PBF

This case study focuses on tibia trays in orthopedic manufacturing and the challenges faced in producing highly complex and customized implants. Additive Manufacturing (AM) using biocompatible materials like titanium offers a solution by allowing the production of unique implants in a shorter time frame.

INDUSTRY

Medical

CHALLENGE

3D print a plate of tibia implants in Titanium

KEY BENEFITS

• 3D Print customized metal parts
• Titanium is a durable & biocompatible material
• Quality and productivity improved

Custom Shape

Reduced Lead Time

Weight Reduction

Performance

History

To ensure the best possible patient care, modern medicine must explore the forefront of technology.  The medical industry has demanding requirements: complexity, precision of parts, customization, biocompatible materials, and durability.   One of the challenges in orthopedic manufacturing is to create an implant that has the capability to quickly integrate into the human body.  This is called osseointegration and is not easily accomplished with standard manufacturing practices today.  Some of these devices are specifically tuned to the patient’s specific need.  These devices or implants used during surgery can be customized but require extensive development time and that is not always to the patient’s advantage.  Additive Manufacturing (AM) makes it possible to produce unique, customized metal parts in a shortened time and at a reasonable price.  There are more than 25,000 implants used each year that are the result of 3D printing.  The most common material used in this process is titanium as it is one of the few materials that is both durable and acceptable to the human body.  For all of these reasons, the medical field is a key industry leading the utilization that of AM technology today.

Challenges

The purpose of an orthopedic implant is to replace a bone function seamlessly for the duration of the patient’s life. To accomplish this, the implant must fully integrate with the patient’s bone and tissue structure.  If traditional production methods are used, providing such implants and patient matched devices can be very expensive and time-consuming. Thanks to the advanced biocompatible materials available for use in AM, more and more medical applications are benefiting from this technology.  Because of their geometric complexity and need for biocompatible material, these medical parts designed by OEM’s globally are impossible to manufacture using conventional processes.

The spine industry has been utilizing AM on a mass scale for years. This is thanks to the size and quantity of implants which can be situated onto a build plate coupled with the volume of implants needed needed by the market. The next medical application emerging for AM success are tibial trays.  The challenge for tibial trays is that the throughput of standard AM machines makes the idea of producing enough implants of varying sizes and shapes improbable.  The overarching need is to have a printer that can make enough tibial trays to meet OEM demands.  Typical build plates can only hold 9-12 tibial trays.  This is not conducive to meeting industry demands without adding a significant amount of capital equipment.  Consider that the average size build plate industry wide is about 290 millimeters (11.5 inches) squared.

SOLUTIONS

AM technology can print highly complex and customized medical parts using a lattice structure to improve osseointegration, expedite production time and improve surface finish to reduce post-processing. AM allows for geometric complexity to create lattice structures for medical implants which creates a porous surface to improve bone integration while simultaneously reducing the weight of the implant. For traditional manufacturing, to achieve osseointegration it may be necessary to apply a coating to the titanium, which is expensive, time consuming, and difficult to validate.  Additionally, AM reduces the manufacturing steps and number of components, therefore cutting down production times and costs.

The AddUp FormUp® 350, a metal 3D printer using powder bed fusion (PBF) technology, showcases its capabilities through the quality and productivity output for tibia trays.

The build plate on the AddUp FormUp® 350 is 350 millimeters squared and can hold more than two times the tibial trays compared to typical build plates available.  The use of 4 lasers also offers a distinct advantage allowing 20+ tibial trays to be printed in less than a day.  Throughput is such an integral part of manufacturing today.  When space is limited and demand is high, machines like the AddUp FormUp® 350 are a welcomed technological addition. The FormUp 350 utilizes a powder roller technology which allows for geometric complexity using minimal supports and results in optimal surface finish and a reduction in post-process machining. This reduction saves time and overall production costs.

Results

The tibia tray implant manufactured on the FormUp 350 delivered a porous structure and optimal surface finish to improve overall bone integration. The extended build plate and powder roller technology allowed for increased production as well as time and cost savings thanks to less post-processing.

ANNUAL THROUGHPUT PER LASER BAR GRAPH

Running 1 shift per day for 52 weeks per year 1-1.5hrs from laser off to laser on (build flip)

• Increased production – larger build plate, fewer components and fewer manufacturing steps, including less post-processing, means production times are shortened!

• Geometric complexity – the AddUp FormUp® 350 offers the freedom to design implants to be geometrically optimized using lattice structures and overhangs, all with minimal support structures.

• Reduction in support structures – with the AddUp FormUp® 350, extensive support structures are no longer required, resulting in less post-processing machining, and therefore saving time and costs!

