Edge radius measurement

Measuring System: EdgeInspect
Keywords: edge break, edge radius, sharpness, cutting edge, cutting tool geometry, blade edge, leading edge, trailing edge

The quest for the perfect edge

Edge finishing processes are a crucial component of manufacturer guarantees. Whether it is for deburring or deflashing, or conversely ensuring edge sharpness, having a solid quality assurance edge inspection method can add tremendous value to a product.

Novacam EdgeInspect metrology system measures edges in a raster pattern, at high speed (2,100 to 100,000 3D-point measurements per second), with sub-micron precision, and in a non-contact manner. The system provides 3D characterization of:

  • Any type of edge: round holes, straight edges, cross holes, inside or outside edges
  • Any number of edge specifications: edge break requirements, angle measurements, as well as matching edge radiuses or checking tolerances after burr removal
  • Edges on machining tools tools: high-precision reamers, drills (PCB, PDC, PCD, etc.), thread mills, boring bars, cutters, etc.
  • Very sharp cutting tools: scalpels or razor blade edges (see image below)
  • Defects on edges: e.g., burrs or deviations such as undercuts or passing. See example of  chamfers defects on fir-tree bases of jet engine turbines (see image below)

With EdgeInspect, all dimensional and roughness data on edges is captured down to the micrometer. Any sharp edges, cracks, scratches, dings, or defects the user deems important are detected automatically based on user-defined dimensions and tolerances.

Measurement of cutting tool edges

To help ensure edge sharpness, the EdgeInspect verifies that the cutting edge of machining tools is as per requirements—either at the manufacturing stage, during routine inspection, or during tool reconditioning.

Characterization of the edge and any defects and visualization of the acquired data is made easy with EdgeInspect. The 3D point cloud acquired by the system is fed to the accompanying metrology software (e.g. PolyWorksTM) on a PC.  From there, several data viewing options are available, including:

  • 3D models
  • Comparison to CAD model
  • Deviation maps
  • Exportable reports.

Users can zoom from an on-screen rendering of the acquired drill bit (top left) into the edge area selected for analysis. The enlarged edge segment (bottom left) shows a colour-coded deviation map of the edge sharpness. Users may choose to view edge radii measurements at various points of analysis (right).

Razor blade sharpness measurement

This 3D point cloud generated for a razor blade characterizes an edge radius of less than 6 µm (222 µin.).  As shown, a cylinder fitted within the points acquired at the edge gives a micron-precision breaking-edge diameter measurement.

Point cloud generated for a razor blade edge with radius less than 6 µm (222 µin.)

Defect inspection on a fir-tree base of a jet engine turbine disk

A fir-tree base of a jet engine turbine was measured to assess the edge’s conformity to specifications. On this part, a chamfer defect was detected, measured and flagged.

A chamfer defect is detected and measured on a fir-tree base of a jet engine turbine disk

Automated or in-lab inspection

Automation of edge metrology is fully supported by the EdgeInspect system capabilities such as datum alignment, automated pass/fail reporting, and exportable reports. Edge break data may be evaluated with respect to user-defined criteria (GD&T, sharpness, surface roughness, and detection of defects), or compared to a reference CAD model. For in-lab inspection, accompanying metrology software on a PC (e.g., PolyWorksTM) enables full viewing and analysis of the acquired point cloud as a 3D interactive map. Views such as deviation maps provide key insight into edge machining and finishing processes.

Advantages of measuring with a fiber-based metrology system

EdgeInspect, like all Novacam metrology systems, uses low-coherence interferometry (LCI) technology along with fiber-based modular design.  As such, the scanning component of the EdgeInspect system – the galvo (raster) scanner (pictured on the right)

  • is connected to the system’s signal processing detector (low-coherence interferometer) via an optical fiber that can be hundreds of meters long
  • can be mounted on inspection stages and angled to suit the majority of edge features
  • is easily integrated as either a robot arm end-effector or as a 3D vision component in automated or semi-automated systems on the plant floor
  • provides the versatility and latitude needed to acquire almost any geometry in a single scanning sequence—no need for composite imagery.

See a more complete list of advantages of our fiber-based LCI systems.

The galvo scanner is the optical scanning component of the EdgeInspect system.  It sends measurement data to the system interferometer (not shown) via an optical fiber for processing.

Related links

Download application note “Inspecting Edge Breaks / Edge Radius” [4 pages, PDF, 0.8 MB] for more details on edge measurement applications

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 Contact us or request free sample analysis to see if EdgeInspect is suitable for your application