Faced with a demand for production increase, the foundry commissioned the country’s Demag distributor, Dematek, to supply a new process crane with an integrated weighing and position measuring system.
Anders Nilsson, project manager at Arvika explained that the company sought to speed up its charging crane and to operate it with greater precision to meet the growing requirements of its customers.
The charging crane collects scrap material, or charge make-up, and takes it to the induction-smelting furnace to be smelted down so it can later be cast.
The scrap is sorted in nine boxes. Crane staff in the control station receive orders for material pick up with quantities to be removed from each of the individual boxes, and operate the crane to move quantities of scrap. The program specifies these quantities of scrap to be smelted to create ore. The formulations specified give the cast material precisely the properties Arvika Gjuteri needs.
Calibrated crane scales in the open winch crab determine the weight of material collected.
On the basis of the weight, the system determines how much more material is needed, transmits it to the cab by radio and displays it to the operator.
As soon as the desired final formulation is complete, the mixture is then tipped onto a heap of scrap from where it is conveyed to the smelting furnace.
The precision of weight measurements is important. It impacts the overall cost of the procedure, as a less exact mixture will require more costly alloys.
To achieve both speed and prevision, Arvika decided to install a 4.8t Demag ZKKW double-girder process crane.
The Demag ZKKW double-girder crane has a span dimension of 22.65m and travels along a 40m crane runway with a multi-purpose MPW open winch.
For picking up the load, the ZKKW has a round magnet connected to the hoist by a 4/2 reeving arrangement.
The crane’s high speeds, at 80m per minute in long travel, 60m per minute cross travel, and load-dependent hoist speeds of up to 66m min, allow operators to reach high handling rates.
Frequency inverters contribute to safe operation by allowing infinitely variable motions in three axes.
In the cab, Demag provided a control panel. Cameras fitted to the crab and crane allow the control station to monitor the process.
Using the previous crane, employees worked 24 hours a day in the scrap yard and melting shop, while the new crane can handle the same weight of scrap in less than two shifts.
The higher speed of the new Demag ZKKW crane allows more rapid handling rates for scrap, increasing production capacities five-fold.
Installing the new crane made a huge difference in cycle time.
"While the old crane needed up to 60 minutes for a single operating cycle, the new crane manages this work in only 12 minutes."
This allows the crane to work five days a week in two-shift operations. Demag designed the charging crane to accommodate the requirement to increase production capacity even further in the future.
Nilsson confirms that the new installation has entered into production. "The start of productive operation already confirmed our decision to trust Demag Cranes as a solution provider to supply us with tailored technology."
Lutz Dowy, senior vice president process cranes at Demag Cranes said that to develop the crane Demag relied upon knowledge of foundry industry operations. It has also developed customer-specific charging cranes.
"The excellent co-operation with our Swedish agent Dematek also contributed to the successful processing of the project," said Dowy.
