In 1828, Joseph Kuhn, a blacksmith from the small town of Eckartswiller, France, began manufacturing livestock weighing equipment at his village forge.
From that humble beginning arose the KUHN Group, one of the world’s leading manufacturers of agricultural machinery, including mowers, tedders, swathers, chaff cutters, tillage equipment and seeders. Now based in Saverne, near Strasbourg, in northeastern France, the KUHN Group tallied sales of more than 1.5 billion euros last year, and it employs some 6,000 people worldwide. The company operates factories on three continents and distribution subsidiaries and importers in more than 100 countries.
Operations at the company’s primary assembly plant in Saverne have been expanded multiple times during the past few decades, adapting to growing demand for ever larger agricultural machinery. Eventually, however, the width of the existing shop floor—a maximum of 15 meters—necessitated a larger facility. So, a few years ago, KUHN completely revamped its assembly plant in the neighboring town of Monswiller.
The Monswiller plant was expanded by 20,461 square meters: 11,065 square meters for a new assembly facility, 5,437 square meters for an extension to the logistics facility, and 3,017 square meters for a shipping facility. Additional outdoor areas and a new cafeteria round out the plant premises. More importantly, the shop floor at the new, state-of-the-art facility is 20 meters wide to accommodate the next generation of agricultural machinery.
“The Monswiller assembly plant was opened in 2008 with four assembly lines and had an annual output of 9,000 machines. We’ve now doubled that capacity with the expansion, and now we have eight assembly lines and 350 people making agricultural machinery for haymaking, tilling and sowing,” says Stéphane Schissele, building and maintenance manager at KUHN’s Saverne plant.
KUHN’s main plant in Saverne produces smaller agricultural machinery, as well as components for larger machinery made in Monswiller. These components, as well as purchased parts, are picked in the warehouse and delivered to the assembly lines. In fact, around 100 tons of parts are picked every month. Components are powder-coated and painted at the company’s cathodic electrodeposition shop. The machinery is then assembled step by step on assembly lines. Once final assembly and functional testing are done, the machines are prepared for shipping.
Delivery areas for intralogistics are located alongside the assembly lines. Among other things, workers use overhead cranes to transport goods brought in from the warehouse and paint shop to the assembly area. Cranes also play a role on the assembly line, enabling workers to install subassemblies on machinery precisely, efficiently and safely.
At the end of the production line, universal cranes help with final assembly. Depending on the type and size of the machine, bulky and heavy components may need to be installed at the end of the line. At the shipping facility, cranes help with loading the machinery onto trucks.
All the cranes for the Monswiller assembly plant were supplied by Demag Cranes & Components GmbH. Specifically, Demag provided nine ZVKE V-type girder overhead travelling cranes with an individual load capacity of 20 tons and 120 DC-Pro chain hoists. Some 3.2 kilometers of track were installed above the shop floor, creating a network that completely span the new assembly lines.
Modular, Safe And Efficient
Workers move machinery components with KBK single-girder and double-girder cranes overhead from the logistics area to the assembly stations, covering an area 100 meters long and 25 meters wide. When the plant was being planned, engineers made sure that KBK systems would be installed across the entire area to ensure that they would be available to assist with every step.
DC-Pro chain hoists are used to raise and lower parts. These units have load capacities of up to 1,000 kilograms when moved by hand and up to 2,000 kilograms when moved electrically. Components can be moved smoothly with either drive method. Articulated connections between the crane girders and trolleys ensure that subassemblies can be smoothly transferred from an assembly station to the machine frame. Throughout, the partially variable and low speeds of the DC-Pro chain hoists help crane operators easily and precisely position subassemblies.
The compatibility of Demag components with each other ensures that KUHN was able to reuse some existing chain hoists in the new facility. However, assemblers are enjoying the advantages of the newer DC-Pro hoists. Components can be positioned precisely thanks to variable speed operation. With load capacities of 500 to 2,000 kilograms and a standard hook path of 5 meters, the hoists can be flexibly used at all workstations. The ergonomic handle design and height-adjustable control cable for the DSC pendant controller ensure optimal user comfort. The same controller is used for all the cranes and hoists, which maximizes efficiency.
“We’re still using a large number Demag’s older generation hoists in Saverne today, so we’re very aware of just how durable Demag products are,” says Schissele. “We’ve been using chain hoists from a wide variety of generations on a daily basis for decades now, and they all continue to work perfectly. When our employees let us know that variable lifting speeds would come in handy for their work, we upgraded the hoists with devices from the new DC generation.”
