How Meta-Lax® Vibrational Stress Relief Works
Meta-Lax Stress Relief removes thermal stress from a metal part. Thermal stress or heat stress is caused by a sharp temperature drop in metal. It creates problems of distortion (immediately following machining or over time) and premature cracking. "Stress relieving" reduces these effects.
All metal structures exhibit harmonic and non-harmonic behavior (Scan 1). Yet if the part had experienced a sharp temperature drop (which causes heat-induced stress), the harmonic curve will be out of phase from its natural frequency location.
By applying sub-harmonic vibrational energy pockets of high-stress concentration are redistributed, reducing the effects of heat stress and causing the harmonic curve to shift (Scan 2).
When the workpiece becomes free of thermally induced stress, the harmonic curve will stabilize in its natural frequency location (Scan 3). It has been proven mathematically, in the laboratory, and in-field applications that the mild vibrations that Meta-Lax processing uses are more efficient than violent, high amplitudes in relieving stress. An analogy would be like an athlete "warming up" versus a strenuous workout before his race. Only the Meta-Lax method of certifying stress relief eliminates guesswork and assures the confidence of operation and consistency of results.
It may be helpful to relate Meta-Lax to "heat" stress relief in that both induce internal accelerated motion in the metal to cause stress relief. It also may be helpful to compare Meta-Lax to "natural aging" in that both do not cause heat side effects like scaling, softening, or reducing mechanical properties. Meta-Lax processing usually takes 1/2 to 2 hours for application and does not cause treatment distortion.
Meta-Lax stress relief relies on two key operating principles, both of which have been mathematically proven as valid:
Meta-Lax Patented Principle #1 - SUB-harmonic vibrational energy must be used for the stress-relieving frequency. "The amount of energy being dissipated by vibration determines the amount of "backoff" from [the harmonic peak] to be at the most efficient stress relieve range."
Richard Skinner, PE, Lockheed Missiles & Aerospace
Meta-Lax Patented Principle #2 - The harmonic curve shifts and stabilizes as the part becomes relieved of thermally induced stress. "The findings regarding the shift in natural frequency as a result of residual stress may provide a method for examining the effectiveness of stress-relieving processes."
University of California - Berkeley