Features

For years, the medical device industry has been leading the adoption of additive manufacturing. With the evolution of high-precision printers that span a large offering of performance resins, thermoplastics, and metals, the small size and high customization requirements of today's medical components fit perfectly into the capabilities and value return of additive manufacturing. In addition, quality controls and regulatory adoption of numerous additive manufacturing technologies and materials are allowing designers, manufacturers, and end users unparalleled ability to design, validate, and bring to market the next generation of medical technology.

ProX™ DMP 320 Direct Metal Production 3D Printer.

Quantum Equipment Advancements

Additive manufacturing technologies offered today are unsurpassed in capability, performance, quality, and reliability. Extrusion, photopolymerization, jetting, fusion, and metal additive systems now use production-level equipment that is capable of output that meets the most demanding needs of the industry. Production-grade print heads, optimized post-processing, integrated recycling and feedstock supply, and a step change in throughput and computing power have been combined to deliver highly sophisticated production equipment.

In addition, these production machines have advanced process controls that monitor and regulate oxygen content within the building cycle, ensuring the highest levels of product performance and quality. For all metals and high-performance thermoplastics, oxygen levels must be controlled in every layer of the process to prevent oxygen from causing improper fusion leading to degraded material properties. Process monitoring and feedback systems for abnormal operating conditions are now offered to monitor, record, report, and provide real-time feedback to the system and operator.

Advances in Materials for Additive Manufacturing

To augment the advances in machine capability, the materials used in additive manufacturing have also gone through revolutionary improvement. Continued expansion of resins in the photopolymerization and jetting systems have created polymers with strength and durability that rival injection molding. Solidification and curing rates have increased substantially, driving improvements in printing time and capabilities.

Metals used throughout the additive processes have increased from cast properties to that of forged processes, and densities now exceed 99.5 percent, with many reaching greater than 99.9 percent. Powdered alloys, the raw material used in the metal processes, are now produced alongside traditional production metal powders and have the same certifications, traceability, and quality controls established.

Spinal implants.
Custom dental application.

The Role of Software, Design

To complement the advances in machine and material technologies, software continues to evolve and transform how designers and manufacturers implement additive manufacturing. CAD systems and optimization solutions continue to develop advanced routines that further enhance product design and capability. Combining software, machine, and materials together has created a solution set that far exceeds what traditional manufacturing has been able to provide. With the ability to design intricate lattice structures, randomized osseointegration, organic structures that mimic skeletal behavior, and geometries that match a patient's own physiology, medical companies now have unparalleled ability to design cutting-edge devices to revolutionize the industry.

For example, combining the 3D scans taken during investigation and diagnosis of a patient, a designer can use advanced CAD to create an implant that precisely conforms to the patient's body for devices such as dental bridges and crowns; bone replacement such as jaw, cranial, clavicle; spinal implants; and bone plates. Producing these custom components using traditional manufacturing with the unique programming, setup of specialized tooling, and the machining of each device independently would be unachievable with conventional processes such as milling and turning. Long cycle times would increase production costs, and more importantly, delivery time to a patient, making traditional manufacturing impractical. Instead, additive manufacturing allows the manufacturer to build multiple custom solutions simultaneously within a single process. This drives capability, productivity, and affordability to a whole new level.

Hip cup with advanced osseointegration.

Understanding FDA Controls Via Additive Manufacturing

As with any new process or technique being introduced into a medical device, it is important to understand the level of regulation and controls applied by the Food and Drug Administration (FDA). The implementation of additive manufacturing is no different, but it is important to understand how and where these requirements will be applied. In general, there are major activities along the way that all FDA-regulated manufacturing processes are controlled by: receipt of materials, design of product, premarket testing and activities, manufacturing of product, final inspection of the product, and shipment. With additive manufacturing, there are many areas in this cycle that are identical, but other areas are often streamlined due to the nature of the manufacturing process.

Receipt of materials is essential with any manufacturing process, as it dictates the quality control of products even prior to manufacture. With additive manufacturing, the materials are provided in controlled containers including all certifications and traceability. For many materials, this information includes RFID identification of the material, foundry, production date, lot numbers, and other necessary details. Since additive manufacturing material is loaded and used at the point of manufacture, tracking and accountability is streamlined.

Enhanced Product Design and Pretesting

Design of the product is enhanced and greater control established with additive manufacturing. With the direct-from-CAD capability of additive manufacturing, the CAD design directly controls the production of the finished part, therefore eliminating the need to translate and convert original CAD designs to 2D prints and tool path geometry. Eliminating design steps in the process improves overall quality and communication throughout the product development and production cycle, providing full downstream and upstream evaluation to design intent.

Polished knee implant.

Premarket testing and activities are improved and accelerated with additive manufacturing. The ability to produce, test, respond, and retest at an accelerated pace with additive manufacturing enables the manufacturer to test more iterations and quantities of parts than was previously possible with traditional manufacturing.

The ability to produce variations in design and test procedures allows the manufacturer and FDA the ability to test and evaluate cases in months rather than years. Manufacturing of the product is the single most influenced step by additive manufacturing. The ability to produce complex geometries, assemblies, and functional products within the confines of a single machine provides greater control over the manufacturing process. Additive manufacturing can replace multiple machining and setup operations with a single printing process, which reduces the complexity of overall manufacturing requirements, as well as minimizing the introduction of variations and potential failure points.

Clavicle with lattice structure.

Optimizing QC/Inspection

Lastly, inspection and quality control can be optimized by taking advantage of the true digital thread that ties additive manufacturing together. As stated earlier, the same model used during the design process is used to print the part, but it is also the same model that can be used to inspect the finished geometry. By combining additive manufacturing with advanced inspection and metrology techniques such as bluelight scanning or computer aided tomography (CAT), the manufacturer can inspect, verify, and record more data than ever before. Having the ability to apply full dimensional evaluation of the product improves quality for the manufacturer, FDA, and the customer.

Conclusion

Additive manufacturing continues to revolutionize the medical device industry by providing advanced processes, tools, and materials to designers and manufacturers to produce the next generation of superior products. By incorporating high-performance plastics and metals with the advanced design and manufacturing capabilities of additive manufacturing, designers and manufacturers will succeed in advancing medical device development to market devices faster at lower costs and with greater quality than ever before. Improving product designs, enhancing patient solutions, and streamlining the manufacturing process will continue to accelerate the implementation of the wide array of additive technologies available and will result in continued growth and advances in medical technology.

This article was written by Benjamin Fisk, General Manager of Methods 3D, Inc., Sudbury, MA. For more information, Click Here.