Pure copper and copper alloys are widely used in electric power, heat dissipation, pipelines, decoration and other fields due to their excellent electrical conductivity, thermal conductivity, corrosion resistance and toughness. Some copper alloy materials have good electrical conductivity, thermal conductivity and relatively With high strength, it is widely used in the manufacture of electronic, aviation and aerospace engine combustion chamber components. However, with the increasing demand for components with complex structures on the application side, traditional processing techniques have gradually been unable to meet all requirements.
Metal 3D printing technology can manufacture complex functional integrated parts. This advantage can also be reflected in the field of copper metal manufacturing. For example, in the field of copper inductor coil manufacturing, metal 3D printing technology can be used to replace traditional manufacturing processes. Manufacture complex inductance coils to avoid the need for assembly and the deficiencies caused by welding. Regarding copper 3D printing technology, it is showing more and more economic and diverse development trends. This issue of 3D Science Valley and Gu You will learn more about the Fraunhofer ILT Laser Research Institute after launching a solution to melt pure copper through a green laser. Its brother research institute Fraunhofer IWS Institute of Materials and Beam Technology has achieved the 3D printing of complex copper products.
Start the manufacturing of complex copper parts
Fraunhofer IWS, the Fraunhofer Institute for Materials and Beam Technology in Dresden, Germany, uses short-wave green lasers to treat metals with almost defect-free treatment, realizing a new production method that was not possible with pure copper before. It can be used to manufacture complex parts made of pure copper and copper alloys in the aerospace and automotive industries, and can improve the efficiency of electric motors and heat exchangers.
3D printing-additive manufacturing copper components are particularly suitable for the manufacture of components that require high heat exchange and electrical conductivity. For example, it is possible to manufacture more efficient and compact radiators in next-generation power electronic equipment, as well as electrical drives for satellites, cooling systems in space propulsion systems, and engine parts.
With the TRUMPF green laser series TruPrint1000 metal 3D printing equipment installed by Fraunhofer IWS, Fraunhofer IWS can design and manufacture pure copper components with excellent electrical and thermal conductivity. These components can achieve more efficient motors, new radiators and other parts in power electronic equipment. In addition, it can also be used in the production of inductor coils.
The TruPrint1000 metal 3D printing system does not use infrared light with a wavelength of 1064 nanometers (one millionth of a millimeter), but uses a high-energy green laser with a wavelength of 515 nanometers. 3D Science Valley learned that, according to Fraunhofer IWS, previous experiments have repeatedly shown that infrared laser beams with a power of up to 500 watts are not enough to completely melt copper, and only 30% of the energy used reaches the copper material-the rest is reflected by the metal. The new green laser with a maximum power of 500 watts provides a unique solution: the copper powder absorbs more than 70% of the energy and melts completely, making it usable for additive manufacturing.
Pure copper has very good thermal and electrical conductivity
Today, many copper parts are processed through forging or casting manufacturing processes. However, the 3D printing-additive manufacturing process has opened up new options for the production of highly complex geometries, which is simply impossible to achieve in conventional manufacturing processes.
Because copper has very good thermal and electrical conductivity, when this metal can be processed in a 3D printing-additive manufacturing system, it will constitute a significant potential for improvement in the design and manufacturing of current and future copper products.
Components made of pure copper and copper alloys play an important role in the aerospace, electronics and automotive industries, such as engine combustion chambers, electric drive components or heat exchangers. Additively manufactured copper parts are superior to many aluminum and other alloy solutions due to their higher volume ratio and conductivity.
Regarding copper metal 3D printing, the most popular applications on the market currently include engine combustion chambers with cooling channels, copper inductor coils, copper heat exchangers, and motor stator windings.
Engine combustion chamber
Many aerospace companies in the market have made breakthroughs in rocket copper alloy thrust chambers. Among them, Aerojet Rocketdyne's breakthrough in the field of 3D printing of rocket copper alloy thrust chambers has brought the possibility of manufacturing a new generation of RL10 engines. 3D printed copper alloy thrust chamber parts will replace the previous RL10C-1 thrust chamber parts. The thrust chamber components to be replaced are manufactured by traditional processes and are welded by multiple stainless steel parts, while the 3D printed copper alloy thrust chamber components are composed of two copper alloy parts.
Compared with the traditional manufacturing process, the selective laser melting 3D printing technology brings a higher degree of freedom to the design of the thrust chamber, allowing designers to try advanced structures with higher thermal conductivity. The enhanced heat transfer capability makes the design of the rocket engine more compact and lightweight, which is exactly what the rocket launch technology needs.
Launcher, an aerospace start-up engaged in the manufacture and launch of small rockets, also tested copper alloy rocket engine components. Launcher has been working on the development of the proof-of-concept engine E-1 since last year, which is a 3D printed copper alloy (Cucrzr) engine component that integrates complex cooling channels. This design will improve engine cooling efficiency.
