The flawless production techniques of the Heli-Cal beam flexible shaft coupling avoid stress-raising areas found in other cross-slot designs. Cross slot designs have their purpose if torsional stiffness within the system is of paramount importance and that angular and parallel shaft misalignments are minimal.
However, once any shaft misalignment is added to the system the nature of their design means that they are prone to fatigue. Most importantly, it is the way in which the start and finish of the slot is manufactured that raises more stress within the cross-slot design. With any Heli-Cal beam, flexible coupling it is imperative that the start and finish of the slit is finished smoothly and without scarring or swarf residue, as this will shorten the working life of the shaft coupling dramatically. The way in which other designs are manufactured results in a relatively sharp edge that may act as a stress riser in the more ardous of applications. In certain cases this stress riser is where a crack will form and most likely lead to a complete failure of the part.
As standard, all Heli-Cal shaft couplings are shot peaned and hard anodized to further reduce the stress raisers within the coupling to make a more reliable part. For the more ardous of applications we incorporate a stress relief hole that reduces the stress concentration the coil finish to the solid hubs.