Binder Jetting (BJ) Machines: Definition, Applications, Types, Advantages, and Disadvantages
Binder jetting is a 3D printing technology in which solid objects are printed using a binder agent that is selectively deposited onto a powder bed. This technology is used to print high-value parts and tooling and can use materials such as sand, metals, composites, and ceramics. Due to its wide range of material selection, binder jetting has found use in a wide range of industries, including construction, aerospace, and the arts.
This article explains how binder jetting works, its advantages and disadvantages, the process of binder jetting, and the types of binder jetting machines available. It will provide an in-depth look at the capabilities and limitations of binder jetting, making it a useful resource for anyone interested in this 3D printing technology.
Binder jetting is a 3D printing technology in which an industrial printhead is used to selectively apply a liquid agent onto a layer of powdered particles to bond the material in layers. This is done to create a solid object. The powdered particles used to print can be sand, metals, composites, or ceramics. This process is similar to an inkjet printer and is used to print high-value parts and tooling.
Binder jetting uses a digital CAD file as a reference to print the desired 3D object. The print software is used to “slice” the model into extremely thin layers that the printer then uses to print the object in a layer-by-layer fashion.
There are two key components in this technology: the printhead and the recoater. These two components work together to print the 3D object. The recoater applies a very thin layer of powder onto the building platform. After the powder has been laid onto the platform, the printhead then passes over and selectively applies binder liquid to the areas that will be printed, according to the sliced data file. Once this is done, the platform is lowered by one layer of thickness, and the process is repeated by applying a fresh layer of powder, which is then selectively bonded by the binding fluid.
All the process steps are repeated until the object is fully printed. Once the printing stage is completed, the object can be removed from the machine and cleaned of any excess material that is not bonded.
Binder jetting has several advantages, including:
- Achieves highly precise dimensions. It operates at room temperature, eliminating concerns about warping. When working with metal, this method also avoids the need to relieve residual stresses during secondary post-processing. However, shrinkage may still occur following sintering.
- Binder jetting is economical. It's also a more energy-efficient option, utilizing a liquid binding agent rather than a laser. Additionally, binder jetting of ceramic and metal powders is typically more budget-friendly than powders used for SLS and SLM. Binder jetting can provide substantial cost savings compared to material jetting, SLS, or SLM with full-color prototypes.
- The unbound powder serves as a natural support. This removes the need for additional structures and provides more design flexibility. This feature also results in reduced post-processing times and less material usage compared to other 3D printing technologies.
- All unused powder in binder jetting can be repurposed for future printing jobs, resulting in less waste and lower material costs.
- Large build volumes are available, allowing for the production of large parts or multiple smaller parts simultaneously.
- A relatively fast process compared to other additive manufacturing techniques, making it suitable for the production of large and complex parts.
Despite its numerous advantages, there are some disadvantages to consider when using binder jetting. These are listed below:
- Metal binder jetting parts may have lower mechanical properties due to their higher porosity compared to their SLS counterparts.
- Parts produced via binder jetting are brittle in their “green” state, limiting the level of detail that can be printed.
- Most binder jetted parts require post-processing. It can significantly lengthen production times and could result in inaccuracies.
- The resolution of binder jetting is relatively low compared to other additive manufacturing techniques, which may limit its use for producing small, intricate parts.
- Binder jetting is not always suited for structural parts, due to the use of a binder material.
The steps for printing a part with binder jetting are as follows:
- Create and slice a CAD file of the part. This file is then used to send instructions to the printer in the correct sequence for the part to be printed.
- The build platform is covered with a thin layer of powdered material, which is evenly distributed using a roller.
- The printhead applies the binder adhesive selectively onto the powder where it is needed, based on the sliced file of the object.
- The build platform is then lowered by the thickness of one layer.
- Another layer of powder is spread over the previous layer. The powder particles are then bound together by the liquid binder, forming the object. This process is repeated layer by layer until the entire object is created.
- Any unbound powder remains in place around the object. This is removed in the post-processing steps.
The types of binder jetting machines are distinguished by the type of binding agent used to combine the powdered material. Some common types of binders used in binder jetting include:
- Polymer Binders: These binders are often used with ceramic powders and can be removed by heat treatment. Polymer binders are typically low in viscosity and can be applied easily with binder jetting printing.
- Water-based Binders: These binders are often used with sand and other mineral powders. They are environmentally friendly and can be easily removed through drying or sintering.
- Solvent-based Binders: These binders are often used with metal and ceramic powders and are removed through a process called solvent debinding. Solvent-based binders have a high solid content and can be easily applied to the powder bed.