NASA made progress in 3D printing of copper alloy parts in 2015. The manufacturing technology is also selected laser melting 3D printing, and the printing material is GRCo-84 copper alloy. The 3D printed part made by NASA using this technology is the lining of the rocket combustion chamber. The part is divided into 8,255 layers and printed layer by layer. The printing time is 10 days and 18 hours.
There are more than 200 complicated channels between the inner and outer walls of the copper alloy combustion chamber components. Manufacturing these tiny internal channels with complex geometric shapes is a big challenge even for additive manufacturing technology. After the parts were printed, NASA researchers used electron beam free manufacturing equipment to coat them with a nickel-containing superalloy. NASA's ultimate goal is to greatly increase the manufacturing speed of rocket engine parts while reducing manufacturing costs by at least 50%.
Chinese metal 3D printing company Blite has made progress in the field of copper metal laser forming. It has developed a 3D printing process for refractory metals and high thermal conductivity and high reflective metals, and realized the copper material manufacturing process of complex runners, and successfully prepared 3D printed copper alloy tail nozzles.
Copper inductor coil
Generally speaking, the inductance coil in the electric inductor needs to go through several mechanical manufacturing processes. The coils are manually bent and welded to achieve the desired shape, in which small pieces of copper (tubes) are put together and welded. The welding is a time-consuming process and causes a lot of production costs.
The more complex the geometry of the inductor, the more individual components need to be welded. When multiple solder joints adjacent to each other are required in order to obtain the required geometric shape, several solders with different melting points must be used so that the first solder will not loosen when the second solder is applied.
The working time and quality of hand-made inductors cannot meet the increasing demands of the industry. And through metal additive manufacturing (AM), high-quality parts can be realized, these parts have a highly complex geometry, so as to meet the needs of large-scale production. 3D printed inductors without solder joints require less energy, have higher efficiency and can achieve uniform hardening results.
In addition, 3D printing is not only recommended for the production of fine geometric shapes that traditionally cannot be achieved. For standard geometries, 3D printing is also attractive and profitable. Users can expect 3D printing to achieve the same manufacturing cost as traditional welding inductors, and 3D printing can eliminate all the disadvantages of traditional welding coils. For example, the service life of inductor parts produced under GKN powder metallurgy process is 4 times the service life of parts produced by traditional manufacturing processes.
Copper heat exchanger
Powder bed fusion (PBF) additive manufacturing technology makes it possible to manufacture a new generation of compact and efficient heat exchangers. If metal 3D printing technology is combined with copper with excellent thermal conductivity, it will be an improvement in electric vehicle heat exchanger technology. Bring huge room for imagination. As the additive manufacturing of copper alloys and pure copper has become more mature, it has also paved the way for the manufacture of high-performance copper metal heat exchangers. Combined with the design for additive manufacturing, it will accelerate the innovation of heat exchanger products in fields such as new energy vehicles.
Motor stator winding
In terms of electric vehicles, 3D printing of copper also has certain application potential. Electric drive and control systems are the core of electric vehicles, and they are also the biggest difference from vehicles with internal combustion engines. The electric drive and control system consists of a drive motor, a power supply and a motor control device. Other devices of electric vehicles are basically the same as those of internal combustion engine vehicles. The electric drive subsystem is composed of an electric control unit, a controller, an electric motor, a mechanical transmission device and driving wheels. The main energy subsystem is composed of main energy, energy management system and charging system. The auxiliary control subsystem has functions such as power steering, temperature control and auxiliary power supply.
In the market, the German Additive Drives company uses 3D printing to additively manufacture motor stator windings and is expected to significantly improve the performance of parts.
The maximum output power of the motor is limited due to its preheating, for example due to the allowable winding temperature. There are usually two levers to increase the power limit: first, to reduce losses with the same power, and second, to improve heat dissipation. The design of the winding plays a major role here because it is the main heat source.
The classic round wire winding has many limitations: the copper conductor, winding process and slot geometry must match. The conductors wound around each other form a strong pattern. In addition, the round wire (the classic conductor shape) does not fit well with the trapezoidal groove in terms of geometry. As a result, each groove is half filled with copper, thereby forming a void. The relatively small conductor cross-section can ensure a large electrical heating loss.
The German Additive Drives company has achieved a higher degree of freedom through 3D printing. Through the powder bed-based SLM selective metal 3D printing process, the copper content in the groove is greater. Physically, this means the largest cross-section of the turns and a smaller resistance. The variable shape achieved by 3D printing is also good for heat dissipation, because each wire is in thermal contact with the so-called laminated core of the coil.