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Simplified Ventilation Systems

Andreas Bauer's picture

The use of metal sheets with a low thickness deviation led to significant material savings for NESTRO Lufttechnik GmbH. The material savings had a positive effect on the economic situation of the small business. In particular, it is worth noting that the use of metal sheets with a lower thickness deviation does not require design modifications. Therefore, production can be quickly and simply converted. This indicates great potential for material savings beyond NESTRO Lufttechnik GmbH.

The small business
NESTRO Lufttechnik GmbH was founded in 1977. It manufactures suction and filter installations as well as special ventilation systems for various industrial uses. The company is based in Schkölen, in the northern part of the Saale-Holzland district. NESTRO Lufttechnik GmbH employs more than 180 people and has one of the most modern sheet metal working centers in Europe. The small business’ high-quality products are exported to the whole world.

The issue
NESTRO Lufttechnik Gmbh uses metal sheets with a standard thickness deviation (in accordance to DIN EN 10143) for the manufacturing of ventilation systems. For a metal sheet with the nominal thickness of 4.0mm, a thickness deviation of -0.24mm to +0,24mm is allowed. On average, the metal sheet has a thickness of 4.0mm, but in component design the material requirements for the sheet have to be set with the minimal tolerated thickness of 3,76mm. This leads to the fact that in theory a metal sheet thickness of 3,76mm is sufficient, but in practice because of the thickness tolerance a metal sheet with an average size of 4,0mm is used. This leads to around 6% of additional material use.

Material saving measures
Steel strips – the input material of metal sheets – can be produced by modern steel mills with significantly lower thickness deviations. Using steel strips with low thickness deviation makes it possible to decrease the average metal sheet thickness without changing the guaranteed minimal thickness.
Metal sheets with lower thickness deviations are also available for a range of dimensions for rapid delivery on the market. Through the use of metal sheets with lower thickness deviations, NESTRO Lufttechnik GmbH could reach material savings of around 3.5%. As constructive changes were not necessary, the production processes could swiftly be shifted to using metal sheets with lower thickness deviations.
Based on projections of yearly use, 80 tonnes of steel sheets could be saved annually. Those savings mean that even factoring for the additional price of metal sheets with lower thickness deviations, the firm’s expenses for raw material inputs could be reduced by around 35,000 EUR. Furthermore, it was determined that the subsequent forming processes with the use of metal sheets with lower thickness deviations are running more robustly, which leads to a noticeably lower rejection rate. This leads to an addition material saving of several tonnes a year.
The use of higher-strength steel was considered as an additional measure for material savings. This way, the metal sheet thickness can sometimes be reduced by up to 50% without sinking the specifications for the metal sheet. The use of higher-strength steel does however require structural adaptation of the components produced from it; in addition, the use of these metal sheets is not suited to all load types.
Using a filter with a total weight of over 3,400 kg, experiments were conducted to determine which metal sheets could be replaced with high-strength materials. As a result of the redesign of the filter, a material savings potential of over 900kg per filter was identified. The new filter now weighs nearly 2,800 kg.

As a result, approximately 24% of the previously required sheet materials could be saved. Despite the higher procurement price of higher-strength steel sheets, a material cost reduction of around 400 EUR per filter is expected.

Summary
The use of metal sheets with a low thickness deviation led to significant material savings for NESTRO Lufttechnik GmbH. The material savings had a positive effect on the economic situation of the small business. In particular, it is worth noting that the use of metal sheets with a lower thickness deviation does not require design modifications. Therefore, production can be quickly and simply converted. This indicates great potential for material savings beyond NESTRO Lufttechnik GmbH.

Project theme:
Demonstration of material savings potential in the manufacturing of ventilation systems.

Project implementation:
NESTRO Lufttechnik GmbH
Paulus Nettelnstroth-Platz
07619 Schkölen
Telefon: +49 36694 41-0
Fax: +49 36694 41-260
Internet: www.nestro.de

Contact:

PIUS-Internet-Portal
c/o Effizienz-Agentur NRW
Henning H. Sittel
Tel. 0203 378 79 51
E-Mail: info@pius-info.de

Green Eco Net
c/o Ecologic-Institut gGmbH
Dr. Martin Hirschnitz-Garbers
Tel. 030 86880 272
E-Mail: martin.hirschnitz-garbers@ecologic.eu

Source in german: BMWi http://www.pius-info.de/dokumente/download/1985/