Relay—remove metal filings and impurities,

Potentiometer-- impurities and oil stain on moving contact,

Vacuum tube parts-- Dirt and impurity on the polar plate of the electron gun,

Semiconductor element--Dir on the surface of the silicon wafer and crystal wafer,

Capacitor--Dirt on pins of the capacitor,

Printed circuit board--Ink and oxide left during processing printed circuit board,

Magnetic head--Dirt on the surface of the magnetic head.

Bearing, gear--Metal filings and impurities left during the processing of internal and external sheath of bearing,

Spring--cleaning before spring turning black,

Vernier caliper, measuring tool--Metal filings and oil stain left during the processing of parts,

Oil choke, oil pump--Metal filings and dirt left during the process of the inner hole of oil choke and oil pump,

Screw rod, air valve, pneumatic elements--Iron filings, cutting oil and

abrasive left while processing.