Hard to process titanium alloy material

90% of medical device implant parts are made of Ti6Al4V titanium alloy, which is derived from light weight, high strength and high biocompatibility. Titanium alloy 6AL-4V has become a commonly used material for medical implant devices. Titanium alloy 6AL-4V is commonly used in the manufacture of hip joints, bone screws, knee joints, bone plates, dental implants, and spine connecting elements.

Titanium alloy has the characteristics of work hardening. During the machining process, the shear angle is large, the chip produced is thin, and a relatively small contact area is formed on the tool. In addition, the high cutting force during the machining process, combined with the frictional force when the chips are flowing, will comprehensively cause the cutting tool to have excessively high cutting heat. The poor thermal conductivity of titanium alloys prevents the cutting heat from being conducted quickly. Therefore, a large amount of cutting heat is concentrated on the cutting edge and the tool surface. High cutting force, cutting heat will cause the generation of crescent pits, and cause rapid tool failure.

‘S relatively low modulus of elasticity makes titanium alloys more resilient 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 tremor, friction and even tolerance problems. 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 alloy with cutting tools at high temperatures, and their chips tend to be welded to the tool surface.

Reliable and compact machine tool fixture

Medical device machining equipment needs to be able to process small and complex parts made of difficult-to-machine materials (such as titanium alloys or stainless steel) with high accuracy requirements, such as the replacement of bones and joints is quite complicated. Due to the poor cutting performance of the material being processed, the blank is usually a bar stock-this means that a large amount of metal needs to be removed. Therefore, a part of the part is cast into a shape close to the finished product, but this also increases the trouble-the need to manufacture complex and expensive fixtures. Another factor that increases machining complexity is the narrow tolerance range.

Medical equipment parts, workpiece materials, machining accuracy, surface finish and other requirements are high, which requires high reliability of the machining system. Therefore, high demands are placed on machine tools, fixtures, tools, CAM software, etc. Workpieces are usually processed on advanced medical equipment machining equipment such as Swiss automatic lathes, multi-spindle machine tools and rotary tables. The characteristics of these machine tools are mostly very small size and very compact structure.

The characteristics and requirements of medical device parts machining undoubtedly promoted the development of machining technology and solutions to improve the competitiveness and production efficiency of small and medium-sized medical device machining.

Stable and efficient tool

Generally speaking, the medical device industry is different from other mechanical machining industries in three points:

  1. The requirements for machine tools are relatively high. Advanced medical machining equipment such as Swiss automatic lathes, multi-spindle machine tools and rotary tables are completely different from the usual machining centers and lathes. Their size is very small and the structure is very compact . To meet such requirements, the structure of the tool also needs to have a special design, the size of the tool needs to be small, and the rigidity of the tool must also be guaranteed. The ISISS SWISSCUT series is specially designed for cam-type machine tools, which reduces the problem of interference in small machining areas and can easily replace the blades from both sides of the arbor. The high-precision blades and solid tool holder design ensure high Repeatability. MINCUT is the latest tool developed by Iscar. It can be used for both turning and milling. The small size tool has high rigidity and can be applied to multi-spindle machine tools or machining centers.
  2. High machining efficiency requirements. For medical devices, the most important thing is the machining efficiency, that is, the machining cycle. It is required that the blade can be replaced in the shortest time. Iscar’s MULTI-MASTER Transformers series can be replaced with different milling heads in just a few seconds. The concept of quick-change tool heads has a good guarantee for the machining cycle. 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 a combination of coating, cutting edge, chipbreaker and tool structure. In this way, the machine can be guaranteed to run 24 hours, and can compete with other competitors on the market with very high production efficiency, so as to obtain a competitive advantage.
  3. From the workpiece itself, it is very different from other mechanical parts. Medical devices implanted into the human body must firstly have a very good surface finish, very high accuracy, and no deviations. This requires the tool to meet the high machining 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 can not ignore the high quality requirements while ensuring the improvement of efficiency.

Complete solution

PTJ Cnc Machining Shop deeply analyzes the characteristics of medical device industrial implants to improve the processability of these very critical components. Therefore, PTJ Cnc Machining Shop also designs and manufactures special tools, inserts and chip flutes to process titanium alloy Ti6Al4V and obtains the high-precision tolerance values ​​required in this particular field. In order to cooperate with such parts manufacturers to use their existing production equipment, Iscar also provides special tools to meet different applications.

The solid carbide end mill with sharp cutting edge developed by PTJ Cnc Machining Shop can be used for machining concave parts and eliminating burrs. These end mills can achieve polishing and milling with a maximum margin of 0.01mm in semi-finishing and finishing. We also develop tools for machining titanium alloys and stainless steels at the same time-PVD coating based on ultra-fine grain substrates to achieve high-speed machining with high cutting speed + high feed. The milling cutter has a small diameter, and a skew machining strategy can be used in programming. Its advantages are that it can obtain the cutting speed on the outer diameter of the tool, smooth chip evacuation, and lower cutting heat under the contact area of ​​the cutting area.

The R & D department of PTJ Cnc Machining Shop found that in the medical device industry, turning needs to be improved for blade grades or chip flutes. To meet the needs of users, PTJ Cnc Machining Shop has developed high-quality grinding blades, such as VCET, DCET, CCET, etc. The blade geometry is WF. The advanced production technology of PTJ Cnc Machining Shop guarantees such improved blades with polished chip flutes to achieve excellent surface quality for semi-finishing and finishing. In some special applications, PTJ Cnc Machining Shop can provide VCGT inserts with MD chip flutes for high surface quality. PTJ Cnc Machining Shop’s JET-CUT series cutting blades, with blade widths of 3mm and 4mm, have high surface quality and long tool life. Originated from the belief of PTJ Cnc Machining Shop-upgrade without limits, PTJ Cnc Machining Shop has developed HP high-pressure cooling system tools based on TANG-GRIP series.

Using proven technology and tools and verified cutting parameters can more timely face the market of medical device parts and components. Based on years of experience in the medical device industry, PTJ Cnc Machining Shop has also launched a tool case for the medical device industry, which, together with DMG machine tools, provides customers with turnkey projects.