Bristol, UK – Lasers are commonly used to mark surgical instruments but the effects of the parameters used in this application are not always fully appreciated. According to Charlie Plain-Jones, development manager at laser-marking-systems-supplier Instrumark, the requirements for a mark on surgical stainless steel are clarity, durability and minimum invasiveness into the parent material.
This last requirement is due to the decontamination processes that instruments are subjected to after every operation. These processes include exposure to highly caustic wash chemicals followed by high temperature steam sterilization, which tests the resistance of the particular alloys used in the manufacture of instruments.
Plain-Jones says it is vital therefore that the marking has as little effect as possible on the natural resistance of surgical alloys. Traditionally, instruments have been marked using what is known as anneal marking, which is a dark heat affected zone on the surface of the metal but this process, usually conducted at laser pulsing frequencies below 100 KHz, is accompanied by a degree of surface melting. This melted region does have an undesirable effect upon the corrosion resistance of some stainless alloys.
Instrumark compared the performance of low frequency annealed marks with the high frequency dark marking proposed in an IPG Applications Note by Dr.Tony Hoult. These tests were performed using an YLP 200 Khz IPG laser. Dark marking gave the following benefits compared to lower frequency anneal marks:
- Superior definition of mark, rendering finer detail and improving the clarity of smaller marked details.
- Improved resilience of mark to decontamination processes.
- Increased corrosion resistance compared to lower frequency marking.
- A virtually smooth surface finish with no adverse effects on the 'cleanability' of the instrument.
- Faster marking performance compared to lower frequency marking.
To conclude, the high frequency dark marking capabilities of the IPG YLP laser are now the default parameters used by Instrumark when marking surgical instruments for its clients.