With the recent “successful” test of the SpaceX Starship spacecraft atop their Super Heavy rocket — which comprised a significant proportion of 3D printed parts prior to the “rapid unscheduled disassembly” — it was timely to find Nadcap announcing the establishment of a Task Group for Additive Manufacturing (AM). This Task Group will develop and maintain the auditing requirements for AM processes used to accredit suppliers for critical processes in the same way they do for the 23 other Task Groups at Nadcap.
As a Nadcap accredited Materials Testing Laboratory, we have been deeply involved with clients looking to develop and optimize AM manufacturing processes. While amazing things are possible with AM, enabling production of parts never before possible, none of the various AM processes are perfect. Each type of AM presents situations where nondestructive testing (NDT) can help companies develop and tune production. Material fusion and geometric complexity considerations are the primary issues where NDT evaluation can significantly improve production and part approval.
AM Parts as Continuous Welds
At the most basic level, all AM processes using any medium rely on the precise deposition of one layer of material on another. Essentially, AM turns a part into one continuous weld where the parameters of the process must be precisely controlled to eliminate fusion issues, porosity and dimensional variation. For decades, NDT has been the de facto method for proving out the strength of any type of arc or resistance weld for manufacturing metal parts — that doesn’t change with the advent of AM.
One client moved to AM production of a large, heavy casting that took months to produce using traditional methods. They were thrilled with the new process and the resulting dramatic reduction in production time. They shipped a completed part to us for inspection and the results were simply stunning. Porosity issues riddled the part. After inspection, the number of multi-colored circles used to indicate the dozens of indications made the part resemble a child’s drawing. Sections were taken for metallographic analysis to further dig into the specific issues that plagued the production to help the client improve their process.
Given the incredibly complex part geometries possible using AM, thought needs to be given to planning part inspection. Access to interior cavities and internal structural features may prove difficult to impossible when parts become incredibly intricate. Considering inspection requirements and access during the part design phase becomes crucial with AM because traditional machining and milling processes didn’t cause this type of issue. Finding out only after production that validation will be difficult to impossible is always a good time.
With the incredible potential for new ways of manufacturing leveraging AM, it also requires a new way of thinking about how NDT and inspection need to be considered and used to ensure those new parts are ready for use. Like Johnny 5 says, “No rapid unscheduled disassemble!”
Contact us now to talk about optimizing your AM process.