Spline shafts are also common in aircraft engines where the propeller are being mounted. In the case of bigger engines, the use of a master spline is usually helpful. These splines are typically wider to enable the propeller to go on at just one orientation, which is crucial in maintaining the dynamic balance and prevent malfunction. Such setup of spline is very common in large aircraft engines but is not practical in smaller ones that use a series of threaded fasteners only.
When it comes to manufacturing spline shafts, the processes involved vary depending on the specific spline type is being produced. There are various methods used to manufacture external splines, including shaping, broaching, milling, hobbing, rolling and grinding. On the other hand, the methods available in manufacturing an internal spline is quite limited due to the restrictions posed by accessibility. Hobbing, in particular, is not possible with internal splines as there would be no access at all. Usually, their splined portion don’t have a through-hole. In this case, a broach or extrusion method will be more practical.
The main cause of a failure with spline shafts is a poor design which results to stress concentrations on the ends of the splines. In order to avoid this issue, the splines are chamfered, making them more durable and resistant to stresses.