"MULTI-START," MACHINED SPRINGS PROVIDE MULTIPLE ADVANTAGES     w:pix

SANTA MARIA, CA., April 4, 2001--Helical Products Company’s unique machining ability to incorporate multiple spring coil sets (“multiple starts”) in a given part provides a broad range of spring rates and functionality within a given size (envelope).  A “single start” is a single, continuous coil element which starts at one end and terminates at the other end, as is the case with all wire wound springs.  A “double start,” machined spring has two coils phased at 180°.  In effect, this puts two independent helixes in the same package envelope.  Multiple start coils, such as triple, quadruple start etc., are similar extensions of the concept.

Multiple start coils, or “flexures” as Helical calls them, make sense because they not only provide redundant elastic elements should a failure occur, but a failed element (coil) will be physically trapped by the remaining one(s).

When compressed (or extended), single start springs provide a reaction force plus a moment.  This moment is created because the line of action is through the longitudinal centerline of the spring, and the spring force is acting at the coil mean centerline.  The distance between these centerlines provides the moment arm of the subject moment.

With multiple start, machined springs, all internal moments are resolved within the spring.  The big benefit is that these multiple start springs then compress (or extend) in a very straight manner.  There is no tendency for the spring to squirm when deflected, and no restraint is necessary to resolve the free moment.  

With machined springs, Helical’s engineers can choose coil size, number of coils and multiple start coil features to achieve specified, different, elastic rates to meet the customer’s application.

For more information or a free catalog, please contact us or fill out our online request form.

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