Laser Powder Bed Fusion (L-PBF) is the most industrialized metal AM technology today. After early adopters within the medical and aerospace industry have proven the suitability of L-PBF for end use parts, companies across all industries have identified further cases in recent years.
L-PBF can be used to produce complex geometries ranging from several millimetres to dimensions close to 1m. Recent advancements in productivity and the increasing automation of subsequent process steps make L-PBF more and more suitable for applications in higher volumes. The technology therefore has a wide range of applications, including prototypes, end-use components, toolings and spare parts.
Air purification component. 3D printing gives the free form design possibilities to fully optimize the structure of a catalytic reactor, going beyond designs made with traditional processes. This enables AddCat to improve the catalytic process making the air purification more efficient and reliable in a smaller reactor volume. Courtesy of AddCat
The anti-scatter grid (ASG), made out of pure tungsten, is placed on top of CT detectors to enhance image quality by rejecting scattered radiation. Through additive manufacturing, it is possible to 3D print 100 micron thick walls at a positional accuracy of 25 microns. Ability to print highly accurate and thin walls (100 microns). Courtesy of Dunlee
Cutting tool innovation by ARNO and Rosswag with patented coolant supply design manufactured in serial production. The additive manufactured grooving tool delivers coolant directly to the cutting zone of the insert and underneath the tool flank for highly efficient parting off, grooving and groove turning. This leads to financial and technical benefits due to an increased tool life of the insert and a higher process security. Courtesy of Rosswag GmbH.
Airbus
Aviation
Stainless Steel
Laser Powder Bed Fusion
Qualified end part
The objective was to replace a conventionally manufactured high-pressure hydraulic valve block with an additively manufactured one. The component is produced by LIEBHERR AEROSPACE and used on an AIRBUS A380.
The primary flight control component moves the spoiler of an aircraft to the desired position during take-off and landing and must thus meet highest quality standards.
The original component is machined from a forged block with several drillings and assembly operations. This leads to limited design freedom and long lead times.
The autoclave with integrated tempering channels is certified according to the European Pressure Equipment Directive (2014/68/EU) Category III. It has an operating pressure of 225 bar. The autoclave features a more than two meter long interior channel for tempering fluid which winds around the container wall. The AM design enables faster temperature cycles, better regulation of an even temperature distribution as well as optimized tempering of the component. The component is produced with L-PBF from stainless steel alloy. Courtesy of BASF SE.
The part transmits and distributes compressed air. Advantage by Additive Manufacturing through economic substitution of costly extrusion press part. Images courtesy of Festo AG & Co. KG
The sinter-based AM (SBAM) technologies have, as the name suggests, the sintering process in common. In this process, the printed green part is consolidated into a dense part and receives its final properties. The green part can be printed in advance using different technologies.They all have in common that metal powder is bound to the desired shape by a binder. The best-known printing technologies include Binder Jetting and Filament Material Extrusion.
In this section, you learn everything about the sinter-based AM process chain and get an overview of the different printing technologies.
This course is aimed at engineers, designers and other professionals that are working closely with sinter-based AM technologies. The goal is to cover the most important aspects that will enable engineers and designers to fully grasp the capabilities and technical limitations of the printing technologies and the sintering process to succeed in technology selection and part design. Besides going through the course from the beginning until the end, this course can also act as a constant source of knowledge while working on AM projects.
The course is structured into the following sections.
This section will start with an overview of the sinter-based AM process chain and its printing technologies, followed by a technology deep dive into the most important aspects of the BJT technology, followed by a closer look at the debinding and sintering step also including sintering simulation .
The second section will provide an overview of the different materials that are available as well as part characteristics that can be achieved with the BJT process and typical methods for quality assurance. Finally, several common defects in the BJT process are presented.
The last section will act as a guideline for designers. Besides generally describing the process when designing for Additive Manufacturing, actionable restrictions and guidelines for the BJT process are provided. The final section will present several design examples from different industries.
Simulation to compensate the deformation during the sintering step, nesting of parts and definition of printing parameters
Through various printing processes, different feedstocks such as metal powders, filaments, pellets or dispersions are processed into green parts
Unpacking of fragile green parts needs to be done carefully and is typically a manual process.
Debinding describes the process of removing the binder which results in a brown part
To reach the structural integrity of a metal part, a sinter process is required. The powder particles fuse together to a coherent, solid structure via a mass transport that occurs at the atomic scale driven via diffusional forces.
The brown part shrinks ~13-21 % in each direction.
The process chain of sinter-based technologies differs from other AM Technologies. Especially the post-printing processes (debinding and sintering) are crucial to achieve the intended mechanical properties.
