Metal additive manufacturing, widely known as 3D printing, started as a technology for the testing and evaluation of concept models and prototyping of new components. Metal additive manufacturing has quickly become more widely adopted by manufacturing processes, particularly with the improvements and availability of existing and new metal powders.
More and more businesses turn to this technology to produce custom parts and products. The benefits of using 3D printing to create metal objects are primarily faster turnaround times and increased flexibility to create complex structures. This combination frequently results in better product performance and significant cost reductions. To ensure the 3D manufacturing system is running efficiently and delivers the optimal quality, the manufacturers of the 3D printers use many sensors and monitoring instruments on their machines. In this article, we look at the role of an oxygen analyzer in metal 3D printing and why it is important to have one in your additive manufacturing process.
The metal 3D printing process involves fine layers of finely powdered metals being fused together layer by layer using laser technology. The ability to build parts while minimizing the risk of impurities being present is a major challenge in the metal additive manufacturing industry. Metal 3D printers usually feed their stock into an inert environment to eliminate contamination and prevent quality issues. Inert gases such as argon can be used to improve the quality of the weld or bond. This process requires a well purged print chamber where the environment is closely monitored for oxygen. High levels of oxygen can result in oxidation of the feedstock powders, directly impacting the quality of the manufactured part due to a reduced weld strength between layers.
The role of inert gases in the metal AM is a critical one. Argon prevents the risk of oxidation by extracting and displacing oxygen from the 3D printing chamber. Argon reduces the oxygen levels to ppm levels or less, creating a perfect environment for the metal parts being built.
An oxygen analyzer is used to monitor and control oxygen levels while the printer is in operation. Having the ability to measure oxygen is important in detecting changes in the chamber environment. The atmosphere within the 3D printing chamber must remain stable during the process. Small changes in oxygen content can negatively impact the properties of metals, particularly titanium and aluminium. For industries such as aerospace, automotive, and medical, it is critical that the quality of the end-product is not impaired by the presence of oxygen during the metal 3D printing process.
Argon has proved to be an incredibly useful gas in the metal AM process, used to reduce oxidation and prevent corrosion. Using an oxygen analyzer not only protects the powders and parts created during the printing process, but it can also be used as a workplace safety device.
Argon is much heavier than air, and therefore it can replace breathable oxygen in an enclosed space or facility. Due to the colourless and odourless properties of argon, a leak could go unnoticed. An oxygen analyzer can monitor percentage levels of oxygen in an environment and would provide an alert if the O2 levels dropped as a result of an argon leak protecting personnel.
When handling and moving powdered metals, it is important that the oxygen level in the confined area is monitored. Dust explosions can occur if oxygen levels rise above the explosive limit. Purging vessels and transport lines with an inert gas are required and continuous monitoring of the level of oxygen is good practice. In addition to oxygen, the monitoring of moisture within metal powders is also important. Wet powdered metals can produce hydrogen and/or steam, which may lead to an exothermic reaction that may cause an explosion.
3D printing is only one element of the additive manufacturing process. Having the ability to monitor oxygen levels at each stage of the manufacturing process is critical.
Ensuring high quality metal parts in additive manufacturing also relies on the pre-and post-production activities in the overall process. Inert gas also plays an important role in the production of metal powders, storage, and post-processing. Metal powder quality is important as it can have a significant impact on physical properties, including tensile strength and brittleness; not to mention its effect on heat tolerance or resistance to corrosion.
To avoid contamination of the feedstock material, measurements are taken at metal powder production sites. Manufacturing and storage can typically occur within an inert atmosphere with argon being the preferred gas given its properties. Powders made from different materials have unique characteristics that affect how they behave when mixed.
Earlier in the article, we covered what happens within the 3D printing chamber with high-purity inert gas creating an oxygen-free environment. However, it is not only during the printing process that the environment needs to be monitored and maintained. Between printing cycles, the atmosphere is purged.
Impurities can remain present in the chamber due to incomplete purging or poor gas quality. The metal powder itself may also cause an impurity, which will then reside there permanently unless removed.
As more businesses across numerous industries start embracing the opportunities with metal 3D printing, it is important to consider the importance of end-product quality and the safety of your employees and equipment. That is why oxygen analyzers are a necessary part of your metal 3D printing process.
By implementing the correct safety measurement procedures and ensuring that oxygen levels are maintained at the appropriate level, you can be confident that your end product will meet quality expectations.
At Process Sensing Technologies (PST) , we are leading providers of gas analyzers, oxygen sensors and trace moisture analyzers, helping provide confidence and certainty throughout your additive manufacturing process with consistent monitoring.
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