Automotive: test bench and production control

Fully automatic paint defect inspection of car bodies and attachments

Particularly with shiny surfaces, a faultless production chain is expected in order to lend a sophisticated visual appearance to the final product. For fully automatic defect detection on car bodies and attachments, the reflectCONTROL inspection system is used. The system projects a striped pattern onto the surface. Deviations caused by defect are recorded with two cameras and evaluated via software.

Detecting surface defects

As well as the visual requirements, instrumentation panels also have to fulfill functional and security requirements. Often the passenger airbag has a predetermined breaking line which is generated using a laser. This »weak point« ensures the safe opening of the airbag at the predetermined breaking line. Sink marks may appear, which can be recognised under certain light conditions. In order to recognise these defects, surfaceCONTROL inspection systems are used which enable fast and objective evaluations to be made of the characteristics of any shape deviations, both on grained and smooth surfaces.

Behaviour of the combustion engine in the test bench

Eddy current sensors from Micro-Epsilon are considered as proven measuring instruments in the test bench of combustion engines. In towing mode as well as in the firing mode, the sensors detect different quantities which contribute to the improvement of the engine characteristics. In particular, the high measuring accuracy provided under harsh conditions in the engine distinguishes the eddyNCDT eddy current sensors.

Gap measurement in aluminium die casting processes

In aluminium die casting, liquid aluminium is poured into molds under high pressure and at high speeds. The high pressure acts on the closed mold and pushes it apart, which is why splinters and burrs might occur during casting. In order to measure the pressure-induced movement of the molds, eddy current sensors detect the change in distance. These robust sensors provide reliable measurement results despite high temperatures, ambient pressure and a dirty measuring gap.

Monitoring the sheet metal infeed during pressing

During forming in the pressing plant, the presence detection and the detection of the exact sheet metal position are required. Therefore, laser triangulation sensors measures on the sheet between the dies. The challenge here is to achieve high measurement accuracy in tight spaces despite oil mist, vibrations and shocks. Since the measuring gap is very small, the diameter of the laser must be correspondingly low.

Measuring the brake disc deformation (Disc Thickness Variation)

With the capaNCDT DTV, Micro-Epsilon has developed a product range that is specifically used for non-contact detection of the Disc Thickness Variation. Thickness measurements of brake discs can be carried out in test benches, in road tests or in car repair shops using non-contact, capacitive displacement sensors, which detect the thickness of the brake disc from both sides.

Recommended sensor technology

Measuring Disc Thickness Variation

Road tests - Detection of the brake temperature under load

The temperature behaviour of brakes plays a major role in vehicle development. In particular, the duration of heating and cooling of the brake discs provides information about the efficiency of the brake system. In test bench and road tests, non-contact temperature sensors from Micro-Epsilon measure the temperature development during braking. The compact design and the short response time of the pyrometers enable universal use in test bench and road test applications.

Gap measurement in robot-based assembly

In modern production lines, scanCONTROL laser scanners are used to reliably inspect the gap sizes of the car body quickly and consistently. Thanks to surface compensation, measurements are possible on a wide variety of body paintworks.

LED colour inspection of vehicle lights

Colour and intensity of vehicle lights must be reliably inspected prior to assembly and delivery. Homogenous distribution of light should also be ensured with fluctuating LED batches. The colorCONTROL MFA is a special LED test system designed to test inaccessible and widely spaced test specimens. Optical fibres enable simultaneous measurement of up to 20 measuring points.

Position detection of car bodies in the processing line

Before a car emerges from a bodyshell, it passes through numerous stations within the production, in which fully automatic processing steps are carried out. In order to enables the processing robots to recognise the exact position of the car body, several laser triangulation sensors measure the car body and transmit the position data to the robot controller.

Colour inspection and sorting of supplier parts

Before installing front aprons, Micro-Epsilon colour sensors check if the colour of the attachment matches the body colour. Different colour groups can be defined to cover all coatings.

Recommended sensor technology

Compact True Colour Sensor

Inline burr measurement on sheet edges in body manufacture

In order to avoid corrosion, continuous and error-free corrosion protection is a critical factor in the painting process. As the thickness of the applied painting on burrs can only be determined under challenging limitations, it is a decisive advantage that the burrs are recognised early in the production process before the corrosion protection and other paint layers are applied.

In contrast to fixed solutions that enable a random test, Micro-Epsilon offers its scanCONTROL 2910-10/BL Plug & Play system which provides the required precision with its high point resolution of approx. 8µm along the laser line in order to recognise burrs reliably even during inline measurements.

Distinction of brake discs

When processing car brake discs, the correct brake disc must be chosen before each stage of production in order to assign them to the manufacturer's different models. Laser scanners are used to recognise and classify the brake discs. The challenge of brake disc distinction is that the test objects are the same with regard to form, height and diameter. The gapCONTROL laser scanners are used for 100 % recognition and subsequent sorting. The only distinctive feature is a gap between two ventilation blades that signifies the respective models of the manufacturer.

Colour comparison between parking sensor and body shell

Car attachments such as parking sensors are painted separately. However, during assembly there must be no difference in colour between the parking sensor and the bumper, which means the two colours must be identical. The colourSENSOR sensor from Micro-Epsilon enables a direct colour comparison between the parking sensor and the rear bumper.

Colour recognition for seams in automotive interiors

A well-known German car manufacturer relies on poka-yoke mechanisms for assembling interior components. The poka-yoke process prevents product defects due to random human errors and ensures that all parts are assembled correctly. However, similar types of component often have different coloured seams, which is why error prevention is critical. Previously, these checks were performed manually - experts inspected the seams visually. Micro-Epsilon’s colourSENSOR  colour sensors are now used to automate this process and to make it more efficient.

Automatic positioning of synchroniser discs

Synchroniser discs are used as a synchroniser package in automatic transmissions. Behr Systems in Germany created a handling and processing plant for deburring the front side of the synchroniser discs using a laser. An essential part of this plant is the measurement technology, which guarantees the precise positioning of the synchroniser discs under the deburring laser.

Vibration displacement measurement in road tests

With cars, tests on the running gears form the basic requirements for driving safety. Here sensors are needed which can also withstand the high demands of road tests. As an example, draw-wire sensors are mounted in parallel to the shock absorbers for the vibration displacement measurement and the data is recorded for varying road-surface quality. The displacement signal obtained is differentiated to give the vibration velocity and vibration acceleration.

Micro-Epsilon UK Ltd
No.1 Shorelines Building
Shore Road
Birkenhead
CH41 1AU
info@micro-epsilon.co.uk
+44 151 355 6070
+44 151 355 6075

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