A methodology to develop part acceptance criteria model using non-destructive inspection technique for FDM printed part

Abstract

Additive Manufacturing (AM) has transit over the years from simple prototyping to high-mix-low-volume production. Sectors such as Aerospace or Biomedical that have adopted Additive Manufacturing for parts production have stringent requirement for strength and minimal tolerance for sub-surface defects. The presence of embedded defects usually leads to premature failure and additional cost for reinstallation. The current gold standard for Non-Destructive Inspection (NDI) technique is the use of 3D micro-CT scan. 3D micro-CT scan although provide the best resolution for defect detection, it is expensive, time consuming and laborious. The defects found in polymer 3D printed component, e.g., Fused Deposition Modeling, may not require high resolution imaging for defect detection due to the nature of printing process. Therefore, 2D X-ray imaging known for its short imaging and processing time has been used in this study with Acrylonitrile Butadiene Styrene (ABS) as the model material. Defects of various void sizes were introduced to tensile test coupons to determine the effect of void sizes on tensile properties. Good linear agreement (R2 = 0.998) has been observed between the void sizes and tensile strength which was then used to develop the part acceptance criteria model. The part acceptance criteria model developed from 2D X-ray imaging and mechanical test data suggest the feasibility of using such methodology to perform quality checks on 3D printed part which obviates the need for time consuming 3D micro-CT scans and unsustainable destructive testing.