06/04/2019

For even more quality in the production process

Automation, flexibility and visualization of surface measurements

Surface measurement techniques are becoming increasingly important in more and more industries. The areas of application are also versatile. In the automotive industry, for example, appropriate measuring tools are used to measure cylinder liners, head gaskets, slush skins, artificial leather and acceleration sensors. Due to the possibility of fast measurements and automatic evaluation, very complex process parameters can be monitored. This further reduces rejects. Even large samples can now be analyzed directly in the production environment. In rubber production, surface measuring tools are used, for example, to measure filler dispersions. Manufacturers of cylinder-head gaskets measure both the product quality of their products and the wear and setting parameters of the moulding tools - in a process accompanying and automated manner. With the continuous automation and flexibilisation process, more and more areas of application for surface metrology are opening up, and the number of industries continues to grow.

Surfaces and product-determining structures of components are becoming ever smaller and more complex. Let's take an example from the semiconductor industry: the structures generated on the wafers are already in the nanometer range today. This means that they are up to 70,000 times thinner than a human hair. The trend is also continuing in other industries. Therefore, measuring tools are needed that enable non-contact, non-destructive and high-precision measurements at the same time. This is particularly important when measuring in areas where surfaces are very sensitive. Only optical surface metrology can meet these requirements. Another plus is the time factor. Optical surface measurement techniques deliver the measurement results in just a few minutes. For comparison: tactile systems often require several hours for the same measuring task.

Production processes are also becoming more and more complex. At the same time, the pressure to reduce time and costs is increasing. Automation and flexibilisation of applications determine the direction for further developments. The advantages of automation are obvious - efficiency, shorter throughput times and cost savings. All companies have to face this challenge. At the same time, surface measurements in various industries such as automotive, MEMS or semiconductors must be used for quality control in the production process. More complex and automated production processes place new demands on surface measurement technology. Everything must become even faster and more accurate. However, there is often a contradiction between these two parameters. Multi-sensor measuring tools in combination with powerful software provide the solution. Today, they already open up the possibility of carrying out different and complex measurements fully automatically. This means that the user is able to measure various parameters, combine and analyze the results. In this way, a lot of information about the product and also information that is not accessible with a sensor alone can be obtained in a single measurement sequence. In addition, modern surface measuring tools can be integrated into existing production lines.

The big advantage of multi-sensor measuring systems is the additional information. They can be used to check the surfaces of components and materials for a variety of parameters using various measurement techniques. Multi-sensor measuring technology offers the possibility to perform several measuring tasks with only one tool and one software. A second advantage is the flexible degree of automation of this measurement technology. Everything is possible from random sampling to 100% and inline inspection, manually or as a one-button solution. Most measuring tools have appropriate interfaces for further processing the information in ERP or PPS systems. The semiconductor industry relies on proprietary SECS/GEM interfaces, other industries on open XML standards.

For example, chromatic white light sensors, infrared film thickness sensors, thin film sensors, atomic force microscopes or confocal microscopes can be used - to name just a few. Of course, this depends on the parameters that are of interest to the customer. By combining the sensors, almost any statement about layer thickness, flatness, thickness variation, roughness, contour, topography, wear and others can be verified. The user is thus really and directly involved in the design and properties of the surfaces and layers. Chromatic white light sensors, for example, work on the principle of chromatic distance measurement. Depending on its wavelength, the light is focused at different distances in front of the measuring head. By evaluating the reflected light spectrum or the superimposed partial beams, surfaces can be analyzed non-contact and non-destructive.

The complexity and functionality of surface structures is basically invisible to the human eye. Surface structures are generally in the micro- and nanometer range, thus an image-giving evaluation software is essential. It enables the analysis and visualisation of measurement results, for example on roughness, profile and 3D measurement data. Thanks to 3D views, details can be analyzed even more precisely, for example by perspective display at any angle. The evaluation of lateral and vertical distances, histograms or load curves is also easy. Another important point is the flexible applicability. Open applications have the advantage that they can be used for different measuring tools and can process several formats, i.e. have maximum compatibility. Thus, data from already existing or later purchased measuring tools can be processed by one software and costs can be saved.

Many companies in the field of surface metrology offer software developed in-house for their measuring tools. Often these are only applicable especially for the respective measuring system. Of course, universal software that allows modifications and other data formats makes more sense here.

The evaluation software Mark III developed by FRT is a universal standard software for the analysis of profile and 3D measurement data. With Mark III a variety of different data in different file formats can be evaluated. 

The extensive program functions make detailed evaluations of the geometry and numerous surface parameters possible. Thus, primary characteristic values such as roughness, waviness, flatness and coplanarity can be determined according to DIN EN ISO and also according to the MOTIF method. The calculation of surfaces, volume, frequency, power spectrum, autocorrelation, fractal dimension, histogram and load curve as well as particle counting methods are also integrated into the program. Batch processing is available which applies the evaluation of defined surface parameters to several measurements.

In addition to the top view, a comfortable 3D view is available in the program, which allows the perspective display of the data at any angle. A switchable virtual light source "illuminates" the surface and thus clarifies structural details. A zoom function is also integrated in the program, which allows you to select and enlarge the desired areas. All representations can be labelled for presentation-oriented preparation. All diagrams and analysis results can be exported in common graphic formats or in ASCII format. By means of user-defined measurement protocols, the user has numerous options for print output. Various filter functions are available to process the measurement data according to presentation requirements.

The 3D data can be provided with any profile sections and these can be fitted with polynomials and aspherical functions. In this way the shape and contour of components (e.g. radii of curvature) can be easily determined. The comparison function allows a detailed analysis of target and actual data. If required, Mark III can be extended by an import filter for reading in any special image format. This means that the software can also process data from existing or later acquired measuring tools.

Do not hesitate to contact us if you have any questions. Our experts will be glad to support you in solving your measurement tasks by assembling the best possible system configuration for you.

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