TECH TIP – IMPELLER/PROPELLER MEASUREMENT

Impellers and Propellers come in all shapes and sizes, presenting unique challenges to Inspection or Measurement (for Reverse Engineering. However, Impeller/Propellers do offer standard features to use for collecting the measurement data you require.

Since Impeller/Propellers always have a flat surface and a centerline axis, aligning to the propeller is simple and enables the operator to utilize different measurement methods offered in Verisurf.

Depending on your application, whether Inspection or Reverse Engineering, the measurement method you choose may vary. This Technical Tip outlines the different measurement methods available. It highlights each method's benefits to help you determine which is best for your particular application.

The following paragraphs outline the Measurement methods dependent upon two typical applications; Inspection (verifying the existing part to its CAD Model) or Reverse Engineering (use measurements to create a CAD model). When performing an inspection, there may be critical areas of the part that must be inspected and evaluated. The point measurement for Reverse Engineering requires a much denser point cloud to ensure accurate part definition. This Technical Tip only addresses the best methods for collecting the point cloud data. 

Before taking Inspection or Reverse Engineering data, you must align your measurement device to the part. If a CAD model is available, you can easily align your device using the Auto-AlignAuto Align process; for alignments without a model, measure the propeller's features that the blueprint designates as Datums and select Feature Alignment to align. The example (right) hub Plane and cylindrical center define the Alignment.

After aligning the device to the CAD model, it is easy to use Inspect/Build to quickly and easily collect measurement data using the Measurement Settings and Measurement Filters dialog.

The Measurement Filter – Radial Polar Slice allows the operator to define a Grid measurement by defining “Slices” and “Radial” Offsets. As shown in the following diagram, you set your Alignment to the part axis and Plane.

Including the Z allows measuring about the hub in this example.

Drawback – points are measured when the measurement probe (or scanner) crosses the predefined Grid; depending on the operator and device type, data points may be dense in one direction and sparse in another; requiring additional filtering for good results. For the best results using a Laser Scanner, measure multiple scans perpendicular to one another.

Creating Surface Points requires a CAD model and is ideal when inspecting specific areas of a part or multiple parts. This method requires some pre-planning; however, it allows for quick and consistent inspection of duplicate parts and reporting in your predefined format once complete.

Using the Surface Grid tool, the operator may create a unique Grid for each surface. Multiple surfaces may be selected to receive a typical Grid pattern; the operator Saves the Surface Points to a Plan, adjusts the Measure Settings in the Plan, and performs the measurement, analysis, and reporting as required.