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Table 3 Classification of occurrence degree

From: Weakness Ranking Method for Subsystems of Heavy-Duty Machine Tools Based on FMECA Information

Category

Description

Reference value of failure frequency

OPR score

Class I

Occur frequently

> 20%

10

Class II

Occur sometimes

10%–20%

9, 8, 7

Class III

Occur occasionally

1%–10%

6, 5, 4

Class V

Occur less

0.1%–1%

3, 2

Class V

Occur rarely

< 0.1%

1