Binder Jetting is a powder based Additive Manufacturing technology in which a liquid polymer binder is selectively deposited onto the powder bed binding the metal particles and forming a green body.
The metal powder is applied to a build platform in a typical layer thickness of 40 µm to 100 µm. Subsequently a modified 2D print head apply a binder selectively onto the powder bed. Depending on machine technology a hardening or curing process of the binder is performed in parallel for each layer and/or at the end of the whole build. During the in-situ curing process a heat source is used to solidify the binder and form a solid polymer – metal powder composite.
Afterwards the build platform moves downward by the amount of one layer thickness and a new layer of powder is applied. Again, the liquid binder is deposited and hardened in the required regions of the next layer to form the green body. This process is repeated until the complete part is printed. After the complete printing process is finished the parts have to be removed from the “powder cake” meaning the surrounding loose but densified powder. To improve the removal of the excess powder from the green body often brushes or a blasting gun with air pressure are used.
To create a dense metal part the 3D printed green body has to be post-processed in a debinding and sintering process. Similar to the metal injection molding process BJT parts are placed in a high temperature furnace, where the binder is burnt out and the remaining metal particles are sintered together. The sintering results in densification of the 3D printed green body to a metal part with high densities of 97 % to 99,5%, dependent of the material.
In classic Binder Jetting systems such as the ones distributed by EXONE or DIGITAL METAL the liquid binding agent is selectively deposited with a single print head. Meaning the width of the print head does not cover the full width of the powder bed. Therefore, the print head moves multiple times in xy-direction over the powder bed to completely cover the printing area and distributing the polymer binder.
The SINGLE PASS JETTING technology was developed by DESKTOP METAL and HEWLETT PACKARD. The width of the printing head covers the full width of the powder bed. When the printhead passes over the powder bed, binder is released from more than 30,000 small nozzles and the whole powder layer is selectively immersed in binder in one pass. The process is bi-directional which means that the binder deposition takes place in both moving directions of the printhead. With these modifications the printing speed is significantly increased.
A similarly fast technology is the METAL JET process by HEWLETT PACKARD. In a single pass, a liquid printing agent is applied to the powder layer and subsequently partially evaporated to form the binding polymer around the metal powder. After the completion of the print an additional curing to achieve the full green body stability is needed.
3DEO combines the Binder Jetting process with a subsequent machining process. Different from conventional Binder Jetting processes, the binder is not only deposited selectively but onto the entire powder layer. After hardening of the complete layer, the part geometry is shaped through a milling process every couple of layers by cutting the part contour out of the binder powder composite.
Binder Jetting is a powder based Additive Manufacturing technology in which a liquid polymer binder is selectively deposited onto the powder bed binding the metal particles and forming a green body.
The metal powder is applied to a build platform in a typical layer thickness of 40 µm to 100 µm. Subsequently a modified 2D print head apply a binder selectively onto the powder bed. Depending on machine technology a hardening or curing process of the binder is performed in parallel for each layer and/or at the end of the whole build. During the in-situ curing process a heat source is used to solidify the binder and form a solid polymer – metal powder composite.
Binder Jetting is a powder based Additive Manufacturing technology in which a liquid polymer binder is selectively deposited onto the powder bed binding the metal particles and forming a green body.
The metal powder is applied to a build platform in a typical layer thickness of 40 µm to 100 µm. Subsequently a modified 2D print head apply a binder selectively onto the powder bed. Depending on machine technology a hardening or curing process of the binder is performed in parallel for each layer and/or at the end of the whole build. During the in-situ curing process a heat source is used to solidify the binder and form a solid polymer – metal powder composite.
Binder Jetting is a powder based Additive Manufacturing technology in which a liquid polymer binder is selectively deposited onto the powder bed binding the metal particles and forming a green body.
The metal powder is applied to a build platform in a typical layer thickness of 40 µm to 100 µm. Subsequently a modified 2D print head apply a binder selectively onto the powder bed. Depending on machine technology a hardening or curing process of the binder is performed in parallel for each layer and/or at the end of the whole build. During the in-situ curing process a heat source is used to solidify the binder and form a solid polymer – metal powder composite.
Binder Jetting is a powder based Additive Manufacturing technology in which a liquid polymer binder is selectively deposited onto the powder bed binding the metal particles and forming a green body.
The metal powder is applied to a build platform in a typical layer thickness of 40 µm to 100 µm. Subsequently a modified 2D print head apply a binder selectively onto the powder bed. Depending on machine technology a hardening or curing process of the binder is performed in parallel for each layer and/or at the end of the whole build. During the in-situ curing process a heat source is used to solidify the binder and form a solid polymer – metal powder composite.