LASER is the mechanism for emitting electromagnetic radiation, as light or visible light, via the process of stimulated emission. Laser is the acronym of Light Amplification by Stimulated Emission of Radiation.
The growing number of industries and the competition among them will always force them to introduce latest technology, this lead to implementation of Laser systems for many industrial applications including cutting, marking, stamping, embossing and engraving. The major difference of laser marking systems from other forms of marking is the unique combination of speed, permanence and the flexibility of computer control. The software used for laser marking system is accessed via a PCI interface card. This sends the digital signals of the computer based marking or etching files to the motors and directs the laser beam to the product being laser marked.
Lasers used for marking are:
CO2 Lasers – it will create permanent codes for lifetime traceability, this will reduce manufacturing costs and can be easily integrated with automated systems.
Excimer Lasers – are available in the following UV laser wavelengths: 157 nm, 193 nm, 248 nm, 308 nm and 351 nm. It is mainly applied on Inkjet Nozzle Drilling, Marking Eye Glasses etc.
YAG Lasers – are most often used as the base platform for producing different wavelengths when it is properly configured. The most versatile wavelength is Infrared (1064nm). This wavelength is used to mark a variety of materials including metals, ceramics, composites, and some plastics.
Different types of processes involved in laser marking systems are:
Surface annealing will draw carbon and/ or oxides from the base material for getting a contrasting mark. The marking beam will produce sharp contrasting line to surrounding area with little or no penetration. This is excellent for applications where a smooth, undamaged surface and contrast is needed. The surface annealing is used mainly on medical implanting, bearings, tooling etc.
Surface etching is the ability to alter reflectivity and enhancing contrast of metals by changing the surface finish of metals. This is one of the most commonly used laser marking technique whose Penetration depth is typically not more than 0.0001″ deep.
Ablating is used to create contrast without damaging the base material, this method is typically done with anodized aluminum, backlit buttons, and painted steel.
This method works by controlling heat using different laser parameters such as marking speed, pulse frequency, power, and focus. It is mainly applied to certain alloys which results in color variations.
In this method depth required is produced by the vaporization of base material. This form of marking is identical to surface etching; this is used typically for 0.0001″ to 0.005″ depth. Repeated passes will increase the depth of the mark.
The specialty marking system is commonly used in plastics. There can be change in contrast naturally in some plastics by heat or coupling with a wavelength which causes a chemical change. Additives can also be used with most plastics to achieve different colors. One of the example of Specialty Marking is Product Traceability, which is the ability of a manufacturer to trace a product through its processing procedures and to also have the ability to re-trace a product back to the manufacturer.