The program WKAgraf has grown from my design work in the range of contour measurement and is an evaluation and graphical program with C/C++ library for the tolerance control in quality assurance or technical research.

During outline measurements with a 2D or a 3D measurement system, points (junctions) are generated which reflect the image of the test specimen as accurately as possible. The accuracy increases with the number of measured values rising, but diminishes by the width of dispersion, which is influencing each physical measurement. Generally, it applies that arbitrarily distributed points within the 2D plane can be assigned to a point, line or circular arc. Task of the outline analysis is the selection of a suitable cut-out and assignment. Only with the clear allocation of the outline sections can the parameters of the outline elements be computed.

• What is WKAgraf?
• Where can WKAgraf be used?
• How does WKAgraf  function?
• Which outline elements can WKAgraf analyze?
• Sample calculations

What is WKAgraf?

The program WKAgraf is a development tool for the analysis, evaluation and pattern recognition of geometrical outline processes. Default is the description of an object by its base points, junctions or a point cloud, which were produced as ASCII file by measurement (e.g. CALYPSO) or mathematical modelling (e.g. ABAQUS). These data files can be imported and assigned to the geometrical basic elements point, line or  circle and their parameter in such a way that they can be compared with the parameters of the sample that the user has to define for its setting of task. 3D elements are illustrated by selection of suitable cutting planes on the 2D plane. In the horizontal and vertical axis both cartesian and polar co-ordinates can be used. By combining the results from the 2D plane, the shape and position tolerances for rotationally symmetric parts can be computed.

Where can WKAgraf be used?

The program is preferably used in the laboratory for research and development. It covers a C/C++ function library, which places a concept to the programmer for the realization of portable applications (embedded system) within the range of the outline analysis and pattern recognition, e.g.:

• Measuring systems for quality assurance (shape & position tolerances)
• Subsequent treatment of the data produced by the programs ABAQUS or ANSYS (Infinite element method, FEM)
• Pattern recognition of outlines or signals within the image processing
• Definition from characteristics to the identification or assessment of quality
• Derivation from measured values to the control

How does WKAgraf function?

With the program WKAgraf, existing data can be imported for evaluation and comfortably plotted. The function library is integrated, so that the different methods of analysis can be tested interactively. A cut-out for evaluation can be selected from the point cloud, which defines a 3D object or from a 2D outline. With the help of a menu system, a procedure can be selected in each case. The result is indicated both graphically and numerically with the describing parameters.

Which outline elements can WKAgraf analyze?

The system is developed in a modular mode, so that also the special setting of tasks can be solved in the range of the outline analysis. Under the condition that the measurement data recording system supplies the profile, data can be analyzed for following outline elements:

Geometrical outlines:

• Diameter, lengths, cone angles
• Straightness, roughness
• Center of radius and sector of a circle
• Position of corner points
• Phase and roundness radius of corner areas

	Technical representation of some selected outline elements
	Source: OMT measuring technique, Munich

Form and position tolerances for rotationally symmetric parts according to DIN ISO 5459:

• Roundness
• Cyclic testing
• Concentricity
• Coaxiality

	Technical representation of some selected elements to the position tolerance
	Source: OMT measuring technique, Munich

Further computations and procedures:

• Fourier Analysis
• Filter procedures
• Search functions for the range limits (flanks, groove, spring)

Sample calculation

Some typical sample calculations for the 2D contour analysis and the 3D evaluation you find here.

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