The use of 3D printers to build titanium alloys has been utilized in many fields, such as aerospace and medical device industries. 3D printing is attracting attention because it enables the production of complex geometries that are difficult to produce with conventional manufacturing methods.
In this column, we will explain the basic knowledge of titanium alloy 3D printing, the difference between LB-PBF and EB-PBF, and examples of utilization in an easy-to-understand manner.
※LB-PBF：Laser Beam Powder Bed Fusion
※EB-PBF：Electron Beam Powder Bed Fusion
Why use titanium alloys with metal 3D printers?
In addition to its basic properties of being "light and strong," titanium alloys are being used in a variety of fields because of their excellent compatibility with 3D printers, which offer a high degree of freedom in design.
Lightweight and High Strength | The compatibility of titanium alloy properties and 3D printing
Titanium alloys are known as metal that is both "light" and "strong," and has gained attention as materials suitable for 3D printing. While being approximately 40% lighter than steel, even pure titanium has high strength, and titanium alloys exhibit even higher properties.
Furthermore, it has corrosion resistance against sea water and salt water, heat resistance against high temperatures, and high durability for stable use under severe conditions. By utilizing 3D printers, it is possible to design products with internal hollows or lattice structures, which reduces weight while maintaining strength. 3D printers are being used in a variety of fields, including aircraft parts, artificial joints, racing vehicles, and bicycle frames.
Printing Titanium Alloys with Metal 3D Printer (difference between LB-PBF and EB-PBF)
This section describes two typical printing methods used for 3D printing of titanium alloys, "LB-PBF" and "EB-PBF," along with their advantages/challenges.
Features and challenges of laser-based LB-PBF
LB-PBF (Laser Beam Powder Bed Fusion) is a method to melt metal powder by applying a laser beam to a powder bed, which is then repeated layer by layer to form a three-dimensional structure. The laser beam is very fine and controllable, making it suitable for the printing of parts that require fine shapes and high precision. In particular, it is often employed for products requiring dimensional accuracy such as precise mechanical parts.
However, there are some issues. Repeated rapid heating and rapid cooling during the printing process can induce residual stresses, potentially causing cracking or warping. This necessitates post-printing processing and careful design considerations. Additionally, handling titanium alloys which oxidize rapidly in high-temperature environments, requires sophisticated gas management, presenting another hurdle to adoption.
This is a strong option when accuracy is a priority, but it is important to consider and compare with other methods in terms of print speed and stability.
Features and benefits of electron beam-based EB-PBF
Electron Beam Powder Bed Fusion (EB-PBF) is a printing technology that uses an electron beam to melt and solidify metal powder, which is then repeated layer by layer to form a three-dimensional structure. This method is characterized by its ability to produce a high-quality finish while reducing oxidation, since all of the process is performed in a vacuum environment. The benefit of this is stable part quality as titanium alloy is hard to oxidize in this method due to printing in a vacuum environment. In addition, by preheating the entire powder surface before melting, the temperature gap during printing is reduced, resulting in little to no residual stress. This prevents problems such as cracking and warping and reduces the occurrence of part defects. In addition, EB-PBF printed parts do not require heat treatment to remove residual stresses from the parts, reducing the required number of manufacturing operations.
The EB-PBF has faster printing speed and is suitable for printing large size and thick-walled parts. It is increasingly being used for artificial joint and structure parts for aircraft. However, compared with the LB-PBF, in some cases, it is not suitable for printing parts with extremely fine features.
In general, EB-PBF is the leading choice for manufacturers where stability and productivity are critical.
For LB-PBF, in order to prevent deformation and cracking, significant support material is required. EB-PBF method requires relatively little support material for printing. In addition, the support material does not require an EDM (Electrical Discharge Machining) or sawing to remove the support material from the build plate. The figure shows a manufacturing example of over-hung section at low angle without support material.
Because of EB-PBF being a hot process, warping and cracking of printed parts can be reduced, and stacking up printed parts in the vertical direction is also possible. The same quality is assured for printed parts stacked at the top and at the bottom. Also, vertically arranged rods can be manufactured without warping.
＊Heaters may be used in place of preheating, but distortion is likely to occur if printed products are stacked vertically.
