Manufacturing hypersonic missile parts is a delicate process. They need to be able to withstand extreme temperatures and pressures, as well as the stresses of traveling at high speeds.
Traditionally, these parts have been made using subtractive manufacturing processes like machining or milling. However, there is now an innovative way to make them that is being perfected by the US and different countries: additive manufacturing.
Here, we will discuss the fascinating laser powder bed fusion process for additive manufacturing and illustrate how organizations can use it for defense applications.
American scientists were convinced that hypersonic missiles were still a long way off because current materials and manufacturing techniques are not capable of producing components that can withstand the searing temperatures, they would be exposed to in engines capable of propelling vehicles to speeds of up to Mach 5.
Researchers and scientists are turning to additive manufacturing techniques and exotic refractory alloys to overcome these problems, and many of them believe that using the powder bed fusion process to make complex hypersonic parts out of niobium alloys will lead to a breakthrough.
What Is Powder Bed Fusion?
Powder bed fusion is an additive technique that creates parts one layer at a time. Additive techniques like PBF allow engineers to create far more complex parts than subtractive processes like grinding or milling could produce, and they are also much faster. Creating a prototype using traditional methods could involve weeks or even months of tooling but configuring a 3D printer can be done in a matter of minutes.
Creating a 3D model of the desired part with CAD software is the first step in the PBF manufacturing process. This can either be done from the ground up or by scanning an existing component and then making changes. When the 3D model of the component is complete, a device called a slicer is used to cut it into layers. These layers are usually between 20 and 60 microns thick.
Once the CAD model has been created and sliced, the data is sent to a 3D printer. The powdered material that will be used to create the component is placed in a hopper attached to the printer, and a blade or roller is used to spread the required amount of material for each layer over the build platform. Before creating each layer, the 3D printer calculates the scan path that an energy beam or laser will follow to bond the material together.
Sintering and Melting
During the PBF process, material can be bonded by either sintering or melting. Sintering does not create temperatures high enough to turn materials into liquid, which means the resulting part is not quite as strong. Sintering is usually used to make components out of polymer materials, and melting is the method used to create parts out of refractory metals like niobium.
Post processing is usually required when parts are 3D printed using the PBF process. The two most common types of post processing are heat treatment to improve the material’s mechanical qualities and reduce residual stress and surface finishing and polishing.
PBF offers several benefits over traditional manufacturing techniques. Only the amount of material to create the desired part is used, so less is wasted and costs are lower. Production development times are far shorter when computers are used to design products, and 3D printing makes low volume production financially viable.
PBF can be used to bond ceramics, glass and metals together, and unused material can be recycled efficiently. When materials are melted rather than sintered, the finished component is as strong as a cast or machined part.
PBF has traditionally been used to make jewelry, automobile parts and medical components like titanium implants, but the process is now becoming far more common in the aerospace sector. PBF gives scientists the ability to create geometrically complex parts very quickly, and it also allows them to test new ideas without worrying about tooling and machining costs.
The only real disadvantages of PBF are the high costs involved. Refractory metal alloys and 3D printers are very expensive, which is why the government has made billions of dollars available to fund hypersonic research.
This research is already bearing fruit. Boeing’s latest 777 airliner contains more than 300 additively manufactured parts including a nozzle in its GE9X engines that is five times stronger than the part used in the previous engine. This added strength allowed engineers to really push the envelope, and they created the largest turbo-fan aircraft engine ever made.
NASA has been making space rocket components out of niobium for decades because it is extremely strong, resists corrosion and can withstand extreme temperatures, and now the refractory metal is being used to make spacecraft parts in the private sector. The material was recently used by Space X to make nozzles for its Falcon 9 rocket. The nozzles will be fitted to the company’s latest Merlin engines.
PBF has also become common in the automobile industry. The Swedish manufacturer Koenigsegg only makes a few dozen hypercars each year, so it must make extremely complex parts in very small numbers. The company’s One:1 hypercar was designed using CAD software and 3D printing shortened the prototyping process. Also, PBF was used to create metal parts including exhaust components and turbocharger housings.
The PBF Experts
Castheon Hypersonics is leading the way in hypersonic materials research and manufacturing. Founded by a 25-year space industry veteran in 2016, Castheon uses refractory metals and alloys to produce components that minimize drag and improve cooling at hypersonic speeds.
Castheon founder Dr. Youping Gao joined the Addman team in February 2022, and he joins a team of world class scientists, engineers and manufacturing professionals.
During his long and distinguished career, Dr. Gao has developed new approaches for making additive manufacturing materials, and he was the first individual to be awarded a production certificate by NASA to create mission critical components for human space flight using BFP. He also invented the Gao Block, which is an additive manufacturing development tool that has revolutionized rapid prototyping.
A New Frontier
Additive manufacturing has changed the way products are designed, tested and made, and it could provide the breakthroughs that America needs to create a working hypersonic missile. There is still much to be done and many problems remain unsolved, but the research conducted so far looks extremely promising.
Addman and Castheon look forward to helping researchers overcome these challenges, and they can also help your business to enjoy the benefits of additive manufacturing. If you would like to know more about Addman, Castheon or PBF, you can use our online form to contact us.