Life Testing

1. Life Testing A Reliability Engineering Concept By: Nicole Panaccio

2. Life Testing Overview • What is Life Testing? • Life Testing in Organizations • How Does Life Testing Work? • Who Uses Life Testing? • Motorola’s Process • Paper Clip Life Testing • Summary

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

4. Life Testing in Organizations • 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: Idea Design Prototype • Prototype is tested for failures • Design cycle stops with prototypes

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

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

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

9. ESS-Environmental Stress Screening • Applies environmental stimulus to products • Goal: 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 Testing • Testing moves at a faster pace • Uses quantitative data • End 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 ¹ • 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 ¹ • It increases the time to make failures happen quicker than if it were used normally

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

14. How Does Life Testing Work? • Majority of tests done on small sample • 4 to 6 units • Begin test with lowest level of the product • Failures 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 state • Hard failures are permanent damages done to the product

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

17. Who Uses Life Testing? • Motorola • 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. Motorola’s Process • Determine environment • Perform life testing in all environments. • Four to six weeks of testing is required ¹

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

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

21. Motorola’s Process • Vibration 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. Motorola’s Process • Environmental Aging Tests ¹ • Temperature cycling: moving from low to high heat and cold • Temperature shock • Certification Testing ² • Sudden Impact Testing • Endurance Testing • Package Drop Testing • Transport Simulation

23. Motorola Summary • Life testing cuts Motorola’s costs • Less return of products that fail for the customer • Their 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. 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. • Repeat until the paper clip breaks. Count and record the cycles-to-failure for each clip.

29. Summary • Quality is inherent in most products • Life 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 not • Prototypes 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 detail • Any way it is done it will yield the same information • The tester must document what and how they do things