Vacuum refining of raw materials for centrifugal impellers for air compressors
CD Centrifugal Impeller Vacuum refining of raw materials for centrifugal impellers for air compressors Last week we got a call from a maintenance engineer at a process plant. Their 200‑kW air foil bearing blower had thrown a blade on the second‑stage impeller after less than 9,000 hours. The machine was barely past its second oil change. When the impeller came into our shop, we didn’t need a microscope to know where to look. The fracture face showed a classic fish‑eye pattern around a cluster of subsurface alumina inclusions, right at the root fillet. The 5‑axis CNC machining was spotless. The geometry matched the drawing. But none of that mattered, because the raw material had never seen a vacuum