NOZZLE NEEDLE | CBN COMPLETE MACHINING

BAHMÜLLER employs a concept in which we replace previously used ceramic grinding tools for match grinding of jet needles for diesel injection with CBN.

The following convincing arguments were ultimately decisive in the optimizations that were achieved:

• oversize of 30 μm (precondition of ceramic match grinding) eliminated by removing 300 μm with CBN grinding tools
• cycle time reduced by 50% compared to conventional machining
• higher profile accuracy (straightness) through in-process deflection compensation with piezo-tailstock, additional 3 sec. cycle time reduction + gap dimension tolerances in the range of ± 0.0005 mm
• process stabilization through dressing interval increase from 25 to 500 work pieces, despite longitudinal grooves in grinding zone

The challenges BAHMÜLLER faced were successfully mastered: the effect in production was extremely drastic, and BAHMÜLLER could change over the existing "old machines" to the new technology with
few limitations.
The deflection compensation during grinding, by means of the piezo "driven" tailstock, is now
used for nearly all slender "long parts" for cycle time reduction and quality increases.

The process has since been further optimized so that the conical shape of the guide bore is modified during match grinding of the ground guide part, which allows for entirely new gap dimension reductions.