3D printing is a great tool to make medical implants, and materials have a significant influence on the quality of the final product.  This blog focuses on materials for metal 3D printing implants.

3D Printing medical implants is a new tool to complement an already very advanced medical device industry. 3D printing is becoming more common with manufacturing high-value medical implants, which require osseointegration and/or patient-specific shapes. 

Beyond geometry, it is especially important to figure out what material is used in the 3D printing of the implant. For metals, a metallurgical process and metallurgy are what make it beautiful.

Materials for metal 3D printing implants: feedstock is the key

The 3D printable material or ‘feedstock’ starts as a powder and needs to be well known from the beginning, in contrast to the usual machining process, where a solid metal block is carved using the ‘milling’ process. The 3D printing process melts the powder to form the implant, which opens a myriad of variables that can change the material microstructure and chemical composition.

Feedstock characterization comes in place to avoid uncertainties in the final product, each character has an influence on different aspects of the final implant.

Materials for metal 3D printing implants: Left in the Dust!

The 3D printing processes for metal implants start by making the feedstock. The powder makers get a solid material and break them into small particles in a process called ‘atomization’. There are several ways to make it happen, but the best method for 3D printing feedstock is ‘plasma atomization’. 

To make a long story short, ‘plasma atomization’ is a process where a flow of melted metal passes towards a high-pressure gas torch with a sun-like temperature, creating a zillion small metal droplets that cool down and solidify while falling. This happens inside a tank that collects these droplets thru a bottom-funnel and is sieved to be separated by grain size, which typically ranges from 5 to 105 microns. 

Materials for metal 3D printing implants: Are you in good shape?  

Powder bed fusion relies on powder spread over a platform in a very even way to be melted in the contour of the implant, so the shape and size of the powder grains are very important in the quality of this “bed”. Uneven powder spreading generates difficulties in the powder spreading system which also leaves spaces for undesired porosity and oxygen contamination in the final product. 

Powder bed fusion using Laser or Electron Beam as a heat source is the most used 3D printing process for metal implants. Variations in handling, quality control, and safety limitations related to powder size and flowability. Therefore, inspecting the powder in relation to these parameters is important to have a stable, precise, and safe process. On a more mundane aspect, the smaller the powder particle size, the higher its price.    

Materials for metal 3D printing implants: Chemical composition 

Chemical composition determines biocompatibility, microstructure, and subsequently mechanical properties of the implant. Perhaps the biggest difference between 3D printing and other processes is the fact that the material’s chemical properties change during the process. Different chemical elements have different melting and boiling points so the vaporization rates are different for each element in the alloy, so this must be compensated in the feedstock. 

How we handle, blend, sieve the powder, and clean the part impacts the quantity of humidity and contamination in the feedstock. Therefore, most implant makers having strict control over the powder before and after the building process. This allows implant makers to control humidity and oxygen during printing, which has a direct influence on the mechanical properties of the resulting implant.

Materials for metal 3D printing implants: Like in cheese, better check the texture and quantity of holes.   

Morphology and composition have a direct effect on the final implant microstructure. The microstructure has great importance in the implant strength. The smaller the material crystals are, the more grains there are, and consequently more internal boundaries. Internal boundaries lead to bigger resistance to the atom’s mobility, which is related to strength.

When material failures, normally happen by cracking, cracks are generally initiated by irregular pores, rounded pores usually do not initiate cracks, so control feedstock is mandatory to control the process-induced porosity and cracking. 

3D printing medical implants are trending. The beautiful pieces of metal that look like cyber limbs or mimic nature are very compelling images, but material science cannot be left behind or we risk the benefits these incredible implants can bear. 

About the Author: 

Fabio Sant’Ana has a Precision Mechanics degree and a Business Administration Bachelor’s, born and raised in São Paulo he has 25 years of experience in helping companies to acquire and take full advantage of 3d Machining and Additive Manufacturing Equipment. Entrepreneur and knowledge avid is a member of standards organizations ASTM F42 Additive Manufacturing, ABNT CEE-261 Manufatura Aditiva e ABNT CB-26 Odonto-Médico-Hospitalar. CAD/CAM, Surface Modelling, and EBM specialist is passionate in connect people and companies to the right tools to accomplish the mission.

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(Translated from Portuguese)

It’s a Long story.

Information storage and distribution is something old, started with memory recap and speeches, passed by stone sculpting, handwriting, was highly improved by Gutenberg and now relies on computer files and the “cloud”. On additive, the information had been transferred mostly by “Standard Tessellation Language” –. STL computer files.

Created to take the geometry from CAD to the stereolithography machine it is a simple way to give shape to the computer information by making a huge list of point coordinates.

Figure 1- Segmented CT SCAN of my back – STL format

What is the AMF format?

But nowadays, with the wonders of “additive machines”, we need more information than geometry to be able to define a part. We need to define color, material, quantities, geometry, textures, design, authorship, intellectual property information to more precisely define additive manufactured parts. 

