Page 269 - Intro Predictive Maintenance

260 An Introduction to Predictive Maintenance

—Stroboscope —Gas sensor
—Ultrasonic listening —Quick-disconnect gauges
—Laser alignment —Manometer
4. Materials Defects 7. Electrical
—Magnetics —Cable fault detector
—Penetrating dyes —Outlet checker
—Eddy currents —HiPot
—Radiographs —VOM
—Ultrasonics —Oscilloscope
—Rockwell hardness —Static meter gun
—Sonic resonance —Frequency recorder
—Corona listener —Phase angle meter
—Fiberoptics bore scopes —Circuit-breaker tester
5. Deposits, Corrosion, —Transient voltage
and Erosion 8. Chemical/Physical
—Ultrasonics —Spectrographic oil analysis
—Radiographs —Humidity
—Cathodic potential —Water or antifreeze in gases/liquids
—Weight —O 2
6. Flow —CO 2
—Neon freon detector —pH
—Smoke bomb —Viscosity
—Metals present

Tests may be made on functionally related components or on the output product. For
example, most printing presses, copiers, and duplicators are intended to produce
high-quality images on paper. Inspection of those output copies can show whether the
process is working properly. Skips, smears, blurs, and wrinkles will show up on the
copy. A good inspector can tell from a copy exactly what roll is wearing or what
bearing is causing the skips. Careful inspection, which can be done without “tearing
down” the machine, saves both technician time and exposure of the equipment to pos-
sible damage.

Rotating components find their own best relationship to surrounding components. For
example, piston rings in an engine or compressor cylinder quickly wear to the cylin-
der wall configuration. If they are removed for inspection, the chances are that they
will not easily fit back into the same pattern. As a result, additional wear will occur,
and the rings will have to be replaced much sooner than if they were left intact and
performance-tested for pressure produced and metal particles in the lubricating oil.

12.1 VISUAL INSPECTION METHODS
Most of the visual inspections that are performed as part of a preventive maintenance
program are ineffective. The primary reasons for this ineffectiveness is that the
methods used are almost totally subjective. For example, a preventive task may read,