Can 3d printers print metal With 3D printing rapidly changing the traditional way of production and lifestyle, 3D Printer can print out the various models we want. Work watching video using a mobile phone at home, but there is no suitable mobile phone support, 3D printer can help you achieve; when shopping saw ornament design high-class shops is very good, but no extra budget, 3D Printer can help you achieve; even, if you want to print the food, now 3D Printer can help to achieve.

For many 3d printing beginners, it is not very understanding some of the development trend of the 3D Printing, they are very confused, since the 3D Printer so that can print equal to anything, metal? The answer is absolutely yes, our ancestors as early as in many years ago this idea and trying to implement. With the development of science and technology and the requirement of popularization and application, the rapid manufacturing of metal functional parts has become the main direction of rapid prototyping.

At present, can be used for rapid prototyping manufacturing method of metal functional parts directly mainly include selective laser sintering (Selective Laser Sintering SLS) technology, Direct Metal Laser Sintering(DMLS), Selective Laser Melting (SLM) technology, Laser Engineered Net Shaping(LENS) and Electron Beam Selective Melting (EBSM) technology.

Through continuous accumulation of these years of 3D technology, some manufacturers have also launched their own commercial metal 3D printer, the main method of rapid prototyping for Alunar direct manufacturing of metal function parts are summarized.


Metal Printing Method one: Selective Laser Sintering




SLS model example_main

Selective laser sintering (SLS) is a SLS method using infrared laser as energy source. Most of the modeling materials used are powder materials. When processing, first preheating to slightly below its melting temperature, then the powder paved in scraping stick under the action of laser beam; under the control of the computer according to the hierarchical information section selectively sintered layer after sintering under a layer of sintering after all, remove excess powder, then you can get a good sintering parts. At present, the mature process materials are wax powder and plastic powder, and the process of sintering with metal powder or ceramic powder is still under study.

The SLS process is made of powdered material. The material powder spread on the surface of formed parts, and leveling; CO2 laser with high strength in just laying new layer scan section part; powder material in high intensity laser irradiation are sintered together, get the parts in cross section, and has formed part of the adhesive as below; a layer of cross section after sintering, covered with a new layer of powder material, selective sintering layer section.

In the molding process, because the powder is sintered, so there will be a lot of powder objects contaminated office space, general equipment should be placed in a separate office. In addition, the molded product is an entity that can not be assembled directly for performance verification. In addition, when the product is stored for too long, it will deform due to internal stress release. Design support for deformation prone areas, surface quality in general. The production efficiency is higher, the operation cost is higher, and the equipment cost is more expensive. Energy consumption is usually over 8000 watts. Material utilization rate is about 100%.


Metal Printing Method two: Direct Metal Laser Sintering (DMLS)




How did DMLS form

SLS manufacturing of metal parts, there are two methods, one is the indirect method, the polymer coated metal powder SLS; the second is the direct method, namely direct metal laser sintering(DMLS). Since the research of direct laser sintering of metal powders in Leuvne University of Chatofci in 1991, the direct sintering of metal powders by SLS process is one of the ultimate goals of rapid prototyping. Compared with the indirect SLS technology, the most important advantage of DMLS process is the removal of expensive and time-consuming pretreatment and post-processing steps.


Metal Printing Method three: Selective Laser Melting (SLM)




What is Selective laser melting

The idea of Selective Laser Melting(SLM) was first proposed by the German Institute of Fraunhofer in 1995. In 2002, the Institute achieved great success in the study of SLM technology. The world's first SLM device by the MCP group of companies under the jurisdiction of the German MCPHEK branch has launched at the end of 2003. To obtain the compact laser forming, but also benefit from the great progress of rapid prototyping equipment in 2000 after laser (for use, advanced high energy fiber laser powder to improve the precision, etc.) completely melted powder metallurgy mechanism which is used for laser rapid forming of metal components. For example, EOS, a famous German rapid prototyping company, is the world's earliest specialized company for metal powder laser sintering, which mainly engages in research and development of SLS metal powder, process and equipment. The company's newly developed EOSINTM270 / 280 type equipment, although the continued "sintering" in this statement, but the assembled 200W fiber laser, and the metallurgical mechanism completely melted metal forming component, forming performance can be improved significantly. At present, as an extension of SLS technology, SLM technology is booming in Germany, Britain and other European countries. Even though the expression of selective laser sintering (SLS) continues to be used, the actual forming mechanism has been changed to the complete melting mechanism of powders.


Metal Printing Method four: Electron Beam Melting (EBM)




The principle of electron beam selective melting (EBSM)

A patent application in 1994 the Swedish ARCAM company, has developed a technique called electron beam melting technology (Electron Beam Melting), ARCAM company is also the world's first commercial electron beam rapid manufacturing company, and in 2003 launched the first generation device, then the United States Massachusetts Institute of Technology, NASA, Beijing Research Institute of Aviation Engineering and China's Tsinghua University have developed a rapid manufacturing system based on their electron beam. Electron Beam Solid Freeform Fabrication (EBSFF) developed by Massachusetts Institute of Technology. EBSFF technology uses wire supply forming material two by electron beam melting metal wire, electron beam fixed, metal wire by wire feeding device and a movable working table, and the lens technology, electron beam freeform fabrication, the influence of many factors, such as electron beam, acceleration the voltage, current, focusing deflection scanning, working distance, workpiece speed, wire feed speed, range, feeding angle, wire end from the workpiece height, wire length etc.. These factors affect the welding section geometry parameters, distinguish between the single factors is very difficult; selective melting of Swedish ARCAM company and Tsinghua University developed electron beam (EBSM) metal powder by electron beam melting shop on the work table, similar to the selective laser melting technology, to achieve real-time deflection by electron beam melting, the technique does not require two-dimensional moving parts, fast scanning can be achieved in metal powder forming.


Metal Printing Method five: Laser Melting Deposition Technology (LMD)




LMD laser takes shape quickly

Laser melting deposition (Laser Metal Deposition, LMD) for the first time in the last century in 90s by the U.S. Sandia National Laboratory is put forward, then in many places around the world have been developed by many universities and institutions are studied independently, so the name of this technology are. For example, near net forming technology of LENS laser Sandia Laboratory (LaserEngineeredNetShaping), direct metal deposition DMD American Michigan University (DirectMetalDeposition), the University of Birmingham in the UK, the direct laser forming DLF (DirectedLaserFabrication), Chinese Northwestern Polytechnical University laser rapid forming LRF (LaserRapidForming) etc.. Although the name is not the same, but they are basically the same principle, molding process, the powder to the working plane through the nozzle, the laser beam is gathered to the point, the coincidence of powder optical action points, through the table or the nozzle moving, get cladding entity accumulation.

LENS technology is the use of laser kilowatt laser beam, due to the large, generally above 1mm, it can get dense metal metallurgical bonding but its solid, dimensional accuracy and surface finish are not too good, the need for further processing to the machine. Laser cladding is a complex process of physics, chemistry and metallurgy. The parameters in cladding process have great influence on the quality of cladding. The process parameters of laser cladding in the main laser power, spot diameter, defocusing amount, powder feeding rate and scanning speed, the temperature of the molten pool, their dilution of the cladding rate, crack, surface roughness and cladding parts density have a great impact. At the same time, each parameter also affects each other, and it is a very complicated process. Proper control methods must be adopted to control various influencing factors within the allowable range of the coating process.