Ultrashort pulsed lasers for marking easily damaged and highly sensitive materials

Ultrashort light pulses in the picosecond range afford astoundingly precise machining results in the micrometre range. These lasers permit high-precision machining with minimal damage to the workpiece material. ACI's new DFL Brevis Marker ultrashort pulsed laser caters to the particular demands of medical applications.

 

Permanent marking and full traceability

The use of lasers for machining and marking materials has been well established in many industries for years now. The benefits are clear: Lasers are the best option for very precise, fine marking. Neither ink nor solvent is required. This low-impact, environmentally friendly process permits materials to be marked permanently without the use of added substances, so that this marking cannot readily be worn off by abrasion. Product traceability and protection against counterfeit products are of particular importance when it comes to medical equipment. Instruments, implants, pacemakers and tubes made from various materials need to be marked as quickly and as precisely as possible to very exacting standards for the purpose of identification. And manufacturers are obliged to ensure that their medical devices are each assigned a unique identifier in accordance with the requirements of the Unique Device Identification (UDI) system. This is to ensure patient safety, which is always paramount. Full product traceability is essential if safety is to be prioritised. The UDI system provides a standardised framework for assigning internationally unique identifiers to medical devices, with the aim of ensuring even greater transparency throughout the supply chain. Lasers are the standout choice for marking applications of this kind. Laser beams are able to mark identifiers such as barcodes and 2D codes containing information about the serial or batch number, expiry date, etc., quickly, precisely and to consistent quality standards in a huge variety of materials such as metal and plastic.

Medical equipment is also subject to a range of further, quite specific requirements. For example, any markings made must not alter the surface texture as this can result in the equipment harbouring bacteria, viruses or pathogens. In addition, repeated sterilisation is very damaging to markings. Conventional marking processes using solid-state or fibre lasers cause markings to corrode, flake off or fade. In answer to this specific problem, ACI Laser has developed an ultrashort pulsed laser. This laser is ideal for preventing material damage and associated corrosion and altered surface texture.

 

"Cold laser marking" for easily damaged and highly sensitive materials

With lasers that operate in the nanosecond range, the marking process is always accompanied by significant heating of the target material due to the laser energy it absorbs, which makes it difficult or even impossible to mark easily damaged or highly sensitive materials without compromising their texture. With pulse widths in the picosecond range, however, enormous pulse powers can be achieved in conjunction with low heat input. The pulse width is short enough that heat is not conducted sufficiently quickly to significantly heat the surface. Ideally, the area of the material on which the laser beam is acting will transition directly from the solid phase to the gas phase, drastically reducing the occurrence of burring. The extremely limited impact of heat is probably the ultrashort pulsed laser's greatest advantage. This "cold laser marking" process opens up a whole host of applications that would not otherwise have been feasible, such as marking easily damaged and highly sensitive materials used in medical applications, sensors and the aerospace industry. The shorter pulses cause less damage to the surrounding material and afford greater precision in terms of material removal, allowing for incredibly fine marking. The benefits range from improved surface quality to a greater level of detail and a more exact result.

 

Wide variety of applications

Amongst its many applications, ACI's DFL Brevis Marker is particularly well suited to burr-free engraving of stainless steel, hardened steel, aluminium or glass. Additionally, identifiers can be marked in black on raw aluminium, stainless steel and high-speed steel in next to no time and without the need for surface finishing beforehand. USP lasers can also be used to achieve colour changes on plastic, to mark silicones and to cut thin materials.