• Optimal surface finish – thanks to the powder roller technology on the FormUp 350, the surface finish is ideal directly off the printer, resulting in less post-processing time and costs!

• Functional integration – the AM process and materials create a porous structure and ideal surface finish which improves overall bone integration for medical applications.

• Biocompatible materials – the FormUp 350 allows a variety of different materials to be used and has already optimized Ti64ELI at both 30 and 60 micron layers.

The FormUp 350 machine is ideal for medical applications because it provides an improved and cost-effective process to mass-manufacture highly complex and/or customized medical parts.

Volume

• Individual part: 25.604 cm3
• Full Build Plate: 25.604cm3 * 22 parts = 563.288 cm3

Bounding Box

• With orientation (image): 86.7 mm x 56.7 mm x 52.4 mm (XxYxZ)

	1 LASER	2 LASER	3 LASER	4 LASER
Parts built per laser	22 parts	11 parts	7-8 parts	5-6 parts
Time to build with 30-micron medium powder (melting + recoating)	49.36 hours	28.92 hours	20.91 hours	16.76 hours
Medium, 30um powder (hrs)	49.36	28.92	20.91	16.76
Annual throughput	2612	4424	6077	7536

INDUSTRY

Medical

CHALLENGE

Bringing Laser Powder Bed Fusion (LBPF) to Total Hip Replacements to reduce production costs using a multi laser system and a larger build plate

KEY BENEFITS

• Maximum throughput with 78% OEE
• No supports = reduced post processing = lower part cost
• Reduced lead time
• Fine feature resolution and optimal osseointegration for better patient outcomes!

Integrated Features

Reduced Lead Time

No Support

Performance

History

Acetabular cups are used during the total hip replacements to sit against the native bone of the illum and articulates with the femur through the hip stem. Inside of the hip cup there sits a liner that connects with the head of the stem for articulation of the hip.

Acetabular hip cups are traditionally manufactured by casting and forging. This method has a long turnaround time from order to final product. This is primarily because of the lost wax method. This method creates a sacrificial wax mold in which a shell is formed around. Then the wax is melted out of the shell and the metal of choice is poured into the shell. The shell is then broken to reveal the final part in the metal of choice. Then these acetabular hip cups must have some sort of porous structure applied to them, which is either expensive to manufacture or difficult to validate.

When additively manufactured, the part is originally printed using Electronic Beam Technology (EBM). This manufacturing process uses a stream of electrons guided by a magnetic field to melt layers of powder on top of each other. The EBM technology is subject to unpredictable failures. This is particularly unsatisfactory when multiple hip cups are being stacked onto one another in a single build. This creates a cascading effect where one failed part can create a large amount of scrap at once. Additionally, it complicates the validation process as each layer must be mechanically validated independently. Although EBM can be faster than Direct Laser Metal Sintering, DMLS produces smoother and more accurate parts with no supports.

Challenges

Casting and forging parts require a large amount of time to manufacture. This method requires foundries that are only justified with large part volumes. The long primary process along with the additional steps creates a bottleneck in the supply chain. This leads to increased prices, inventory, and lead times.

Parts manufactured by EBM technology are less precise and have a higher surface roughness. This results in increased post-processing costs. More material that is melted must be traditionally machined away and the medical device industry is specifically sensitive to roughness that can lead to an increase in risk of build failure as the build time is longer. This does not coincide well with a technology that has a lower Overall Equipment Effectiveness (OEE).

SOLUTIONS

Laser Powder Bed Fusion (LPBF) technology provides a closer net shape part compared to EBM technology. There are also no supports needed in LPBF technology. All of which significantly reduces less post processing, reducing lead times. The FormUp 350 also has a larger build plate with more lasers compared to EBM printers leading to potentially more than double the throughput. AddUp’s FormUp 350 also has a fine feature resolution and a roller recoater which allows for a lattice structure printed with the implant. Lattice structures improve osseointegration which allows for longer lasting implants and better patient outcomes.

Results

The FormUp 350 from AddUp delivers throughput capabilities currently unchallenged on the market. This can be seen in the below Hip Cup Productivity Study. Parts shown were printed with a compression roller technology in 30µm layers of Ti6Al4V ELI. Compared to EBM technology, the FormUp 350 has a shorter run time of 12:41 compared to 15:23 (EBM) which leads to an improved annual throughput of 9,309 (16,403 LPBF, 7,094 EBM).

	2 Lasers Competitor 250	4 Lasers AddUp 350
Parts per Laser	10	8-9
Runtime 30μm	15:23	12:41
Annual Throughput 30μm*	7,094	16,403