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Planning the Process for Additive Manufacturing

By Jon Carlson GF Machining Solutions

Healthy medical manufacturing requires more than just additive machines

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Dental Bridge

The medical industry is booming. Aging populations, rising rates of health care utilization and advancements in manufacturing technology are driving the industry forward—and toward a future that includes additive manufacturing (AM) as a major part of the part-production environment. More additive processes have been validated by national and international regulators, which means the array of possibilities grows wider by the day.

But it isn’t enough to simply bring an additive machine into your shop.

Even if an additive machine meets all the necessary requirements, it is unlikely to lead to massive process improvements on its own. Instead, manufacturers need a turnkey solution for the entire additive workflow, from part programming and design to build plate separation and beyond. Furthermore, this workflow should be easy to integrate into existing subtractive manufacturing processes because despite the common assumption that shops are either additive or subtractive, these technologies are complementary.

Begin at the Beginning

Starting with the additive machine itself, medical manufacturers must meet numerous requirements for parts that can be safely used for health care applications. Implants, surgical instruments and more must be produced with the highest quality materials with exceptional precision. For medical additive machine applications, this generally means the use of powdered medical-grade titanium and a laser sintering process, which delivers the required material purity and precision.

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Femoral Implant (partial knee)

Powdered titanium will rapidly oxidize, so a truly effective AM solution for medical manufacturers will provide the lowest possible concentration of oxygen in its build area and material container. This process, which generally involves creating a vacuum and backfilling the chamber with argon, a non-reactive gas, also helps remove moisture and oxygen trapped in the powder itself, allowing for better use of expensive medical-grade powder along with higher part build quality.

Beyond Additive Machines

Manufacturers can further improve material utilization at the same time they speed up the overall process—and avoid problems that can be caused by highly reactive powdered metals—with powder cartridge systems analogous to those used by office laser printers. These cartridge systems enable operators to reload powders of the same type in about 30 minutes and switch from one kind of material to another in two or three hours—a process that in non-cartridge-based systems takes two or three days.

These integrated cartridge material handling systems can do more than reduce risk and simplify the use of powder, however. They also improve the machine’s ability to direct the powder, which further speeds up the process. A machine with bidirectional powder deposition, for example, can improve cycle times by up to 50 percent over those with unidirectional systems simply by recoating powder beds in both directions.

AM machines must also allow for the flexibility manufacturers need with respect to part size and quantity. Many build chambers are highly restrictive, or only allow for a single style of build plate that limits the variety of parts that are possible. An effective AM solution for medical manufacturers will allow for fully customizable plate configurations, particularly as the health care industry moves toward the high-mix/low-volume manufacturing environments necessary to meet customer demand for patient-specific medical devices.

All-encompassing AM part processing also involves other systems and capabilities. For example, zero-point referencing throughout the entire AM part-production cycle ensures that automation can be set up to seamlessly move parts from additive to subtractive machines for the highest production efficiency possible. So to help manufacturers achieve highly efficient and productive AM operations, OEMs like GF Machining Solutions has worked to go beyond simply talking about 3D printing or part building, but to discuss the entire system, including post-processing—or as the company puts it, going from “art to part.”

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Spinal implant

The Agie Charmilles CUT AM 500

This device is an automation-ready horizontal wire EDM built with AM in mind. For many medical manufacturers, band saws and low Z-height vertical wire EDM processes are far too inaccurate for medical applications, particularly as larger and larger AM machines are becoming common. The CUT AM 500 goes beyond improving the accuracy of part separation – though it delivers ±0.1 mm accuracy and surface roughness of less than 6 µm – but also resolves a number of quality barriers when using band saws. These include but are not limited to geometric inaccuracy, loss of workpiece material (kerf) and damage and contamination to parts.

Accommodating parts up to 510 x 510 x 510 mm (including the base plate) and up to 500 kg in weight, the CUT AM 500 uses 0.2 mm diameter wire to separate additively manufactured parts from build platforms at a maximum cutting speed of 300 mm2/min. The CUT AM 500 blends a horizontal wire orientation, a rotary axis and an integrated basket to catch those separated parts. This combination creates a robust process, which supports the part, allows for easy part handling, prevents part damage and offers full automation readiness.

The layout of the CUT AM 500 is designed to accommodate the integration of a clamping system for easier clamping and referencing. As additive manufacturing evolves into mass production, automated AM processes will be needed. For example, System 3R, a GF Machining Solutions brand, specializes in tooling, automation and software and offers in-house expertise and technology to drive manufacturers’ future success in AM.

GF Machining Solutions DMP Flex 350

The CUT AM 500 is a major reason why manufacturers are able to achieve exceptional part-production speeds with additive machine solutions such as the GF Machining Solutions DMP Flex 350. That recently developed machine is a robust, flexible 3D metal printing solution for 24/7 production of parts up to 275 x 275 x 380 mm in size. With integrated 3DXpert software and LaserForm materials, as well as application support from GF Machining Solutions and its AMotion Center for Additive Manufacturing Excellence, medical shops can achieve full part production with high process integrity.

The DMP Flex 350’s improved gas flow technology ensures improved, uniform part quality across the entire build area—even for parts made with the world’s most challenging alloys and extremely dense, pure metals, such as medical-grade titanium. Furthermore, the machine delivers a pure, low-oxygen environment (fewer than 25 ppm) during printing for excellent microstructures and very high part density. With these fully repeatable and stable mechanical properties, the DMP Flex 350 ensures consistent accuracy from one job to another, key to meeting the needs of demanding medical sector customers.

Dependable, high throughput is essential to productivity for manufacturers, even in the medical industry. To maintain the highest level of 3D metal printing throughput, the DMP Flex 350 offers fast, bidirectional material deposition. At the same time, users’ productivity is accelerated by optimized printer utilization, short changeover time and enhanced scanning strategies.
The DMP Flex 350 machine also boasts a low total cost of ownership (TCO). Its high powder recyclability, modest consumable usage, and safe, long-lasting process filter make the machine affordable to operate, reducing users’ per-part costs.

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Hip Cup

Prototype to Manufacturing

It wasn’t all that long ago that what is now known as additive manufacturing or 3D printing was referred to as “rapid prototyping.” The earliest forms of the technology were developed to make prototype parts—but nothing else. Even then, however, manufacturers were intrigued by the prospect of someday being able to use the technology to make cost-effective metal parts in a real production environment.

For today’s medical manufacturers, however, the inclusion of AM processes isn’t a question of “if,” but one of “when.” Allied Market Research found that the size of the global market for 3D printing in health care was worth $973 million in 2018, a number the researchers expect will grow to well over $3.5 trillion by 2026. The future of medical device manufacturing has arrived in the form of additive manufacturing, and to take advantage of this, shops can and should partner with OEMs capable of supporting their entire workflows, additive and all.

Jon Carlson is product manager-advanced manufacturing
at GF Machining Solutions.

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