Cutting Lead Time In Half

AUMA Riester GmbH & Co. KG in Muellheim, Germany, is uniting its four divisions under the slogan “AUMA – one brand.” The synergies between these areas are exploited in procurement as well as in development, design and engineering.

The AUMA Drives GmbH division is based in Coswig, Germany, and is an international active system supplier for custom gear units and actuators. To boost production of gear units, the company acquired a mill-turn machine from WFL Millturn Technologies GmbH & KG in Linz, Austria. (WFL Millturn Technologies Inc. is in Wixom, Michigan.)

The product life cycle is a unique selling point at AUMA. The customer’s product idea is first taken into development, followed by the creation of a product concept before a prototype is then produced and analyzed. Once quality and production planning are completed, it is on to parts procurement.

Labeling and traceability are becoming increasingly important. It is essential in concentrated solar power, for example, because 80,000 drives are delivered to this area.

“It all works using QR codes and is traceable,” said Marko Kost, technical support team leader at AUMA Drives. “In case of a failure in the gear unit, [such as] a defective worm shaft, which is due to a material defect, you search in the corresponding material batch and know exactly which gear unit this affects, and which ones have to be replaced. This is done for all standard products in the powertrain or according to customer requirements.”

The worm shaft, worm gear and housing are the most important parts made at AUMA and are located in the powertrain. This is AUMA’s main area of expertise. The goal is a product whose performance and efficiency become a competitive advantage for the customer.

The machines in the AUMA Group are procured by a cross-group project team. In the case of the M40X-G mill-turn machine, it was a project team consisting of Jochen Pfeiffer, the lathe specialist coordinator and project manager from the AUMA Riester plant in Ostfildern, Germany, and Kost, as well the production management and the shift leader for turning from Coswig, and central purchasing at the AUMA Riester plant in Muellheim.

The worm shafts are produced on the WFL machine. AUMA’s high-performance worm gear units can be found in concrete mixing plants, among other applications. The previous machining process for producing worm shafts was less than ideal, according to Kost. “The process for manufacturing this shaft part used to involve a lot of individual steps: turning, clamping, pre-machining, pre-milling the gear teeth and grinding the gear teeth — an extremely expensive process. Then it was time for the heat treatment. The part has to be annealed because the milling and turning process sometimes causes the shafts to twist. “After that, it was on to the finish milling of the shafts. We would pre-grind the gear teeth and finally carry out the heat treatment and case hardening before re-clamping the shaft on the turning machine. Both sides were turned, and slots were then milled before moving the part to yet another machine for the finish grinding of the gear teeth. Finally, we carried out finish grinding the seats externally in the cylindrical grinding machine. That’s a lot of individual processes with an extremely long lead time.”

With the mill-turn machine from WFL, the worm shaft can be preturned completely in just one clamping operation. The gearing is pre-machined, which means that there is no longer any need to pregrind them. The shaft goes from the machine straight to case hardening. Once this has been completed, the rest of the machining process — right through to the finished worm shaft — continues in the M40X-G.