Too Little, or Too Much?
Vision Sensors Measuring Salt Filling Levels of "Bad Reichenhaller Markensalz"
Südsalz is the most efficient and biggest German supplier of salt. You will find this market leader's brand name in every kitchen cabinet: "Bad Reichenhaller" salt. Südsalz covers all uses like salt for human consumption, animal-food salt, industrial-use salt, pharmaceutical salt and road salt with their comprehensive program of rock and salt produced by boiling. To assure the quality of their human consumption salt the Bad Reichenhall, Bavaria, based salt works employ sensors by Wenglor. Not only optoelectronic and induction sensors are applied, but the processes are also improved by vision sensors.
Deep under the mighty layers of rock of the Bavarian Alps, for more than 250 million years the salt of the primeval sea has been resting. Dissolved by rock water it settled, as alpine brine, in a hollow of the Bad Reichenhall Depression. This alpine brine, with its maximum salt content of 26.5 %, contains vital minerals and trace elements. From this natural alpine brine the pure alpine salt for Bad Reichenhaller brand name salts, spice salts and spice salt mills is obtained.
From Alpine Brine to Quality Product
The subterranean brine deposits are exploited through deep-reaching drilled holes, the alpine brine being pumped through a pipe line to the Bad Reichenhall salt works. Alpine brine production is about 300,000 m3 per year. It is used solely for the production of the finest kinds of food salt. First, the alpine brine is passed into the huge containers of a vaporizing plant, freed of impurities and then heated to its boiling point. Thus, the water evaporates, with the original alpine salt settling. For this procedure, the people at Bad Reichenhall use a special energy-saving thermo-compression method.
In a centrifuge any residual water is separated from the salt, and the salt is hot-air dried. What remains, is alpine salt of the highest quality. This very costly method will yield pourable salt, the edges of its tiny crystals being rounded.
"When the salt is purified, dried and refined it is packaged," explains Thomas Oeggl, the responsible person for electrical engineering at Bad Reichenhall. He has been with the salt works since his apprenticeship in 1975 and knows every detail of the packaging machines.
"The quality of the products shipped got to be right," he says. And one of the main criteria is the filling volume in the package. For measuring the filling levels in each package, Oeggl, a master craftsman, decided on the use of vision sensors.
When possible suppliers were considered, Alexander Berchtold, Wenglor sales engineer prevailed over his competitors. "Berchtold came and had a look at this application, installed and tried out the vision sensor, and after a few minutes, detection of the filling level was functioning," recounts Thomas Oeggl.
The salts works at Bad Reichenhall use five BS40 vision sensors. The sensors belong to the group of identification products that include industrial imaging, OCR readers and scanners. Wenglor's vision sensors in their compact housing do a fast and reliable job of imaging. Camera, lens, lighting and processing unit are integrated in the compact housing, with the optional possibility of external lighting. A further asset: a motorized autofocus, always guaranteeing a sharp image.
Resolution, reduced optionally, allows an image repeating frequency of up to 100 images per second. The image can be processed in either color or monochrome form. The adjustable exposure time and LED brightness of the sensor will give an optimum adaption to the application. A USB connection and an operator-friendly software simplify sensor-to-PC data transfer.
This vision sensor offers numerous functions which can also be interconnected. Objects are identified independently of their position and their angle of rotation. Also, the working area can be defined individually and areas causing interference can be cut out. This is why the Wenglor vision sensor functions with any background. For purposes of quality assurance the sensor will deliver pictures for diagnosis to the personal computer.
Among its functions are analysis of shape, pixel comparison, linkage of functions, presence check, and comparison with a reference image. The vision sensor has four outputs which can be adjusted to different events. Up to three objects can be linked together.
The Wenglor software allows the sensor to be quickly adjusted to the desired application. Using the operator-friendly software, configuration can be carried out via a PC or a laptop. In addition, selection of up to ten pre-stored projects can be done via the digital input or on a touch screen.
No Standstill When Using Vision Sensor
"We package 400 packs per minute," says electrical-system master craftsman Thomas Oeggl. Cartons are folded, pasted and filled. The vision sensor supervises filling volume. If, for instance, there is a dark area on the reference image, that is, the number of pixels does not tally, the sensor will issue a fault signal. A fork then removes the product. "The dark area in the image indicates that salt is leaking somewhere," explains Wenglor sales engineer Alexander Berchtold. If the filling volume is o.k., packs are folded on top and pasted and the correct number of them are cross-shifted into a larger carton for shipment.
Thomas Oeggl is happy with the function of the vision sensors. Nevertheless, Alexander Berchtold is always there when a question arises. "Also, we can always count on getting through on the hotline, which is not the case with every company," says Thomas Oeggl. The Wenglor technical support personnel will quickly find an answer to a customer's urgent question. This way, Südsalz, too, is able to optimize their processes and avoid standstill of their machinery.
Valuable content and the natural purity of the alpine brine are the reasons for the high quality of Bad Reichenhall products. Wenglor vision sensors make sure that it remains that way.