Shredding for efficiency

The RM 1350 shredder was adapted to work best with the BMW plant’s processes.

In the light-alloy foundry at the BMW Group’s plant in Landshut, Germany, all scrap products such as punching waste and sprue systems are recycled and then remelted. But the process in place until recently was unwieldy.

The scrap was manually collected in containers and removed from the basement of the foundry. The process was labour-intensive and because the parts were large – up to two metres by 1.4 metres – the collection bins needed frequent emptying.

The light-alloy foundry at the BMW Group plant in Landshut is one of the most modern foundries in the world. Every year, around five million aluminum casting components, such as engine parts or structural pieces for the vehicle body, are produced there using five different casting processes, with a total weight of 84,000 tons. As in all areas of the company, the aluminum foundry works with maximum efficiency in order to keep the scrap rate as low as possible.

So, when it came time to renew the casting cells in the foundry hall, the company took the opportunity to look at the processes as well as the equipment involved.

A custom solution

Erdwich Zerkleinerungs-Systeme GmbH from Igling in Upper Bavaria, Germany, has decades of experience in the construction of recycling plants. It got the order to plan and commission the metal shredder.

But when their staff arrived on site they found a surprise. Richard Adelwarth, project manager at Erdwich Zerkleinerungs-Systeme GmbH, reports: “When we visited the site, it quickly became clear that the solution requested in the project tender would not have the desired effect. We carried out many trials and consulted another company in the industry in order to be able to offer an optimum solution.”

The project brief was to design a plant that enabled the collection and shredding of the foundry’s aluminum waste directly from the press. For this task, the recycling expert adapted an RM 1350 pre-shredder to the local conditions.

This machine is characterized by fast and easy maintenance, long service life, optimum shredding and high throughput. To date, seven systems with soundproof enclosures have been installed for the eight casting cells and punch presses in the plant.

“Loading takes place in free fall. The moulds, which are to be returned to the melting process, now fall from the pressing plant directly into the hopper of the pre-shredder and then into a container measuring 1.4m by 1.4m by 90 cm,” Adelwarth explains. When the container is full, it is transported outside, emptied into a large container; and this in turn is brought to the smelter.

The shredded material now takes up less than half the volume of the scrap in the old system.

The shredding process has reduced the volume of cast parts by 50 to 60 percent, which means that the disposal containers have to be emptied far less frequently and thus require less time and manpower.

The pre-shredders were adapted to the special conditions prevailing on site. The drives of the machines, for example, had to be mounted on one side instead of the usual two to accommodate the columns of the building, which were located in the installation area and therefore required a narrower design. In addition, the crushing tools themselves and their arrangement within the cutting chamber were adapted to the on-site conditions.

Safety modifications

In cooperation with the technical department of the BMW Group, Erdwich also developed a sophisticated safety system for monitoring the condition of the machine. The standard version of the RM 1350 already has a safety system. This includes a PLC controller with automatic reverse and cut-out control, so that the machine is protected from damage in the event of overload or bulky solid parts.

In addition, each shaft is equipped with an energy-optimized frequency converter, which ensures that the two cutting gear shafts are driven separately. This enables optimum adaptation to the shredding process. The safety system was extended with new custom features.

“Both the filling level of the removal box located in the basement and the monitoring of the shredder itself are now displayed transparently, so that a quick response can be made if necessary,” Adelwarth said.

Future potential

The shredder’s housing had to be adapted to the site.

With all the casting cells replaced, a conveyor belt system could be installed to further optimize the disposal process. With the conveyor system the shredded rejects would no longer to be collected in containers that have to be removed and emptied by hand.

Instead, the rejects would be transported directly into the large container via a conveyor belt. In this way, scrap products and punching waste from all casting cells could be disposed of simultaneously and without additional effort or manpower.

As for the work completed, the BMW foundry has gained efficiency by reducing the number of person hours required to move the scrap metal to the remelting location. Choosing to shred the material as it comes off the press has streamlined operations and improved safety at the same time.