10.000 pcs of tapped holes and the VÖLKEL GREEN RING Machine Tap is still in use without any visible wear. The Customer is fascinated and satisfied with this great result. Workpiece: Automotive part (Steering knuckle) Material: GGG40 Rotation speed: 550-600 RPM Pre-hole diameter: 5,0 mm with extra chamfered edge at entry position Lubricant: Emulsion (mixed of water-oil) Length of thread: 8mm Type of hole: Blind hole Machining direction: Horizontal