A product can perform well during development and still contain weaknesses that only become visible after months or years of use. This is why aging tests are an essential part of product reliability testing and evaluating long-term reliability.
Jack Welch shared a memorable example in his autobiography, Jack: Straight from the Gut. Early in his GE career, the company was developing a promising new thermoplastic called polyphenylene oxide, or PPO.
The material appeared to have excellent resistance to high temperatures. GE believed it could replace copper pipes in hot-water systems and stainless steel in certain medical applications. Based on that potential, the company approved a $10 million investment in a pilot manufacturing facility.
Construction was already underway when aging tests uncovered a serious reliability problem related to material aging.
Over time, the plastic became brittle and cracked when exposed to the high temperatures it was intended to withstand. This thermal aging meant it was not reliable enough for one of its most promising applications: replacing copper hot-water pipes.
Fortunately, the project did not fail. GE’s researchers blended PPO with polystyrene to create a more practical material called Noryl. It eventually became an extremely successful product that reportedly generated more than $1 billion in annual sales.
What Aging Tests Can Reveal
The lesson from the GE story is not that the original material encountered a problem. New materials and products often behave differently outside controlled development conditions.
The important point is that aging tests exposed the weakness before customers widely used the material.
Without aging tests, GE might have scaled production and supplied the plastic for demanding applications before discovering that it became brittle over time. Warranty claims, field failures, safety concerns, and damage to customer relationships could have cost considerably more than the testing program.
Aging tests help manufacturers examine how a material, component, or finished product changes after prolonged use or environmental exposure. Depending on the product, this product durability testing may involve temperature, humidity, vibration, electrical loading, repeated mechanical movement, or combinations of several stresses.
Accelerated Life Testing
At Agilian, one method we use is Accelerated Life Testing, commonly known as ALT.
ALT subjects the product to more demanding conditions so that potential failures appear sooner. It can help uncover defects and degradation mechanisms that might otherwise take months or years to emerge in the field.
However, the results must be interpreted carefully. A product may fail sooner under accelerated conditions than it would during normal use. Accelerated aging testing methods like ALT are highly useful for identifying weaknesses but do not always provide a direct measurement of the product’s actual service life.
This is usually done toward the end of the product design phase. Often in the “engineering validation” phase.
Life Testing Under Normal Conditions
We may also perform what our team sometimes calls “ALT-Life” (this testing is not accelerated in the same way as ALT and is not to be confused with it). That’s often done later than ALT (closer to the pilot runs that immediately precede the ramp-up into mass production).
A clearer description is service life testing under normal operating conditions.
The product is operated in an environment that closely reproduces its expected real-world use. The objective is to observe how it performs over time and estimate its expected operating life under normal conditions.
Conclusion
The two methods therefore answer different questions:
- Accelerated Life Testing asks: What defects or failure mechanisms could appear over time?
- Life testing under normal conditions asks: How long is the product likely to remain reliable during expected use?
Aging tests take time, but skipping them can allow long-term reliability problems to reach customers.
By combining accelerated life testing with testing under realistic operating conditions, manufacturers can identify hidden weaknesses, estimate product life, assess mass production readiness, and make better decisions before committing to mass production. As the GE example demonstrates, discovering a problem during testing can ultimately lead to a stronger and much more successful product.
Related reading
- Reliability Testing on Electronic Products in China: Don’t Skip It
- Reliability Validation Testing vs. End-Of-Line Quality Control
- How Reliability Testing Is Critical To Obtaining Great Mass-Produced Products
