1. Scope

The high demand for reliable AM parts requires the additive manufacturing process to be repeatable and with minimal deviation in order to confidently fabricate parts that meet specific quality standards. Therefore, there are procedures implemented to qualify a metallurgical process QMP (e.g., MSFC-SPEC-3717), but these are time consuming and can potentially increase downtime during the evaluation period. Additionally, there is little guidance in how to monitor and understand build health during the intervals between QMPs. Undesired variations in powder feed stock, recoater blade, substrate condition, laser calibration, additive machine maintenance, etc., can adversely affect the final part quality. More importantly, detecting such variations are very challenging, costly and time consuming. Hence, implementation of a rapid, efficient and effective procedure capable of detecting potentially major issues after fabrication or between QMP evaluations is indeed needed. The rapid quality inspection specimen (RQIS) will contain several features designed to identify and quantify any deviations build/material quality through a series of tests that can be performed within a few hours after the build is removed from the machine. These include: dimensional accuracy, geometry compliance, surface roughness at various surfaces, and mechanical properties that can be rapidly evaluated such as torque and angle of twist. There will be 4 total builds fabricated in two different additive machines (2 each) using one material system (TBD), or one additive machine using two material systems (TBD). The intent for these builds will include a variety of process parameter variations that induce a range of defect states in the material to provide a measure of correlation between RQIS results and the material quality. NASA and Oerlikon will be requested to support this activity as in-kind and fabricate similar builds to check the robustness of the approach; however, their in-kind support for fabrication is not guaranteed. For each combination of machine/material two sets of fabrications will be performed; 1) using manufacturer recommended process parameters to capture any location dependencies, and 2) deviated process parameters to capture the sensitivity of the approach to the presence of defects.

Keywords

Rapid qualification; Build health monitoring; Calibration verification

Rationale

The proposed statement of work targets process qualification and build health monitoring. The following standard gaps are expected to be partially addressed: Gap PC3: Machine Health Monitoring. (Low Priority) Gap M6: Tracking Maintenance. (Medium Priority) Gap D17: Contents of a TDP. (High Priority) Gap D26: Design for Measurement of AM Features/Verifying the Designs of Features such as Lattices, etc. (Medium Priority) Gap PC2: Machine Calibration and Preventative Maintenance. (High Priority) Gap PC4: Machine Qualification. (Medium Priority) Gap FMP1: Material Properties. (High Priority [Metals])

The title and scope are in draft form and are under development within this ASTM Committee.