Metal binder jetting is a revolutionary additive manufacturing technology that has gained significant traction in recent years. With its high speed, precision, and cost-effectiveness, this technology has the potential to transform the manufacturing industry. In this article, we will explore the origins and advancements of metal binder jetting, its post-processing steps, and the latest developments in the field.
Origins of Metal Binder Jetting
The roots of metal binder jetting can be traced back to 1993 when the Massachusetts Institute of Technology (MIT) developed an inkjet-based process for creating three-dimensional objects using metal powders. It was during this time that the term “3D printing” was coined by MIT in reference to metal binder jetting technology. The manufacturing company Extrude Hone Corporation obtained an exclusive license for this technology in 1996 and went on to develop and commercialize metal binder jetting systems.
What is metal binder jetting? How does it work?
Metal Binder Jetting is a metal additive manufacturing (AM) technology that utilizes powdered materials and a binding agent to create three-dimensional printed metal parts. The process involves spreading a thin layer of metal powder onto a build platform and selectively applying the binding agent using a printhead in specific areas. The binding agent causes the metal powder to coalesce and form a solid structure. This process is repeated layer by layer until the entire metal part or mold is completed.
After printing, the metal binder jetted parts require post-processing steps. This may include removing excess powder, sintering, or heat treatment to improve part density and mechanical properties. Surface finishing and machining steps may also be performed to achieve the desired accuracy and surface quality, depending on the application requirements.
Metal Binder Jetting technology offers several advantages, including the ability to produce complex geometries, high production speeds, no need for support structures, high material utilization, and the ability to use various metal materials. It finds wide-ranging applications in aerospace, automotive, medical devices, and other industries for rapid prototyping, small-batch production, and customization. However, Metal Binder Jetting also presents challenges that require further research and improvement, such as control over part density, surface quality, and mechanical properties.
Post-Processing Steps for Metal Binder Jetting
- Curing: Curing is the first post-processing step for metal binder jetting. It involves increasing the strength of the green parts so that they can be safely removed from the printing bed. During the curing process, the parts are hardened in an oven at around 200°C for several hours, resulting in much stronger parts.
- Sintering: Despite the curing process, the metal parts remain highly porous. Sintering is the next step to reduce the porosity of the parts. The parts are heat-treated in a controlled atmosphere furnace at approximately 100°C for 24-36 hours, causing the binding agent to burn away and the metal particles to fuse together. This results in strong metal parts with low porosity. However, it is important to consider non-homogenous shrinkage during the sintering process.
- Infiltration: To achieve high density, the sintered parts need to be infiltrated to fill the voids left by the burned binding agent. This is typically done by applying molten bronze to infiltrate the remaining voids in the part. Infiltration significantly enhances the mechanical properties of the metal parts.
- Finishing: The final optional step in the post-processing of metal binder jetted parts is finishing. This involves polishing the part and plating it with gold or nickel, resulting in aesthetically pleasing surface finishes.
These post-processing steps are crucial for enhancing the mechanical properties and surface finish of metal binder jetted parts, making them suitable for various applications.
How long to metal binder jetting parts sinter?
The duration for sintering metal binder jetting parts can vary depending on several factors, including the specific material being used, part size and complexity, sintering equipment, and process parameters. Generally, the sintering process for metal binder jetted parts can take several hours to complete.
During sintering, the parts are heated to a temperature below the melting point of the metal powder, allowing the powder particles to fuse together. The sintering temperature and time are carefully controlled to ensure proper densification and mechanical properties of the final part.
The sintering time can range from a few hours to several tens of hours, with larger and more complex parts typically requiring longer sintering times. Additionally, the sintering cycle may include heating, dwell time at the sintering temperature, and cooling stages.
It’s important to note that the specific sintering time for metal binder jetting parts may be determined through experimentation and optimization for each material and application, considering factors such as part requirements, sintering equipment capabilities, and desired properties of the final part.
Advantages of Metal Binder Jetting as a Production Technology
Metal binder jetting offers several unique advantages that make it an appealing production technology. Firstly, unlike other metal 3D printing processes, metal binder jetting does not involve melting the metal powder, eliminating issues related to residual stresses. Additionally, since printed parts are surrounded by loose, unused powder, no support structures are required, reducing the need for post-processing.
