Request a Quote

Please note - we are closed for summer holidays and will reopen on Tuesday August 3

Message / Order details:


Keep up to date with us on the latest industry news as well as what's going on at True Gear & Spline Ltd. We also post articles for insider tips and tricks, so make sure to check back frequently.

The Various Ways of Machining External and Internal Splines

March 25, 2021

Internal splines are mechanical devices widely used in mechanical drive systems. Typically, they are seen in most rotating mechanisms that transfer rotary motion from an input to an output via a splined shaft. It usually has teeth around its circumference, which are parallel to the axis of rotation of the shaft. These teeth or grooves are formed in many different ways. They come in the involute form, straight-sided, or in an angle form called serrations.

The externally splined shaft mates with internal splines that have spaces formed in reverse to that of the shaft’s teeth.



Moreover, the torque of the splined shaft is being transmitted to the internal spline member that usually takes in the form of a gear. With this kind of spline connection, the load is equally distributed along with the teeth, delivering a longer fatigue life compared to a keyed shaft. The numerous types of teeth enable the facilitation of rotational concentricity, stronger drives, provision for misalignment, ability to slide, and other functions. These types of splines can be processed in almost the same ways, aside from hobbing that is too difficult to do with the spline. 


When it comes to the different methods of machining splines, these are the top three. The first is hobbing which is applicable to external splines. The ratio of the hobbing machine is determined by the number of starts of the hob and the number of spline teeth. The hobbing machine then rolls along with the spline while the cutting teeth remove the material from the spaces between spline teeth. The second option is milling, which is used to mill various types of internal splines. A milling cutter with a reverse form of the involute is used to machine involute splines. The last method is called shaping which is used to make both internal and external splines. Both the cutter and workpiece roll together with the cutter removing the material from the workpiece when in down stroking action. Whether you need a small or large volume of splines, no matter the type, the expertise of True Gear can best serve you. Call us today to know how we can meet your business’s needs.