In-Situ Monitoring vs. Post-Process Inspection: Which Method Better Ensures Quality in Additive Manufacturing?

When metal parts are produced using additive manufacturing for demanding industries such as aerospace, medical, and automotive, failure is not an option, and simply having the printer complete a job is not enough. Manufacturers need to be sure there are no hidden pores, poorly fused layers, or deviations invisible to the naked eye. That is why the industry relies on two quality control strategies: in-situ monitoring and post-process inspection. To understand how they differ, we first need to look at the relationship between them.

In-situ monitoring tracks the printing process in real time, layer by layer, acting as an early-warning system. Post-process inspection is not an alternative to it, but rather the step that formally certifies that the finished part meets the required specifications, something monitoring alone cannot guarantee. Both aim to ensure defect-free parts and are particularly important in metal additive manufacturing, where the cost of an undetected defect is higher than in plastic 3D printing.

AMiRIS®, Additive Assurance’s in-situ monitoring solution for L-PBF machines (Photo credit: Additive Assurance).

What Is In-Situ Monitoring?

It involves monitoring the printing process as it happens, layer by layer, rather than waiting until the part is finished. The goal is to detect a problem the moment it occurs, so it can be corrected or the print can be stopped immediately before wasting material and time.