Test gauges and calipers have always been a part of the standard equipment in production for measuring profiles such as gaps, flushes, radii or corners. However, these manual tools have a huge drawback: The measurement process is both time-intensive and error-prone. An alternative is now offered by the British manufacturer Third Dimension who has developed an optical laser device called GapGun.

Today, this innovative measurement system is being used anywhere from the energy industry to consumer electronics but originally designed for application in the automotive and aerospace industry; these are still the largest markets for Third Dimension where the GapGun is most commonly used.

Profile check in vehicle production

In many leading automotive manufacturer plants across the world, the GapGun has become an integral part of the production process for quality control and inspection on the shop floor. The areas of application cover the whole production process including tool making, sheet metal working, body construction, and final inspection. For instance, many automotive manufacturers use the GapGun to measure the radii of sheet metal parts. Firstly, they can identify the degree of abrasion to tools and secondly inspect the radii after clinching. The vehicles appearance has always played a decisive role during the final inspection of a painted vehicle because every single new car has to be aesthetically pleasing to the new owner. To help achieve this, the precision of the gap and flush dimensions and therefore the geometries around the vehicle can be determined by GapGun. Moreover, the laser measurement system is used for validating simulation data generated in virtual assembly. In this case, the GapGun operator walks straight to the assembly line at defined intervals, conducts random gap and flush measurements on fully assembled and painted cars, and then compares measured data with simulation data. Therefore, the auto manufacturer is in the position to identify and eliminate unwanted deviations arising during the actual assembly process at a very early stage. In this context, the operators appreciate the fact that the measurement system can handle all kinds of surfaces, even very dark paints or bright machined edge conditions.
Designed with the operator in mind, the handling of the GapGun is very operator friendly as it is comfortable to hold and the graphical display guides the operator through the measurement process by showing both the point of the next measurement and how to position the system. Therefore only minimum training is necessary to use the GapGun.

Measurement principle

he laser measurement system, which uses the principle of laser triangulation, projects a visible line on the object. The intensity of the laser line adjusts and adapts to the surface as the integrated camera focuses. Once triggered, the GapGun then automatically takes 16 images of the feature point being measured within only two seconds. Based on these 16 images, the system calculates the 2D geometry data and displays the average result. The fact that the values for gap and flush are detected at the same time, i.e. only one measurement is necessary to analyze both features, has proven to be very convenient to the users. The measured data can be stored in many different formats, e.g. in an Excel file or in custom ASCII-templates.

New area of application: Measurement of undercuts

In recent times, new industrial areas of application have evolved as the systems capabilities have developed. Today, not only companies from the aerospace and automotive industry count on the system. Businesses from the wind energy sector have also discovered the potential of the laser measuring system. In this field, the GapGun is applied for measuring undercuts of rolling bearings. In detail, defects of the shape are investigated as well as the angles and depths of the undercuts themselves. Subsequently, the measured data is compared with the nominal values in the drawings.
Thanks to Third Dimension's system, the test handling has improved significantly. Whilst the old measurement process required the component's transportation to a contourograph, the measurement can now be done right on-site. This especially pays off in case of heavy objects in excess of 50 kg for which the transportation is very time-consuming. Furthermore, when measuring the test objects while still placed on the processing machine it is possible respond to variation and rework the component immediately, without any loss of accuracy and no realignment is necessary. The measurement reports may be stored in the company's internal network, e.g. as PDF-files, and can be consulted quickly if required.