Failure Modes and Effects Analysis (FMEA)

Failure Modes and Effects Analysis (FMEA) is a systematic, proactive method for evaluating a process to identify where and how it might fail and to assess the relative impact of different failures, to identify the parts of the process that are most in need of change.

Failure Modes and Effects Analysis is a process analysis tool that depends on identifying:

  • Failure mode: One of the ways in which a product can fail; one of its possible deficiencies or defects
  • Effect of failure: The consequences of a particular mode of failure
  • Cause of failure: One of the possible causes of an observed mode of failure
  • Analysis of the failure mode: Its frequency, severity, and chance of detection

Purpose

FMEA is used to evaluate processes for possible failures and to prevent them by correcting the processes proactively rather than reacting to adverse events after failures have occurred.

Types of FMEA

There are two types of FMEA:

  1. Design FMEA (DFMEA) and
  2. Process FMEA (PFMEA).

Design FMEA

Design FMEA (DFMEA) is a methodology used to analyse risks associated with a new, updated or modified product design and explores the possibility of product/design malfunctions, reduced product life, and safety and regulatory concerns/effects on the customer derived from:

Process FMEA

Process FMEA (PFMEA) is a methodology used to discovers risks associated with process changes including failure that impacts product quality, reduced reliability of the process, customer dissatisfaction, and safety or environmental hazards derived from the 6Ms:

When to Use FMEA

You should use a FMEA when:

  • A product’s design is being modified a new design (includes new products altogether)
  • A service is being altered with additional, new, modified steps
  • A process or a supply chain is being transformed, changed, and modified
  • When developing new or revised control plans.
  • When developing improvement goals.
  • You are analysing failures of existing processes, products, or services.
  • There are periodic checks during the life of a product, service, or process.

Methodology

Once each failure mode is identified, the data is analysed, and three factors are quantified:

  • Severity (SEV): The severity of the effect of the failure as felt by the customer (internal or external). The question may be asked, “How significant is the impact of the effect on the customer?”
  • Occurrence (OCC): The frequency which each failure or potential cause of the failure occurs. The question may be asked, “How likely is the cause of the failure mode to occur?”
  • Detection (DET): The chance that the failure will be detected before it affects the customer internal or external). The question may be asked, “How likely will the current system detect the failure mode if it occurs, or when the cause is present?”

Each of the three factors is scored on a 1 (Best) to 10 (Worst) scale. The combined impact of these three factors is the Risk Priority Number (RPN). This is the calculation of risk of a particular failure mode and is determined by the following calculation: RPN = SEV x OCC x DET

The RPN is used to place a priority on which items need additional quality planning.

Tools

The following list is not a complete list of tools, but a sampling of tools which may be used depending on the available data.

  • Control Chart
  • Histogram
  • Pareto Chart
  • Block Diagram
  • Selection Matrix
  • Scatter Plot
  • Fault Tree Diagram

Benefits

  • FMEA provides a structured approach to identifying and prioritizing potential failure modes, taking action to prevent and detect failure modes and making sure mechanisms are in place to ensure ongoing process control.
  • FMEA helps to document and identify where in a process lies the source of the failure that impacts a customer’s CTQ’s.