Inert gas finds new way in metal 3D printer

Industrial gas has started to be used for a new processing technology called the 3D printer. In 3D printing, successive layers of powdered metal material are laid down under computer control, producing a 3 dimensional object as one likes. Inert gases such as nitrogen and argon are indispensable when processing metal with lasers such as titanium, and inconel, as well as stainless steel and aluminum.

The metal 3D printer is a remarkable technology having the potential for making great changes in manufacturing. The quality of metal processing has greatly improved with the increase of the output of laser beams in recent years. With the penetration of this technology into the manufacturing sector, in places where the development of prototypes takes place, it is anticipated that the time to produce prototypes using metal molds and the expense will be far less than up to now. Gas Review visited a company called J・3D located in Nagoya which quite early on (October 2013) began a business of processing items under commission using a metal 3D printer. We conducted an interview with President Fumio Takaseki regarding the relationship between this manufacturing process and industrial gas.

3 dimensional product made up of successive layers by laser

The 3D printer is a facility which, while piling up metal powder 5/100 mm each and solidifying it, creates a 3 dimensional form. It is called a ?printer? because it faithfully reproduces a structure as per the plan. Substantially it is nothing more than a processing device which uses a laser beam.

What becomes the material used is resin and metal. What first appeared in the market was a processing device using resin. The actual form and size can be reproduced by making a 3 dimensional item out of resin. If the item is made in transparent form, the inner structure can be checked. Later, in addition to resin, metal items came to be formed using metal. An evaluation of product in the light of the actual usage environment was made available. It also became possible to examine the effect of heat and force which could not be done with resin.

Just as with a laser finishing device, the atmosphere is controlled with inert gas

What exactly does the manufacturing process with a metal 3D printer involve? Looking at the flow of the process reveals first of all metal powder, which is the raw material, is spread uniformly with a thickness 0.05mm onto the table inside the chamber of the device. This is then illuminated with a laser from the top of the chamber. The part of the metal hit by the laser is fused. When the illumination ends, the table drops one level. This is to make the spacing which the laser illuminates constant. When the table is lowered metal powder with the same thickness as before is again spread onto the surface. The laser beam illuminates this again. This process is repeated, and the layers of metal powder with each 0.05mm thickness are piled up, and this causes a 3 dimensional figure to form. Inert gases such as nitrogen and argon are used as atmosphere gases to prevent oxidation of the metal while it is being illuminated.

J・3D uses a generator to generate nitrogen while argon is supplied from liquid gas containers (LGC). Takaseki stated, “Argon is used with titanium and inconel. Depending on the work, a time framework of 100 continuous hours is required. During that time, gas flows freely inside the chamber so that the contents of one LGC are consumed.” There is a ventilation facility inside the chamber to eliminate sputter and the excess metal powder during the time of laser illumination. Therefore, the argon gas needs to be replenished continually. There is one chamber in a processing facility. If the number of facilities increases, the amount of gas consumed increases accordingly. The accumulation process based on the 3D printer, just as with laser welding and cutting, involves nothing more than just heat processing of the metal. An inert gas environment is indispensable for prevention of oxidation.

More information is shown in The Gas Review magazine issue No.404.

19 May. 2015

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