Metal parts from the 3D printer - industries such as medicine and aerospace are already turning to this in isolated cases, because additive manufacturing, i.e. "layer by layer", opens up many new constructive possibilities in the design of a product.
What is new is that additive manufacturing is now also increasingly able to score in terms of metallurgical product properties: companies such as DEW (Deutsche Edelstahlwerke, Swiss Steel Group) and research institutes such as RWTH Aachen are working flat out on the development of innovative powder materials that are designed to bring more corrosion resistance, strength and resource efficiency to each layer. A first groundbreaking innovation milestone was recently achieved: DEW recently presented a new metal particle powder that is also suitable to produce tool steel in 3D printing for the first time. There is no longer any question: additive technology is now changing the DNA of metals beyond the design benefits, giving you entirely new material properties. Anyone who still shies away from the new technology or labels it as economically irrelevant is making a potentially fatal mistake.
The extent to which 3D printing has now arrived in business and society is demonstrated by a study conducted by French 3D printing service provider sculpteo, in which around 1,900 people from more than 71 countries were surveyed on their opinions of 3D printing:
According to the survey, half of the respondents expect a now dawning "prosperous age" for 3D printing with an important role in production, the economy and even in the lives of individuals. Only 3%, on the other hand, still consider 3D printing to be a passing fad.
Just over two-thirds of respondents cite the printing of complex geometries as the most important advantages of the layer-by-layer process, and half cite rapid iteration, i.e. the ease with which the production process can be repeated. In third place, for 42% of survey part-takers, is the individual modification of a product to suit the wishes of the buyer, so-called "mass individualization".
To boost the growth of the 3D printing industry, reliable technologies, new materials and low entry costs are now needed above all. Only in fourth place comes the term sustainability, although 3D printing, because some of the metal powders used in it come from scrap, also holds good cards when it comes to decarbonization.
Important to know: There are various processes for 3D printing. One of the most widespread is the Laser Powder Bed Fusion (L-PBF) process. The energy source here is a laser, which welds the powder material at millimeter level.
Around 50 different powders based on iron, aluminum, titanium, nickel, cobalt, etc. already exist. A fraction compared to the more than 2,000 materials used in conventional steel production.
For the production of the powder, the 3D printing specialists have so far taken their cue from the existing materials and transferred their chemical composition into powder form.
The most popular variant of DEW in additive manufacturing, for example, are iron-based austenitic materials such as 1.4404 / 316 L, which shines with properties such as toughness, corrosion resistance and good-natured workability, but does not have much hardness or strength.
For tool steel, however, hardness is the most important factor. With this in mind, DEW metallurgists decided on a new approach with a completely new way of thinking: a material specially designed for 3D printing. The result is "Printdur HCT," an innovative tool steel that is easy to print, without complex process parameters such as a 500°C preheating temperature. The HCT offers high hardness between 54-57 HRC, corrosion and tempering resistance, and improved wear resistance, and it is free of nickel and cobalt to boot. This also has a due economic advantage, as the two metals are both expensive and cost volatile. More importantly, however, they are potentially hazardous to health during processing, which is why the company wants to specifically remove these substances from production.
"Additive manufacturing has long since outgrown the idea of pure development and preliminary testing," says Dr. Horst Hill, head of special materials at DEW.
Rather, it is the costs that still deter the industry. A look back at the study shows: Low entry costs are the mandatory prerequisite for the expansion or introduction of additive manufacturing. However, looking only at manufacturing costs when checking costs is the wrong approach. Only when considering the entire manufacturing process and the entire product life cycle do the cost benefits of 3D printed components become apparent.
For example, because of their layer-by-layer composition, printed components often have properties that are not possible when milling them out, for example. As a result, a significantly more expensive 3D-printed part can sometimes optimize an entire process, e.g., ensure a longer system runtime and help significantly reduce expensive downtime.
A prime example of this is a "guide arm" from the 420 block of the DEW rolling mill in Siegen. The component has classically high delivery times, whereas with 3D printing the component can be printed and delivered on demand. In addition, 3D printing optimized the geometry of the guide arm by tailoring it to the mill, and the additive material used, Bainidur AM, has better mechanical properties in terms of wear. The printed guide arm can therefore lead to cost savings in the rolling mill in the long term.
But savings can also be made in terms of resources. For example, in the modeling of cooling channels in injection molding. Instead of milling them out of a block, they are designed directly as required using laser and powder. Firstly, this saves a lot of material, and secondly, the cooling capability is improved, and cycle times are reduced. Output per hour increases.
But is 3D printing also sustainable? You bet. The metallic powders used for additive manufacturing are "green powders." They are produced in an induction furnace powered by electricity. As long as this is powered by green electricity, it remains virtually emission-free steel. Just as in the Electric Arc Furnace, steel scrap is melted for the most part.
This makes 3D printing maximally resource-efficient compared to, for example, subtractive processes such as milling out of a block, in which, as already mentioned, a lot of cutting is lost. The additive process, on the other hand, uses only the material that is also needed during printing.
Additive manufacturing in series production?
Currently, metallic 3D printing still has the highest market entry threshold in large-scale production, whereby "large" in this case can furthermore be referred to the size of the parts. The 3D printing process is limited in terms of large metal parts. Many components in the steel industry, for example, are far too large to print.
Nevertheless, there are enough other application areas in the metal and metalworking industry. For 3D printing, the motto is always "use it where it makes sense." So, it will not replace the conventional process, but support it. Additive manufacturing is best suited for specialty applications, as batch size 1 manufacturing is not a circumstance. There is also great potential in the ability to mass customize by simply making changes to the digital pattern.
For scaled production on a large scale, the most important factors are 3D printing equipment automation and printing speed. Thanks to the high degree of digitization, this hurdle should also soon be overcome.
Currently, quantities of 1,000 to 10,000 parts can already be produced economically using 3D printing, depending on the application. The automotive industry is already doing this, printing brake calipers or pistons in these orders of magnitude, for example. But 3D printing has already arrived in our everyday lives as well, with highly accurate and precision-engineered dental implants or bicycle components now mostly coming from a 3D printer.
Because only 3D printing can optimize at the millimeter level. It will not replace the classic process, but it will now become increasingly indispensable for certain components.