The vast range of materials and laser marking applications often make it challenging to choose the right machine for your purposes. It requires a good understanding of the characteristics of laser technology and the material attributes play a crucial role in choosing your ideal laser machine.
The factors that make a difference in the laser marking processes include the quality of the mark needed, the type of material being used, and the speed at which the laser can mark. For instances, CO2 lasers are often used for marking, but not on metal. On the other hand, solid-state pulsing laser technology offers more options for marking applications.
For the purpose of this article, we will concentrate on the solid-state pulsed type of laser machines like Nd:YAG, fiber lasers, and Nd:YV04.
Solid-State Pulse Laser Technologies
- Nd:YAG – It’s been 25 years since the first Nd:YAG laser was introduced. Today, it is considered the workhorse of the marking industry. The big benefit of the Nd:YAG laser type is the quality of its beam, which allows for a smaller, more focused spot size of the laser. This makes it ideal for deep engraving with clear marks, small characters, and a crisp finish.
- Vanadate – Vanadate lasers emit at three varying wavelengths. They deliver good beam quality, are diode pumped, and offer pulse-to-pulse stability. They are ideally suited for HAZ applications and ablation marking.
- Fiber Laser – Around six years ago, fiber laser technology entered the marking industry and has become another staple technology in the industry. It doesn’t have the same beam quality as the vanadate or Nd:YAG lasers, therefore the peak power is limited. The biggest benefit of the fiber laser lies in its ability to anneal stainless steel due to its large spot size, which draws carbon to the surface of the material.
Factors to Consider
- Beam Properties – The beam quality of a laser marking machine is one of the first things people look at before choosing one. The term used for determining quality is M2. The M2 value of a laser machine tells you the smallest spot size it can produce. For instance, a Gaussian beam features an M2 of 1, which allows for the smallest size spot in relation to the optics and wavelength used. Nd:YAG technology has an M2 value of 1.2. Fiber-based laser technology has an M2 value of 1.7, which produces a larger spot size with less power density. Better beam quality is capable of producing smaller linewidths, higher marking speeds, deeper engraving, and sharper contours. A laser marking machine with good beam quality also produces high depth of focus over one that has less beam quality.
- Pulse Repetition Rate–There is a vast difference between the YAG and vanadate compared to the fiber laser as far as peak power and pulse repetition is concerned. The pulse duration of fiber systems can be adjusted, which affects the pulse repetition rate, which optimizes laser marking. Make sure you research pulse repetition rates to ensure you’re getting the right laser marking machine for your applications.
- Applications – Common terms used in the laser marking industry include, annealing, engraving, color change of plastics, and ablation. Every laser marking machine discussed here are capable of optimizing the performance of laser marking processes. For example, the vanadate laser performs very well for ablating day/night designs because of its short pulses, higher repetition rates, and pulse-to-pulse stability. Ablation is the most forgiving process in laser marking.
Each of these laser marking machines has its benefits and purpose in the marking field. It’s important that you know their purpose and features before choosing your laser marking system.