The Secret to Sigma Pool’s Success

The Sigma Pool—a collaboration between industry giants Klingelnberg, Liebherr, and Oerlikon—is providing solutions to the global gear market.


The Sigma Pool was formed in 1991 to be a market-focused, single-source supplier for gear manufacturers around the world. Alone, each company served a specific niche of the overall gearing field. Together, they were able to expand their offerings to every corner of the globe, while simultaneously cutting costs and sharing technology. Liebherr brought expertise in all areas of gear hobbing, Lorenz handled shaping, Oerlikon knew high-volume hypoid gear production, and Klingelnberg rounded out the group with their gear inspection, worm and rotor grinding, and jobbing systems for bevel gears.

The Sigma Pool consistently continues to develop and improve the equipment that has made it a leading force in the global gear industry. The following is just a sampling of the many innovations that have resulted from this collaborative effort.

Figure 1 The "P Series" Gear Measuring Centers–These centers have been in successful use for many years. Each is suitable for workpieces up to 400 mm outer diameter. In addition to cylindrical gears with external and internal teeth, worms, and wormgears, spiral bevel gears, rotors, camshafts, and other curved workpieces can also be checked. The inspection machine itself has an extremely compact design, and thanks to the optimal arrangement of all control elements and user-friendly software operator guidance, any operator can perform quick and reliable measurements after brief introductory training.

Figure 2 Worm and Rotor Grinding Machine H10–With the H10, Klingelnberg presents its newly developed worm-, rotor-, and thread-grinding machine to a wide audience for the first time. It is designed for the grinding of workpieces up to a diameter of 100 mm. The H10 and its software packages are integrated in a comprehensive software system for the design, calculation, and production of worms, compressor rotors, pump spindles, and other thread-type components.

Figure 3 Gear Form Grinding Machine Sigma Opal F75–The Sigma Opal F75 is a CNC controlled gear form grinding machine for fast and efficient grinding of spur and helical gears and forming grinding wheels, as well as special gears with other profile shapes. It is designed to directly implant conventional grinding wheels. For special applications, vitrified dressable and non-dressable CBN grinding wheels and electroplated CBN wheels can be applied.

Figure 4 Klingelnberg-Oerlikon C27 Spiral Bevel Gear Generator–Greater productivity in the automotive industry has required improvements in machine design. The C27 was specially developed for the interests of the automotive industry. On the C27, instead of fitting the tool and workpiece spindles with high-precision gear trains and related spindle motors, direct drives have been employed. This technological leap in drive engineering became possible through a special spindle design that permits the control system setup necessary for this drive to be adjusted once for all practical conditions. The C27 also provides a considerable reduction in processing time. Acceleration of the spindles to working speed occurs in less than one second so that non-productive time can be reduced to an absolute minimum. The freedom from maintenance of these drives, and their very high positioning accuracy, guarantee high-quality bevel gears during the entire service life of the machine.

Figure 5 LC120 Hobbing Machine–Based on the existing platform design of the successful hobbing machine, with the further development of individual components, Liebherr exhibited a new generation of this series of machines. A redesigned cutting head represents the core of the machine evolution. Here, speed and torque of up to 6000 rpm at 18 kW required power have been realized by means of new direct drives, enabling the use of both HSS and hard-metal tools in dry and wet processes.

Figure 6 Profile Grinding and Generating Grinding Machines LCS200 and LCS300–Based on its successful profile grinding and generating grinding machines using CBN-coated grinding tools, Liebherr has introduced an interesting expansion with an optional dressing facility for SG (Sintered Gel corundum) tools, considerably increasing both the flexibility and economy of gear grinding.

Figure 7 LFS200e Gear Shaping Machine–This gear shaping machine was conceived for the universal production of prototypes and small lots. For this, the machine has been equipped with an NC-controlled tilting column and a corresponding side adjusting mechanism. This makes possible the production of cylindrical and conical gears using a convenient set-up procedure.

In the past, advances in general machining technology often took decades to migrate into the gear industry. Today, the lag still exists between when a technical improvement occurs in turning or milling, for example, and when that technology becomes successfully applied to gear manufacturing. However, through the work of the Sigma Pool and other industry leaders, that gap is narrowing.

At the EMO Machine Tool Exhibition this year, the Sigma Pool exhibited many of the new machines described above. The EMO showcased the wide variety of technological improvements that are changing the gear industry today: increased use of direct drives and linear motors, higher levels of tool stiffness and accuracy, and reduced auxiliary times through improved CNC, to name just a few.

The Sigma Pool is constantly working to develop and implement improvements such as these, which promise to make the future of gear manufacturing every bit as exciting as its past!