4.1.1

The process chain for a typical implant begins in the clinic, where the doctor uses CT scan imaging data to select an appropriate implant

Today’s machine shops, whether in the medical technology or tool and moldmaking sectors, can take advantage of an integrated Siemens CNC solution for everything from the design concept to the finished product.

The production of today’s medical implants involves an entire process chain, starting with the doctor and ending with the finished device. Doctors use the imaging data of a complex fracture, acquired with a computed tomography (CT) scan, to select an appropriate implant and then position it in the fracture area of the patient on the computer. Of course, this is only possible if the implant geometries are stored in a database, and the doctor has implants in stock or can access them immediately from a manufacturer.

Simulation of machining sequences

NX CAM programming from Siemens PLM enables realistic simulation of machine tool functions.

NX CAM programming from Siemens PLM enables realistic simulation of machine tool functions.

In plastic surgery, however, where implants specifically manufactured for each individual patient are needed, a different process is employed. Instead of pre-machined parts, implants are custom-made with the help of 3D imaging. In this case, the machine tools are controlled using the implant geometries. Calculated contours and shapes are acquired by the CT scan to produce implants that are literally a perfect fit. However, the feasibility of the planned production process can first be determined on a monitor using, for example, an NX graphic simulation from Siemens to avoid potential collisions or damage to the workpiece contours.

Technology package for milling

Implants for knee joints are precision machined with the High-Speed Cutting HSC process on a machine tool run by Siemens SINUMERIK 840D solution line CNC technology.

Implants for knee joints are precision machined with the High-Speed Cutting HSC process on a machine tool run by Siemens SINUMERIK 840D solution line CNC technology.

High-speed cutting (HSC) is a machining process with high material processing speeds. HSC machine tools achieve high spindle speeds, combined with feed rates that are much higher than those of conventional machine tools. Consequently, they require control systems and part programs that perform equally fast. The Siemens Sinumerik® 840D solution line CNC is specifically designed for the requirements of medical technology and this precision part HSC work. Integrated functions onboard the CNC assist users with set-up and programming, thus allowing faster and more precise production sequences.
Together, the Sinumerik CNC system and ShopMill® software from Siemens form a milling technology package that allows machine operators rapid access to the functions they need. Thanks to graphic function display and plain language input dialogs, cycles can be used quickly and effectively, after a brief training period. Even the smallest errors can be corrected during operation, using multi-axis kinematic analysis. The Siemens Safety Integrated® solution further provides protection for personnel and machinery. This software can be used to interlink emergency stop buttons and light barriers. In the event of an operating error, dangerous movements are immediately brought to a standstill and the power supply to the motor is quickly cut.

The use of measuring probes

The production of artificial knee joints on an HSC 20 linear milling center manufactured by DMG, for example, can be fully controlled and monitored by a Siemens Sinumerik CNC system. With its broad range of functions, this milling center is particularly well suited for use in the medical technology sector. It is equipped with linear drives on all axes and achieves acceleration rates over 2g. The machine can also generate a surface finish down to 0.2 micrometers Ra. The liquid-cooled machining spindle operates at speeds up to 42,000 rpm, thereby covering an extensive range of potential applications in the medical sector, where materials such as titanium, chromium-molybdenum, tantalum and niobium are typically milled.

In order to achieve maximum precision during implant production, while also maintaining a consistently high level of product quality, parametric measurements must taken continuously from both the machine and the workpiece. probes, for example, on HSC production machines measure tool dimensions in-process, detect broken tools and are used for the set-up and measurement of workpieces. In medical machine shops currently, the targeted use of such measuring probes can reduce set-up times by up to 90%, while substantially improving process control.

Cost-effective machining

The finished implant is a perfect fit

The finished implant is a perfect fit

Metal parts used in medical technology are often extremely complex. Therefore, choosing the right tooling can have a great impact on the quality of the finished products. After all, proper cutting tools ensure that the parts leaving the machining center are absolutely precise and require no further finishing work. Although the materials used for many medical and orthopedic parts are often quite difficult to machine, the tools must fulfill high performance requirements with respect to the precision and surface quality of these implants. Iscar, one supplier of such tools, offers a program for monitoring the use of precision tools on turning, drilling, milling and finishing jobs. They also help users assess the performance qualities of non-vibrating carbide milling cutters, which are well-suited for machining implant materials, plus they can offer information on more cost-effective and efficient machining processes.

For more information on Siemens SINUMERIK CNC, visit www.usa.siemens.com/cnc.

For specific product information and inquiries, call (800) 879-8079 ext. Marketing Communications or send an e-mail to: SiemensMTBUMarCom.industry@siemens.com.

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Siemens Industry Sector is the world’s leading supplier of innovative and environmentally friendly products, solutions and services for industrial customers. With end-to-end automation technology and industrial software, solid vertical-market expertise, and technology-based services, the sector enhances its customers’ productivity, efficiency and flexibility. With a global workforce of more than 100,000 employees, the Industry Sector comprises the Industry Automation, Drive Technologies and Customer Services Divisions as well as the Metals Technologies Business Unit. For more information, visit http://www.usa.siemens.com/industry.

The Siemens Drive Technologies Division is the world’s leading supplier of products, systems, applications, solutions and services for the entire drive train, with electrical and mechanical components. Drive Technologies serves all vertical markets in the production and process industries as well as the infrastructure/energy segment. With its products and solutions, the division enables its customers to achieve productivity, energy efficiency and reliability. For more information, visit http://www.usa.siemens.com/drivetechnologies.

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