Speed and accurate differentiation of even the lowest contrasts are essential for detection of printing marks on continuous material. Edale, a UK manufacturer of flexo printing presses, amongst other machinery, found that SensoPart’s miniature contrast sensor fulfilled both requirements when it came to replacing the standard sensors it previously used, saving not just space but also halving the costs. 
“Miniature contrast sensors are tailored precisely to our needs. Their small size means they can be fitted discreetly into our machine and we are extremely satisfied with their performance thus far,” said Antony Neaves, Edale’s senior buyer.
The Flexo printing press FL-3 from the UK manufacturer Edale, is equipped with 15 contrast sensors. These sensors control the printing and die cutting processes on continuous paper or foil by identifying crop and registration marks on the material. The standard size contrast sensor had to be replaced by a more compact version.
With the miniature contrast sensor FT 25-RGB, SensoPart fulfilled all requirements: measuring just 34 x 20 x 12 mm3, it is approximately only a fifth of the size of the previous sensor and its performance data is superior. Thanks to multi-colour analysis – the sensor automatically selects the optimum emitter colour (red, green or blue) for the given contrast – low or difficult contrasts, such as yellow printing marks on a white background, can be reliably detected. The requirement for a very fast print mark detection, due to the high web speed of up to 200 m/min, is achieved by the switching frequency of 25 kHz. It also has a short response time of 20 µs and a minimum jitter of 10 µs which guarantees accurate positioning and precise die cutting of the continuous material.
The teach concept of the contrast sensor FT 25-RGB has been customised, so that Edale could maintain the same operating concept of the previous sensor. The cost of purchase combined with savings achieved through the flexible mounting concept reduced costs by approx. 50% – a welcome spin-off from the change by Edale.