TPT January 2020

AR T I C L E

Coherent Inc

show similar results, and while marks on some lower quality steels are very slightly faded by this type of corrosion testing, they are still very readable with no signs of surface corrosion/ oxidation. Similarly, figure 4 shows the ability of black marks to withstand subsequent passivation. Here a 2D barcode mark was subjected to a typical passivation cycle of immersion in 7 per cent Citrisurf ® 2250, for 20 min at 50°C. No significant change in mark readability is seen. Similarly, black marking does well when subjected to the repeated re-processing (ie autoclaving) that re-usable medical devices typically experience. Figure 5 shows a typical UDI mark, containing alphanumeric data and a 2D barcode, after 50 cycles of autoclaving. There is no fading of the mark and, just as important, no signs of any surface corrosion.

Figure 6. Turnkey systems for black marking applications are completely self-contained, including a robotic interface and a compliant exhaust system

Figure 5: This image shows a UDI mark after 50 autoclaving cycles with no significant effect on readability and no observable corrosion

this can be combined with an optional rotary axis for tubes and other curved parts. Custom part fixtures and clamping can also be supplied. In addition, the turnkey systems include an optional vision system (both camera hardware and software) to enable automated pre- and/or post-processing inspection needs. Control software and external interfaces are designed to simplify integration into a networked factory. Within the Automation Pyramid, the Laser-Framework I/O provides various interfaces to MES/ERP systems, supporting both highly standardised and proprietary interfaces, including Host-Coupling (HK), Marking Job Control (MJC), TCP IP), WS Siemens Webservice, HTTP, Unified Automation (OPC UA), Industry 4.0, etc. In highly integrated manufacturing processes, equipment often also needs to communicate horizontally to other systems or PLC controllers. Multiple Fieldbus systems can be connected via a TwinCat package component that accommodates all common bus types: EtherCAT, Ethernet, TCP/IP, Profibus, Profinet, EtherNet/IP, CANopen, Modbus, IO-Link, RS232 and RS485. Summary In conclusion, direct marking on stainless steel substrates is becoming increasingly desirable in order to comply with medical device regulations or for aesthetic (eg brand logo) purposes. A new laser process addresses this market need, providing a permanent mark that has no need for re-passivation and that is clearly legible even after tens of autoclave cycles.

Another important advantage of black marking stems from the minimal thermal effects associated with this process. Specifically, it is well-suited for use with thermally vulnerable and fragile parts, such as wires, tubes, thin sheets and small implants, with no risk of any shape change to these parts. From a practical manufacturability standpoint, it is important to note that the process results are fairly insensitive to changes in the laser power, focus and so forth, unlike the case with ns lasers. This results in a large process window, maximising both throughput and yield. Laser systems and production integration Picosecond lasers are well-proven over the last 15 years; for example, there are hundreds of the Coherent PowerLine Rapid NX in the field. But, with the exception of laser job shops and speciality tool builders, most applications today need much more than just a laser. Coherent supports this need with different levels of integration. The two most popular are laser sub-systems such as the PowerLine Rapid NX that includes a laser, beam delivery optics and scan head, and complete stand-alone systems including robotic automation – see figure 6. Both sub-systems and turnkey systems are supplied with a picosecond laser with a pulse repletion rate up to 1 MHz to enable fast marking. They also feature the VisualLaserMarker (VLM) software suite. VLM consists of a graphic editor to generate the layout plus a CAD extension to import all common file types: DXF, BMP, JPG, PDF and AI. Special objects and other parameters for marking are all easily configurable. The turnkey systems feature a granite mounting platform for maximum stability and mark resolution. The workspace is designed for maximum flexibility to accommodate different part sizes and geometries. Up to three linear axes of motion operate under servo control, and

Coherent Inc – USA Website: www.coherent.com

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JANUARY 2020