The DC-Pro chain hoist features a gearbox, slipping clutch and brake that are maintenance-free for up to 10 years. The hoists feature automatic cut-off and braking in the event of a control failure. In addition, the hoist’s safety-related functions conform at least to Performance Level C and Category 2 as specified in EN ISO 13849-1.
The nine ZVKE double-girder overhead travelling cranes with V-type girders offer maximum operating safety and efficiency. The diaphragm joints of the V-type crane girder design allow light to pass through. Thanks to the reduced amount of material, the innovative crane girder has a lower deadweight, which is beneficial for the building structure. The overhead travelling crane spans a range from 10.4 to 28.3 meters.
“The first time I saw the crane was at another customer’s facilities, and I have to say I was impressed right away. The crane girder is almost invisible, since it lets so much light through, and that also gives the impression that the crane is very light,” says Schissele.
Given that all the cranes have a load capacity of 20 tons, KUHN will be able to transport larger and heavier agricultural machinery for final assembly and to the shipping area in the future. At the end of the production line, five cranes assist with the last assembly steps, making it possible to join preassembled and significantly heavier components.
Another four ZVKE units are in use at the newly built shipping area, where they load packages of finished components and agricultural machinery onto trucks so that they can be shipped from Monswiller to customers all over the world.
A Demag DMR modular rope hoist makes it possible to integrate mechanical and electrical improvements. Frequency-inverter control of the cranes plays an important role when it comes to comfort and convenience and enables operators in the shipping area to pick up and move pallets with agricultural machinery components or even whole agricultural machines with precision. Cranes can start moving and accelerate at variable speeds, so that operators are able to control the long-travel, cross-travel and lifting motions with precision and focus on taking full advantage of the cargo space in the truck.
Safe Crane Operation
On all nine cranes, the smart SafeControl system monitors and ensures safe operation at all times. The two-stage cut-off prevents the crane and the trolley from colliding with the limit stops. When the first limit switch is reached, the long-travel or cross-travel speed switches to creep speed. As soon as the second limit switch is reached, the long-travel or cross-travel drive is switched off, gently braking the travel motion. Load sway is prevented with a combination of continuously variable control and limit switches, ensuring that loads will not sustain any damage or damage trucks or their surroundings. Crane operators benefit from the electronic assistance, and the crane provides help and protection in the event of unforeseeable situations.
Two of the ZVKE units operate on a crane runway at the new production section. An optical crane anti-collision system is used to prevent collisions: Dual laser sensors redundantly measure the distance between the corresponding cranes on the runway, and if previously defined minimum approach distances are exceeded, the relevant crane is safely shut down in two stages. In the first stage, the crane can only be moved at slow speed. In the second stage, the crane is safely switched off. This concept of independent safety shutdown with dual-channel hardware corresponds to safety category 3 in the EN 13849-1 standard.
With the Demag StatusBoard on the crane girder, operators can always see the weight of the load on the hook. In addition, the StatusBoard displays the current operating status of each crane in real time. These include load capacity, total load, overload, service information or the activated assistance and convenience features of the SafeControl system.
The modular KBK crane construction kit enables KUHN to create custom lift and positioning systems at each workstation. It also enables the cranes can be extended at any time.
“We remove and reinstall some of our cranes at individual production lines 30 or 40 times a year to allow them operate in a different direction, for example,” says Schissele. “In addition, the KBK system here in Monswiller is set up in such a way as to cover the biggest area possible. All in all, however, it’s impossible for us to determine in advance whether an assembly line will stay the same for eight or 10 days, for instance. In fact, requirements can even change daily. Twenty years ago, we assembled 1,000 machines on a single line, and now it’s 80, 60, 50, sometimes even only 40 machines. Batch sizes are becoming smaller and smaller, and that means that we need our lines to be extremely flexible. That obviously goes for the crane runways as well.”
Crane runways, as well as pillar and wall-mounted slewing jib cranes, can transport components across the entire area. KBK versions made of steel and aluminum are equally suitable for various requirements and can be combined.
For more information on cranes and hoists, visit https://www.demagcranes.com/.
ASSEMBLY ONLINE
For more information on cranes, visit www.assemblymag.com to read these articles:
Cranes, Hoists and Lift-Assist Devices Aid Workers on the Assembly Line
