Accurate temperature measurements during the laser powder bed fusion process in additive manufacturing are crucial for producing high-quality parts. Conventional thermal infrared cameras have been used to measure melt pool temperatures, but they often lack the necessary frame rate and resolution, leading to approximations with potential temperature errors. To address these limitations, researchers from Carnegie Mellon University developed a groundbreaking single-camera method that provides valuable insights into the physics occurring in the melt pool.
The team employed a commercial color camera with a built-in Bayer filter to sense visible colors. Each pixel captured light from a specific color, allowing the researchers to acquire unique measurements for temperature calculations. By using a technique called demosaicing, they reconstructed a full-color image and measured color ratios to accurately determine the temperature. This ratiometric approach overcomes challenges associated with surface properties and view factors, which are common in conventional infrared imaging methods for additive manufacturing.
The benefits of this method extend beyond accurate temperature measurements. The researchers have gained valuable insights into previously unknown parameters in the computational fluid dynamics model. By understanding peak temperatures and gradients in the melt pool, they could study material vaporization and the microstructure of the final part.
This new technique has shown promising results in capturing melt pool temperature transients with high precision. Additionally, it eliminates the need for prior knowledge of melt pool emissivity and plume transmissivity, simplifying the measurement process.
Moving forward, the researchers plan to apply this method to other additive manufacturing processes, such as wire arc additive manufacturing and directed energy deposition. The potential applications of this single-camera approach open up new possibilities for advancing the quality and efficiency of additive manufacturing, ensuring better control over the production of critical parts – vital for high end manufacturing industries such as aerospace and nuclear.
You can read the full research paper from the team, titled “High-resolution melt pool thermal imaging for metals additive manufacturing using the two-color method with a color camera” at the Additive Manufacturing journal, at this link.
Come and let us know your thoughts on our Facebook, Twitter, and LinkedIn pages, and don’t forget to sign up for our weekly additive manufacturing newsletter to get all the latest stories delivered right to your inbox.
