Laser marking process

This paper will present information which is essential for the laser marking of plastics. The laser marking process and the advantages of operating a laser versus traditional methods will be discussed. The required equipment and pigment additives necessary to successfully mark plastics with lasers will be presented with samples demonstrating the effectiveness of each. 

Laser marking is an ink-free process which produces a permanent rub-fast, solvent resistant, scratch proof mark with no waste, and is free of flammable or volatile solvents and then-subsequent disposal. These permanent markings cannot be removed without damaging the product, which is ideal for safety concerns. The laser marking process does not require any form of surface treatment, in fact, a film of water on the product will have no effect on the marking process. Since the mark is etched into the plastic product, there is no problem of adhesion, even on polyethylene and polypropylene. 

Flammability requirements are stringent for electrical meters and are covered by EN 62053. Capacitor housings require good thermal resistance and dimensional stability. Additionally, both meters and capacitor housings are frequently laser marked, so materials that are compatible with laser marking processes have an advantage. Materials for transformers and insulation systems are tested in accordance with UL 1446 and EN 60085. 

For laser marking to be effective, the energy of the laser beam must be retained in the material to cause local charring. Properly selected fillers are sufficiently opaque to absorb radiation and aid the process of marking. ... 

Hydrogen adsorption has been examined on transition metal clusters, since this is a bench mark process in the catalysis studies. Clusters produced by the laser ablation method are allowed to collide with a hydrogen gas in a narrow reaction tube and are photoionized for mass-spectroscopic identification. The relative reactivity is estimated from the ratio of the intensities of a given cluster ion with and without a hydrogen gas in the tube. 

Laser Beam Machining, Fig.1 Overview of laser machining processes and their typical laser-matter interaction times and power densities. The red line marks the 1 kJ/cm energy density level, where most processes are distributed. The dotted line indicates the melt boundary of metals (Reprinted from Meijer et al. (2002), with permission from Elsevier)... 

Packaging of the chip portion of the chip/lead combined unit into a plastic or ceramic container is a semi-automated process involving the use of epoxy resins, usually epoxy novolak resin formations [15]. These should be fully cured prior to use, but unreacted monomers may be present, which can sensitise, as may other diluent and flame retardant materials, such as halogenated derivatives of bisphenol A, which are added to the resin prior to use. The completed devices are then laser marked in an enclosed system and tested, again in an automated process, prior to delivery for sale. 

Laser markable materials are available that allow identification numbers to be burnt onto the surface of a package, removing the need for an ink marking process. 

In medical technology, there is an increasing trend for smart products. These are made possible by modem processes such as laser marking, two-component injection moulding and MID technology. Current examples include functional dmg delivery systems like pens for active ingredient injection and needleless syringes. 

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