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Colour recognition

Every visible body emits light, which is why colour can be used to evaluate objects in automation technology. Sensors sort products by colour, inspect incoming goods, detect colour and print marks, control LED intensity and colour, and much more.

In-line detection of protective film on PVC window frames

Company „Schüco“ manufactures PVC window frames. The PVC profiles are provided with a protective film after they are extruded. This film protects the frames from scratches and dirt. The colorCONTROL ACS7000 colour measurement system checks if the protective film has been applied correctly.


Marking detection on cosmetics bottles

Before the printing process, a reference mark is embossed into the bottles. Due to the depression of the embossment, the colour of the reference mark deviates slightly from the rest of the bottle surface. The colorSENSOR CFO100 detects this minimal colour difference, which enables the exact determination of the printing position below the embossment. For a flawless print, accurate and reproducible positioning is crucial. If the marking is missing, the bottle is considered as faulty and will be rejected immediately. Therefore at the same time, a good / bad evaluation can be carried out as part of a quality control. A machine turns the cosmetics bottle while the colorSENSOR CFO100 constantly measures the surface of the bottle at a distance of less than 10 mm. The embossment is detected quickly and reliably. Next, the exact position for the bottle printing is determined and further process steps can be carried out. The colorSENSOR shows clear advantages over other measuringmethods. First, it masters the semi-transparent surface easily. Second, it is ideally suited to this kind of position measurement task due to its favorable price/performance ratio.


Colour detection of kitchen fronts

Kitchens are available in many different colours. In order to guarantee that the customer receives the desired colour, the colorSENSOR OT-3-MA-30-16 inspects the colour of the kitchen fronts in the painting plant.


Colour recognition for seams in automotive interiors

In the assembly line of a well-known German car manufacturer, similar car interior parts must be differentiated from each other based on the respective seam colour. Previously, professional testers have visually checked the seams. In order to automate the process and to optimize it economically, colorSENSORs from Micro-Epsilon are now being used.


Colour and intensity tests of vehicle lights

At the end of their production process, vehicle lights must be 100% inspected. Colour and intensity of the finished lights are the primary inspection criteria. Homogenous distribution of light should also be guaranteed with fluctuating LED batches. The LED colorCONTROL MFA Analyzer performs this colour inspection. The lights are positioned via a corresponding form so that the optical fibre can test at different points simultaneously, which ensures that every single LED is controlled. State-of-the-art 3D printing technology enables the adaption to the vehicle light.


Colour measurement of car attachments

colorSENSOR CFO sensors from Micro-Epsilon are ideally suited to this kind of precise colour comparison measurement as they reliably recognize different colors while enabling 100% quality control. The sensors are calibrated once to the prevailing measurement conditions such as ambient light and measurement distance. Therefore, it is necessary to calibrate the illuminating LED. The sensor is calibrated to the target with the brightest colour shade. In order to achieve optimal measurement results for shiny surfaces too, a reflex sensor is used in addition to the colorSENSOR CFO controller. It is arranged at an angle of 25 degrees to the measurement object. This ensures that the distances and angles remain constant.


Colour measurement of the floorboards

Plastic floorboards are made of coloured granules and shaped by deep-drawing. After the production process, it must be guaranteed that the colour of the floorboards is homogenous and that there are no colour differences.


Colour measurement of liquid paint

Measuring the colour of liquid paint is extremely complex. To date, paints have been typically applied on a test area first and then measured only after the drying process in order to achieve reliable measurement results. If the measurement results reveal that the paints are faulty, the paint con­tainers must be mixed again or even disposed of which partly involves long waiting times until a new measurement process can be started. In order to accelerate this process, Micro­-Epsilon has developed a sys­tem that enables the measurement of liquid paint during the production process.

This application therefore includes the colorCONTROL ACS7000 colour spectrometer for colour measurements and the optoNCDT 1420-­50 laser triangulation sensor for distance measurements. The latter is ideally sui­ted to this application due to its compact size and excellent performance. A linear unit offers automatic readjustments.


Colour measurement of LED panels (RGB)

When RGB LED panels are produced, the challenge is to create a uniform, completely homogenous surface. Therefore, a diffuser layer is used, which enables a regular scattering of the otherwise point-shaped LED light. In order to avoid defects in the material and during production, the inline colorCONTROL ACS7000 colour measurement system is used with the ACS3-TR receiver unit. Errors can therefore be recognised during the production process itself rather than the previous method of manual final inspection, which is no longer necessary.


