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Chapter: Mechanical - Total Quality Management (TQM) - TQM Tools & Techniques

Failure Mode and Effects Analysis

Failure mode and effect analysis also known as risk analysis is a preventive measure to systematically display the causes, effects, and possible actions regarding observed failures.


FAILURE MODE AND EFFECTS ANALYSIS

Prerequisite discussion:

 

Failure Mode and Effects Analysis (FMEA) is a method designed to:

Identify and fully understand potential fail

the system or end users, for a given product or process.

Assess the withrisktheidentifiedassociatedfailuremodes,effects and causes, and prioritize issues

for corrective action.

Identify and carry out corrective actions to

An FMEA is an engineering analysis

done by-functionalcrossteamofsubject matter experts

 

that thoroughly analyzes product designs or early in the product development process. Finds and corrects weaknesses beforemer. the pro

 

 

If effectively used throughout the product life cycle, it will result in significant improvements to reliability, safety, quality, delivery, and cost

 

MEANING:

 

Failure mode and effect analysis also known as risk analysis is a preventive measure to systematically display the causes, effects, and possible actions regarding observed failures.

Objectives of FEMA:

 

1.     The objective of FEMA is to anticipate failures and prevent them from occurring. FEMA prioritizes failures and attempts to eliminate their causes.

 

2.     FEMA is an engineering technique is used to define, identify and eliminate known and or potential failures, problems, errors which occur in the system, design, process and service before they reach the customer.

 

3.     FEMA is a before the event action and is done when existing systems products processes are changed or redesigned.

 

4.     FEMA is a never ending process improvement tool.

 

 

Types of FEMA:

 

1.     System FEMA

2.     Design FEMA

3.     Process FEMA

 

4.     Service FEMA

5.     Equipment FEMA

6.     Maintenance FEMA

7.     Concept FEMA

8.     Environmental FEMA

 

Benefits of FEMA:

 

1.     Improve product/process reliability and quality.

2.     Increase customer satisfaction.

3.     Early identification and elimination of potential product/process failure modes.

4.       Prioritize product or process deficiencies

5.     Capture engineering/organization knowledge

6.     Document and track the actions taken to reduce risk

7.     Provide focus for improved testing and development.

8.     Minimize late changes and associated cost.

9.     Act as catalyst for teamwork and idea exchange between functions.

 

 

Meaning of reliability:

 

Reliability is one of the most important characteristics of any product, no matter what its application. Reliability is also an important aspect when dealing with customer satisfaction. Whether the customer is internal or external. Customers want a product that will have a relatively long service life, with long times between failures. However, as products become more complex in nature, traditional design methods are not adequate for ensuring low rates of failure. This problem gave rise to the concept of designing reliability into the product itself.

 

Reliability requirements:

 

The acceptance of a certain product or process is subject to meeting certain set of given requirements for reliability of the product or process. It is however important to realize that although the definition for reliability is relatively simple, the customer and the supplier may have different definitions of what failure constitute. This common agreement on what constitutes reliability should be defined in terms of influence on other related systems, the complexity of the failure, and finally the relative criticality of the failure.

 

Failure rate:

 

A vast majority of products follow a very familiar pattern of failure. When no information is known about the reliability or conversely, failure of a product, component, system or process, except the failure rate which is a constant, periods of failure can conveniently be modeled by an exponential distribution. The failures of most products can be classified in to three main categories: debug, chance, and wear out. The first of these includes a high failure rate at the initial stages because of inappropriate use or flaws in the design or manufacturing. The next category is the failure of the product due to accidents, poor maintenance, or limitations on the design. The final category covers failure after the product or process has performed as expected for at least the amount of time given by the manufacturer as the product or process life. A successful design or process ideally fails only in this method.

 

STAGES OF FEMA.

 

The FEMA methodology has four stages: they are:

 

Stage1: specifying possibilities

 

1.     Functions

2.     Possible failure modes

3.     Root causes

4.     Effects

5.     Detection/prevention

 

Stage 2: quantifying Risk

 

1.     probability of cause

2.     severity of effect

3.     effectiveness of control to prevent cause

 

4.     Risk priority number

 

Stage3: correcting High risk causes

 

1.     prioritizing work

2.     detailing action

3.     assigning action responsibility

 

4.     check points on completion stage4: re-evaluation of risk

 

1.     Recalculation of risk priority number

 

STAGES OF FEMA:

 

1. Specifying possibilities

 

a. functions

 

b. possible failure modes

 

c.  root causes

 

d. effects

 

e.  detection/prevention

 

2. Quantifying risk

 

a. probability of cause

 

b. severity of effect

 

c.  effectiveness of control to prevent cause.

 

d. risk priority number.

 

3. Correcting high risk causes

 

A. prioritizing work

 

B.detailing action

 

C. assigning action responsibility.

 

D. checks points on completion.

 

4. Re-evaluation of risk

 

A. recalculation of risk priority number

 

The design of FEMA document:

 

1.     FEMA number

2.     item

3.     Design responsibility

4.     prepared by

5.     model number/year

6.     key date

7.     FEMA date

8.     Core team

 

9.     Item function

10.potential failure mode

11.potential effects of failure

 

12.severity

13.classification

14.potential causes mechanisms of failure

15.occurrence

16.current design controls

17.detection

18.risk priority number

19.Recommend actions Responsibility and target completion dates

20.actions taken

 

 

The process of FEMA and documentation

 

1.     process function requirements

2.     potential failure mode

3.     potential effects of failure

4.     severity

5.     classification

6.     potential causes mechanisms of failure

7.     occurrence

8.     current process controls

9.     detection

 

 

Risk Priority Number (RPN) 10

“RPN” is a numerical ranking of the risk of each potential failure mode/cause, made up of the

arithmetic product of the three elements:

severity of the effect

likelihood of occurrence of the cause likelihood of detection of the cause.