Comparison of LB-PBF and EB-PBF(heat source/material/accuracy/cost)
Both of the LB-PBF and EB-PBF are printing methods using powder material. However, there are clear distinction on heat source, environment, and printing results.
| Item |
LB-PBF (Laser) |
EB-PBF (Electron beam) |
| Heat source |
Laser |
Electron beam |
| Environment of use |
Inactive gas atmosphere |
Vacuum(In some cases, inactive gas is introduced during printing) |
| Oxidization |
Oxygen management required |
Difficult to oxidize and product quality is stable |
| Material |
- |
Suitable for high melting point material and high reflectance |
| Powder diameter |
Approx. 30 μm |
Approx. 70 μm |
| Printing speed |
Relatively slow |
Fast |
| Residual stress |
Easily distorted with rapid cooling |
Gradual cooling suppresses stress/distortion |
| Characteristics |
Fine surface finish, good resolution, and internal flow paths |
Strengths in no residual stress in parts,thick-walled parts can be printed with ease, no EDM or sawing required for support material |
The EB-PBF printing method is excellent in terms of printing stability, speed, little oxidization risk. In particular, its introduction has benefited industries where large-size parts and high quality are required. Selection of a method according to the usage and purpose can improve accuracy and yield.
3D printing example of titanium alloy
3D printing of titanium alloys is utilized in the fields where precision and lightweighting are required. Here are some typical applications at the medical and aerospace sites.
Medical field (hip joint/spine cage/implant)
In the medical device field, 3D printing technology for titanium alloys is utilized in product tailored to individual patient. For example, for an artificial hip joint, custom implants can be manufactured according to the shape and movement of the bones, improving fit and durability.
3D printing also makes it possible to design parts that support the spine, known as spinal cages, with an internal mesh structure that makes it easier to integrate with the bone. In the field of implants also, product with optimized size and shape can be manufactured, by designing the implant based on the patient's skeletal data in advance.
Improved fit and stability compared to conventional products can be achieved with custom implants, resulting in reduction of post-operative recovery and burden.
The new product offers both a high level of fit and safety, which was difficult to achieve with conventional products, and also reduces post-operative recovery and improved patient outcomes.
Aerospace industry
Turbine blade
In the aerospace industry, 3D printing of titanium alloys has been extended as very suitable technology, as light weight and high durability are required. For example, a turbine blade is required to be as light as possible, at the same time as durable in severe environment of high temperature/high pressure.
Use of 3D printing allows for designing internal hollow and lattice structure inside the part, assuring necessary strength while reducing unnecessary weight.
Moreover, manufacturers of aircraft use 3D printing of titanium alloys for part consolidation by merging multiple part designs into one part design, which is difficult with conventional manufacturing methods, leading to reduced manufacturing costs and required inventory.
As such, 3D printing technology using titanium alloys not only improve product performance, but also produce added value in terms of lightweighting parts and manufacturing yield.
Points to consider for 3D printing titanium alloys
For the 3D printing of titanium alloys, there are some points to consider in advance such as price of material, cost of printer, whether outsourcing is possible or not, etc.
Price and market distribution trend of titanium alloy powder
For 3D printing of titanium alloys, dedicated metal powder is used. However, the material costs are expensive in general. In particular, spherical and high purity powder is required, the cost tends to be higher than the other metal materials. However, most of the metal powder surrounding the printed product can be recovered and reused for printing, eliminating the wasteful disposal of materials compared with conventional machining methods.
Moreover, supply system also needs attention. Titanium alloy powder is produced in special production facilities, its distribution volume is limited. The price can largely fluctuate due to supply-demand balance in the market and international conditions. Against this background, securing stable procurement route is also an important point to consider.
Initial installation costs and maintenance costs of 3D printer
While 3D printer for titanium alloys results in high performance parts, the printer itself is also expensive.
After installation, cost of materials as well as periodical maintenance costs, resource cost of dedicated operator, and facility investment for safety measures will be needed.
In addition, the cost of process maintenance required for post-processing and quality inspections after printing is also high. Designing by evaluating the entire manufacturing operation will be required, not only for the facility. Consistent operation is achievable after printer installation, by estimating the various costs and preparing in advance.
Points that need attention in using outsourcing and contract services
As a measure to reduce risks in initial investment, some companies may utilize outsourcing and contract printing services. It is an effective method to utilize outside dedicated services for prototyping with short lead times and verification in small batches.
However, outsourcing needs specific attention. For example, advance confirmation is needed in handling of design data that is involved with the company secrets and requirements for desired material and accuracy as these may not be responded by some contract 3D printing suppliers. Moreover, in case of product that needs integrated operation from designing to manufacturing, it may be difficult by outsourcing.
Therefore, while outsourcing is utilized only as an option in the early stages of implementation, long-term utilization is possible by planning for future in-house production.
