Porosity/Inclusion Analysis

Determine these global porosity parameters for the entire component:

• Total pore volume
• Total material volume
• Total porosity
• Total surface of the pores
• Projected total area of all pores in any spatial direction

Determine these parameters for individual pores:

• General:
  • Position
  • Deviation of gray values
  • Minimum, maximum, and average gray value
• Size:
  • Volume
  • Surface
  • Equivalent diameter (diameter of a sphere with the same volume)
  • Radius or diameter of the circumsphere
• Shape:
  • Compactness
  • Sphericity
  • Shape of fitted ellipsoid (from a Principal Components Analysis)
• Projected dimensions:
  • Projected length in arbitrary spatial directions
  • Projected area in arbitrary spatial directions
• Additional features:
  • Classification (inside, outside, or cut from the machined surface)
  • Minimum and maximum edge distance
  • Cut surface with component surface
  • Distance to next pore (gap)
  • Wall thickness at the location of the pore
  • Relative diameter (i.e., diameter of the pore relative to the local wall thickness)

The results for certain porosity parameters allow you to draw conclusions such as:

• Total porosity: Fluctuations in the production process can be detected easily by monitoring the total porosity over a longer period of time. An increase in this value may indicate unsuitable casting speeds or insufficient venting of the mold cavity.
• Sphericity: The sphericity value, which is calculated from the pore volume and the pore surface area, allows you to distinguish between gas pores (which are characterized by higher sphericity values) and shrinkage holes (which have lower sphericity values). Knowledge about the shape of discontinuities supports process optimization and also provides information about the durability of the component.
• Distance to surface: By calculating the distance to any surface, you can check sealing and thread surfaces for suitability before machining. The porosity analysis simulates the surface to be processed. The depth of the remaining porosity in the machined area can be calculated and visualized. This is, for example, important for sealing surfaces, since air inclusions in open pores can displace the sealing material under thermal stress.

Limit analyses to relevant areas:

• With regions of interest (ROIs), you can apply porosity analyses to specific regions of the part using different filter and tolerance settings. For example, the porosity analysis can be limited to the area of the casting skin if the goal is to examine gas pores near the casting skin surface.
• Discontinuities can be linked with wall thicknesses.

Shows whether and how pores would be cut during machining:

• Pore position and size can be calculated not only in relation to the current component surface but also to any other surface.
• Thus, you can include subsequent machining of the part (for example, drilling) in a porosity analysis and determine the distances of the pores to a machined surface. In particular, you can check whether pores would be cut, rendering the machined surface useless. This way, you can sort out a part before cost-intensive machining.

Perform tolerancing with decision trees:

• Automate casting inspection by defining the tolerances for individual porosity parameters for functionally relevant areas (special attributes)—e.g., number, size, and position of individual pores—while defining the tolerances for the entire casting as global porosity parameters (for example, maximum total porosity in %).
• Map more complex issues by combining tolerance statuses of individual analyses, which is especially useful in automated inline scenarios. For example, a casting can be classified as "not okay" if a certain porosity has been exceeded and there is a huge amount of porosity in the region of the cast skin. If none of the parameters are exceeded, the part is marked as "okay."

To classify porosity parameters in slice images, VDG Specification P 201 (VW 50097) as well as BDG Reference Sheet P 202 (VW 50093) is used. These analyses provide a digital, fully non-destructive take on the classic micrograph analysis, which was achieved by sawing open the component.

With the analyses according to VDG - P 201 and BDG - P 202, you can tolerance the following parameters in arbitrarily oriented digital component sections by means of a porosity key:

• Maximum surface porosity
• Maximum pore diamenter (equal area of circle [ØF])
• Maximum length of pores ("Ferret"; compared diameter [ØL])
• Minimum normalized distance between adjacent pores
• Maximum number of pores

The evaluation is performed both in the entire section and in reference areas (square, rectangle, triangle, circle) set by the user.

The BDG Reference Sheet P 203 not only extends VDG - P 201 and BDG - P 202 to 3D but also puts an additional focus on the specific assessment of functionally relevant part areas by using free-form regions.

Volume Graphics software integrates important specifications according to the BDG Reference Sheet P 203 for the definition of the volume for pore assessment as well as for the definition of three-dimensional characteristics of internal volume deficits. Intuitive input functions make it easy to define porosity specifications based on the porosity key according to BDG - P 203.

Volume Graphics software supports the fully automatic determination of the called "Q factor" as proposed by the BDG Reference Sheet P 203. The Q factor is a simple, user-independent approach for verifying the quality of the gray value volume and documenting the quality of your CT scan data directly in the P 203 analysis. 

Volume Graphics software also allows you to perform the porosity analysis according to BDG - P 203 on raw parts with additionally inserted reference surfaces, such as a 3D CAD machined part. This allows you to evaluate the porosity on the to-be-machined surfaces in advance.

You can automatically display the corresponding BDG P 203 porosity key and the analysis results for each analyzed freeform partial volume (ROI) in the 3D window and the 2D windows. This simplifies the evaluation of the porosity analysis as well as the orientation in the examined data set. Quick OK/NOK ("not okay") decisions can be made and documented.

You will also receive the number of NOK ("not okay") pores for selected porosity parameters that are out of tolerance within the global volume and within a freeform partial volume (ROI). This allows you to differentiate between outliers and a systematic production problem, which leads to better process control.

Furthermore, the porosity key according to BDG - P 203 can also be used to exclude discontinuities from the evaluation due to their porosity parameters, such as gas pores and micro-cavities with a maximum diameter of, for example, 0.6 mm.

Unlock the real value of your results with the comprehensive yet easy-to-use visualization features.

Navigation in individual parts and series of parts:

• Discontinuities can be colored according to a selected parameter
• Discontinuities are displayed in a combination of 2D and 3D views
• Analysis markers can be created manually and automatically
• A series of parts can be reviewed in VGinLINE APPROVER

With Volume Graphics software, you can partially or fully automate manual workflows with just a few simple clicks. This not only saves you time in your daily work but also gives you the option of exporting your automated workflow to VGinLINE for use in an at-line or in-line CT environment.

Porosity analyses in particular offer a consistently high level of detectability, even in serial inspection, by taking production-related variations into account.

Modern reporting, statistical evaluations (Q-DAS), and a platform for manual re-evaluation of fully automatically inspected components (VGinLINE APPROVER) allow you to master the challenges of tomorrow's non-destructive testing today.

Comprehensive reporting features allow you to share your results with different audiences, even if they're not using Volume Graphics software.

The reporting features in Volume Graphics software allow you to:

• Report not only the results and document the evaluation process itself.
• Create highly customizable reports.
• Export results in the industry standard Q-DAS format to see dependencies between production parameter adjustments and changes in the part quality.

Use the results of a porosity analysis in subsequent simulations to further investigate the effect of the defect.

The simulation features in Volume Graphics software connect porosity/inclusion analysis to the simulation world:

• By exporting the porosity values to volume meshes (Abaqus, Patran, and Nastran).
• By meshing macropores.
• By simulation right within VGSTUDIO MAX, such as in the Structural Mechanics Simulation Module.