Lukas Tonetto
Micro waterjet cutting is already being used successfully in the production of implants. By means of a new injection procedure used by Swiss Microwaterjet AG, surface structures can now also be processed using pure water.
Medical technology is under a great deal of pressure to innovate, as are other medical areas, in particular with regard to implants. This pertains to medicine itself on the one hand, but also to the manufacture of the materials being used on the other hand, as well as the actual production of the implants. In addition to new procedures such as stereo-lithography for the manufacture of biocompatible implants made of bio-ceramics, boring and cutting, implants are also being produced in well-known procedures such as vulcanisation (silicone). In the field mentioned just above, a new branch is meanwhile making its presence felt, which just a few years ago was unheard of in medical technology: waterjet cutting and micro and precision waterjet cutting, a development of Swiss Waterjet Group with its Microwaterjet product and the procedure known as AWJMM (abrasive water jet micro machining).
Waterjet cutting is a cold separation process, which processes or cuts through any desired material using high kinetic energy. No thermal tension is generated inside the material thanks to the temperature-neutral process; the material’s structure and strength are preserved. In this process, which was notably refined over the last 10 years by Microwaterjet AG — based in the Swiss city of Aarwangen — a specialist in abrasive procedures cut special materials such as titanium, nitinol or niobium. In the abrasive procedure, processed particles — usually garnet sand — are added to the water, and accelerated by the waterjet, making it possible to cut hard or complex materials. Today, in series-tested procedures and in addition to surgical tools such as levers made of tool steel or PEEK, Microwaterjet also produces implantable X-ray reflectors, ball sockets made of titanium webbing, or socket blanks made of chromium-nickel steel, ceramics or plastic. But when it comes to implants, the quality of the processed material is important along with the processed material itself. A properly altered surface quality promotes the growing together of implants with the human body.
Alongside popular procedures for processing surfaces, Microwaterjet uses a specifically developed procedure for injecting materials. Injection by means of waterjet occurs via a WJIP (water jet injection pulse) procedure, which Microwaterjet AG applied in the production of a hip joint socket made of plastic. With this procedure, with patent applied for by Waterjet Robotics, the properties of any number of materials can be changed and adapted. Injection involves relevant advantages compared to other procedures, in particular thermal or chemical procedures. Chemical procedures, such as coating, may contaminate the implant with residues.