Failure Analysis

BENHA UNIVERSITY
SHOUBRA FACULTY OF ENGINEERING

Industrial Engineering Department

Failure Analysis
Eng . Abdulrahman Yossri

CONTENTS
Gears
 Gear Specifications  Gear Types  Gear Failure Analysis

Bearings
 Bearing Construction  Bearing Types  Bearing Failure Analysis
Failure Analysis 2

Part 1

Failure Analysis

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Gear Specification

Failure Analysis

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Gear Specification
 Pitch circle diameter of any gear: Where : D m Z

������ = ������ × ������
is the pitch circle diameter is the module is the number of teeth

 Clearance between mating tooth:

������ = 0.157 × ������
Failure Analysis 5

Gear Types

Failure Analysis

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Gear Types

Failure Analysis

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Gear Types

Failure Analysis

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Gear Types

Failure Analysis

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Gear Types

Failure Analysis

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Gear Failure Analysis

Failure Analysis

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Gear Failure Analysis
-1.1INITIAL SCORING
Initial scoring occurs at the high spots left by previous machining. Lubrication failure at these spots leads to initial scoring or scuffing as shown in Fig. Once these high spots are removed, the stress comes down as the load is distributed over a larger area. The scoring will then stop if the load, speed and temperature of oil remain unchanged or reduced. Initial scoring is non-progressive and has corrective action associated with it.

Failure Analysis

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Gear Failure Analysis
-1.2MODERATE SCORING
After initial scoring if the load, speed or oil temperature increases, the scoring will spread over to a larger area. The Scoring progresses at tolerable rate. This is called moderate scoring as shown in Fig.

Failure Analysis

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Gear Failure Analysis
-1.3DESTRUCTIVE SCORING
After the initial scoring, if the load, speed or oil temperature increases appreciably, then severe scoring sets in with heavy metal torn regions spreading quickly throughout as shown in Fig. Scoring is normally predominant over the pitch line... [continues]

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