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Fraunhofer ILT: Making Tungsten Carbide-Cobalt Cutting Tools with LPBF 3D Printing

Obviously, the Fraunhofer Institute for Laser Technology ILT does a lot of work with lasers, and, in the same vein, with metal 3D printing processes that use lasers. Now, it’s teaming up with scientists from the Institute for Materials Applications in Mechanical Engineering IWM and the Laboratory for Machine Tools and Production Engineering WZL, both at RWTH Aachen University, to investigate laser processes for the 3D printing of cutting tools made of tungsten carbide-cobalt (WC-Co).

The new AiF project – “Additive Manufacturing of Machining Tools out of WC-Co – AM of WC-Co” – began on October 1st 2019 and will last for 30 months; funding is provided by the Otto von Guericke e.V. working group of industrial research associations.

Cutting tools made of WC-Co are very heat- and wear-resistant, which is what one generally wants in this type of application, but it’s not easy to use conventional methods of manufacturing to create them. Complex sintering processes are currently used, but it’s not ideal, as only a restricted amount of geometrical freedom is possible, and it’s expensive and difficult to introduce complex cooling structures into the tools as well.

The process development aims to generate a homogeneous, almost dense structure of the WC-Co-composite, as shown here in this SEM measurement. [Image: Institute for Materials Applications in Mechanical Engineering IWM, RWTH Aachen University]

One of the project goals is to create cutting tools with integrated complex cooling geometries in order to ensure longer tool life. That’s why the Aachen researchers are looking into Laser Powder Bed Fusion (LPBF) 3D printing for WC-Co cutting tool fabrication, which offers near-net-shape production for generation of cooling structures within these tools, and far more design freedom. This technology requires users to carefully choose their process and material parameters in order to create components with strength that’s comparable to what could be achieved with conventional manufacturing methods.

For the past few years, Fraunhofer ILT scientists have been researching a major problem in the LPBF process – temperature distribution in the part. Conventional systems slow down the cooling process with a heated base plate, but with LPBF, the metal powder is melted where the laser touches it and cools down quickly, which can cause cracks and tension.

Fraunhofer ILT has been working with adphos Innovative Technologies GmbH on this issue, and together the two created a system which uses a near-infrared (NIR) emitter to heat the component from above to over 800°C. This system is what Fraunhofer ILT and its fellow Aachen researchers are using to process tungsten carbide-cobalt material for cutting tools in the “AM of WC-Co” project.

Under the scope of the project, the researchers are investigating the process route all the way from powder formation and 3D printing to post-processing and testing the components. Together, they will qualify the materials and processes that will replace complex sintering processes in fabricating these cutting tools.

Preheating the machining plane with the NIR module significantly reduces stresses in the laser-manufactured component. [Image: Fraunhofer ILT]

3D printed WC-Co cutting tools will have a hardness comparable to those made with conventional manufacturing methods, but because of the cooling structures that the LPBF process can be used to create, they will have a longer service life. Additionally, the NIR emitter system developed by Fraunhofer ILT and adphos can lay the groundwork for processing refractory alloy systems in the future.

At formnext 2019, in Frankfurt from November 19-22, you can stop by the Fraunhofer Additive Manufacturing Alliance booth D51 in Hall 11 to learn more about the collaborative “AM of Wc-CO” project.

Discuss this story and other 3D printing topics at 3DPrintBoard.com or share your thoughts in the Facebook comments below. 

[Source: Fraunhofer ILT]

The post Fraunhofer ILT: Making Tungsten Carbide-Cobalt Cutting Tools with LPBF 3D Printing appeared first on 3DPrint.com | The Voice of 3D Printing / Additive Manufacturing.

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Patented Metals with Extremely High Carbide Content

Metal materials with remarkable properties. This has been the focus of Swedish company VBN Components since the very start. In the middle of the financial crisis in 2008, VBN saw the opportunity to turn the steel business upside down by using additive manufacturing of high strength, carbide-rich materials. Today they present a range of patented alloys with unique performance.

The Vibenite® materials

VBN Components nurtures the Swedish heritage within the metal industry by continuously developing new and improved materials branded Vibenite®. Sweden was one of the first countries in the world to produce industrial steel with purity as a key factor. VBN takes this to the next level by 3D printing materials unique in their composition, offering exceptional wear resistance. Their properties are achieved by a patented additive manufacturing process through which metal materials with 100% density can be produced. Small sized uniformly distributed carbides in a specific matrix are the reason for the materials’ performance. They are all produced from a base of gas atomized metal powder and are therefore classified as powder metallurgy materials.

Vibenite® technology allows the user to switch to a more wear resistant material than what can be produced with traditional manufacturing. When 3D printing, most production and transportation steps are eliminated, material usage optimized, and environmental impact significantly reduced. Both performance and life-time of components increase with Vibenite®. These properties are easily tested by simply printing a full-quality prototype and running it! Better material properties are normally not heard of in the 3D printing business today, where typically difficult geometries are promoted.

Your application of choice can be printed with Vibenite® materials.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Cross section of shaper cutter showing a 100% dense material.

 

 

 

 

 

 

 

 

 

 

 

 

 

Caption: Hardness of Vibenite® materials compared to H13, a common tool steel.

Vibenite® 290, the world’s hardest steel

Today there are five different types of Vibenite® materials, with a hardness range from 58-72 HRC (600-1100 HV). Among them we find the world’s hardest steel, Vibenite® 290 with 25% carbide content. Its hardness of 72 HRC means it could never be processed traditionally. It was recently put through two abrasion tests to measure wear against rock, in collaboration with Robit Plc. The results spoke for themselves; Vibenite® 290 showed only 50% of the wear rate compared to reference material H500 (51 HRC) in the first test, and 25% of the wear rate in the second. H500 is commonly used in these types of abrasion lab-tests.

Total wear in grams in high-speed slurry pot test.

 

 

 

 

 

 

 

 

 

 

 

 

 

Vibenite® 480 – a new type of cemented carbide

Recently, VBN Components announced that they can print cemented carbide. This type of material has previously been considered “impossible” to print, due to high carbide content. Vibenite® 480 contains an astonishing ~65% of carbides, which really beats al the odds. There is no mixing, drying, pressing or sintering needed, as in the traditional process. It has a long-term heat resistance of 750°C, is corrosion resistant and magnetic. Vibenite® 480 is niched both towards applications where steel is normally used, but where replacing it with hard metal would increase production efficiency, and also towards hard metal applications with complex geometry. Since it combines the best of two material worlds – powder metallurgy high-speed steel and cemented carbide, it is referred to as “hybrid carbide”.

3D Benchy printed with Vibenite® 480.

 

Milestones and future projects

These material innovations have raised quite a lot of attention. Already in 2013, VBN Components was awarded with Sweden’s largest and most important innovation prize, SKAPA, established in honor of Alfred Nobel. In that same year, Swedish steel giant Uddeholms AB contested VBN’s first patent regarding high purity in high carbon content materials. It took five years before the battle was finally settled, in favor of VBN Components, at the European Patent Office (EPO) in Munich. Not long thereafter, just before Christmas of 2018, a multi-million license agreement was signed with a global engineering group. It implies an exclusive license within a specific niche of high-strength components, which is kept confidential for now.

VBN Components is the only company 3D printing alloys with high carbon content, resulting in hard and wear resistant unique materials. The extremely high cleanliness of Vibenite® alloys gives very high fatigue resistance. Following this path, VBN will continue developing new metal alloys and novel ways to print these. The possibilities are vast, from “Vibenite® Combo” which implies printing Vibenite® upon other existing components, to “Vibenite® Grado” which would give different properties in different parts of the component.