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Marking & Coding

Laser marking and coding are closely related applications. Marking involves physically creating a contrasting surface mark on the target material by discoloration or surface melting. Coding is a type of marking, however instead of marking with a static graphic or text, the mark varies, either from item to item as in a serial number, or from batch to batch as in an expiration date. 

    Surface discoloration produces a contrasting mark by creating a heat-induced color change in the target material; there is no melting or removal of material. This is the most efficient marking process since speeds are very fast and power requirements are low, typically below 25 W.

    Surface melting produces a contrasting mark by physically melting the material surface. The melting creates a color change in the material that contrasts with the unaffected (unmarked) areas. Typically, the melted material changes density and volume, creating a raised surface.

    Marking and coding with a high performance CO2 laser system offers several key advantages over traditional methods:

    • Lower operating costs - no consumables, and very little required maintenance
    • High speed capability, suitable for high volume processing and production lines
    • Crisp, clear imagery and text
    • Wide range of type fonts and sizes
    • Permanent marks that will not smear or rub off
    • Wide range of materials, including challenging materials like polyurethane foam and glass

     

    For detailed coding application examples click here.

     

    Anodized Aluminum

    Laser marking bleaches out the anodizing pigment leaving a high contrast white mark. The marking process is fast with low power requirement, typically between 10W and 30W. Unlike solid state laser marking, the anodized protection is left intact when marking with a CO2 laser. Recommended lasers:

    Plastic

    Glass-filled plastics, like polycarbonate, and thermoset resins will mark well, inducing a color change using lower power lasers, typically 10W – 30W. Thermoplastics on the other hand will produce a readable contrast for simple text without a color change, however the mark is not adequate for barcode and other scanning equipment. Recommended lasers:

    Printed Circuit Boards (PCB)

    Solder masks are easily marked without damaging the electrical traces. Laser marking permanently adds text, numbers, and 2D codes for traceability. The process is fast with cycle times in the 0.5 – 1.0 second range and often done cost effectively with low power (5 - 10 W) lasers. A PCB marking application note can be found here.

    Rubber & Compounds

    Rubber and polymer compounds can be marked with a laser. Marking speeds vary slightly depending on the exact chemical makeup, rubber compounds in general exhibit similar behavior when marked with a CO2 laser.

    Glass

    Glass marking applications were once thought of as outside the domain of CO2 lasers since glass readily absorbs the laser radiation, causing fractures to relieve thermal stress. Synrad pioneered glass marking with CO2 lasers, which now replaces sandblasting as the preferred method due to the accuracy of the marking and the lower costs of downtime associated with set up and change-over. The most common lasers power used is 25W – 30W to reduce fracturing to acceptable levels. Recommended lasers:

    Paper & Paperboard

    Marking and coding of paper and paperboard products involves the removal of a surface treatment, typically printed ink to reveal the contrasting paper color beneath the print. In some cases the surface treatment may be a clear or nearly clear coat that when removed reveals a slightly contrasted mark. Synrad offers a wide variety of lasers for this application, including compact, lower power lasers to mark single items and higher power lasers for high-speed production and processing systems. Recommended lasers:

    Metals

    CO2 lasers can mark steel directly, and mark treated metals like powder-coats or anodized aluminum. Copper, brass, nickel, and gold reflect, rather than absorb CO2 wavelengths, preventing CO2 lasers from directly marking products made from these materials. With the cost efficiency and popularity of laser marking, several companies produce coatings for reflective metals so that bar codes, 2D Data Matrix codes, and other laser marks are possible on these materials. Recommended lasers:

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