Page 292 - Improving Machinery Reliability

Life Cycle Cost Studies 263

Table 5-1
Life Spans of Selected Machinery Components and Equipment

10 3 10-2 lo-' 100 10' 10' 103
Componenls
Ball bearings
Roller bearings
Sleeve bearings
Belts, drive
Bellows, hydraulic
Bolts
Clutches, friction
Clutches. magnetic
Couplings
Couplings. gear
Cylinders. hydraulic
Diaphragm, metal
Diaphragm. rubber
Gaskets, hydraulics
Filter, oil
Gears
Impellers. pumps
Joinls. mechanical
Knife edges. fulcrum

10-2 lo-' lo-' 100 10' io2 103
Failure Rate (failures per lo6 hours)
Corresponding mean-time-between4ailure. month, year 99Y 16Y 3Y 1Y 1M

Component Upgrading and Its Influence on Equipment MTBF
Equipment mean time between failure (MTBF) can be calculated with reasonable
accuracy from the expression

Here, L = estimated life, in years, of the component subject to failure?

Et is often possible to identify wear parts of the most failure-prone components of
a machine and assign experience-based or otherwise known values of L,, &, etc. to
these components. The influence or effect of individual component upgrading on
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