Tube ID and OD measurement

Measuring System: TubeInspect
Keywords: tubes, cylinders, barrels, inside diameter (ID), outside diameter (OD), O-ring grooves, threads, splines, undercuts, cross-holes

Tube measurement requirements in high-precision industries

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.

3D measurement with TubeInspect

Novacam’s TubeInspect, a modular non-contact metrology system, greatly speeds up the task of high-precision tube measurement and facilitates automation. The system uses a small-diameter non-contact optical probe to enter the interiors of tubes, acquiring their inner 3D topography:

  • With sub-micron precision and
  • At high speeds:  2,100 to 30,000 of 3D points per second

If the application requires the entire ID surface measured, then the tube is rotated while the optical probe is advanced inside, acquiring the surface as a dense spiral of 3D points. The same system is used to measure the tube exterior, with the optical probe this time on the outside of the rotating tube.

Fuel injection nozzle and needle – acquired 3D point clouds

The inner suface of a Bosch fuel injection nozzle and the outer surface of the matching nozzle needle were both acquired. Micron-precision measurements of such surfaces can serve as a basis of calculations to determine whether the two machined surfaces meet as required.

Inside diameter (ID) surface of a fuel injector nozzle

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

Rifle barrel measurements – reaching in deep

The ID of an 18″ 0.22 caliber rifle barrel (length≈46 cm, diameter≈5.6 mm) was measured. Multiple geometrical dimensioning and testing (GD&T) parameters were calculated to ensure compliance to QA/QC requirements.

Rifle barrel ID – analysis using 3D deviation map

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

Related links

Download application note “Measuring Tube ID & OD” [4 pages, PDF, 1 MB] for more details on this application

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