Reishauer RZ 400

In continuous generating grinding (Reishauer process), a helical grinding worm (a grinding wheel shaped like a multi-start worm gear) simultaneously engages multiple gear teeth as the workpiece gear rotates. The workpiece and grinding worm rotate in a synchronized gear mesh, with the grinding worm traversing along the gear face width. Because multiple teeth are engaged simultaneously, the cycle time per tooth is very short - a 30-tooth gear is ground in approximately the same time as a single tooth takes in profile grinding. Profile grinding (Kapp, EMAG profile wheels): grinds one tooth slot at a time with a profile-shaped wheel. More flexible (handles irregular tooth forms), but slower for high-volume production of standard involute teeth. Generating grinding is the automotive industry standard for high-volume parallel gear production due to its superior throughput.

Achievable accuracy on the Reishauer RZ 400 in production: AGMA Quality 12 (DIN/ISO Grade 4) achievable routinely in production; AGMA Quality 13 (DIN/ISO Grade 3) achievable with optimized process parameters and premium CBN wheels. Key parameters measured per AGMA 2000 or ISO 1328: single pitch deviation (fp): 2.5-4 µm; total profile error (Fa): 3-5 µm; total helix error (Fb): 3-5 µm; total pitch deviation (Fp): 5-8 µm. For context: automotive transmission gears require AGMA Quality 10-12 (DIN/ISO Grade 4-6) for NVH compliance. The RZ 400 produces gears significantly above the minimum required quality, providing process margin for handling material and setup variation.

For a typical 5th-gear spur gear (60 mm diameter, 30 teeth, module 2, 20° helix angle, 8 mm face width): continuous generating grinding cycle time approximately 20-35 seconds. For a larger 1st-gear helical gear (100 mm, 24 teeth, module 3, 30° helix, 25 mm face width): approximately 45-70 seconds. Production capacity: 100-180 small transmission gears/hour, 50-80 larger gears/hour. At 120 small gears/hour x 2 shifts x 250 days: 1,440,000 gears/year from one RZ 400. For automotive production lines building 200,000-500,000 transmissions/year, 2-4 RZ 400 machines typically produce the complete gear set. Cycle time depends heavily on face width (the primary grinding time driver) and module (larger module = more material removal per tooth).

CBN (Cubic Boron Nitride) electroplated or vitrified wheels: very high hardness (second only to diamond), extremely long wheel life (50,000-100,000 gears before dressing for electroplated CBN), and high grinding temperature tolerance. Suitable for hardened steel (58-65 HRC). CBN wheel cost is 5-10x vitrified wheel cost, but the much longer life amortizes the cost. Vitrified conventional abrasive (alumina, SiC) wheels: lower initial cost, require more frequent dressing, produce more heat per unit material removal. Better for softer workpiece materials and lower production volumes where wheel change frequency is less critical. For high-volume automotive gear production (1M+ gears/year), CBN wheels are standard - the reduced dressing frequency and consistent wheel profile across the production run provides better process capability and lower total cost.

Standard automotive gear production line integration: (1) Hobbing (Liebherr LHH, Index GE, or Gleason 500H) soft-cuts gear blank to final tooth number and rough tooth form; (2) Heat treatment (carburizing/case hardening to 58-62 HRC); (3) RZ 400 hard-gear grinding to final accuracy and surface finish; (4) 100% gear measurement (Gleason 350 GMM or Klingelnberg P 40); (5) Assembly into gearbox. The RZ 400 typically sits at the beginning of the hard-finishing cell after heat treatment. Automation: load/unload robot with gear pallet conveyor for continuous unattended operation. The Reishauer CNC interfaces with the production line MES (Manufacturing Execution System) for traceability and quality data logging on each gear ground.