In recent years, medical device parts have shown a dynamic growth trend, and medical device manufacturers have continued to look for better turning centers and tools to enhance their competitive advantages. This has also become an important channel for the growth of the tool industry. ISCAR saw this huge development prospect and invested a lot of manpower and material resources to develop special cutting tools for medical device processing. Iska has established a dedicated medical device R&D department at its headquarters. There are 7 professional engineers engaged in program design. They have rich experience and have been engaged in the research of medical device processing tools for more than 12 years. At present, the proportion of cutting tools used in the medical device industry in Iscar's cutting tool products is about 6% to 7%. It is expected that this proportion will rise to 10% to 12% in the next 2 to 3 years.
Difficult in machine titanium alloy materials
90% of medical device implant components are made of Ti6Al4V titanium alloy. Due to its light weight, high strength and high biocompatibility, titanium alloy 6AL-4V has become the most commonly used material for medical implant devices. Titanium alloy Ti6Al4V is usually used in the production of hip joints, bone screws, knee joints, bone plates, dental implants, and spinal connecting elements.
Titanium alloys have work hardening properties. The machining process has a large shear angle, resulting in thin chips and a relatively small contact area on the tool. In addition, the high cutting force during machining, combined with the friction during chip flow, will comprehensively lead to excessive local cutting heat of the tool. Titanium alloys have poor thermal conductivity, so the cutting heat cannot be conducted out quickly. Therefore, a large amount of cutting heat is concentrated on the cutting edge and tool surface. High cutting forces and cutting heat will combine to cause craters and rapid tool failure.
The relatively low elastic modulus makes titanium alloys more elastic than steel. Therefore, excessive cutting force should be avoided to ensure that the rebound of the workpiece is small. Thin-walled parts have a tendency to deform under tool pressure, causing chatter, friction and even tolerance issues. The key to solving the problem is to ensure the rigidity of the entire system. It is very necessary to use tools with sharp cutting edges and correct geometry. In addition, titanium alloys have a tendency to chemically react with cutting tools to alloy at high temperatures, and their chips tend to be welded to the tool surface.
Reliable and compact machine tool fixtures
Medical device processing equipment needs to be able to process small and complex parts made of hard machine materials (such as titanium alloys or stainless steel) with high precision requirements. Processing of bone and joint replacement parts is quite complex. Due to the poor machining properties of the material being machined, the blank is usually bar stock – meaning a large amount of metal needs to be removed. Therefore, a portion of the part is cast into a near-finished shape, which adds to the hassle of creating complex and expensive fixtures. Another factor that adds to the complexity of machining is the narrow tolerance range.
Medical device parts have high requirements on workpiece materials, processing accuracy, surface finish, etc., which requires high reliability of the processing system. As a result, extremely high requirements are placed on machine tools, fixtures, cutting tools, CAM software, etc. Workpieces are typically processed on advanced medical device processing equipment such as Swiss automatic lathes, multi-spindle machine tools and rotary tables. Most of these machine tools are characterized by their very small size and compact structure.
The characteristics and requirements of medical device parts processing have undoubtedly promoted the development of processing technologies and solutions to improve the competitiveness and production efficiency of small and medium-sized enterprises in processing medical devices.
Stable and efficient cutting tools
Generally speaking, there are three differences between the medical device industry and other machining industries:
First, the requirements for machine tools are relatively high. Advanced medical device processing equipment such as Swiss automatic lathes, multi-spindle machine tools and rotary tables are completely different from ordinary machining centers and lathes. Their sizes are very small and their structures are very compact. In order to comply with such requirements, the structure of the tool also needs to be specially designed, and the size of the tool must be small while ensuring the rigidity of the tool. The ISCAR SWISSCUT series is specially designed for cam-type machine tools, which reduces the problem of interference in small processing areas. The blades can be easily replaced from both sides of the tool holder. The high-precision blades and solid tool holder design ensure high precision. Repeatability. MINCUT is the latest tool developed by ISCAR. It can be used for both turning and milling. The small-sized tool has high rigidity and can be used on multi-spindle machine tools or machining centers
Second, there are high requirements for processing efficiency. For medical devices, the most important thing is processing efficiency, that is, the processing rhythm, which requires that the blade can be replaced in the shortest time. ISCAR's MULTI-MASTER series of interchangeable cutter heads can be replaced with different milling cutter heads in just a few seconds. The concept of quick-change tool heads ensures the processing rhythm. In addition, the tool life is required to be as stable and as long as possible. High-quality tools should be used as much as possible, with an overall combination of coating, cutting edge, chip breaking geometry, and tool structure. In this way, we can ensure that the machine tool operates 24 hours a day and compete with other competitors in the market with very high production efficiency, thus gaining a competitive advantage.
Third, the workpiece itself is very different from other mechanical parts. Medical devices implanted in the human body first require very good surface finish, very high precision, and no deviation. This requires the tool to meet high processing requirements from the design of the blade structure to the design of the blade coating. In addition, it also includes the repeated positioning accuracy of the blade, which cannot ignore the high-quality requirements while ensuring improved efficiency.
