Environmental stress screening, or ESS, is a process used to identify potential problems in products or systems before they are put into service. By subjecting products or systems to conditions that simulate the real-world environment, ESS can uncover weaknesses that would not be apparent during normal operation. The levels of stress applied during ESS testing often exceed the stress those products would normally experience to precipitate failures and reduce test time.
ESS is often used on products expected to operate for long periods without failures, especially electronics such as medical devices, aerospace components, or military equipment. By testing products under extreme conditions, manufacturers can be confident that their products will perform as intended when they are used. By identifying potential problems early on, ESS can save manufacturers time and money by preventing costly recalls or repairs down the line. For some products, environmental stress testing is a legal or industry requirement. Let’s take a look at some of the most common types of ESS.
Thermal Cycling Testing
Thermal cycling is one of the most common types of environmental stress screening and is often used on electronic components. It involves subjecting a product to extreme hot and cold temperatures to replicate the temperature changes it would experience in real-world use. Thermal cycling can identify potential problems with seals and gaskets, solder joints, plastics, and other materials that could cause the product to fail. Products commonly tested using thermal cycling ESS include electronics, automotive parts, and medical devices.
Thermal cycles typically occur when:
- A product is powered on and off in a controlled environment.
- A product experiences slower outdoor temperature changes from morning until night.
The test conditions will vary depending on the item being tested. Typically they are performed in a chamber that controls the number of cycles, dwell times, transfer times, or ramp rates.
Thermal Shock Testing
This type of environmental stress screen goes beyond thermal cycling. Thermal shock and cycling testing both expose products to extreme temperatures. However, the transition from one to the other is accelerated with shock testing.
Thermal shock can occur when:
- A product is transferred from an inside temperature-controlled environment to extreme outside temperatures.
- Turning on equipment that has been stored outside in extreme arctic-like temperatures.
- Equipment experiences abrupt or significant changes in internal power.
- A product is transported from a high-temperature ground environment to a high-altitude environment.
Thermal shock testing can be done in two ways. It is typically performed in a dual compartment chamber, with one compartment for hot temperatures and the other for cold. Products sit in a carriage that shuttles them between the hot and cold compartments within seconds, causing the product to experience thermal shock. When testing larger items, a single compartment chamber capable of performing rapid temperature changes is used.
Vibration testing is a type of environmental stress screening used to test products for potential problems that could lead to failures during normal use. Vibration testing subjects products to extreme vibrations to find flaws that could go undetected during normal operation. This helps to ensure that products are of the highest quality possible before being released to the public.
Vibration testing is commonly used on electronic devices, electrical components, and mechanical parts. By subjecting these products to extreme vibrations, manufacturers can find potential problems that could lead to failures during normal use.
Vibration damage can occur from:
- Vibration and shock stress during shipping.
- Mechanical stress from application and usage throughout the product’s lifespan.
Environmental stress screening for vibration requires temperature testing, electrodynamic vibration testing, or both. The product being tested is placed in an environmental chamber and monitored while experiencing vibrations, temperature changes, and other stimuli. Vibration testing is used to reveal weaknesses or defects in the product’s construction.
Environmental Stress Screening by Quality Testing Services
Located in Huntington Beach, Quality Testing Services began as a HALT/HASS testing facility. With more than two decades of experience, it has become the industry leader for product testing in Southern California.
We have expanded over the years and now offer a wide range of product testing services including, ESS, Vibration and Shock Testing, Temperature and Humidity Testing, Life Testing, and much more. While we may not be the largest product testing company in the industry, we believe our attentiveness and flexibility set us apart from other companies. We meet with our clients to get a complete understanding of their testing needs and develop a relationship with them. If their product needs special equipment for testing that isn’t standard, we will do our best to fabricate the equipment needed.