pair of slab electrodes inside a sealed tube with a mirror at each end, forming an optical resonator.  The tube is filled with a gas mixture including carbon dioxide, nitrogen and helium.  RF power is applied to the electrodes, exciting a gas discharge between them.  As the gas molecules subsequently lose energy, photons are emitted.  The photons travel back and forth within the resonator, stimulating the emission of more photons as they collide with the gas molecules.  These photons, all travelling in the same direction, in phase and with the same wavelength, combine to form a laser beam. 

Why are CO₂ lasers used for marking glassware?

The CO₂ laser operates with a wavelength in the infrared spectral region, which is absorbed very strongly by most types of glass.  What does this mean in practice?  Because the light does not penetrate the glass but interacts with its surface, the laser can be used to mark the surface very effectively.  Different effects are possible, depending on the method used.

A lens focuses the laser beam to a small spot, which is moved quickly and accurately across the surface of the glass using a galvanometer scanner – essentially a pair of motorised mirrors – to steer the laser beam.  The laser marks the glass by locally heating its surface to a high temperature, and causing microscopic cracks to form.  The laser process can mimic sandblasting in order to mark high quality logos and graphics, and the surface roughness of the laser mark can be used to create “head keepers” – marks in the bottom of beer glasses, which act as nucleation sites to promote the formation of bubbles and maintain the frothy head on the beer for longer. 

Marking glassware while still hot from the manufacturing process produces a very different effect.  Hot glass marks are smooth and free from microcracks.  The resulting marks are of high quality, discreet appearance, and fine details such as Data Matrix codes can be marked with clarity.  This is of particular use in the pharmaceutical industry; the laser marking process can be automated so that manufacturers can automatically assign unique codes to every vessel, syringe or vial, with no risk of human error.  Laser marks onglass cannot be removed, smudged, or altered,, eliminating security concerns and enhancing traceability. 

Of course laser marking glassware is not restricted to the pharmaceutical industry.  Laser codes can be applied to beverage bottles, automotive glass, architectural glass and more.  Examples of decorative marking include perfume bottles, cosmetics packaging, drinking glasses and tableware.

Laser marking instruments from Luxinar

Luxinar is dedicated to focusing on customers’ individual needs and helping to optimise their applications.  Our applications engineers have expertise in working with glass for a range of different industry sectors.

For 25 years, Luxinar has been leading in laser technology, and our experienced team has installed over 20,000 laser systems worldwide. Although we offer lasers for a wide range of industries, if you’re looking for a CO₂ laser system for glassware etching, our MULTISCAN® range provides the perfect solution.

MULTISCAN® VS

The MULTISCAN® VS is a compact, fully-integrated system that can easily be moved around. It has a small footprint with reduced running costs and can be used for many applications. Key features of the VS include the 1.2m articulated arm, easy integration into existing production lines, low maintenance requirements, and the ability to mark with high precision and speed.

MULTISCAN® HE

Our other CO₂ laser system is the MULTISCAN® HE, designed to be used in harsh environments where dust or liquids might impact processes. It has an IP66 rating, which means it has been suitably tested against these harsh conditions. The HE system comes with a 1.6m articulated arm and a remote display and  keyboard for easy process monitoring.

If you’re looking for the right system for your glassware marking applications, we’re ready to help you. Contact us today for more information.