What machine is for medical parts? | Blog
Quality, safety, productivity, traceability… For the medical industry that wishes to manufacture surgical implants via metal 3D printing, there are many criteria to consider. In this field, AddUp’s FormUp® 350 machine has many advantages to offer.
The market for surgical implants and patient-specific solutions is undergoing major changes. Manufacturers in this sector are seeking to provide doctors with more efficient and personalized devices, at costs acceptable to patients, while complying with particularly strict requirements for certification. New generations of 3D printers are achieving high levels of productivity/ quality and can produce parts in biocompatible materials like titanium. The new and improved printers allow implant manufacturers to consider the migration to metal additive manufacturing for many applications.
3D printed implants
Surgical implants are medical devices that have the specificity of being adapted to the bone and tissue morphology of each patient. In addition, their surfaces must be specially designed to integrate with the patient’s bone structure; this is called osseointegration and refers to the implant’s ability to promote the solid and lasting reconstruction of bone. For all these reasons, implants made using conventional techniques, such as machining, are very expensive. Indeed, customized implants require manufacturers to provide numerous variations of each model, with associated tooling for each unique geometry. Additionally, surfaces that promote the reconstruction of organic tissue are obtained through additional surface treatments that are both time-consuming and difficult to achieve.
Metal 3D printing, on the other hand, is particularly well suited to manufacture complex and customized parts. This is the reason why medical manufacturers have been interested in this technology since its appearance in the early 2000s. The first applications were slow to emerge for a couple of reasons. First, the Medical Certification Authorities imposed drastic constraints in terms of safety and quality. Second, the productivity and repeatability levels of the machines did not allow the manufacturers to make their investments profitable. However, in recent years, thanks to progress made by metal 3D printing machine manufacturers, applications are multiplying, and the technology is spreading rapidly throughout the sector.
What is a machine designed for the medical sector?
The FormUp® 350 machine offers many advantages to meet the expectations of surgical implant manufacturers. Designed and produced by AddUp, a company created by the French groups Michelin and Fives, this 3D machine uses a technology called Laser Powder Bed Fusion (L-PBF). This process is particularly well suited to the production of complex, customized metal parts with high mechanical properties. It is also one of the most mature technologies in the metal 3D printing market. Several manufacturers, including AddUp, offer recipes for the use of biocompatible materials., In the medical implants field, the most common of these materials is a titanium alloy called Ti6Al-4V ELI, also referred to as Grade 23 Titanium.
AddUp’s L-PBF machine, the FormUp® 350, differs significantly from machines on the market in the following ways:
- Medium or fine powder usage. The flexibility to use metal powders with a small particle size (less than 25 microns) allows the machine to build parts with low roughness surfaces, fine feature details, and “lattice” features that promote osseointegration.
- The ability to use a variety of powder-spreading devices, including the roller device. The roller device creates a high-density powder bed that is suitable for the manufacture of unsupported parts, which greatly reduces the costs associated with post-processing operations. The roller recoater provides this advantage with both fine and medium powder sizes.
- Safety is of the utmost importance to AddUp. . Titanium alloys, in powder form, present risks for both equipment and operators. This risk is mitigated in the FormUp® 350 because the powder is always in an inert environment. The FormUp® 350 is the only machine on the market that allows for the supply and recycling of the powder without any contact with the ambient air. This prevents the risk of user exposure while simultaneously and consistently building parts that meet or exceed industry standards.
Beyond these characteristics, AddUp’s LPBF machine exceeds the industry requirements and expectations of OEM’sgiven the demands of productivity, quality, repeatability, and traceability.
The FormUp® 350 machine was designed based on Michelin’s early adoption of metal additive manufacturing. The challenge was not the technology but rather the consistency and throughput in a high-demand manufacturing environment. Developed by a manufacturer for manufacturers, the FormUp® 350 machine has been fine tuned to promote high productivity. One example is the use of large build plates (350 x 350 mm) with a quick loading and leveling system that avoids any loss of useful surface. In addition, four 500-watt lasers are used, each one with the ability to cover the entire surface of the build plate. The advantage for the user is great flexibility in the placement of the parts on the platform and in the assignment of the lasers (one or more based on need) to the parts to be manufactured.
