THE ROOTS RUN DEEP

Maschinen- und Antriebstechnik Maschinenbau GmbH & Co. KG (Güstrow, Germany), or MuA, is a contract mechanical engineering firm that builds propulsion technology systems in the northern state of Mecklenburg-Western Pomerania. Though the company was founded in 1999, its roots reach back to the year 1900 (see sidebar).

Although Mecklenburg-Western Pomerania was never considered one of Germany's industrial regions, the farming areas in and around Güstrow were fertile ground down through the years for educating MuA's employees deeply in the technical know-how of agricultural machines, gear wheel drives, drivetrain elements and steel assemblies. Because the availability of specialists in this region remains rather low, training and constant qualification are very important to MuA, where 80 of the near 110 employees work in the manufacturing process, mostly in an 18-shift system.

This employee experience is one reason MuA now has around 250 clients, including Siemens Bahntechnik, Deutsche Bahn, Sauer-Danfoss, HaWe Inline, URACA, Siemens PT, Siemens HV, Hauni and the Dräger-Werke. Another reason is MuA's investment in nine Okuma horizontal machining centers (HMCs) and five CNC lathes, which are usefully complemented by conventional machines. The accuracy and flexibility of these new machine tools have enabled MuA to maintain low-price unit costs while offering value-added services, such as custom color scheme and the assembly of entire units.

"All on one stop, at one place, fast and flexible," is how managing director Birgitt Pusch describes the company's philosophy, which directs the machining of cylindrical, tapered, spherical and tooth-flank cut gears, as well as shafts, geared shafts, chain sprockets, and belt sprockets up to entire special gears in a wide range of sizes, from small wheels of 12 mm in diameter up to cast housings with drill diagram dimensions of 1400 mm x 1250 mm x 1250 mm. Around 70 percent of these workpieces are castings and 30 percent of them are steel. Typical batch sizes are between five and 30 units, but batches up to 1200 units may be machined if required.

MuA controls the entire processing chain, which currently involves a well-equipped machinery park of CNC machines, four toothing machines, four grinding machines and the Okuma machining centers. "Our services include CAD construction, CNC programming, turning, boring, broaching, gear hobbing and grinding, along with cleaning and preserving the workpieces and the pre-finished final paintwork in all current color systems up to assembling entire units," explains Dipl.-Ing. Gerhard Hinrichs, the manager of the planning operations. Comprehensive QC equipment, including two Mitutoyo coordinate measuring machines, are used for inspection and process control. The smooth mesh of all the processes in this complex chain is documented by the certifications DIN EN ISO 9001:2000 and DIN EN ISO 14001:2005, among others.

"During the last two years we have designed approximately 800 construction diagrams and working plans," says Hinrichs. "We carefully observe which parts and services are needed by our clients." He has identified some clear trends in this remarkably diversified product range. For example, workpieces are constantly becoming more complex ? not least due to the great success of the 3D CAD systems ? which require more comprehensive mechanical processing. At the same time, accuracy requirements are increasing, which means manufacturing tolerances are shrinking. And of course, the dictates of the global determination of prices is growing.

To obtain operating profit from its production, MuA relies on the application advice and the service qualities of its German exclusive partner Hommel CNC-Technik in Cologne. Last year, MuA invested ?1.2 million in two Okuma MA 500 HB machining centers and one Okuma LB 300 lathe. This year ?2 million is budgeted for new machinery, including MA-400 HA and a MA-800HB machining centers. The machine park also includes an Okuma MA-500HB and a MA-600HB.

The MA-600HB has strokes of 1000 mm x 900 mm x 1000 mm; the diameter of the interference area is 1000 mm. The greatest drilling diameter is 420 mm. The biggest tool can be 450 mm long. Other characteristics include a magazine for 60 tools and a 60 bar spindle internal cooling and in-process measurement with Renishaw MP10 probe.

MuA will qualify for bigger workpieces with the MA-800HB starting in October. The strokes of its X, Y and Z axes are 1400 mm, 1250 mm, and 1250 mm, respectively. The maximum tool length is of 600 mm. All the machining centers of the MA-H series share a double pallet changer for parallel set-ups that take place during the main working cycle, and a B axis which is controlled numerically to 0.001 deg accuracy as a controlled feed axis.

As special feature, the MA-600HB and the MA-800HB can machine contours on the lathe with the Turning Cut function. The MA machining centers possess absolute path measurement systems (require no reference point), spherical rolling spindle cooling, spindle load monitoring, tool position and procedure time monitoring. The adapted OSP-P200M high-speed control allows programming of parameters/variables and the I-MAP cycles dialog, making it possible to define 100 workpiece zero points and 200 tool lengths and radius adjustments. Synchronized tapping can be performed as reliably as thread milling, even at maximum spindle speed through helix interpolation.

"These machining centers are a successful compromise between great chip removal performance and constant high machining quality," explains operations and human resources manager Andreas Kuntosch. "We achieve chip removal volumes to 740 cm3/minute in steel on one side. On the other side, required shape and position tolerances of 20 µm or clearances in IT 6 are no problem at all."

Next to productivity and quality, flexibility is very important. "We must be able to machine big housings as accurately as middle-sized workpieces," emphasizes Kuntosch. With table loads to 800 kg on the MA-500, to 1200 kg on the MA-600 (630 pallets), and to 2000 kg on the MA-800 (800 pallets), MuA is optimally equipped for special "heavy cases." Short set-up times are also important. In this sense, Kuntosch appreciates how the machine pallets can be prepared using the required clamping devices to "considerably speed up changing the job." The current capacity of the HMCs is up to 18 shifts per week.

Next to application flexibility, process stability is a decisive factor. In this context, Reinhard Dirks, a sales engineer with Hommel CNC-Technik, confidently refers to the general expertise in mechatronics of the Japanese machine tool manufacturer. "The Thermo Friendly Concept in all new Okuma models is a controlled thermal growth of all machine components in combination with many temperature sensors placed on the spindle and in the machine bed, whose values are accounted for in real time by the CNC. Even if the ambient temperature changes 8 deg C during the day, the measurement deviation remains below 10 µm."

A reliable chip disposal is necessary for smooth multiple-shift operation and, at MuA, this includes the filtering of the casting sludge. The machining centers circulate up to 300 liters of coolant per minute. In order to filter the 25 µm small sludge particles, Hommel adapted a filtration plant of the Consep 2000 type.

"Our history proves it is possible to manufacture successfully in a rather structurally weak region," states Pusch. "Our concept of being able to respond flexibly with modern machinery to virtually all customer requests has worked out well. We have prevailed successfully several times against competitors from low-wage countries such as Poland, Russia or Korea."

According to her, the key to this success is the high quality of the products and the ability to supply. Despite this success, the current product range will not stop here. Pusch sees great market potential in the low volume production of custom gears, and will intensively promote its development and merchandising.

Maschinen- und Antriebstechnik Maschinenbau GmbH & Co. KG, Glasewitzer Chaussee 29, 18273 Güstrow, Germany, ( 0 38 43) 34 49 ?0, Fax: ( 0 38 43) 21 23 90, www.maguestrow.de.

Okuma distributor Hommel GmbH, Donatusstraße 24, 50767 Köln, (02 21) 59 89-0, Fax: (02 21) 5989-135, www.hommel-gruppe.de, www.okuma.de.