Laser welding, cutting and marking techniques used in the manufacture of medical instruments were the focus of Trumpf's Medical Technology Day, which took place on 22 April 2009 at its Luton, UK facility. The company's Laser Technology Division produces a range of lasers and laser systems for different fields, including marking and device manufacture in the medical industry.
Speaking at the event, Gerry Jones, general manager for laser systems at Trumpf UK, said that laser processing is enabling much finer and more detailed instruments to be produced. Medical instruments manufactured by other methods cannot match the quality and level of detail available using laser-based methods.
Medical instrumentation is subject to very stringent restrictions as to how it's manufactured, stated Jones. The base material used to produce implants, for instance, is chosen for its biocompatibility, or its inert properties in the body, and any processing shouldn't change that. Changes in the surface finish caused by laser cutting of a titanium implant have to be within certain limits, as the texture of the metal will affect bone growth. For the same reasons, laser marking also must not alter the surface finish and most implant parts are laser marked by annealing, which leaves a smooth finish.
'For fine stent cutting [the medical industry] wants near-perfection,' Jones said. One of the problems with laser cutting is that the beam can leave burn marks, as the part is manipulated to cut round corners. Trumpf's Cutassist module regulates the amount of energy output depending on the velocity, i.e. as the velocity of the beam moving across the part drops to cut a corner, the power drops accordingly. To cut medical tweezers, for instance, to the high quality required would take 11.0 seconds without Cutassist but 7.45 seconds using Cutassist. Jones commented that the increased speed of processing is advantageous, but it's the quality of the cut that is most important to the medical industry.
Ultra short laser pulses, in the picosecond range, are also used to produce fine cuts and create surface structuring through ablation in devices such as stents. Picosecond pulses produce no discernible heat affected zone and are suited to the generation of small features.
Marking is also a major part of medical device manufacture, as a complete inventory of instruments used for each surgical procedure is made. Dot matrix codes are often laser marked onto instruments and the devices are scanned on entering the operating theatre, scanned on exiting and scanned as they are sterilised. In this way, a complete history of the use of the instrument is maintained.
Trumpf will be running a number of seminars and workshops at its Luton, UK, facility throughout April, May and June as part of its technology events programme. The events will cover laser processing, punching, bending and programming.