The term Margin Testing is generally applied to those procedures where the level of input is increased until failure occurs in the test specimen. This is distinguished from “normal” testing where the procedure terminates if the product survives a certain specified input level.
The value of margin testing lies in its ability to determine the headspace or safety margin in the design of a product or package system beyond specification levels. In addition, margin testing can be very useful to compare different design iterations, different materials, different suppliers, or similar. Margin testing can be an extremely valuable tool in overall product reliability analysis as well as failure analysis.
High excitation level tests are normally used for margin analysis. This includes shock testing high-intensity random vibration testing, acoustical emission testing, thermal shock testing, and similar. The purpose of the test is to cause the product to fail and thus a variety of different excitation methods can be utilized.
So how does "margin testing" compare to "HALT" or similar procedures? The highly accelerated life testing or HALT procedures are an attempt to force a failure to occur in order to identify the weakest component within a system. Following this, the weak component is ruggedized and the procedure continues. There is no attempt to force failures using real life failure mechanisms, only to cause a failure. Thermal shock and acoustics/vibration are the typical excitation methods. Thus, HALT procedures are often referred to as a "stimulation" of the product rather than a "simulation" of the environment hazards at high levels. Margin testing is generally an attempt to "simulate" the environmental hazards (shock, vibration, temp & humidity extremes, altitude/pressure differentials, etc.) using high input levels to force failures. The result of margin testing should be an understanding of the "headspace" or safety margin between "spec" levels of ruggedness and actual physical performance of the product or package system.
MIL STD 810G
Westpak continually upgrades and expands its equipment line-up. Therefore this list is a minimum of our capabilities:
(8) Mechanical Shock Machines(2) Thermal Shock chambers(19) Vibration systems