DREI Wetter Taft is one of the best-known hair spray brands in Germany. The product is manufactured and loaded into aerosol cans by Schwarzkopf and Henkel GmbH, in Wassertrudingen.
Capping machines produced by Alcoa Deutschland GmbH handle the attachment of the aerosol caps. These high-performance plants can automatically put aerosol caps on five cans a second.
From the advertising point of view the caps must be attached in such a way that the nozzle is always in the middle above the Taft lettering and the company logo.
Detecting this proved difficult for standard sensors because of the many colours and contrasts.
This problem was solved using bar-code scanners of the CLV 410 series.
With a plant capable of handling 18,000 cans an hour it is clear how important rapid and reliable detection of a positioning mark is.
Which is why the idea of using the EAN bar codes already on the cans (they are required by the scanners on the retailers' tills) for aligning the cans in the capping machine, was jointly developed by Alcoa and SICK.
By modifying the software, the scanners at Alcoa can send a continuous signal to the control system along the entire length of the barcode during rotation of the can in the machine - which takes place at 80rpm.
The machine control system calculates the rotational position of the can from the time period between ‘reading’ and ‘not-reading’ the barcode, and turns it appropriately before the cap is attached.
Maximum accuracy of barcode detection is of prime importance: no more than ±1° deviation is permitted. And if this tolerance is exceeded by just 1 per cent of the cans passing through the machine in an hour this would result in 100 cans of top-quality hair spray becoming 100 rejected cans.
The CLV 410 offers certain features that provide the required positioning accuracy. Thanks to a special algorithm, the device generates a correct output signal even with partially covered codes.
In addition, the high scanning frequency of 800Hz means that the bar code is scanned often enough, and thus precisely enough, for this application.
So it is no accident if the aerosol cap (and its nozzle) is correctly attached to the Drei Wetter Taft hair spray can - it's all down to the CLV 410 bar-code scanner. Erwin Sick Optic Electronic 1800 334 802.