After the first printer is running in production, you quickly stand in front of the process chamber to observe and analyze the process. Time is not an issue, as you want to understand the process. Quickly you ask yourself, "Is the process going to run successfully or will a crash occur overnight?"
Predictions on process stability are quickly developed and indicators such as lines in powder bed, craters or irregularities are evaluated down to the last detail. Did the process preparation take everything into account: All overhangs were supported and was the right support geometry selected for connection? Did you choose the right settings in the process chamber? Layer application, frequency of the pump for shielding gas flow?
This is exactly what makes AM so exciting, even the smallest deviation will show up and it will be visible in form of an anomaly in the powder bed or on the exposure surface.
Just an example, high shielding gas flow may help remove the welding spatter faster. However, the powder layer also becomes thinner and thinner, because the powder is also removed in addition to the spatter.
The overall concept must be well thought for a robust process and adapted to the component to be printed, otherwise you will not be successful. Process markings in powder bed help to optimize the process. If they are not visible, you have already taken a big step forward as a homogenous powder bed is already a very good indicator for a successful print.
Process Engineering in L-PBF is simply great and I guess all of us have spent some hours in front of the machine to observe and analyze the process.
What are your experiences in relation to process anomalies? Have you spent some hours in front of the process chamber as we already did it in the Process Engineering team? Looking forward to your feedback.