Ahmet Simsek is Head of Tool Management at automotive supplier Neapco's Düren site. The company site, which specializes primarily in the production of drive shafts, has already received a number of inquiries regarding components for electrically powered vehicles. Neapco supplies many well-known car manufacturers with drive shafts from its plant in Düren and is ideally positioned to do so. "We have recently been successfully certified in accordance with the IATF 16949 standard (quality management in the automotive industry), as a high level of flexibility, efficiency and quality is required in a highly competitive environment," says Simsek happily, "so we not only meet customer expectations, but also exceed them."

The collaboration between Neapco and Mapal began long before Industry 4.0 and networked systems became part of the production halls. "It must have been the end of the 1980s when the first joint projects took place," Ahmet Simsek and Klaus Schwamborn, Area Sales Manager at Mapal, try to reconstruct together. "We have also been working together successfully for several years in the field of ball track milling for homokinetic joints," says Simsek.

Production of the drive shaft started successfully at the beginning of 2018, and the production volume will already be 35,000 units in 2019. "We use the ball track cutters to machine the ball tracks of the so-called bell or axle journals, with tight tolerances," explains Ahmet Simsek. It is important that this drive shaft joint transmits the torque with as little influence on the steering as possible, even with large deflection angles on the drive wheels of front-wheel drive vehicles - therefore all requirements regarding quality, dimensions and surface finishes must be met with process reliability. Among other things, the contact angle must be within a tolerance of ±5°.

Neapco relies on ball race milling cutters from Mapal for the hard machining of the ball raceways of the ball shell. © Mapal

Machining the forged axle journals on an Emag VSC 250 Twin machining center places high demands on both the machine and the machining technology. The material C50 mod. has a hardness of 58 to 63 HRC after induction hardening. "The final hard machining of the raceways is carried out with our ball race milling cutters," explains Schwamborn. The tool with four soldered PcBN cutting edges removes between 0.2 and 0.4 mm of material.

The tool and tool holder are connected via Mapal's own HFS interface (Head Fittings System). The milling head is pulled into the holder with a high-strength clamping screw. The head is radially aligned with µm precision via the short taper and clamped against the flat surface so that the length dimension to the HSK flat surface is also precisely maintained. This very stable separation point also enables a high feed speed.

Neapco specializes in the manufacture of drive shafts at its site in Düren. © Neapco

"The biggest challenge when designing the tool was maintaining the tolerances in terms of symmetrical contact angle and surface quality," recalls Schwamborn. In order to produce economically, Neapco also attaches great importance to a long tool life. "Based on our in-depth knowledge, which we have built up over many years, we tailored the tool precisely to the application and Neapco's requirements," says Schwamborn. The tool geometry was adapted to the required values in terms of web clearance and the forging of the balls, which later lie between the inner and outer race.

Optimal technical support

The machining process was up and running within just a few days at the beginning of 2018 and Neapco's requirements were met. Reliable production was guaranteed after a very short time. Mapal helped the automotive supplier to restart production and provided technical support. In addition to Klaus Schwamborn, application engineers and product specialists from the precision tool manufacturer are frequently in Düren for this purpose. Neapco has also set up a consignment warehouse with the tools. In addition to the ball nose end mill, the automotive supplier also uses other tools from the Aalender manufacturer, primarily fine boring tools as well as drills and milling cutters made from solid carbide. "We also use the regrinding service and send our tools to the precision tool manufacturer for reconditioning," concludes Ahmet Simsek.

According to documents from Mapal / ag