Failure Rates

Failure Rates..

Basic Information on Failure Rates

The following tables includes a number of mechanical items and representative failure rate information. The tables also include qualifying factors. The information included is of limited value and is not current and is in no way representive a specific products. The failure rate of one company's product could be an order less than another companies.

The only real value of this table is in providing realistic relative reliabilities of different components. For most of the components in the table below more accurate reliability information is provided in the suppliers literature.

Note: 10⁶ hours = 114 years continuous operation....

Failure Rate F_o = F_r. C₁ .C₂ .C₃

Mechanical item	Modifier	Failure Rate = F_r
		/ 10⁶ hours
Ball Bearing	Heavy Duty	20
Ball Bearing	Light Duty	10
Roller bearing		5
Journal Bearing		5
Shafts	Highly Stressed	0.2
Shaft	Lightly Stressed	0.02
Pins		15
Pivots		1
Couplings		5
Belt Drives		40
Spur Gears		10
Helical Gears		1
Friction Clutches		3
Magnetic Clutches		6
Springs	Highly Stressed	1
Springs	Lightly Stressed	0.2
Hair Springs		1
Calibration Springs	Creep	2
Calibration Springs	Breaking	0.2
Vibrations Mounts		9
Mechanical Joints		0,2
Grub Screws		0,5
Nuts		0,02
Bolts		0,02
Rack and Pinion Assemblies		2,0
Knife Edge fulcrums		10
Bellows		5
Diaphragms	Metal	5
Diaphragms	Rubber	8
Gaskets		0,5
Rotating Seals		7
Sliding Seals		3
O Ring Seals		0,2
Filters	Blockage	1
Filters	Leakage	1
Fixed Orifices		1
Variable Orifices		5
Restriction		5
Pipes		0,2
Pipe Joints		0,5
Unions and Junctions		0,4
Hoses	Heavily stressed	40
Hoses	Lightly stressed	4
Ducts		1
Pressure Vessels	General	3
Pressure Vessels	High Standard	0,3
Relief Valves	Leakage	2
Relief Valves	Blockage	0,5
Hand Operated Valves		15
Ball Valves		0,5
Solenoid Valves		30
Control Valves		30
Pistons		1
Cylinders		0,1
Jacks		0,5
Pressure Gauges		10
Pressure Switches		15
Bourdan Tubes	Creep	0,2
Bourdan Tubes	Leakage	0,05
Nozzle/Flapper assembles	Blockage	6
Nozzle/Flapper assembles	Breaking	0,2

Environment Factor	C₁
Ideal Static	0,1
Vibrations Free	0,5
Ground based	1,0
Ship	2,0
Road	3,0
Rail	4,0
Aircraft	10,0

Rating % of Normal	C₂
140	4
120	2
100	1
80	0,5
60	0,3
40	0,2
20	0,1

Temperature (Degrees C)	C₃
0	1,0
20	1,0
40	1,3
60	2,0
80	4,0
100	10,0
120	30,0

Failure Rates..

See Also