Tube ID and OD measurement

Measuring System: TubeInspect
Keywords: tubes, cylinders, barrels, inside diameter (ID), outside diameter (OD), 3D metrology, GD&T, internal features, grooves, threads, splines, undercuts, cross-holes

The inner and outer surface topography of manufactured tubes can greatly affect their intended functional performance.  For this reason, tubes in many high-precision sectors (automotive, aerospace, medical instrumentation, etc.) need to adhere to strict specifications in terms of:

  • inside and outside dimensional parameters (GD&T): diameter, straightness, cylindricity, conicity, ovality, taper
  • dimensions of inner features, such as steps, splines, threads, chambers, cross-holes, and O-ring grooves
  • distortion, chatter or lobing, and runout
  • absence or low incidence of defects
  • roughness characteristics.

Novacam’s TubeInspect, a modular non-contact metrology system,  greatly speeds up the task of high-precision tube metrology and facilitates automation. The TubeInspect uses a non-contact optical probe to enter rotating tubes to acquire their inner 3D topography down to the micron.  The same equipment and setup is used to acquire tube exteriors.

Example 1: The inner suface of a  Bosch fuel injection nozzle and the outer surface of the matching nozzle needle were both acquired with TubeInspect (below).   Micron-precision measurements of these surfaces support analysis of whether the two machined surfaces meet and seal as required.

Inside diameter (ID) surface of a fuel injector nozzle (click for close-up)

Outside diameter (OD) of the matching fuel injector nozzle needle

Example 2:  The ID of an 18″ 0.22 caliber rifle barrel (length~46 cm,  diameter~5.6 mm) was measured with TubeInspect.

Rifle barrel ID analysis - 3D deviation map

Rifle barrel ID – analysis using 3D deviation map (click for close-up)

Rifle barrel ID - close-up

Rifle barrel ID – close-up for feature and defect inspection

Rifle barrel ID – profile analysis and reporting

Automated or in-lab inspection

With TubeInspect, ID/OD surface acquisition and the subsequent 2D/3D characterization (topography), roughness measurement, and defect detection are easily automated and carried out right on the shop or manufacturing plant floor, bringing high-precision manufacturers significant savings.

  • Automation is supported by system capabilities such as datum alignment, automated pass/fail reporting, and exportable reports
  • Tube ID/OD data may be evaluated with respect to user-defined criteria (GD&T, inner feature specifications, 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 bore machining processes.

Modular & fiber-based design for extra versatility

The TubeInspect system is based on low-coherence interferometry technology. It is a modular and fiber-based optical system; its non-contact optical probe is connected to the signal-processing interferometer with an optical fiber that can be hundreds of meters long. As such, the probe is easily integrated as a 3D vision component in automated or semi-automated systems right on the plant floor.