Furthermore, metal binder jetting machines are less expensive than 3D printers based on other metal additive manufacturing processes, as they do not require costly lasers or electron beams. The ability to use Metal Injection Moulding (MIM) powders, which are cheaper and more readily available, further lowers operating costs.
Metal binder jetting also allows for the production of highly accurate parts with mechanical properties comparable to those of traditionally manufactured metal components. The speed of the process is another advantage, making it a scalable and production-capable technology.
Recent Developments in Metal Binder Jetting
In recent years, a number of companies have been at the forefront of developments in metal binder jetting technology. Let’s take a closer look at one of the more typical Chinese 3D printing equipment manufacturers.
AFS: Innovating Metal Binder Jetting
AFS is a leading enterprise in 3D printing technology in China and has a widely distributed service network. The holding company 3DP Tech Inc has been granted 300+ patents, 3 national standards, and 5 national R&D projects.
AFS specializes in 3DP sand molding, binder jet metal printing, and other cutting edging additive manufacturing technologies. A wide range of products, including equipment, material and industrial solutions, are available for the market.
AFS solutions are oriented for rapid manufacturing of complex metal parts, or small to medium batches, typically 1~200 items. The novel solution is agile and accurate compared to conventional CNC and other molding processes. The business is spread widely across aerospace, automobiles, ships, pumps and valves, construction machinery, scientific research and education industries.
The Future of Metal Binder Jetting
Metal binder jetting, a revolutionary additive manufacturing technique, has gained significant traction in recent years. With its ability to produce complex metal parts with high precision and efficiency, metal binder jetting is poised to shape the future of manufacturing. This article explores the advancements, opportunities, and potential applications that lie ahead for metal binder jetting.
Enhanced Material Selection:
The future of metal binder jetting lies in expanding the range of materials available for printing. Researchers and industry experts are actively exploring new metal alloys, composites, and blends that can be utilized in binder jetting processes. This will enable the production of components with improved mechanical properties, such as increased strength, thermal resistance, and corrosion resistance.
Improved Printing Speed and Scale:
Advancements in hardware and software technology are expected to significantly enhance the speed and scalability of metal binder jetting. Faster printing speeds and larger build volumes will enable the production of larger and more complex metal parts in a shorter timeframe. This will unlock opportunities for rapid prototyping, mass customization, and on-demand manufacturing.
Post-processing plays a crucial role in the final quality of metal binder jetted parts. Future developments will focus on refining post-processing techniques to further improve surface finish, dimensional accuracy, and mechanical properties. Innovations in sintering, heat treatment, and surface finishing processes will ensure that metal binder jetted parts meet the stringent requirements of various industries.
Integration of In-Situ Monitoring and Quality Control:
To ensure the reliability and consistency of metal binder jetting processes, in-situ monitoring and quality control systems will be integrated into the printing workflow. Real-time monitoring of powder bed, binder deposition, and part consolidation will allow for immediate detection and correction of any defects or anomalies. This will enhance process control, reduce waste, and improve overall production efficiency.
As metal binder jetting technology continues to evolve, its applications will expand across industries. Aerospace, automotive, healthcare, and tooling sectors will increasingly benefit from the unique capabilities of metal binder jetting. The production of lightweight, complex geometries, and customized metal parts will drive innovation and cost-effective manufacturing solutions.
Sustainability and Material Efficiency:
The future of metal binder jetting also aligns with sustainability goals. Efforts will focus on optimizing material usage and recycling processes, reducing waste generation, and minimizing energy consumption. Sustainable practices, such as powder reuse, will contribute to a more environmentally friendly and resource-efficient manufacturing process.
In summary, metal binder jetting technology has come a long way since its inception in the early 1990s. Originating at the Massachusetts Institute of Technology (MIT) and subsequently commercialised by major companies around the world, the technology has evolved into a high-speed, cost-effective production capability. The adoption of metal binder jetting has been further accelerated by the introduction of automation, increased print speeds and enhanced material compatibility. Advances in materials, print speeds, post-processing, quality control and sustainability will drive the widespread adoption of this technology. In the meantime, we can expect additional advances that will further cement metal binder jetting’s position as a transformative manufacturing technology for producing complex, high-quality metal parts with unprecedented efficiency and customisation.