By-lined feature for Metal Powder Report
As a pioneer of breakthrough ceramic and metal additive manufacturing solutions, Israeli-based XJet is devoted to the ongoing development of new technological developments. At the recent formnext exhibition in Germany, XJet once again attracted a lot of attention when it announced a new ceramic material and new soluble support material, developed at the company’s recently opened $10m Additive Manufacturing Center. In the following article, Avi Cohen, Vice President, Healthcare & Education at XJet, highlights some of the challenges and advances in ceramics and metal AM.
A NEW REVOLUTION IN PRODUCTION AND MANUFACTURING
3D Printing or Additive Manufacturing (AM) has been a hot topic across many industries for decades. Things have moved fast since Chuck Hull’s first 3D printing machine triggered great interest among manufacturers and engineers in the 1980s. Just how important the technology continues to be was clearly visible at formnext 2018. Exciting new announcements, trailblazing product launches and inquisitive individuals are testament to how buoyant this market is.
As with any disruptive technology, market innovation in 3D printing is incredibly fast with new technologies and substrates being introduced at rapid pace. Metal and ceramics AM in particular are set to propel the market forward. There is a real buzz around the technology, and rightfully so as more and more companies understand that AM’s extreme geometric capabilities are proving ideal for the production of complex ceramic and metal parts.
Although 3D printing is still a small part of the metal and ceramics industries as a whole, it continues to grow rapidly. Wohlers Report 2018 revealed a dramatic increase in metal AM.[1] Industry analysts valued the global 3D printing metal market size at almost $335 million in 2017 and forecasted a compound annual growth rate (CAGR) of 31.8% from 2017 to 2025[2]. Equally positive, ceramics 3D printing market revenues are set to top $3.6 billion by 2028 with a market driven by a strong compound annual growth rate (CAGR)[3].
PLENTY OF OPPORTUNITIES
Traditional manufacturing methods have always employed a subtractive process, using cutting and molding technologies to create limited structures and shapes, with more intricate geometries – such as those with cavities – having to be formed from a number of parts and assembled together. This could take days or even weeks to make and is typically as expensive process. Applying changes or alterations can also be difficult and time-consuming. 3D printing offers designers a way to create complex parts with endless structures and shapes – with precision – allowing them to rethink how they design and manufacture.
Although all metal and ceramic AM technologies claim complete design freedom from traditional production limitations, many AM processes still force designers to consider production limitations such as support for undercuts and draft angles; support removal from cavities; and size and number of fine details. Product design is not yet optimised and parts may still require finishing, thus adding time and cost to the process.
Technological advances such as NanoParticle Jetting (NPJ) enable the production of metal and ceramic AM parts featuring unprecedented levels of detailing, finish and accuracy, while delivering physical, geometric and operational advantages. Hailed as a real ‘game changer’ by industry experts, NPJ offers some very appealing physical benefits over other AM processes. Compared to stereolithography, DLP and binder jetting, parts printed with NJP provide smooth surfaces, superfine details, high density and excellent dimensional tolerance. Its ability to deliver Near Net Shape of ceramic parts means that less machining is required in the green stages, further reducing costs and timescales.
[ALUMINA – NEW CERAMIC MATERIAL
Showcased for the first time at formnext 2018, Alumina, a new ceramic material, is ideal for the use with NPJ technology. Alumina was chosen for development because of its wide use as a technical ceramic. Offering very good electrical insulation, extremely high mechanical strength, high compressive strength and high hardness, it differs from zirconia in that it has lower wear resistance, making it simple to machine and refine both before and after firing.]
THE IMPORTANCE OF SUPPORT STRUCTURES
One of the main issues regarding 3D printing is the need for support when creating overhangs and cavities. Support structures keep parts in place and in position on the plate. When considering what technology to print a 3D model with, it is important to consider support structures and how they may affect the final result.
In some AM processes, support structures are critical in building actual parts because without them, the parts will be unusable or have flaws due to the high thermal stresses involved during the printing process. Support structures can also have an impact on surface finish as they can require post-processing work to remove, resulting in blemishes or surface roughness. In theory, AM enables designers to create truly innovative items. The reality however is not always so simple and planning the support strategy is critical. The designer needs to take into consideration the orientation, location of the parts on the build platform as well as the number of parts to be built.
Unlike typical ceramic and metal AM technologies that use the same material for both the build and the support structures, NPJ uses a different material for support. The ability to jet more than one material simultaneously allows XJet platforms to use a support material that easily disintegrates from the manufactured part afterwards. Cavities and fine details can be created with no concern they will be harmed in the support-removal process.
CROSSING THE FINISHING LINE – THE IMPORTANCE OF POST-PROCESSING
When your metal or ceramic 3D print is done, you just take it out of the printer and start using it, right? Unfortunately, not.
Surprisingly, when it comes to finishing, many companies tend to overlook the importance of post-processing techniques. It is a critical process that can affect the functionality and capability of parts. In addition to support structure removal, another problem associated with powder-bed processes is the loose powder remaining on the part which needs to be removed. The removal is performed either with compressed air or the part is heat treated to remove the internal stresses before the support structures are removed. Designers must consider this early on during planning stages to ensure high quality of the parts.
SOLUBLE SUPPORTS – THE HOLY GRAIL
XJet recently added soluble support material for metal to its portfolio, already having the capability for ceramic additive manufacturing. Dissolving very quickly in a post-processing solution bath, the advantages of soluble support materials are impressive. The process does not require extensive manual labour, large numbers of parts can be processed in very little time and designers can finally achieve the freedom long promised by AM technology. Without hard-to-handle powders, XJet supports offer safe and simple operation. The solution for dissolving the soluble support material is water-based and hazard-free. In addition, both the soluble support and build materials are provided as liquid suspensions which are delivered and installed in hassle-free, sealed cartridges, and printed parts are safe to handle as soon as they are produced. Fine details and complex parts such as internal cavities, lattice structures, and microstructures are no longer at risk of being damaged by the support material removal process and designers don’t need to give special consideration as to how they will be produced.
JETTING INTO THE FUTURE
Industries such as healthcare, energy and automotive industries are at a unique stage in developing 3D strategies. Designers are closer than ever to geometric freedom thanks to NanoParticle Jetting technology which is overcoming many challenges associated with ceramics and metal AM. With no restriction of support material planning and removal, true freedom of design allows designers to focus on the product’s functionality instead of its manufacturability – ushering a new revolution in production and manufacturing.
[1] Wohlers Report 2018 by Wohlers Associates
[2] Grand View Research 2019: the global 3D printing metal market size at almost $335 million in 2017 and forecasted a compound annual growth rate (CAGR) of 31.8% from 2017 to 2025
[3] SmarTech Publishing 2018: Ceramics Additive Manufacturing Markets 2017-2028