INTRODUCTION TO FAILURE MODE & EFFECTS ANALYSIS (FMEA)

DEFINITION, PURPOSE and PRACTICES

FMEA: A SYSTEMIZED GROUP OF ACTIVITIES DESIGNED TO:

1. RECOGNIZE and EVALUATE the POTENTIAL FAILURE of a PRODUCT/PROCESS and its EFFECTS.

2. IDENTIFY ACTIONS which could ELIMINATE or REDUCE the CHANCE of POTENTIAL FAILURE OCCURING

3. DOCUMENT the Process.

FMEA : THE PROCESS 

1. Identifies Potential Product related process failure modes.

2. Assesses the Potential customer Effects of the failure.

3. Identifies the potential manufacturing process causes and process variables on which controls can be focused for reduction or detection of the failure conditions.

4. Develops a Ranked list of potential failure modes, thus establishing a Priority system for corrective action considerations

5. Documents the results of the manufacturing process.

FMEA ADVANTAGES

1. Increased production volumes

2. Enhance design and manufacturing efficiencies

3. Minimize exposure to product failures

4. Augment business records

5. Improve “bottom line” results

6. Add to customer satisfaction

CAUSE AND EFFECT BASICS 

WHY THINGS HAPPEN ? ..........................................> CAUSE

WHAT HAPPENS AS A RESULT ?.......................> EFFECT

QUESTIONS

WHY DID THIS HAPPEN ?................................IDENTIFIES..... CAUSE

WHAT HAPPENED BECAUSE OF THIS?......IDENTIFIES.....EFFECT

CAUSE EFFECT CASCADE

POTENTIAL FAILURE MODE

It is defined as the manner in which process requirement could potentially fail to meet the process requirement and/or design content. It can be a cause associated with the potential failure of subsequent operation or an effect associated with potential failure in previous failure.

POTENTIAL EFFECT OF FAILURE

Potential effect of failure is defined as effect of the failure mode on customer. The customer in this context could be the next operation, subsequent operations or locations, or the end user.

SEVERITY

Severity is an assessment of seriousness of effect of failure mode to the customer. severity applies to effect only. It is measured on 1 to 10 scale.

POTENTIAL CAUSE AND MECHANISM OF FAILURE

Cause of failure is defined as how the failure could occur, described in terms of something that can be corrected or can be controlled.

 

OCCURENCE

Occurence is how frequently the specific cause/mechanism is projected to occur.

CURRENT PROCESS CONTROLS

These are descriptions of controls that either prevent the occurrence of failure or detect the failure mode should it occur (minimize effect). 

The main controls are as below:

1. Prevent cause mechanism or failure mode from occurring or reduce their rate of occurrence.

2. Detect the cause/mechanism and lead to corrective action.

3. Detect the failure mode.

DETECTION

Detection is an assessment of probability that the current process controls will detect a potential cause/mechanism (process weakness)

SEVERITY (S) - Evaluation Criteria

OCCURENCE (O) - Evaluation criteria

DETECTION (D) -  Evaluation Criteria

RISK PRIORITY NUMBER (RPN) 

The Risk Priority Number (RPN) is the product of the Severity (S), Occurrence (O) and Detection (D) ranking: 

RPN = (S) x (O) x (D) 

The RPN is a measure of process. The RPN is also used to Rank order the concerns in processes.

The RPN will be between “1” and “1,000”. 

For higher RPNs the team must undertake efforts to reduce this calculated risk through corrective action (s).