Industries using drive solutions from Getriebebau NORD include airport technology, the logistics industry, the foodstuffs, chemicals and pharmaceuticals industries as well as the steel, cement and minerals processing industries. For the latter sectors, NORD has developed suitably large industrial gear units, which the company began manufacturing in 2009 at its main base in Bargteheide.
As in all products from Getriebebau NORD, the company’s philosophy of a perfectly coordinated modular system is reflected in the manufacture of these industrial gear units. The special nature of this philosophy was discussed in an interview held by the editors of AT MINERALS PROCESSING with Dr Omar Sadi (Fig. 1), Technical Director at Getriebebau NORD and Jörg Niermann (Fig. 2) as Area Manager for Marketing.
Jörg Niermann: Top of the list comes the Unicase housing. Getriebebau NORD was one of the first companies to develop this back in the early 1980s (Fig. 3). This one-piece housing offers some huge advantages.
Dr. Omar Sadi: That’s right. For all NORD gears the bearings are integrated in a single one-piece housing. So there are no sealing surfaces exposed to torque and shear loads. There is only one opening in the housing, through which the individual components, such as gear wheels, are assembled. That is only one large sealing surface exists at the assembly cover in an area that is not exposed to any load from the torque. With split housing, the meshing forces try to separate the two halves of the housing, which must then be prevented with special measures. Split housings are generally heavier as a result.
Our Unicase housing can withstand high loads, ensuring a longer lifetime. The industrial gear units also have a single-piece housing (Fig. 4). NORD is the only manufacturer to use this design principle to a torque of 242 000 Nm.
Jörg Niermann: Another criterion for success is our modular system that we have realized for all product groups. For all sizes we offer a very wide variety of individual components enabling the selection of a perfectly coordinated system. This enables us to tune specific drive solutions individually to the needs and requirements of our customers.
Dr. Omar Sadi: With our line of industrial gear units we can cover a very wide range of variation and supply applications for which our other lines are not suitable. For that reason the industrial gear units already start at a nominal torque of 25 000 Nm – i.e. here there is a deliberate overlap with our other traditional gear units, like the 3-stage helical bevel gear unit with maximum 50 000 Nm or the helical shaft geared motors with maximum 90 000 Nm. For the industrial gear unit line we have extended the torque to 242 000 Nm. In addition, this range offers a wider array of accessories like different motors, couplings, brakes or other components, such as cooling, pumps, etc. Often entire units, consisting of gear unit with motor, coupling and brake mounted on a oscillating crank.
The line comprises various sizes with standardized transmission ratios. Form the many components manufactured at NORD, customer-specific gear units are assembled. This puts us in the position to respond very quickly.
Jörg Niermann: The industrial gear units are manufactured exclusively here in Bargteheide at the central site of Getriebebau NORD – in Plant 8 (Fig. 5). The focus at this site is administration, but the complete assembly of the industrial gear units and special orders, e.g. special shafts, are also completed in Bargteheide. The gear wheels are produced in Glinde near Hamburg, the casings are made in Gadebusch near Schwerin, motors to size 200 we produce in Italy.
Jörg Niermann: The production sites are located primarily in Germany and in Europe but we do make motors, for instance, in North and South America as well as in China for the Southeast Asian market. Otherwise we have, of course, various national assembly sites worldwide. The individual components are delivered there and then painted and assembled on site.
Dr. Omar Sadi: For service orders in the different countries – like, for example, deliveries to the big mines in Australia or Brazil – service is of course provided directly in these countries.
Dr. Omar Sadi: Both. At the larger offices we have our own employees to do service orders. And in some places we have agreements with local firms. To guarantee our high level of quality, we attach great value to a closely knit service network. Then even if there is a long distance to our respective sites, e.g. in the USA, we can respond extremely quickly. Service partners are trained by us and subsequently awarded certification by Getriebebau NORD.
Dr. Omar Sadi: For industrial gear units too, NORD is pursuing the strategy of fast availability ex warehouse. So depending on the gear unit size, we can guarantee a delivery time of four to eight weeks. To this end, we have increased our stocks and optimized workflows, with our suppliers too.
Dr. Omar Sadi: We manufacture, for instance, special shafts when a customer needs a certain size – even when it’s just a matter of 1 or 2 mm difference. We also supply double gear units if required. Here, for example, a gear unit from the classic range may be flanged to an industrial gear unit. This gives the customer extreme transmission ratios, up to 1600 or even higher. For the industrial gear units with a very high power density, as well as the mechanical output, the thermal output must always be taken into account. If at a drive power of 500 kW, the losses are around 2 %, then around 10 kW in heat must be dissipated. With 10 kW you can heat a detached family house. If this cannot be dissipated just through the gear housing, suitable fans or cooling systems are installed.
