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Life Testing A Reliability Engineering Concept By: Nicole Panaccio.

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Presentation on theme: "Life Testing A Reliability Engineering Concept By: Nicole Panaccio."— Presentation transcript:

1 Life Testing A Reliability Engineering Concept By: Nicole Panaccio

2 Life Testing Overview What is Life Testing?What is Life Testing? Life Testing in OrganizationsLife Testing in Organizations How Does Life Testing Work?How Does Life Testing Work? Who Uses Life Testing?Who Uses Life Testing? Motorolas ProcessMotorolas Process Paper Clip Life TestingPaper Clip Life Testing SummarySummary

3 What is Life Testing? A process done under controlled conditions to determine how and when a product will fail in its intended environmentA process done under controlled conditions to determine how and when a product will fail in its intended environment Improves a products reliabilityImproves a products reliability Finds the weakest and strongest points of a productFinds the weakest and strongest points of a product

4 Life Testing in Organizations Design Life Cycle:Design Life Cycle: –Have an idea –Design it –Make a prototype –Final definition –Design and evaluation –implementation

5 Life Testing in Organizations Life testing design cycle:Life testing design cycle: IdeaDesign Prototype Prototype is tested for failuresPrototype is tested for failures Design cycle stops with prototypesDesign cycle stops with prototypes

6 Life Testing in Organizations Customers believe that quality is inherent is all productCustomers believe that quality is inherent is all product Life testing validates this assumption.Life testing validates this assumption. Specific directions are followed in a uniform fashionSpecific directions are followed in a uniform fashion

7 Three Types of Tests Type of tests performed:Type of tests performed: –Qualitative Tests –ESS (Environmental Stress Screening) –Accelerated Life Testing

8 Qualitative Tests Gives the product tested the most failuresGives the product tested the most failures Failures produced by high and low stressesFailures produced by high and low stresses To pass the product must live through the entire test without failure ¹To pass the product must live through the entire test without failure ¹

9 ESS-Environmental Stress Screening Applies environmental stimulus to productsApplies environmental stimulus to products Goal: ¹Goal: ¹ –To find latent defects and eliminate them –To find defects not found with inspection or electrical testing

10 Accelerated Life Testing Similar to Life TestingSimilar to Life Testing –Testing moves at a faster pace Uses quantitative dataUses quantitative data End results yield times-to-failure dataEnd results yield times-to-failure data –Times-to-failure: how long it takes till a failure is made

11 Accelerated Life Testing Life distributions show how fast a product will fail ¹Life distributions show how fast a product will fail ¹ Two methods used to get times- to-failure information:Two methods used to get times- to-failure information: –Usage rate acceleration –Overstress acceleration

12 Usage Rate Acceleration A test used for products that only operate for small amounts of time ¹A test used for products that only operate for small amounts of time ¹ It increases the time to make failures happen quicker than if it were used normallyIt increases the time to make failures happen quicker than if it were used normally

13 Overstress Acceleration Backup to usage rateBackup to usage rate Used if usage rate is not appropriate means ¹Used if usage rate is not appropriate means ¹ Tests products that are constantly usedTests products that are constantly used Uses stress levels that it would not normally encounterUses stress levels that it would not normally encounter

14 How Does Life Testing Work? Majority of tests done on small sampleMajority of tests done on small sample –4 to 6 units Begin test with lowest level of the productBegin test with lowest level of the product Failures must be documented as they happenFailures must be documented as they happen

15 How Does Life Testing Work? Soft failures occur when there is damage made but the product returns to its normal stateSoft failures occur when there is damage made but the product returns to its normal state Hard failures are permanent damages done to the productHard failures are permanent damages done to the product

16 The difference between soft and hard failures is the margin for stress ¹The difference between soft and hard failures is the margin for stress ¹ Once the failures are found and fixed, the margins have reached their maxOnce the failures are found and fixed, the margins have reached their max Maximized margins increase reliability and the life of the productMaximized margins increase reliability and the life of the product Margins and Reliability

17 Who Uses Life Testing? MotorolaMotorola –Mission to produce cell phones with virtually no defects –Use accelerated life testing to accomplish mission –Helps to validate their six sigma corporate standard

18 Motorolas Process Determine environmentDetermine environment Perform life testing in all environments.Perform life testing in all environments. –Four to six weeks of testing is required ¹

19 Motorolas Process Drop Testing ¹Drop Testing ¹ –Samples are dropped on different surfaces of the phone multiple times. Hot and Cold Temperatures ²Hot and Cold Temperatures ² The phones receive extreme temperatures of hot and cold.The phones receive extreme temperatures of hot and cold. –Testing simultaneously with audio quality and simulated calls

20 Motorolas Process Electro-Static Discharge ¹Electro-Static Discharge ¹ –Zap products with an electric pulse at discharge points Dust Exposure ²Dust Exposure ² –Products are placed in dust chamber –Dust is shaken all over the product and then left to settle

21 Motorolas Process Vibration Testing ¹Vibration Testing ¹ –Horizontal and vertical vibration testing. –Placed into vibration table and controlled by tester –The tests vary in the extremes of vibrations given –During the test it places a call and must be stable throughout the process

22 Motorolas Process Environmental Aging Tests ¹Environmental Aging Tests ¹ –Temperature cycling: moving from low to high heat and cold –Temperature shock Certification Testing ²Certification Testing ² –Sudden Impact Testing –Endurance Testing –Package Drop Testing –Transport Simulation

23 Motorola Summary Life testing cuts Motorolas costsLife testing cuts Motorolas costs Less return of products that fail for the customerLess return of products that fail for the customer Their design exceeds customer satisfaction with virtually no defectsTheir design exceeds customer satisfaction with virtually no defects

24 Paper Clip Life Testing Follow these directions to determine how fast a paper clip will break using the life testing methods. ¹Follow these directions to determine how fast a paper clip will break using the life testing methods. ¹

25 Follow These Steps With one hand, hold the clip by the longer, outer loop. With the thumb and forefinger of the other hand, grasp the smaller, inner loop. Pull the smaller, inner loop out and down 90 degrees so that a right angle is formed as shown.

26 Follow These Steps With one hand, continue to hold the clip by the longer, outer loop. With the thumb and forefinger of the other hand, grasp the smaller, inner loop.

27 Follow These Steps Push the smaller inner loop up and in 90 degrees so that the smaller loop is returned to the original upright position in line with the larger, outer loop as shown.

28 Follow These Steps This completes one cycle.This completes one cycle. Repeat until the paper clip breaks. Count and record the cycles-to-failure for each clip.Repeat until the paper clip breaks. Count and record the cycles-to-failure for each clip.

29 Summary Quality is inherent in most productsQuality is inherent in most products Life Testing allows the consumer to have reliable information because it is consistent throughout the testingLife Testing allows the consumer to have reliable information because it is consistent throughout the testing Some life testing can cause permanent damage, and some aspects of the testing do notSome life testing can cause permanent damage, and some aspects of the testing do not Prototypes are used to test because it is cheaper and easier to run tests on samplesPrototypes are used to test because it is cheaper and easier to run tests on samples

30 Summary Life Testing can be done with ease or tremendous detailLife Testing can be done with ease or tremendous detail Any way it is done it will yield the same informationAny way it is done it will yield the same information The tester must document what and how they do thingsThe tester must document what and how they do things


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