The Carbide cutting tool is a finishing alloy with ultra-fine particle tungsten carbide as the main raw material and metal elements such as cobalt and yttrium or other refractory carbide powders as auxiliary materials. It has a series of excellent properties such as grinding, heat resistance, and corrosion resistance, so it is suitable for use in CNC machine tools. Recently, according to the market observation of 3D Science Valley, cemented carbide tools with more complex structures and cooling inner flow channels have been achieved internationally through binder jet 3D printing technology.
Among all the partners in GE Additive's Beta Partner Program, Kennametal - Kennametal is certainly unique————
Binder Jetting is a binder jet printing technology in which powder particles of ceramic hard materials, including tungsten carbide particles, are printed and bonded layer by layer through a binder material containing cobalt, nickel, or iron. This bonding material is not only the binder between the powder layers but also enables the product to have good mechanical properties and produce fully dense parts, even with selective adjustment of flexural strength, toughness, and hardness. These 3D-printed carbide molds have greater freedom in geometric groove shapes than molds produced by traditional methods and can be fabricated into more complex geometries.
High-volume, low-cost 3D printing
Back in 2017, GE Additive Manufacturing announced that GE had been developing a metal binder jet 3D printing technology that would enable high-volume, low-cost additive production.
According to the understanding of 3D Science Valley, for mass production, GE also launched a partner program in 2020 to jointly develop and share knowledge to fully realize the transformative benefits brought by additive manufacturing. Current partners already include Cummins, Westinghouse and Sandvik. These partners target specific verticals with GE’s binder jet metal 3D printing: Cummins for power generation and automotive, Westinghouse for rail, Sandvik for mining, and more.
As the newest member of the program, industrial technology company Kennametal is no exception, known for its expertise in materials science, cutting tools and wear solutions.
GE Binder Jet Metal 3D Printing
Kennametal - Kennametal's tungsten carbide and Stellite™ (cobalt-chromium) alloys are known for their excellent wear, heat and corrosion resistance. As part of this partnership program, Kennametal will focus on optimizing these high-performance, wear- and corrosion-resistant material families into additive manufacturing platforms to deliver complex designs, shorter lead times, and higher performance. Complete components, which are not possible with traditional methods.
Break through the limitations of traditional craftsmanship
According to 3D Science Valley, the traditional machining process, usually by pressing tungsten carbide powder uniformly in a flexible bag, produces large-sized carbide workpieces or carbide workpieces with high aspect ratios (such as end mills and drill holders) ). Although the production cycle of the equalizing method is longer than that of the molding method, the manufacturing cost of the tool is lower, so this method is more suitable for small batch production.
Carbide workpieces can also be formed by extrusion or injection molding. The extrusion process is more suitable for the mass production of axisymmetrically shaped workpieces, while the injection molding process is usually used for the mass production of complex shaped workpieces. In both molding methods, grades of tungsten carbide powder are suspended in an organic binder, which imparts uniformity to tungsten carbide mixtures such as toothpaste. The mixture is then extruded or molded into a mold cavity through an orifice. The characteristics of the tungsten carbide powder grade determine the optimum ratio of powder to binder in the mixture and have a significant impact on the flow of the mixture through the extrusion orifice or into the die cavity.
After a workpiece has been molded, equalized, extruded or injection molded, the organic binder needs to be removed from the workpiece before the final sintering stage. Sintering removes the pores in the workpiece and makes it fully (or substantially) dense. During sintering, the metal bonds in the press-formed workpiece become liquid, but the workpiece retains its shape under the combined action of capillary forces and particle contact.
After sintering, the geometry of the workpiece remains the same, but the dimensions are reduced. To achieve the desired workpiece size after sintering, shrinkage needs to be taken into account when designing the tool. When designing the grade of tungsten carbide powder used to make each tool, it must be ensured that it has the correct shrinkage when pressed under the proper pressure.
It is not difficult for people in the industry who are familiar with the binder jetting metal 3D printing technology to find that the degreasing, sintering process and post-processing process required by the binder jetting metal 3D printing technology in the process of the cemented carbide workpiece manufactured by the traditional injection molding process It is consistent that 3D printing technology occupies an increasingly important position in the manufacturing of cutting tools.
According to the market observation of 3D Science Valley, there are two main 3D printing technologies currently used in tool manufacturing. One is LPBF selective laser melting 3D printing technology, which is used to manufacture special groove shapes of metal tools or complex cooling channels inside the tool; the other is the 3DP binder jet technology mentioned by 3D Science Valley in a previous article.
Compared with the PBF powder bed-based selective laser melting metal 3D printing process, Binder Jetting has several key advantages: more economical powder materials (similar to the metal powder materials used in the MIM process) ); no support structure required; efficient print speeds for high-volume production applications ranging from automotive and aircraft parts to medical applications.
Binder jetting metal 3D printing technology is unique compared to almost all other metal 3D printing processes because there is not a lot of heat generated during the 3D printing process. This enables high-speed printing and avoids residual stress problems during metal 3D printing.
Binder jet 3D printing technology is a combination of material jetting and sintering processes to produce full density metal parts. Lower-cost equipment also means significantly lower parts costs, and high-volume lower-cost parts are a key element in moving toward production. Binder jet metal 3D printing technology has the potential to replace low-volume, high-cost metal injection molding, and can also be used to produce complex and lightweight metal parts in other fields (such as gears or turbine wheels), greatly reducing 3D printing costs and shortening delivery time.
3D printing unleashes a competitive advantage
Interestingly, Kennametal is not the first time to try metal 3D printing. In addition to the binder metal 3D printing technology, Kennametal has previously developed a lightweight boring tool. Additive manufacturing - manufactured by 3D printing technology, used to process stators of new energy vehicle motors.
This 3D printed tool from Kennametal has undergone continuous design iterations to further reduce the weight by 20% compared to the first-generation tool, and the 3D printed stator drilling tool with a carbon fiber body weighs 7.3 kg.
3D printing-additive manufacturing enables complex internal and external features for the tool. As 3D Science Valley understands, worry-free chip evacuation is ensured by the airfoil arm, which ensures precise and powerful coolant supply to the cutting edge and guide pads through the coolant. This would be difficult or impossible to produce economically with traditional manufacturing methods, but 3D printing enables Kennametal to achieve even such complex interior features. Additionally, the Kennametal RIQ reaming system features easy diameter adjustment and trouble-free installation of new inserts. Whether 3DP technology is used in the manufacture of carbide tools or LPBF technology is used in the manufacture of metal tool heads and tool holders, 3D printing technology occupies an increasingly important position in the manufacture of tools.
---POST: Cynthia Lee