Hydraulic station far above the contamination limit — crankshaft manufacturer

The hydraulic station at a crankshaft manufacturer was reading far above its contamination limit. A crankshaft line runs on servo-controlled axes, and the clearances in those valves are smaller than the particles a dirty charge carries; the oil was clean enough to look right and not clean enough to run. The plant was facing a choice between a charge replacement and living with the reading.

Nano ultra-clean screening purification equipment was run on the station, taking the oil to the cleanliness band the components were designed for rather than to the band the plant had been accepting. The membrane stage is the part that matters here: at this level the remaining contamination is below the resolution of the elements in the circuit.

The measured figure came back at NAS 6. The station stayed in production on the same oil, and the reading that had been outside its limit moved inside it -- which for a servo-controlled line is the difference between holding tolerance and scrapping parts.