 

 

Example: 240 (10 x 6 x 4)

 

SIGNIFICANCE:

 

Understanding the fundamentals and procedure of FMEAs, including the concepts and definitions

preparation steps for each FMEA project applying lessons learned and quality objecti providing excellent facilitation

 

and implementing-wideanFMEAeffectiveprocess.   company

 

Implementing FMEA success factors will uniformly ensure FMEAs achieve safe, reliable and economical products and processes.

 

APPLICATION:

 

FMEA OF A CAR DOOR.

 

An automobile manufacturer had a peculiar problem of corrosion of interior door panel in a car. This affected a appearance functioning and added cost of repaint,etc.

 

The failiure effect led to severity ranking of seven.

 

The probability of occurrence of corrosion rank 6 The probability of detection of corrosion rank 7 The rpn number is 294 which is high.

The thickness of the paint coating on the interior door panel was revised and raised by 150mm.

 

The probability of occurrence of corrosion reduced from 6 to 2. The probability of detection of corrosion reduced from 7 to 2. Therefore The RPN number is reduced from 294 to 28.

 

Therefore by conducting FMEA study and carrying out corrective and preventive. .actions one can prevent failures from reaching the customers.

 

INFORMATION TECHNOLOGY.

 

Information technology is a tool like the other tools and it helps the TQM organization to achieve its goals. Over the past few decades, computers and quality management practices have evolved together and have supported each other. This interdependence will continue in the near future.

 

DEFINITION:

 

Information technology is defined as computer technology for processing and storing information, as well as communications technology for transmitting information.

 

Levels of information technology

 

1.     Data

2.     Information

3.     knowledge

 

Computers and the quality function

 

Computers play an essential role in the quality function. They perform very simple operations at fast speeds with an exceptionally high degree of accuracy. A computer must be programmed to execute these simple operations in the correct sequence in order to accomplish a given task. Computers can be programmed to perform complex calculations, to control a process or test, to analyze data, to write reports, and to recall information on command. The quality function needs served by the computer are:

 

1.     data collection

2.     data analysis and reporting

3.     statistical analysis

4.     process control

5.     test and inspection

6.     system design

 

Data collection:

 

The collection utilization, dissemination of quality control information is best accomplished when the information is incorporated into an information technology system. IT maintains relationships with other activities such as inventory control, purchasing, design, marketing, accounting, and production control. It is essential for all the quality needs described in this chapter. Linkages are developed between the stored data records of the various activities in order to obtain additional information with a minimum of programming and to improve the storage utilization

 

Data analysis, reduction, and reporting:

 

While some of the quality information is merely stored in the computer for retrieval at a future time, most of the information is analyzed, reduced to a meaningful amount, and disseminated in the form of a report. These activities of analysis reduction and reporting are programmed to occur automatically as the data are collected or to occur on command by the computer operator.

 

Statistical analysis:

 

The first and still an important use of the computer in quality control is for statistical analysis. Most of the statistical techniques can be easily programmed. Once programmed considerable calculation time is saved, and the calculations are error free.

 

Process control:

 

The first application of computers in process control was with numerically controlled machines. Numerically controlled machines used punched paper to transmit instructions to the computer which then controlled the sequence of operations. Paper tape is no longer used to provide instructions to a machine

 

Automated test and inspection:

 

If test and inspection are considered a process in itself or part of a production process then automated test and inspection is similar to the previous section on automated process control, computer controlled test and inspection systems offer the following advantages improved test quality, operating cost, better report preparation, improved accuracy, automated calibration, and malfunction diagnostics.

 

System design

 

Software applications adapted to the quality function are becoming more sophisticated and comprehensive. Execution of the menu is by function key, cursor and enters key, voice, mouse, or linkage from another program.

 

THE INTERNET AND OTHER ELECTRONIC COMMUNICATION

 

The internet is a world wide network of computer networks. It began in 1969 as a means of exchanging data between universities and the U.S military. In 1991 the national science foundation which was responsible for the internet, released the ban on commercial use of it.

 

Other electronic communication

 

1.               Intranet

2.               Instant messaging

3.               Video conferencing

4.               Virtual teaming

5.               Document management

6.                   E-learning

7.                   E-government

8.                   E-commerce

9.                   Business-to-business

10.              Business-to-customers

11.              Website design

 

 

INFORMATION QUALITY ISSUES

 

Information quality issues encompass:

 

1.     sufficiency

2.     accuracy

3.     timeliness

4.     intellectual property

5.     security

6.     privacy

7.     pollution

8.     creativity control and prevention

 

Glossary

 

 

RELIABILITY

 

Reliability of an entity is defined as the probability that will perform its intended function for a specified period of time under stated operating conditions

 

RPN - Risk Priority Number SEV Severity

OCC Occurrence

DET Deduction


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