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To put it simply, splines are mechanical drive systems that transfer motion from an input to an output. If you want to gain a better understanding of internal splines, you have come to the right place. And if you are asking yourself, “what is an internal spline?” that is okay too. Here, we’ve carved out what internal splines are and how they are used within gearboxes. Start reading below for all the insight you could possibly need on internal splines.

Quick Overview

Let’s keep this technical—internal splines are often defined as any grooves in a mating part where the external splines fit into it, preventing movement between the two parts. Internal splines can be manufactured by using the methods of shaping and broaching.

Spline Types

There are numerous different varieties or types of internal and external splines that can be used in manufacturing. A few of these different types are listed below.

  • Parallel Key Spline – This spline has equally spaced teeth that are arranged in a straight-sided formation.
  • Involute Spline – The involute spline also has equally spaced teeth, just like the spline explained above. However, they are not straight-sided. Instead, the teeth have an involute form to provide greater strength overall.
  • Crowned Spline – Overall, the splines that typically fit in this category are involute as well. Most of them are flat root, fillet root, or major diameter fit. They are designed like this to allow for angular misalignment between the shaft and the mating detail.
  • Serrations – This spline is different from the ones above because it is a non-involute.
  • Helical Splines – The helical spline can be both a parallel or an involute tooth form. However, this form has a specific lead and helix angle that differs from the others. Helical splines are commonly used in manufacturing.

This guide has only scratched the surface but, hopefully, we have answered the question, “What is an internal spline?” There is much more information out there that you can find regarding this element. You can also consult professionals who can provide you with guidance, knowledge, and expertise in this area. Here at Blaz-Man Gear Inc. – Power Transmission Group, our professionals are not only full of knowledge regarding internal spline manufacturing, but they can also lend their experience and expertise. We can create the most unique and customized gearboxes anyone could ever need. Give us a call today to see how we can help you!


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