Edge inspection and 3D metrology

Measuring System: EdgeInspect
Keywords: edge break measurement, edge radius measurement, sharpness, cutting edge, cutting tool geometry, aerospace, automotive, high-precision machining

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’s EdgeInspect 3D metrology system measures and analyzes edge properties at high speed (2,000 to 30,000 3D-point measurements per second), with micrometer precision, and in a non-contact manner. It provides 3D characterization of:

  • Any type of edge: round holes, straight edges, cross holes, inside or outside edges
  • Any number of edge specifications: burr detection, 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., defects on chamfers  on fir-tree bases of jet engine turbines (see image below)

Point cloud generated for a razor blade edge with edge radius of less than 6 µm (222 µin.). A cylinder fitted within the points gives the breaking edge diameter measurement down to the micron.

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 gives a micron-precision breaking-edge diameter measurement.

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

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

The scanner of the EdgeInspect system (see below left) can be mounted on inspection stages and angled to suit the majority of edge features. It provides the versatility and latitude needed to acquire almost any geometry in a single scanning sequence—no need for composite imagery. Scanning sequences can be automated and replicated.

The galvo (raster) scanner of the EdgeInspect provides automated measurement of a high-performance drill bit

The galvo (raster) scanner of the EdgeInspect provides automated measurement of a high-performance drill bit on a rotating chuck.  In a single pass over a blade or an edge of any component, the scanner acquires a 3D point cloud of the surface. 

Users can zoom from an on-screen rendering of the 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. On this micron-precision deviation map, the user may choose to view edge radii measurements at various points of analysis (right).

Users can zoom from an on-screen rendering of the 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. On this micron-precision deviation map, the user may choose to view edge radii measurements at various points of analysis (right).

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 defect inspection), 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.

Flexible installation

The EdgeInspect system is based on low-coherence interferometry technology. It is a modular and fiber-based optical system; its galvo (raster) scanner is connected to the signal-processing profilometer with an optical fiber that can be hundreds of meters long. As such, the scanner 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. It is even rugged enough to withstand hostile environments.

Inspecting edges in tight spaces

Unlike microscope-like instruments, the EdgeInspect system can also be configured to measure edges in hard-to-reach spaces. While the standard galvo scanner that typically comes with the EdgeInspect is the fastest scanning option, a small-diameter probe can be added or substituted to acquire edges in tight spaces such as, for example, inside bores.