Once the parameters and specifications of a fixturing or gauging project have been clearly defined the actual creative part of the design process commences. The development of a concept is performed using the CAD system CATIA V5. The modelling of the fixture or gauge is done in the majority of cases using the CAD model of the part to be measured.


The engineer has to integrate and consider in the conceptual design stage many factors:


Catia screen shot
  • Type of measuring device that will be used to gauge the component (CMM, measuring arm, scanner, dial gauges, etc.).
  • Definition of the points/features to be gauged or measured.
  • Orientation of the part in the fixture.
  • Orientation and position of the fixture in reference to the coordinate measuring system.
  • Position of the fixture in reference to the car-grid.
  • Accessibility of the measuring probe to the areas or features of the component to be measured.
  • Mounting sequence of the component on the fixture.
  • Clamping sequence.
  • Type, shape, dimension and tolerance of the individual features of the datum points.
  • Position tolerance of the datum points.
  • Assembly procedure of the gauge.
  • Calibration and adjustment of the datum / mounting points.
  • Expansion/contraction of the gauge due to temperature fluctuations (when the fixture is not used in an environment with controlled conditions).
  • Deflection of the fixture due to the weight of the part to be gauged.
  • Operational conditions of the gauge (static or mobile application).
  • Budget restrictions.
  • Safety considerations.


Drawings made using Catia softwareThe software CATIA provides the tool to incorporate all the project specifications and requirements into the design. The link between the project variables (position, tolerances, orientation of the component, etc.) and the geometry of the gauge or fixture is done parametrically. Any change in the specification values will be automatically incorporated into the designed geometry of the fixture, making the design loop very efficient. Once the new parameter is loaded the design of the fixture is updated automatically incorporating these modified conditions to generate a new geometry.


The CATIA design is also facilitated by having ample libraries of fixturing components from which the engineer retrieves the required part incorporating it into the model of the fixture or gauge. The application of modular components in the design of fixtures and gauges not only reduces the design time but also brings huge advantages during its assembly and calibration.


The basic concept of a inspection gauge or fixture, once its design has been approved by the client, is detailed and, if necessary, drafted for the manufacture or ordering of the individual components.