Making a medical mark
Comis Orthopaedics of Rotherham is a privately owned business designing, developing, manufacturing and marketing implants and instrumentation for Minimally Invasive Surgery (MIS). Its product range includes the patented Minimally Invasive Hip Resurfacing or Comis MIHR®, that is deliverable as an open surgery implant; the Comis Leg Length System which provides an initial datum measurement of the joint position prior to dislocating a hip joint; and the MIS Retractor System, designed for near assistant-free use in hip resurfacing and total hip arthroplasty.
From the start, Managing Director, Shaun Palmer and his colleague Ryan Taylor, General Manager, knew that they would need to ensure full traceability on every part they made, to meet the strict legislative requirements and customer demands in the orthopaedic market. They decided to implement high-tech laser marking. A laser marks directly into the product’s surface, a process that ensures long-term traceability throughout the product life cycle that includes frequent handling, cleaning and storage.
Every product can be made from different materials and will undergo several processes before it reaches final product stage. For example, a batch of 17 parts could be manufactured from a number of materials. Each batch will be given a lot number. If a recall was required based on the return of one product, the other 16 customers could be contacted through the use of the traceable identifier and the whole process monitored. As Ryan Taylor said, “You have to be aware of where the products are for recall – you need to know who can be at risk.”
Comis Orthopaedics approached Pryor Marking Technology, and the chosen system was Pryor’s HP20 Nd:Yag laser marker with a V2 enclosure, which was installed in September 2006 when the manufacturing site opened. This floor-standing machine has four-axis control, 160mm focal length lens and includes an electrical Z axis. It also has a useful circumferential fixture, an adjustable marking platform of 200x200mm and fume control for use on polymer marked plastics. The system is controlled using the PryorLaser professional marking software on a PC connected directly to the laser system.
A particular feature of the Pryor equipment is its functionality as a diode marker – it maintains the integrity of the mark, even after acid passivation. Some other kinds of mark would disappear or show signs of corrosion during this process but the capability to program the marker’s Q-switch to an unusually high frequency enables marks to be achieved which survive the passivation process and also overcome the problems of mark corrosion.
Taylor explained the rationale for investing in the Pryor system, “We used to use a sub-contracted marking firm which would charge for each different part. There was a £25 set-up charge and then £1.50 charge per mark. We can now do the same marking in-house (and more) for about 50p per mark. There is a definite cost saving to Comis Orthopaedics, but there is also the convenience that we can mark everything on site that we need to.”
Taylor continues, “As well as marking the parts for traceability purposes during the manufacturing process, before they are sold, we have taken the step of marking all of our jigs and fixtures. We mark it all. If parts are hard to handle during manufacturing, we would make a special jig to hold it and we mark those too so that they are easily identifiable and not accidentally discarded.”
In laser marking the products, the identifier includes the stock, field and part number as well as the Comis Orthopaedics logo. On certain parts, such as power driven tools, the company is required to add its CE mark to comply with European safety legislation and this confirms that the part has been tested to European quality standards and has passed final inspection.
Laser marking is one of the final operations undertaken during the manufacturing process. During machining, some materials will be removed; so marking is left towards the end. The Pryor HP20 will mark alphanumeric data onto either of two sorts of surface: polished (mirror-finish) or glass beading that is a grey, satin finish. Marking can be done on a straight surface or in circular patterns around the edge of a product using the circumferential marking axis.
The HP20 is also used to mark the required millimetre scale on surgical measuring devices using straight lines or curves. Comis Orthopaedics has a calibrated reference ruler against which the operator visually checks the marked scale.
Taylor explains, “We mark our own measuring guides and instruments for traceability. We book them in and can follow them through the manufacturing process and usage. We laser mark the products and then acid passivate them to remove all of the ferric material and create pure stainless steel; that finished part is then booked into stock using the lot number. The part can be easily identified from that point on.”
Pryor’s HP20 and other advanced traceability solutions are capable of marking, verifying and reading barcodes and Data Matrix, a code that can contain a great deal of information and link into databases, third party software and be read by scanners around the world. Data Matrix is now being used extensively in a variety of industries from food packaging to scratch cards, medical instrument traceability and automotive engine manufacture. “We have been considering this and it’s a path that may prove useful to the company in the future,” confirms Taylor.
