With the increasing spread of electric vehicles, the issue of smooth running is gaining importance and driving demand for superfinishing technology. A case in point: automotive supplier ZF in Thyrnau is today using a NaShaft Eco 612 superfinishing centre from Nagel for e-transmission shafts.

“This machine proved to be the best system for our application,” explains the process planner responsible on site. “It is loaded by a gantry loader through the roof hatch and will be fully integrated into a belt linking system at a later stage,” he says, outlining the automation concept.

Christian Feuchter, technical sales at Nagel, adds: “The NaShaft series is a highly flexible machine platform with a modular design and is therefore a cost-effective solution.”

ZF uses the NaShaft Eco 612 for various transmission shafts with overall lengths from 150 to 380 mm, with bearing journals in the range D = 30 to 60 mm. Tension is applied between centres. After grinding, the values for cylinder shape and surface finish are around 8 µm and Rz 2.5 µm. The targets for superfinishing are <5 µm and Rz <0.7 µm. Nagel developed a hybrid process for this task. “There is a stone process and a tape process,” explains Feuchter. “The stone process ensures an improvement of the waviness on the bearing journals, optimising the cylinder shape or shape accuracy. The subsequent tape process improves surface quality.” The NaShaft Eco finishing centre is equipped with four finishing modules. The shafts that require machining have two bearing locations. Consequently, it is possible to machine both bearing journals simultaneously, first in the stone process, then in the tape process. The machining time for one shaft is 15 seconds. For further information www.nagel.com

A Chinese manufacturer of industrial refrigeration compressors has chosen a British-built PTG Holroyd TG series CNC rotor grinding machine to bring even higher levels of accuracy and speed to its manufacturing strategies. Valued in excess of £1.4m, the machine, a TG350E, will take shape at PTG Holroyd’s Rochdale technology centre, ready for commissioning in summer 2022. The customer will use the machine to precision-grind stainless steel screw rotors of up to 350 mm in diameter and 1800 mm in length.

PTG Holroyd says that its TG series machines deliver fast, accurate and efficient stock removal. Advanced automation means reduced set-up time, while a significant amount of production time can be saved due to the fact that each machine’s diamond dressing discs are dressed continuously during the semi-finish grinding cycles.

The TG range starts with the TG50E, a machine designed to precision-grind components up to 50 mm in diameter and 610 mm in length, with models offering stepped increases in capability up to the production of helical components measuring 450 mm in diameter and 2020 mm in length.

Equally suited to prototyping, batch and volume production, TG series machines are designed primarily for the finish grinding of helical screw components such as worm screws and rotors after they have been milled to a rough or semi-finished state. Fully automated on-machine probing provides closed loop feedback of corrections to the dresser wheel and does not require a high level of operator skill.

For further information
www.holroyd.com