Quality Control in Additive Manufacturing

Using Industrial Computed Tomography

Quality Control in Additive Manufacturing

   

3D printing is the fastest growing manufacturing technology of this century. New materials, new processes, new machines appear on a daily basis. The success is undeniable and its future shines brightly, but also opens the door for new types of 3D printing defects.

As products with high complexity and a low number of units are the sweet spot of the technology today, first adopters are amongst aerospace, medical, and military usages, with high demands in quality, security, and certification.

The Challenge

The improvement of generative design, topology optimization, light-weight lattice structures, and simulation leads to more complex designs. The freedom of complexity is a significant problem for traditional inspection methods. As more than 50 parameters influence the outcome of a metal printing job, 3D printing quality remains to be a constant challenge.

New technology asks for new inspection methods, taking the possibilities and challenges of the new technology into account. Additively manufactured products need to be thoroughly inspected to certify them for high risk use cases. The best method is computed tomography (CT), delivering the only reliable technology for the identification of 3D printing defects, enabling the best possible 3D printing quality.

The Volume Graphics Solution: 3D Printing Inspection, from Powder to Part

VGSTUDIO MAX enables customers to do powder analyses, meltpool data analyses, and correlation to CT data, as well as post-build dimensional and defect analyses on additively manufactured parts, both internal and external.

VGSTUDIO MAX is therefore a universal tool to identify the most important subjects of 3D printing defects originating from raw material to the post processed end product. No matter how complicated the shape might be, VG enables your metrology department to sign off processes and inspect your 3D printed parts.

A part manufactured using selective laser melting (Image courtesy of FIT AG)

Advantages

Volume Graphics gives you one comprehensive tool for all your tasks that provides you with instructive results and the possibility to establish efficient workflows:

The Volume Graphics Solution in Detail

Additive Manufacturing – Powder Analyses

Powder is the base for many additively manufactured parts. The size and shape distribution of new and recycled powder particles influences the build process. It affects how powder gets distributed, influences the melt process, and can cause defects that are visible later in the final part. Grain contaminations, trapped air, grain sizes, and shapes can be analyzed with VGSTUDIO MAX, automatically for tens of thousands of particles.

Morphological analysis of a metal powder: Volume, Surface Area, Sphericity, Compactness, Grain Size Distribution (Images courtesy of TPW Prüfzentrum)

Open cell struts of a foam (Images courtesy of TPW Prüfzentrum)

Material grain cells of a foam (Images courtesy of TPW Prüfzentrum)

3D Printing Defect: Porosity

Metal printing based on powder is similar to welding, coming with challenges like voids, porosity, and cracks in the final product, which needs to be qualified for its structural integrity.

CT-based defect analyses can be used to identify individual voids and inclusions and determine their sizes and shapes. Filtering of the defects by, e.g., sphericity, compactness, or distance to surface allows to distinguish between defect formation mechanisms.

CT based defect analyses can be used to identify individual voids and inclusions and determine their sizes and shapes (Density cube 10x10x10 mm, AlSi10Mg; Source: FIT AG)

CT-based defect analyses can be used to identify individual voids and inclusions and determine their sizes and shapes (Density cube 10x10x10 mm, AlSi10Mg; Image courtesy of FIT AG)

Meltpool Analysis

The melt pool data is a slice-based information of temperature, geometry, or other physical parameters during the build process. It can be compared with the actual CT data. Conspicuous features in the melt pool can be looked up in the CT data to define regions of interest for thorough 3d printing defect analyses.

Workflow of a melt pool analysis: Center top two images are the CAD design of the sphere with defects and the finished product. Down the right side are the QM Meltpool 3D images, down the left are the CT scan results. Bottom six figures demonstrate the correlation between defects predicted, and then identified, by the two technologies (Image: Sintavia)

Dimensional Part Inspection

Dimensional variations also occur in additively manufactured parts, leading to complex warpage. VGSTUDIO MAX provides a full suite of measurement capability from complex alignments to customizable measurement reports. Dimensions as well as GD&T analyses can be automated and applied to CT and mesh data.

Together with 3D comparisons, wall thickness and surface profile analyses, VGSTUDIO MAX provides full first article inspection capability, helping to certify your additive manufacturing process. VGSTUDIO MAX can also measure geometries resulting from 3D printing simulations, helping to choose the right parameters for your 3D printing job.

Measurements on an additively manufactured part

Structural Mechanics Simulation

VGSTUDIO MAX enables structural mechanics simulation (SMS) directly on CT scans. Loads and constraints are applied to the CT scanned model, not just the CAD file. Stress concentrations due to geometrical flaws and pores can be simulated and visualized without volume meshing.

Read more about our solutions for micromechanics simulation.

Visualized force lines in an additively manufactured part computed by VGSTUDIO MAX

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