- Furan Binder: Furan binders are made from furfuryl alcohol and are commonly used with sand to create molds and cores for casting. They have good mechanical strength and thermal stability and can be cured by heat or acid catalysts. After curing, the molds can be easily stripped from the casting. Furan binder is particularly suitable for creating molds for large, complex castings.
- Silicate Binder: Silicate binders are made from sodium silicate or potassium silicate and are also used for casting applications. They have good refractory properties and can withstand high temperatures. Silicate binders can be used with a variety of sand types and can be cured by drying or by adding an acid catalyst. After curing, the molds can be easily stripped from the casting. Silicate binders are particularly suitable for creating molds for ferrous metals.
- Phenolic Binder: Phenolic binders are made from phenol-formaldehyde resins. They are commonly used in foundry applications to create molds and cores for casting. They have good mechanical strength and dimensional stability and can be cured by heat. After curing, the molds can be easily stripped from the casting. Phenolic binders are particularly suitable for creating molds for high-strength, high-temperature applications.
- UV Binder: These binders are cured by exposure to UV light, which triggers a chemical reaction that causes them to solidify. UV-curable binders are often used in combination with photopolymer resins to create high-resolution, detailed parts. UV-curable binders offer several advantages, including: high resolution, fast curing times, and the ability to create complex geometries with high accuracy. However, they also have some limitations, such as limited material options and the need for UV light exposure during printing.
Binder jetting is a versatile additive manufacturing process that can be used with a variety of materials. Here are some of the materials that can be used in binder jetting:
- Metals such as: stainless steel, titanium, aluminum, and copper can be used to create parts with high strength and durability. These parts can be used in a range of applications such as aerospace, automotive, and medical industries.
- Ceramic parts such as: tiles, sanitary ware, and insulators. Materials such as alumina, zirconia, and silicon carbide can be used to create these parts.
- Sand mixed with binders such as furan, silicate, and phenolic can be used to create molds and cores suitable for foundry casting.
- Plastic parts using powders such as polyamide, polypropylene, and polycarbonate. These parts can be used in a range of applications such as consumer goods, automotive, and medical industries.
- Composite parts using materials such as carbon fiber and glass fiber mixed with a polymer binder.
For more information, see our guide on 3D Printing Materials.
Below are some examples of binder jetting 3D printing systems:
- ProJet MJP 5600 from 3D Systems.
- J5 MediJet from Stratasys.
Binder jetting 3D printing is well-suited for diverse applications and industries. These include automotive, aerospace, art and design, and architecture, among others. Some of its applications include:
- Aerospace components
- Cores and molds
- Casting patterns
- Decorative objects (full-color)
Typically, binder jetting machines cost more than $100,000. In terms of operational costs, the system is very economical, with the use of inexpensive materials and less power consumption than other additive manufacturing processes.
Yes, binder jetting is regarded as the fastest 3D printing technology. It is used for production-volume outputs for very dense and also functional precision parts.
No, binder jetting typically does not require the use of support structures. This is because the part is surrounded by the unbound powder which acts as a support structure. This means that several parts can be printed simultaneously on the same powder bed, which is ideal for low to medium batch production.
No, binder jetting does not only work with metals. Binder jetting covers a diverse range of material options, including sand, ceramics, and some polymers.
Material jetting and binder jetting are two different additive manufacturing (AM) technologies used to create three-dimensional objects. Material jetting uses inkjet technology to print droplets of photopolymer resin onto a build platform. The resin is then cured with UV light to create a solid layer. On the other hand, binder jetting uses a liquid binder to selectively bond layers of powdered material. The binder is applied to the powdered material using a printhead, and the layers are then cured or sintered together using heat or UV light. Table 1 below lists the main differences between the two:
|Material Jetting||Binder Jetting|
Deposition of photopolymer droplets that are solidified through UV light
Depositing a binding agent on a powder bed
Surface appearance, Multi-color, Dimensional stability
No need for support structures, Multi-color, Multi-materials
Brittle parts, Mechanical properties
Post-processing , Brittle parts
Ceramics, polymers, metals, sand, and composites
Prototypes, Anatomical models,Design
Tooling, Prototypes, Foundry molds
Stratasys, 3D systems, Mimaki, XJet
3D systems, ExOne, VoxelJet, Digital Metal
Table Credit: https://www.3dnatives.com/
3D printing has revolutionized the manufacturing industry and is without a doubt the future of manufacturing. Not only does it offer design flexibility and the ability to design custom parts, but it is also more cost effective and time efficient. 3D printing is a must for businesses looking to increase their competitive edge.
This article presented binder jetting, explained what it is, and discussed its various applications and types. To learn more about binder jetting, contact a Xometry representative.
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