Quality Assurance at
Mark Levinson: A Way of Life.
by Dale Seidlitz, Manager of Global Quality
With every product we design and introduce, we have the goal of providing our customer a product they’ll get to enjoy for the rest of their lives. In chasing that lofty goal, we employ Highly Accelerated Life Testing (HALT) and HASS (Highly Accelerated Stress Screen) testing. The goal of these tests is to find the point of failure. Once found, we then must determine the acceptability of that point of failure or change the design. In doing this we have to sacrifice a fully operational unit!
Throughout a HALT process, the intent is to subject the product to stimuli well beyond the expected field environments it would reasonably encounter. In the execution of this process, any failure that would show up in the field at lower stress levels is quickly discovered while applying high stress condition, and subsequently eliminated.
HALT is primarily a margin discovery process. In order to ruggedize the product, the root cause of each failure needs to be determined and the problems corrected until the fundamental limit of the technology for the product can be reached. This process will yield the widest possible margin between product capabilities and the environment in which it will operate, thus increasing the product’s reliability, reducing the number of field returns, and realizing long-term cost efficiency.
HALT will evaluate the design of the product, whereas HASS will monitor the manufacturing process. The HASS process can ensure that the reliability gains achieved through HALT will be maintained in future production.
The data gathered during the HALT will provide the starting point for a successful HASS screen. The general rule of thumb for determining a starting point for HASS is to use 80% of the Thermal Operating Limit and 50% of the Vibration Operating Limit from the HALT. These values will most likely be adjusted during the HASS development steps, which is necessary to provide the most comprehensive screen for the product.
Common profiles consist of both temperature and vibration (Combined Environment) and usually will be repeated two or more times. Vibration may be maintained at a constant level or varied during the profile, and this will depend on the results from the HALT and effectiveness in finding failure.
This testing allows Mark Levinson to have certainty that it is putting the very best designed products in the field for our customers.
The quality assurance of the Mark Levinson production process doesn’t stop here. In fact, it continues with taking at random a product from the production line and put it through the same HALT/HASS tests. This ensures that as time passes, there has been no deviation from our manufacturing team or our suppliers with their products or processes, and guarantees the same level of production quality is being adhered to throughout the entire life cycle of every Mark Levinson product.