3D printing has been a disappointment despite the enthusiasm and fanfare it has received over the last few years. Even though 3D metal printing is possible, it is very expensive and difficult . Only manufacturing giants like GE has been able to 3D print metals using very expensive machines with high-power lasers. The use of metal printing has been limited as it required costly equipment, trained technicians and large facilities to power the lasers. For the process of product development and design, there is no real option available for printing various metal parts.
Metal fabrication with traditional processes like injection molding, can be noisy, create welding fumes and exhaust, and require the use of lots of chemicals by workers. Desktop Metal’s new additive manufacturing method uses Fused deposition modeling (FDM) techniques that are safer and easier to work with. A 3D printer for metal that is safe and capable of printing metal parts in your office. Desktop Metal uses the well-known plastic 3D printing technique, using flowable polymer binder and metal powders instead of a softened polymer. The metal powder is clumped into intended shapes to extrude the formulation.
A lot of the state of the art of metal 3D printers use a power bed fusion technique. The problem with power bed is that it’s messy, it’s unsafe and sometimes you have to suit up to operate with the machine with the powder. It’s expensive, dangerous, not as accessible to everyone. A new approach to extrusion technique is to bind the powder into a polymer matrix, extrude it, and then consolidate it in a furnace. The software has been designed with a slicer and technique thats used to print the part, to support the part layer by layer, telling the operator the best way to build that part. That is then transferred through the furnace. The furnace knows exactly what has been printed and knowns the process which it needs to centre the object as. That creates a solid part when you print it, once you come take it out of furnace, the part can lift right off its supports.
This is a step towards direct manufacturing, with prototyping process that you can develop a functional part with the same materials that you’re going to use in mass production. The production machine can then take the same materials and launch in to mass production. The printing process is going to be competitive with high volume manufacturing processes like metal injection moulding for instance.
The manufacturing process
The manufacturing process starts with 3D design. The designer will either create a new design from scratch or take an existing design and improve it by adding features that take advantage of 3D printing. There is now capability of modelling the process so that virtual designs can be use and simulated in computer to verify that design will work as intended. Once the 3D design is validated, the model will be printed in plastic, which is quick and relatively inexpensive process that allows to give a 3D part versus a virtual design. The printer has a laser and a plate carries powder across and the laser then selectively melts the particles to build a solid part. This process builds layer by layer. The key advantage is the reduction in raw materials needed to process a part because only the power that is needed for the design is used the remaining power is captured. The powders can be re-certified as needed for different industries. Once the part is printed in metal, it can be scanned to measure the dimensions to validate that the criteria from design has been met. This also allows for complex part manufacturing that can’t be designed using conventional manufacturing. This also allows for more innovative designs as new metal printing allows for designs that were not possible in the past.
Studio System by Desktop Metal – Start to Finish
The user can interact with the part and view precise tool paths through a dynamic interface. It then creates a unique build plan and identifies compatible parts from the queue that can be fabricated together. They system brings a wide range of critical alloys to 3D printing. Each alloy undergoes rigorous qualification by world leading material scientists whose expertise is at the core of the studio system technology. Safe to handle hot swappable media cartridges and quick release print heads allow for easy material changes in a matter of minutes instead of hours or even days with other systems.
In a process called bound metal deposition, metal rods, metal powder held together in polymer binder, are heated and extruded onto the build plate shaping the part layer by layer similar to an FTM printer. The printer features automatic extruder calibration and bed levelling based on a software analysis of the part to be printed. There are two extruders. One dedicated to printing metal, and the other for an interface layer printed between the part and its supports. With no loose metal powder of hazardous lasers, this process eliminates safety requirements often associated with metal 3D printing while enabling new features like closed cell infill for lightweight strength. During the print, a removable print sheet is held in place by the vacuum bed beneath it providing a smooth secure platform.
Once the print is complete, the vacuum disengages and the print sheet in part are easily removed from the printer. The flexible sheet is designed to allow easy removal of the part without damaging it during transfer. In the debinder, the parts are immersed in fluid. As primary binder is removed, an open pore structure is formed throughout the part, in preparation for sintering. With a low emission design, it requires no external ventilation. Automatic fluid distillation and recycling means that there is no need to refill between each cycle.
Once the cycle is complete, the parts are ready to go into the furnace no protective gear or drip dry required. Fully automated and sized to fit through and office door, the furnace delivers industrial strength sintering in an office friendly package. The furnace features two on-board gas canisters that are easily removed and equipped with RFID tracking devices. It is equipped with a disposable binder called trap lines, for safe and easy disposal of binder removed ruing sintering. Built-in temperature profiles are tuned to every builder material to ensure uniform heating and cooling, heated to temperatures near melting, remaining binder is removed and metal particles fuse together causing the part to densify up to 96% to 99.8%. Designed to simplify post processing, the ceramic release layer printed between the part and it supports doesn’t bond to the metal enabling separable support that are easily removed by hand. The results is a near net shape part with the strength, accuracy and resolution needed for functional prototyping. The studio system brings metal 3D printing to the engineer, providing the only safe, cost effective, and easy to use solution for printing complex metal parts in-house.
Production System – 3D printing at scale
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Source: Desktop Metal
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