Material & Lot Control
• Grades: 304/316L for corrosion-critical, 17-4 PH for high-strength; every bar lot ships with EN 10204 3.1 certificate.
• Incoming hardness 160-220 HB; straightness ≤ 0.5 mm/m to reduce clamp-to-clamp run-out.
Cell Layout
• 3-phase line: twin-spindle lathe → 5-axis mill-turn → robotic wash station.
• One operator tends two cells; OEE target 85 %, takt time 45 s on Ø25 mm × 60 mm sensor boss.
Tooling Strategy
• Multi-edge coated carbide inserts (TiAlN/TiSiN) changed every 450 pcs or 0.05 mm flank wear-whichever comes first.
• High-pressure coolant 70 bar, 8 % concentration, 10 µm filter; keeps cutting zone < 250 °C and prevents work-hardening layer.
Process Sequence (example)
a. Bar feed → part-off at 120 mm length.
b. Op-1 lathe: rough OD, drill Ø8 mm × 30 mm deep, face.
c. Op-2 mill-turn: mill hex flat, thread M6, turn OD seal groove Ra 0.8 µm, cut 0.02 mm finish pass.
d. High-pressure deburr nozzle removes microscopic burr at groove entrance.
e. Robot loads into basket; CMM samples 5 % every hour.
Dimensional & Surface Results
• ±0.01 mm on OD, ±0.05 mm true-position on hex flat; Ra 0.4-0.8 µm on seal groove.
• Cpk ≥ 1.67 on critical-to-function diameters; scrap rate < 1 %.
Secondary & Packaging
• Passivation 30 min, nitric-acid based, restores Cr-oxide film.
• Laser-mark data-matrix + serial number; vacuum-seal + VCI film, 500 pcs per carton.
Pain Points Solved
• Work-hardening: reduced by climb milling, 0.15 mm semi-finish before 0.02 mm final pass .
• Chip welding: 70-bar through-tool coolant breaks chips, eliminates built-up edge.
• Tool cost: insert price 12 % higher than carbon steel grades, but tool life doubled by high-pressure strategy, so cost per part drops 8 %.
