Contact Us

Use the form on the right to contact us or,

email us at info@elmetlabs.com,

or call us at (248) 957-1170.

We will get back to you as soon as possible.

24073 Research Drive
Farmington Hills, MI, 48335
United States

(248)957-1170

Elmet LLC is primarily a metallurgical and metallographic laboratory focused on the electrical and electronics industries.  All circuit boards, connectors, clips, cages, and electrical devices have metallic components that can suffer damage or fail due to causes such as fatigue, corrosion, stress overload, dendritic growth, and fretting.  These are metallurgical issues, not electrical issues, and a metallurgical perspective brings insight into the problem.  We provide that insight through investigation and thorough explanation of the metallurgical factors at work, from manufacturing defects to design to conditions of use.

Much of our work is solder joint cross sectioning, and we have a large capacity to handle this type of work.  With five automated polishers we can process more than 20 cross sections per day, day after day.  We have two metallographic studios with studio cameras, stereomicroscopes, and metallurgical microscopes to document the incoming parts, the cross sections, and the microstructures. Our scanning electron microscope assists us in evaluating intermetallic layers, microstructures, fretting, and fracture.  The EDS (energy dispersive spectroscopy) system allows us to analyze solder compositions, contamination, and debris observed on circuit boards.

We have staff holding certificates in IPC-A-610 inspection (CIS), electrical engineering, and metallurgical engineering, and we have a great deal of experience with failure analysis of metallic components. 

Tech Topics

Failure Analysis of Springs

Arthur Griebel

Springs are one of the most revealing types of failure analysis because the state of stress in a spring is well defined.  The geometry and use of springs strictly limits the mode and direction of applied loading, and the mathematics that describe resulting stresses are well developed.  The location and magnitude of maximum stress is therefore known and typically correlates with the crack initiation site.  We examine the fracture surfaces (fractography) of springs to locate the crack initiation site.  If this site does not correspond to the point of maximum stress, it is likely that material defects or other factors contributed to crack initiation.  We inspect the crack initiation site at high magnification (using scanning electron microscopes) to look for inclusions or laps in the steel, or for damage to the spring surface, that facilitated crack initiation.

If crack initiation did occur at the site of maximum stress, material factors may or may not have been involved.  We must still verify the material microstructure, hardness and, possibly, the chemistry before ruling out material as a factor contributing to failure.  We metallographically prepare a cross section of the spring to inspect the microstructure and measure the hardness as a function of depth.  Hardness outside of the specified range of course contributes to failure, but bulk hardness can be within spec while surface hardness is low, and this still leads to fatigue failure.  Low surface hardness is often caused by decarburization of the spring wire, which we detect metallographically.

Other factors can be derived from the failure analysis.  If crack initiation occurred at the location of peak stress and there was no material factor contributing to crack initiation, then the spring performed as intended and the conditions of use must be questioned.  Was the loading greater than expected?  Where there more stress cycles than expected?

If crack initiation occurred other than at the peak stress location, and there was no material contribution to crack initiation, then the possibility of improper use must be considered.  Essentially this is saying that the stresses must not have been the normal stresses observed in a spring. 

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