Inert atmosphere generation

What is an inert atmosphere and why is it important?

The term inert means 'chemically inactive', so an inert atmosphere is an environment in which powder bed fusion can take place without the risk of contamination from reactive gases that exist in the air, such as oxygen and carbon dioxide. Renishaw use argon gas for the build environment of its additive manufacturing systems due to the fact that it is both inert and plentiful - the third most abundant gas in the earth's atmosphere.

An inert atmosphere is essential for the powder bed fusion process, in order to ensure that the metal parts being built do not become contaminated by air molecules that can change the chemical and physical properties of the final components.

Class leading technology

Renishaw's additive manufacturing systems are unique in the way that the inert atmosphere is generated. First, a vacuum is created, removing any air and humidity from the chamber. Once complete, the chamber is filled with approximately 600 litres of high purity argon.

Throughout the build process, the atmosphere is always maintained at < 1000 ppm (0.1 %) oxygen, and can be set to run below 100 ppm (0.01 %) oxygen for reactive metals such as titanium.

The AM250 uses relatively low gas feed rates of < 30 L/hr, this means that it is economical to run the system using argon for all materials rather than using N₂ as a cheaper alternative for non-reactive metals.

The graph on the right compares the time taken to create an inert atmosphere using Renishaw's vacuum and argon technique to the technique of filling the chamber with either nitrogen or argon gas.