FMEA - Failure Mode and Effects Analysis

Overview

Apply F.steps in order; final score determines descending ranking.

Output

utility, higher is better

Data

Crisp, complete numeric matrix

Weights

Needs a weight source

Size

2+ alternatives, 3-12 criteria works best

Used for

Risk assessment, manufacturing reliability

How it works

1. 1

   Identify failure modes per item; collect three ratings per failure mode: Occurrence (O), Severity (S), Detection (D) on a 1-10 scale.

   $$O_i,S_i,D_i\in \{1,2,\dots ,10\}$$

   Liu 2016, Ch.1 §1.2 Step 5 (p.7); Stamatis 2003 Ch.4

2. 2

   Compute Risk Priority Number for each failure mode i: RPN_i = O_i × S_i × D_i. Range: 1 (best) to 1000 (worst). Higher RPN = higher risk priority.

   $${\text{RPN}}_i=O_i\times S_i\times D_i,O_i,S_i,D_i\in \{1,2,\dots ,10\},{\text{RPN}}_i\in [1,1000]$$

   Liu 2016, Ch.1 §1.1 Eq.(1.1) (p.4); Stamatis 2003 p.99

3. 3

   Rank failure modes in descending order of RPN. The failure mode with the highest RPN receives rank 1 and is treated as the highest-priority risk for corrective action. After corrections, recalculate RPN to verify risk reduction.

   $$\text{rank}(i)=\text{rank in descending order of }{\text{RPN}}_i;\text{RPN is recalculated post-correction}$$

   Liu 2016, Ch.1 §1.1 (p.4); §1.2 Step 5 (p.7)

Look elsewhere when

Assumptions to verify

• Criteria preferences are independent (no synergistic interactions)
• Compensation is acceptable: high score on one criterion can offset low on another
• Decision matrix is complete (no missing values)

Edge cases and pitfalls

• Applying FMEA without verifying this assumption.

  Requirement: Criteria preferences are independent (no synergistic interactions)

• Applying FMEA without verifying this assumption.

  Requirement: Compensation is acceptable: high score on one criterion can offset low on another

• Applying FMEA without verifying this assumption.

  Requirement: Decision matrix is complete (no missing values)

• Using FMEA when: Criteria strongly correlated → consider DEMATEL/ANP for interdependence.

  An alternative method is recommended in this situation.

• Using FMEA when: Non-compensatory preferences → consider outranking (ELECTRE/PROMETHEE).

  An alternative method is recommended in this situation.

Works with

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