The FormUp® 350 maximizes the portion of the 3D printing process where the lasers are firing and adding material to the parts making it more advantageous in a production setting. The entire process is designed to optimize downtime before the build commences, during the build, and in the post-production steps. The build setup is streamlined with automated build plate leveling and referencing. Inerting times are short as well. Oxygen levels reach 500 ppm in 15 minutes. During the build itself, the bidirectional powder spreading system is 40% faster than the conventional method. Each of the four lasers works in unison over the entire build area to melt material as efficiently as possible. When the build finishes, the active cooling system kicks in to bring the heated platform down to a suitable temperature. That cooling allows for an earlier start of powder vacuuming, which is performed in the inert chamber through a glovebox. An additional benefit is the ability to supply new powder to the system and powder sample acquisition can happen without interrupting production.
Other active technologies include the fume collection system, which avoids possible drifts due to filter clogging thanks to an automatic filter cleaning system, and the Cross Jet device, which ensures the constant cleanliness of the laser windows during production.
AddUp also offers an in-situ solution to track the melting across the build. The system called “Melt Pool Monitoring” measures three essential parameters of the manufacturing process; the variation of the laser position, the variation of the power supplied by the laser, and the temperature of the melt pool. All this data is collected continuously during the printing process and is then mapped and overlaid on the CAD models of the parts. This allows not only to detect the presence of possible defects but also to locate them with great precision. The location of a pore or defect can be considered to downselect a region of interest for non-destructive evaluation. This tool will also detect defects on support structures, which are often acceptable. In this manner, Melt Pool Monitoring can reduce the cost and lead time of post-process inspection.
Medical manufacturers are faced with severe constraints for the certification of their applications. The processes for certification are difficult to obtain and require manufacturers to control all the manufacturing parameters: they must prove that the process can deliver compliant parts and that the quality will be maintained throughout current and future production.
Among the technologies embedded in the FormUp® 350 that contribute to repeatability are the 3-axis laser scanning systems. Unlike passive systems that distort the focal plane of the laser beam, 3-axis systems are capable of dynamically adjusting the focal length of the beam to guarantee a homogeneous focusing quality and beam shape at any point on the platform, and thus a uniform fusion quality regardless of the position of the part on the build plate.
Another repeatability concern is the powder itself. On AddUp’s platform, the powder management module ensures that the powder is systematically sieved and dried before being sent to the manufacturing chamber, thus avoiding the variations in powder properties that can occur when the powder is stored and transferred through different containers. The module always handles the powder in an inert environment, reducing oxygen pickup as well.
Finally, the roller recoater on the FormUp® 350 is a more robust spreading device than a traditional hard blade or scraper. This means flatter, more consistent powder bed shapes from one production run to another.
Once certification authorities have approved the qualification of an application, implant manufacturers must implement systems to ensure seamless traceability of all parts produced. The PBF process is complex, with many influencing variables that control part quality.
To help manufacturers monitor all the production parameters, AddUp Dashboards offers a real-time solution for all the data production and visualization. More than 80 parameters are tracked, time-stamped, and stored without a time limit in a database. Users can then create custom dashboards, either for machine monitoring, detection, maintenance issues, and analysis of production hazards. They can also compare different identical productions to detect differences between them.
Unlike other systems, AddUp Dashboards also offers access to the specific project file identifier called the GUID (for Globally Unique IDentifier). This 128-bit label, created for every build job, automatically changes upon project edits. It reduces if not eliminates any traceability concerns in the quality process.
These machines have been designed from the very beginning to achieve high levels of productivity and quality, but they have also been improved over the years. Each generation of machine and software addresses previous pain points at every step in the additive manufacturing process. Thanks to the experience acquired in their workshops, AddUp experts use their machines to offer part manufacturing services to their customers in addition to being machine supplier. Today, the FormUp® 350 is used by one of the world’s leading implant manufacturers, which has equipped itself with the FormUp® 350 in production facilities in both Europe and the United States and carries out qualified and large-scale manufacturing.
All in all, the FormUp® 350 platform has inherited the experience of the Michelin group. The machine has been tested in real-world manufacturing environments for many years. Mass production of tire mold parts with global efficiency expectations is a solid pedigree that is now being applied to the medical sector. The quality systems and production expectations for Michelin manufacturing and medical manufacturing are nearly identical. With a focus on quality, consistency, safety, productivity, and repeatability, this platform is easily convertible between industries