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| Warranty: | 1 Years |
| File Format: | STL |
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The electron beam is produced in an electron gun. There are tungsten filament in the electron gun, the electron gun adopts the direct heating type tungsten belt three-stage electron gun, to ensure the tungsten filament continuous working life of 40 hours. When electrons are accelerated to 0.1 to 0.4 times the speed of light, their energy density can reach 106kw/cm2. To avoid electron beam scattering due to the presence of gas atoms, the vacuum chamber containing the electron gun and metal powder has a pressure as low as 10E-4mbar. As electrons penetrate the surface of the powder and enter between the particles of the powder, the speed of the electrons decreases. During this time, the kinetic energy of the electrons is converted to heat energy, and the metal powder reaches melting temperature. To excite an electron beam, the gun uses an array of electromagnetic lenses (called a deflector coil) so that the beam scans the surface of a metal powder from side to side and melts it at the desired location (similar to how a regular television set works). X-rays are emitted when electrons in the beam strike the surface of the powder in the molding chamber.
The thermal-electron gun consists of a cathode, a gate and an anode. The cathode is negative and emits hot electrons. The gate is negative, which is more negative than the cathode. The anode is positive, accelerating the hot electrons. The three poles form a compound field and play a focusing role, thus forming a cross beam spot with cross section diameter D0 and divergence Angle A0 between the gate and anode. When the filament is heated to a temperature T, its energy is above φ to produce electrons, which then escape from the filament to form a usable electron beam. Both W and LaB6 filaments are used as tri-pole gun cathodes. In addition to the cathode, there is a grid called a Wehnelt cylinder and an earthing anode with a circular hole in the center. The cathode is connected to the high voltage cable, the other end of the high voltage cable is connected to the high voltage power supply, the high voltage cable is connected to the tungsten filament to provide the current to heat the filament, LaB6 filament is not directly heated, but tied together with the metal rhenium with good heat resistance.
1. High energy utilization rate
The energy effectively absorbed by lasers only accounts for about 5% of the total power input. The energy effectively absorbed by the electron beam can account for about 75% of the total electrical energy input. Therefore, in the long run, the electron beam saves more power and the operation cost is lower.
The output power of electron beam is 3-6kW, and most lasers are 300-500W; The electron beam uses magnetic deflection coil to realize two-dimensional scanning, scanning frequency up to 20,000 Hz, without moving parts, while the laser must replace the mirror or rely on the movement of CNC workbench to realize scanning; SEBM produces titanium acetabular cups 5-8 times more efficiently than SLM at less than half the cost.
3. No reflection, wide range of machined materials
All kinds of metal materials have high absorption rate of electron beam. In laser rapid manufacturing, the absorptance of laser is different metal materials related to the wavelength of the laser, can limit the laser processing, the kinds of materials and in the process of laser manufacturing, the absorptance of laser is solid powder materials is low, the formation of molten pool, the absorption rate will rise suddenly, result in forming material vaporized. At the same time, laser is not suitable for processing high reflectivity titanium, aluminum and high melting point tungsten and other materials. In electron beam rapid manufacturing, a variety of conductive materials can be processed, and the absorption rate of formed materials to electron beam is stable during the whole melting process.
4. Low forming stress
SEBM can preheat the powder bed at 1300ºC and is currently the only 3D printing technology that can achieve high-quality printing of brittle metal materials.
5. High cleanness of vacuum environment
High vacuum environment, reduce oxygen, nitrogen, water vapor and other impurities pollution, suitable for active and oxygen sensitive material printing.
SEBM forming materials and properties
SEBM forming materials cover stainless steel, titanium and titanium alloy, Co-Cr-Mo alloy, TiAl intermetallic compound, nickel base superalloy, copper alloy, niobium alloy and other metals and alloy materials. For example:
1. The heat treatment properties of SEBM formed CoCrMo alloy meet the requirements of medical standards
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1. Aerospace Since 2005, Arcam AB's SEBM forming system has been purchased by American Aerospace Center's Marshall Space Flight Center, CalRAM For rapid manufacturing, and Boeing for Phantom for the manufacture of related aerospace components. |
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2. Biomedical By the end of 2017, more than 100,000 acetabular cups prepared by pulverized bed electron beam 3D printing technology have been implanted into human bodies worldwide, and orthopedic implants prepared by this technology have involved more than 20 parts such as artificial joints, maxillofacial, skull and spine. |
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