One initiative to improve information transfer in additive manufacturing is ISO/ASTM52915 – 16 Standard Specification for Additive Manufacturing File Format (AMF) Version 1.1. ISO and ASTM have a special joint development initiative for additive manufacturing, with a joined committee ASTM/F42 and ISO/TC261. This committee manages how information is transferred, stored and used by the community either for industrial or medical purposes.

The format not only defines the geometry by points and triangles, but also permits a new shape of facet called “curved” where the edges of the “triangle” are interpolated curves. This can be challenging, but it is one step closer to define real world shapes.

Figure 2 – Courtesy ISO/ ASTM 52915-16

The format also includes definition for colors in RGB standard,  for part surface in 2D and 3D textures, and even for materials, which are all new information compared to STL .  This is a huge advance in communication for AM.

As manufacturing information, AMF can pass build positions, quantities, arrays, and others. This has great potential not only in communication but also in file sizes since AMF is XML standardized so it can be compressed via ZIP format.  Using a single shape, we can define a fulfilled building volume in a much smaller file.   

Object definition can contain metadata, which is the space for other information like in CAD files. It can include information about ownership, part ID, object description, producer, tolerances, or how it was scanned or constructed plus two physical properties, elastic modulus and Poisson ratio. Containing these additional information represents a significant improvement in the quality of communication in comparison to an STL file. With more information inside a single file, it can be used directly by the systems to build a much more well-defined part or object.

Future Ahead

A lot of information relevant to the final object and its built process are not yet covered by the standard yet, perhaps omitted to simplify the initial adoption. But some are already in discussion to be added (by ISO/ASTM committee), including information such as critical dimensional and geometrical tolerancing , equation defined geometries , Boolean operations,  surface roughness ( very important on fatigue properties and also in the medical use ) , definition for the type and geometry of particular processes supports , voxel representations (something that may open a completely new technology inside this already new technology) , IP locks and watermarking , surface patterns related to tactile and coatings, and more .

Why Make Sense?

In a broader sense,  it’s easy to understand the beauty of having a common information container.  

Figure 3 – Courtesy Pesquisa Fapesp Magazine

Having all this info is very important down the line when, for example, building a biomodel. It’s important to have a real representation of the anatomy. It should include the texture, the hardness of the material, the feeling in the surgeon hands, the right resistance to the scapel cuts or the tension on the vascular models (for example, that will compress the stent being tested).  Manufacturing implants or surgical guides needs to be done right in the shape, quantity, and material. We cannot waste expensive titanium alloy we are using, so it is important to automate the quantities and shape checking. It is also important for the implant to match the physical attributes tailored for the part and its effects against the bony structure and encourage osteointegration. FDA already realized this and included a recommendation about .AMF inside the “Technical Considerations for Additive Manufactured Medical Devices ; Guidance for Industry and Food and Drug Administration Staff” issued last year.

The community didn’t embrace this format yet due to lack of awareness and discordance on how geometry had been defined among other debates. Other formats like the 3MF for lattices and new formats are coming out, and the constant technology advances are bringing benefits to the additive world. 

In conclusion, on medical or industrial processes, consistency is mandatory, so the more information a file can include, the better the process you get and the less you need to depend on people decision or actions. Consequentially, more information results in more automation, more accuracy, more repeatability, and higher quality.  These factors lead to better life for consumers or patients, independently of what market you are in.

About the Author:

Fabio Sant’Ana has Precision Mechanics degree and Business Administration Bachelor’s , born and raised in São Paulo he has 25 years experience in helping companies to aquire and take full advantage of 3d Machining and Additive Manufacturing Equipment . Entrepreneur and knowledge avid is member of stardarts organizations ASTM F42 Additive Manufacturing , ABNT CEE-261 Manufatura Aditiva e ABNT CB-26 Odonto-Médico-Hospitalar . CAD/CAM , Surface Modelling and EBM specialist he is passionate in connect people and companies to the right tools to accomplish the mission.

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Last week I went back to CIOSP.  It’s the biggest South America Dental Trade Show, similar to European IDS.  During last year’s show, 3D-scanner and dental milling machine were quite popular.  Small benchtop mills and lathes were all over the place and the biggest companies like Cerec and 3shape were dominating the showroom.

2019 brought a new trend: 3d printing was in almost every booth,  including the implant makers. Even little resin photopolymer solidifier has its space. The dental industry is really embracing additive! But how are they using it?

Here is the list :

Instruments

To be able to position the instruments during the implant and restorations many dentists can make the surgical guides themselves or ask the dental lab to make them for the procedure. These devices are designed over the 3D scanned dental models and save lots of time for the dentists and the patients.

Dental Models

The Digital dentistry is moving forward fast, the old plaster models made from mouth alginate impression are in the past,  everyone now wants the intraoral 3D-scanner. Even though it is not so easy to take the scan, because it demands experience with the device, this is becoming increasingly popular. After digital design work (CAD/CAM), the models will be made in small 3d printers, with biocompatible ( or not) resin, and used for many things in dental work.