Titanium alloy printing process in electron beam method (example of JAM-5200EBM)
From here, we will introduce the printing flow of titanium alloy by electron beam method (EB-PBF) such as printing steps and printer composition and certification, with the JAM-5200EBM as an example.
Printing steps by EB-PBF method
First, 3D design data is acquired in dedicated software and prepare data for printing which designates slice data, beam irradiation condition, and support structure. Then, the inside of the printer is evacuated and the entire base plate is pre-heated by the electron beam. Then, following steps will be repeated.
- Lowering the base plate by one layer.
- Spreading metal power evenly (powder bed)
- Preheating the entire powder bed
- Melting and solidifying the metal powder by irradiating electron beam to the area to print.
- Preheating the entire powder bed again
By repeating this process, the 3D structure based on the design data is formed, layer by layer.
After printing is completed, the build tank is cooled along with the base plate. Then, the 3D printer is vented and powder cake in which the powder is temporarily sintered, is taken out.
Further, the surrounding sintered powder is removed by PRS (powder recovery system) and the inside printed part is recovered.
As the EB-PBF method can preheat the entire powder bed extensively at once, it can reduce the scattering of powder and metal distortion during printing, which are the feature.
Composition and process design of electron beam system
The JAM-5200EBM consists of multiple complex technologies. The major components are as follows.
- To generate/control electron beam: electron source (cathode, magnetic field lens, deflection coil)
- To supply metal powder: powder hopper, recoater, powder constant supply unit
- To print: vacuum chamber, build tank
- To keep temperature constant on the build surface: heat shield
- To move up and down the build table: Z-axis drive
- To collect powder after printing: powder recovery box
Electron beams emitted from cathode are accelerated at high voltage and focused into a beam by magnetic field lens. Then, the beam is moved at high speed to a desired position by deflection coil and irradiated to the aimed point.
Such beam control is supported by automatic beam calibration function in the 3D printer. Through calibration, focus adjustment in the entire printing area and aberration correction are performed to keep the electron beam optimal.
In addition, at process design stage, the software analyzes the cross-section shape based on the 3D data loaded, automatically judges coarse and fine sections. Melt conditions and scanning strategies are automatically set accordingly, enabling both printing accuracy and speed.
Handling of field that needs high accuracy/high reliability (AMS certificate)
The JAM-5200EBM is designed based on the assumption for use in the fields that require high accuracy and high reliability, such as aircraft and medical equipment. One of the features of the JAM-5200EBM for such requirement is its compliance to "AMS certificate (SAE Aerospace Material Standards)." This is an international standard developed by the Society of Automotive Engineers (SAE) and it defines the compositions of materials, properties, manufacturing processes and quality requirements for aircraft, spacecraft, and defense systems.
In life-threatening situations such as aircraft engine parts and medical implants implanted in the body, the slightest error in shape or variation in characteristics can lead to major problems.
The JAM-5200EBM is capable of printing a titanium alloy (Ti-6Al-4V) compliant with AMS7011 and has been confirmed to have achieved quality that meets AMS7032. As a result, the JAM-5200EBM is expected to become an important technology that supports highly regulated production facilities where quality control is required, such as for aircraft parts and medical implants.
Backscattered electron monitoring for Ti64 (example of JAM-5200EBM)
JEOL is under development of BSE (Back-Scattered Electron) monitoring capability that only an electron microscope manufacturer can provide. BSE (Back-Scattered Electron) emitted from electron beam can be trapped and the unevenness on the molten surface can be observed in situ.
The technology of electron microscope which can detect back-scattered electron, which is not possible with laser beam, is utilized in quality control of printed product. This function is to melt Ti64 powder by electron beams and acquire BSE image by irradiating the same electron beams to the molten surface again, to automatically detect the inner defect and deformation of parts based on the image of cross section. In-situ observation during printing can assure product quality of the printed product. Currently, internal defects can be observed by BSE only for Ti64 material. In the future, we plan to apply this to other materials.
Conclusion
Titanium alloys are utilized in many fields such as medical devices and aerospace, taking advantage of their lightness and strength. In recent years, advances in titanium alloy printing by 3D printers have made it possible to manufacture complex shapes and lightweight structures.
On the other hand, there are some points to consider when introducing 3D printers, such as printing method, selection of instrument, and material costs. Please feel free to contact us if you would like to discuss the differences between laser type (LB-PBF) and electron beam method (EB-PBF) as well as application examples to determine the best introduction method for your company.