Jörg Niermann: Every order comes with a bill of materials, on the basis of which all individual components needed are laid out ready: housing, gears, shafts, bearings, screws, etc. As we guarantee short delivery times, naturally the larger components, like large gear wheels (Fig. 6), are prefabricated. Otherwise there are also manufacturing instructions, e.g. what oil should be used. From a drawing it is clear how the respective gear unit should be assembled. When all the components are available, assembly starts on an assembly plate. The shafts are inserted into the housing, the bearings and the gear wheels fitted.
Then the gears are tested in an idle run on our test bench for around three hours (Fig. 7). For this we assemble the gear unit exactly how it will be in the customer’s installation. Once the oil supply is set and the cooling water is filled, everything is connected and started up running. We use temperature sensors to permanently monitor the temperature during the trial run. Based on a report we can then see the rise in temperature in the curve and establish whether, for example, the bearing is running true. In addition with a supply of air, it is possible to test whether the gear unit is sealed tight or oil is being squeezed out anywhere.
If the functional test goes well, we send the gear unit to the paint shop (Fig. 8). The standard colour is grey. Our company colour is blue. But we generally match the colours to the customer’s equipment. We can mix any colour the customer asks for. After they have been painted, the components go through the dryers and are then packaged, on a pallet as standard (Fig. 9). But if a long-distance transport is planned or the customer specifies it, they can also be sent in closed crates
Jörg Niermann: In Germany these include Siemens-Flender and SEW, worldwide, of course, there are many more. We recently conducted a market survey according to which the 10 biggest competitors on a global scale hold around 60 % of the market. The remaining 40 % is divided between a number of companies.
Jörg Niermann: That is to do with our customers having branches all over the world – e.g. in Asia or South America. Thanks to such links to the various subsidiaries, we have the possibility to work in other countries too and are included in their portfolio of suppliers. And this is also because our customers are convinced of the quality of our products.
Dr. Omar Sadi: The wide range and variety that we supply in all sizes, and which we have now extended with the production of the industrial gear units, is also a great advantage. Consequently we supply the customers with complete packages from one source with hundreds of gear units and a large number of models and torques.
Jörg Niermann: For our industrial gear units, certainly the belt conveyor drives in the ore mines are some of the biggest applications in terms of market volume. For this reason, this year we were represented at two big trade fairs in the mining and minerals sector: at AIMEX in Sydney/Australia in August and at Exposibram 2013 in Belo Horizonte/Brazil in September.
Otherwise we are at around 70 trade fairs worldwide each year. In Germany the most important trade fairs include Logimat, the Hannover Messe, Airport and SPS Drives (Fig. 10). For bauma we’re still on the waiting list.
Jörg Niermann: The efficiency is naturally in the motor. The efficiency of the gear units per se is influenced by the quality of the bearings and also the alignment and precision of the gear wheels. But the main efficiency is determined by the motor and the overall concept.
Dr. Omar Sadi: Energy efficiency at NORD has a very high priority in product development. We are optimizing our products to minimize any losses inside the gear unit. These occur, for example, in the contact zone of the gear wheels or in the roller bearings. We combat these by manufacturing highest quality components and using the right oil with the optimum viscosity for the specific application.
Dr. Omar Sadi: We have our own central development department with attached test laboratory. From the first concept to the finished gear units, we centrally control all development steps – irrespective of where these products are later sold around the world. This way we ensure our quality standard, both in the mechanical as well as in the electrical and electronic design and the production of our products. Research and development are done exclusively here at the main site.
Jörg Niermann: We always have a number of joint projects with universities and that is not only in Germany, but worldwide. We call it the model factory (Fig. 11). The students are assigned to organize and optimize production of our gear units. The fit in the gear units is a little bigger so that the individual components can be quickly taken apart again, but otherwise it is a real working situation. That is the students learn modern methods of analysis, assessment, productivity increase and assurance of manufacturing processes in a realistic environment. With this model factory we can also arrange employee training.
That’s not only done in Germany at Hamburg-Harburg University of Technology, we conduct joint projects, for example, at various universities in India.
Dr. Omar Sadi: To combat this problem, we are, for example, active in dual training/education and have already recruited a lot of employees through this scheme. Half of the training takes place in our company, the other half at the university. We get to know the students, who can get an idea of our company. Generally, the graduates are taken on at the end of their training and we are deployed at NORD in line with their skills and capabilities. The opportunity is also available to gather international experience at one of our branches abroad.