Castable Resin

Even when a cast is needed,  from metal denture pattern, metal crowns, to ceramic teeth,  we can now have a castable resin that is lost during cast of the parts. Those parts can also be designed over 3D-scanned models and then customized to the shape of the patient, saving a lot of time and effort from labs and dentists.

Dentures and Teeth

Finally even the aesthetic part, gums and tooth, are being made direct by 3d printing in resins that imitate the look and feel of the real thing, small adjustments made by the dentist and voila you have a new set of polymeric teeth with a much more comfortable fit in a very short time.

Aligners

The transparent aligners are being used for some time now. They always had been made using 3d printers to make the molds for the mouthpieces, but now with new resins, even the aligners itself can be made in the machines. This is bringing a new speed to the aligner maker and more players like Strauman and even smaller labs are fighting for the market that was almost exclusive to Invisalign.

To be included in the market all big dental companies are releasing 3d printing dental systems but based on that, I got inspired and just after arrive office started to play with files and my little resin photopolymer solidifier… the result? You find in the set of pictures hereunder.  I think that it proves everyone with some knowledge can take big benefits of the new digital dentistry.

About the Author:

Fabio Sant’Ana has Precision Mechanics degree and Business Administration Bachelor ’s, born and raised in São Paulo he has 25 years experience in helping companies to acquire and take full advantage of 3d Machining and Additive Manufacturing Equipment . Entrepreneur and knowledge avid is a member of stardarts organizations ASTM F42 Additive MManufacturing, ABNT CEE-261 Manufatura Aditiva e ABNT CB-26 Odonto-Médico-Hospitalar . CAD/CAM , Surface Modelling and EBM specialist he is passionate in connect people and companies to the right tools to accomplish the mission. Fabio is our current community manager in Brazil, San Paulo.

The post Digital Dentistry During CIOSP 2019 (Sao Paulo International Dental Meeting) appeared first on 3DHeals.

Last November,  Frankfurt, Germany received the biggest crowd in Additive Manufacturing. Formnext2018 is the major showcase for the AM technology and its accessories. Formnext 2018 filled two halls of Frankfurt Messe, which means a double than last year.

Additive manufacturing is becoming more mature, we can now produce final components in polymers or metals in quantities that make sense in the manufacturing world. In addition, we have full control of this new process, full production was the tone of the show. Machine builders showcased features about fast builds, parts quantities measured in pieces per year, and process automation like heat treatment and build plate management inside the machines.  Most of the demo parts were fully filled build plates.

Picture Courtesy of Materialise

On the healthcare side, companies presented equipment capable of making biomodels with multiple textures and materials, models that can simulate surgical procedures perfectly; polymer cutting guides to make precise bone resections;  equipment capable of making polymer and metal implants with the right geometry, properties, and osseointegration;and computer systems capable of create shapes based on human body physiology.

Most current build preparation systems, with optional functions or not, can simulate the build process with good precision and geometrical correction about the thermal, stress, and supports displacement, in laser powder bed fusion process. Similar systems will be available to other AM process soon. New supports calculation algorithms are making the built more stable and repeatable. DED and EBM processes are being supported by some systems and should have the same coverage as FDM and LPBF processes in a short time.

What is called by the industry post processing, I call finishing,  are advancing fast. Things like automated support removal, build plate separation, heat treatment and surface finish are being really integrated into the chain and had a big exposure in the show.

ASTM and ISO held a joint workshop discussing the standards development for additive, all the most important officers of both organizations were present and a good panel with the biggest standards specialists in industry discussed the main challenges we face while developing it.

Additive manufacturing is a new technology, now available for the manufacturing of real-life products. AM has the innovation capacity for any sector, from fixture devices to medical devices,  aerospace parts, to tooling and production equipment to complete final automotive components. AM should no longer be seen as a substitute to well-established process that make products properly with well-adjusted supply chains. It is important to keep in mind that AM is initial, final and complimentary to processes like machining and injection molding in making large quantities of parts. These traditional processes have precision requirements not met by metal AM yet. By being a polymeric or metallurgical process, AM   has its limitations and needs proper use.

Additive Manufacturing is a process to add to the traditional manufacturing process. It must be integrated into the factories, must be understood and developed. Yes, additive machines and systems have its “marvelous” features as well as challenges, but our industry will progress to implement and improve itself. We can soon experience an exponential jump to better-designed products and massively improved manufacturing. Formnext2018 confirmed we are on the right path!

About the Author:

Fabio Sant’Ana has Precision Mechanics degree and Business Administration Bachelor’s , born and raised in São Paulo he has 25 years experience in helping companies to aquire and take full advantage of 3d Machining and Additive Manufacturing Equipment . Entrepreneur and knowledge avid is member of stardarts organizations ASTM F42 Additive Manufacturing , ABNT CEE-261 Manufatura Aditiva e ABNT CB-26 Odonto-Médico-Hospitalar . CAD/CAM , Surface Modelling and EBM specialist he is passionate in connect people and companies to the right tools to accomplish the mission.

The post Formnext 2018 Healthcare: Production is the Key appeared first on 3DHeals.