Failure Modes and Effects Analysis 280

bolt

A cylindrical threaded fastener with a head that usually mates with a nut. Bolts typically have blunt ends.

computer numerical control

CNC. A combination of software and hardware that directs the operation of a machine. Computer numerical control machines are used for many manufacturing operations, such as cutting metal parts.

contamination

The presence of damaging foreign materials in a substance. Contamination can lead to many types of problems, including failed processes or scrapped parts.

corrosion

A process by which a material gradually degrades or wears away. Corrosion typically occurs when a material is exposed to atmosphere, moisture, or other substances.

criticality analysis

A method of identifying the failure modes that present the greatest risk by creating a criticality matrix of severity and occurrence ratings. A criticality analysis may be either qualitative or quantitative.

criticality matrix

A table that uses modified severity and occurrence ratings to determine the criticality of each failure mode. Criticality matrices use a grid display to show which failure modes present the greatest immediate risk.

customer service

The area of business that focuses on satisfying customers, including timely and complete product delivery and facilitating product repairs and replacement after sales. Customer service professionals often have the best insights on customer needs.

design

The process of creating the specifications for a part or product. The design stage of product development involves defining product requirements and creating prints and prototypes.

design controls

Any procedure or practice used during the design phase of a product to ensure quality and safety. Design controls are considered when assigning detection ratings during a DFMEA.

design FMEA

DFMEA. An FMEA targeted at improving a product design. Design FMEAs usually begin by identifying the failure modes for each individual component of a product.

detection rating

A value assigned to a failure mode that indicates the likelihood that it will be detected before it affects customers. Detection ratings are usually given a scale of 1 to 10, with 1 indicating the highest likelihood of detection.

DFMEA

Design FMEA. An FMEA targeted at improving a product design. DFMEAs usually begin by identifying the failure modes for each individual component of a product.

downtime

A period of time when a machine or system is not operating and is not producing or performing work. Downtime can be reduced with quality improvement methods like FMEA.

external customers

An outside organization or individual that receives a product or service from a company. External customers often determine the required functions and features of a product.

failure modes

Any way in which a product or process may fail to meet customer needs. Failure modes are identified, analyzed, and prioritized during an FMEA.

failure modes and effects analysis

FMEA. A quality approach that identifies ways a product or process may fail and prioritizes them for improvement. A failure modes and effects analysis identifies potential failure modes and evaluates the severity, rate of occurrence, and likelihood of detection for each one to determine which to prioritize.

failure modes, effects, and criticality analysis

FMECA. An expanded version of FMEA that includes an additional criticality analysis step. Failure mode effects and criticality analysis improves upon traditional FMEA by identifying the failure modes the present the greatest immediate risk.

fasteners

A device that holds objects together or locates them in relation to one another. Fasteners include screws, bolts, rivets, and nails.

fault tree analysis

FTA. A method of quality improvement that creates a graphical model of a system in order to predict potential failures. Fault tree analysis uses a top-down approach, unlike the bottom-up approach of FMEA.

FMEA

Failure modes and effects analysis. A quality approach that identifies ways a product or process may fail and prioritizes them for improvement. An FMEA identifies potential failure modes and evaluates the severity, rate of occurrence, and likelihood of detection for each one to determine which to prioritize.

gage

An inspection device used to determine whether or not parts meet required specifications. A gage can be used to determine whether threaded parts pass or fail inspection.

inspecting

Examining a part during or after its creation to confirm that it meets specifications. Inspecting parts is a production control method.

internal customers

A department or individual within a company that relies on other departments or individuals in the company to satisfy external customers. Internal customers work together in a multi-step process.

nickel

A corrosion-resistant nonferrous metal. Nickel is commonly plated onto steel or other metals to prevent corrosion.

nut

A fastener with a threaded hole that mates with a bolt. Nuts are often hexagon-shaped to accommodate a driving tool.

occurrence rating

A value assigned to a failure mode that indicates how often it tends to occur. Occurrence ratings are usually given on a scale of 1 to 10 and may correspond to specific probabilities.

operator error

A mistake made by the operator of a machine or tool. Operator error is a common cause of process variation and scrapped parts.

Pareto analysis

A statistical analysis method for identifying which causes lead to the most serious errors in a process. Pareto analysis is based on the idea that 20% of causes lead to 80% of errors.

PFMEA

Process FMEA. An FMEA targeted at improving a manufacturing process. PFMEAs usually begin by identifying the failure modes for each individual step in a process.

plating

A thin layer of metal that serves as a decorative or protective coating on a part. Plating is used to improve the appearance or functionality of parts.

probabilities

The likelihood that a particular event will happen in the future. Probabilities can be expressed as fractions, ratios, or percentages.

process audits

An audit that examines the effectiveness of company procedures. Process audits can help reduce the occurrence of failure modes.

process capability analysis

A procedure used to determine how well a process can produce products that conform to specifications. A process capability analysis may be used to determine occurrence ratings for FMEA.

process FMEA

PFMEA. An FMEA targeted at improving a manufacturing process. Process FMEAs usually begin by identifying the failure modes for each individual step in a process.

production controls

Any activity undertaken to monitor and maintain quality in the production process. Production controls help to ensure efficiency and detect or prevent errors.

prototyping

The process of creating a preliminary model of a part to evaluate the look and performance of a design. Prototyping helps to determine the specifications for the final part.

purchasing

The department within an organization responsible for acquiring parts and raw materials necessary to make a product. Purchasing professionals often have the best insights on supply costs and supply quality.

qualitative

Describing a characteristic. Qualitative data is subjective information that usually cannot be measured in numbers.

quality

The satisfaction of customer requirements. Quality products conform to specifications and are free of defects, and quality processes produce quality products

quantitative

Measuring an amount or number. Quantitative data is objective information that can be counted or expressed numerically.

redundancy

The duplication of critical components in a product or system. Redundancy acts as a backup or fail-safe to prevent or minimize the effects of breakdowns and malfunctions.

risk priority number

RPN. A value that indicates the relative priority of a failure mode. Risk priority numbers are calculated by multiplying a failure mode's severity, occurrence, and detection ratings.

RPN

Risk priority number. A value that indicates the relative priority of a failure mode. RPNs are calculated by multiplying a failure mode's severity, occurrence, and detection ratings.

scope

The range of products or processes that will be analyzed during an FMEA. The scope of an FMEA may cover a particular product or process or specific product components or process steps.

scrapped

Discarded or otherwise destroyed. Parts must be scrapped if they do not meet specifications.

severity rating

A value assigned to a failure mode that indicates how severely it affects a product or process' ability to meet customer needs. Severity ratings are usually given on a scale of 1 to 10, with 10 being the most severe.

solution

A mixture of two or more substances. Liquid solutions are used for plating metals.

steel

A metal consisting of iron and carbon, usually with small amounts of other elements. Steel is the most common manufacturing metal.

streamlining

Making a process or system more efficient by employing faster or simpler methods. Streamlining helps to reduce disruptions to production operations.

threads

A raised helical ridge around the interior or exterior of a cylindrical object or hole. Threads on the exterior of a bolt mate with threads on the interior of a nut.

value

A real or perceived quality that satisfies the needs and wants of a customer. Value includes the features of a product as well as other qualities associated with the product.

visual inspections

An assessment of quality done with the naked eye. Visual inspection involves closely examining parts to check for defects.

waste

Any thing or process that does not add value to a product. Common forms of waste include scrap and unnecessary machine downtime.