Colour measurement of tablets in pharmaceutical production

In pharmaceutical tablet production different ingredients are used. Changing the concentration of these ingredients affects the colour of the tablet. The colour gradient varies from white and beige to yellow.


Colour measurement of RAL colors (K1/K5 colour fans)

RAL colors are standardized colors with each one assigned to an unambiguous number. They help to precisely determine colors. RAL colors are used in almost every field where surfaces are painted or colored products are manufactured. These colour samples serve as reference values at the end of the manufacturing process during quality control, as well as for comparison purposes. For example, in this application, two shades of red, green and white of the RAL K1 and RAL K5 colour fans are distinguished.

colorSENSOR CFO sensors from Micro-Epsilon are ideally suited to this kind of precise colour comparison measurement as they reliably recognize different colors while enabling 100% quality control. Before the inspection starts, the sensor is calibrated to a 1.25 inch zenith white standard.


Recognizing colour nuances and materials of screw nuts

For this measurement task, the controller is used together with the CFS3-A11 reflex sensor. Beforehand, the sensor is adjusted once to the brightest target, in this case a zinc nut. The nuts are transported on a vibrating conveyor and then pressed into a hexagonal shape by means of bolts. A screwdriver removes the nuts and places them in a holding mold. At this point of the process, the colour inspection is carried out. The reflex sensor measures on the front faces of each nut, detects the colour and performs an internal evaluation. Via digital outputs (0 V or 24 V) this evaluation can be output to a control system.

Up to 320 colors can be taught in 254 colour groups. The colorSENSOR CFO achieves an extremely high recognition performance and process reliability. The web-based interface enables intuitive operation.


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 colorSENSOR from Micro-Epsilon enables a direct colour comparison between the parking sensor and the rear bumper.


Inline colour measurement on the extruder line

A True Colour sensor from the colorSENSOR CFO200 series by Micro-Epsilon is used to detect the fluctuating colour values of the pellets. The sensor measures the colour of the pellets through a sight glass in the suction box of the finished product conveyor and reliably detects the smallest colour deviations (∆E < 1) from the programmed reference value.


Inline colour measurement of plastic injection-moulded parts

In plastic injection moulding, the exact colour shade of the products is important, as the colour changes during cooling. To date, it has only been possible to measure random samples of cooled pieces. However, the colorCONTROL ACS inline colour measurement system from Micro-Epsilon can 100% inspect the products as they are extracted from the mould.


Inline colour measurement of transparent film

In non-contact monitoring of continuously produced transparent strips of film, each millimetre of strip produced must be identical in colour. As well as colour fluctuations, streaks can occur during production. As these films are translucent, the colour is measured in transmission using the high speed, high precision colorCONTROL ACS7000 inline colour measuring system, which is connected to a transmission sensor head (ACS3) comprising a transmitter unit (TT) and a receiver unit (TR).


Inspection of polycarbonate sheets

colorSENSOR CFO200 sensors combined with the CFS3-A20 transmission sensor from Micro-Epsilon are used for this quality inspection. The measurement on the sheets takes place directly after cooling in the production line. The distance between the transmitter and the receiver units is 80 mm. During the production process, the intensity distribution and the colour differences are precisely detected. If the colour of a plastic sheet deviates from the setpoint, the controller transmits the signal to the plant control system via Modbus TCP.


LED testing of electronic assemblies during the in-circuit test

colorCONTROL MFA LED test systems are used, among other things, in the electronics industry when quality control of printed circuit boards is performed by in-circuit testing (ICT) in the clean room. The correct functioning of electronic assemblies is checked in the in-circuit test when the boards are already equipped, many of them with LEDs. In-circuit testing ensures simultaneous tests of functionality, intensity and colour in a test adapter. The colorCONTROL MFA-28 multi-position colour recognition system is used for this purpose. 28 receiver sensors receive the light and transmit it directly to the controller via optical fibers


Measuring the zinc strip colour in production

The company H.D.Lenzen specializes in the field of surface finishing for strip materials, while occupying a worldwide leading position in this market. The steel and aluminium strips are coated during surface finishing with zinc. Zinc is deposited onto the cleaned strip from an electrolyte solution by applying a high electrical current. The strip material not only receives corrosion and wear protection but also defined coloring. Reliable testing of this coloring is necessary in order to ensure consistent product quality.

In order to fulfill the high requirements for precision and speed, the innovative colorCONTROL ACS7000 colour measuring system from Micro-Epsilon is used, which recognizes colour shades to an accuracy of ∆E < 0.1. Manual and visual inspections are not possible in this area as the trained human eye only recognizes colour distances up to max. ∆E 0.5.