Louvered Contact Band
Precision machining practices need to be applied when producing the metal components in which contact bands are used. In addition to very tight dimensional tolerances a very precise and smooth surface machining is required to limit surface roughness, completed with a high quality connector grade surface treatment.
Each type of contact band will have a certain range of working height.and should be provided with a recommended compression value for a optimal starting point to fine-tune electrical and mechanical performance features that will need to be established in testing. As before mentioned this compression value will be achieved by the depth of the groove in which the band rests. It is then up to the designer of the contact system to find the most suited compression rate for the actual application in which the contact bands are used. Maximum compression will provide best power transmission performance but will come with the cost of high mating forces, increased wear on surfaces, lower achievable number of mating cycles and shorter contact life. Minimum compression will cause higher higher contact resistance and will limit the current load capability. Most commonly the best suited value in this trade off will be determined in application testing.
The basic features of a contact band are made up by
- the width of the band
- the thickness of the band
- the pitch of the contact bridges (number of contact points over defined length)
- the height of the contact spring elements
- the length of the band is dependent upon its use
It is important to note that the height of the contact spring elements in their virgin (not yet compressed) state will differ from their height after the first few compression cycles.
This difference is referred to as “spring setting” and it is a typical behavior for any type of spring.
After about the first 5-10 compression cycles the spring will reach its working height and should remain close to this height until end of life.
Continue reading on how to calculate nominal current rating ....