Compared to silk screen printing, vibro or dot peening, machine routing, and chemical etching, laser marking is a faster, cleaner, and more versatile etching and marking approach.
When selecting a marking method, manufacturers need to consider the key factors important to them, which are often driven by market forces or the type of application in which they are invested. Durability of the mark is critical where strict regulations on traceability apply, i.e. the marking of medical devices and firearms. Serial numbers can’t be allowed to wear off due to frequent use or exposure to harsh environments, such as when a medical device is implanted in the body. An implant is also a good example of an application where sterility is key — i.e., the mark can’t release contaminants such as ink or chemical residue.
Durability and sterility fall into the category of performance factors related to the mark itself. Another category might be called production factors — such as how much time it takes or how much it costs to produce the mark. All else being equal, manufacturers would obviously prefer a marking method that is faster and costs less than alternatives. A review of factors in each category reveals that, in most cases, laser marking is superior to other methods.
Laser marks are produced by a laser beam operating under computer control. Typically, the only preparation is to clean the part of any contaminants and program the laser. The part (or sheets of parts) are then placed under the laser at relatively high speed and cut based on the program.
By contrast, chemical etching takes longer because it requires much more prep work. That includes covering the part in a protective coating, which is then mechanically cut wherever the underlying material will be exposed to the etchant (typically acid). The part is then bathed in the acid to produce the mark, after which the protective material and any acid residue are washed away.
Routing engraving, is also slower, depending on the job. With this method the tool, or cutter, cuts into the surface of the material to a predetermined depth and produces a groove of the same shape as the cutter. So, unlike a laser, whose beam width and power are adjustable, the mechanical cutting tool (of fixed dimension) may need to make multiple passes to achieve the same mark. Also, the cutting tool will wear out and so must be routinely replaced — which also takes time — while the laser beam does not wear out.
Light is an inherently more precise marking agent than inkjet (spraying ink on a surface), chemical etching, or mechanical cutting — achieving tolerances down to within 0.001’’ inches. That makes lasers very appropriate for applications like micro coding — i.e., marking very small product codes on very small parts, such as marking model numbers or logos on ceramic substrates used in electronics manufacturing. This factor is key, especially when combined with the next factor.
Not only can laser marks be very small and precise; they are also much less likely to fade — a bigger concern when marks are small, since there is less of a mark there to begin with. Depending on material being marked, laser marks can be highly temperature and corrosion resistant because the only material involved is the material of the part being marked. That points to another advantage of lasers. They tend to be highly versatile, especially when it comes to the range of materials that can be marked.
Range of materials to be marked is one type of versatility. Others are the thinness of the material, the ability to handle intricate shapes (both of the part itself and the mark), and the size of the mark (as discussed under precision). Lasers can mark a very wide range of materials, including:
Lasers can also mark very thin materials (down to 0.003’’ foil) without destroying the material — a thinness that is impossible to achieve with either chemical or mechanical etching. Lasers also have the edge when it comes to the intricacies of the shape to be marked and the part to be marked. Since a laser beam is light, it can be directed under computer control with a high degree of accuracy and flexibility to create virtually any pattern on a wide variety of different shaped and sized parts.
As was discussed earlier, lasers have an advantage over methods that involve inks or chemicals because it leaves nothing behind that wasn’t already there to begin with — making laser marking ideal for applications like biomedical implants or any medically related tool.
Selecting the right marking method can obviously have a big impact on product profitability, the speed with which the product can get to market, and the service lifetime of the product after it leaves the factory. For many products, laser marking has the advantage on all three fronts. To learn more about the advantages of laser marking, read our blog on Why Medical Device Makers Like Lasers.
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