Spline shafts are the products created by spline cutting techniques, which is an external cut like blind broaching. Internal broaching is the other general method of broaching, a technique that involves full penetration of the piece being broached.
As the spline rotates, these grooves interlock with the matching grooves in the mating piece. This connection enables a spline gear to transfer torque. A broach is a hydraulic cutting tool used to cut holes in metal, wood and plastic materials. Metals often used for broaching techniques like spline cutting are the softer metals, such as aluminum, brass and copper.
Products often produced by broaching tools such as spline cutters include gears, screws, nuts, bolts, gun components, small wheels, wrenches and bushings and a variety of other manufacturing tools. Spline cutting mainly serves the automotive industry, although along with other broaching machines, these products are utilized in industrial manufacturing, aerospace, marine, sports equipment, food processing and electronic industries, as well as many others.
Broaching teeth, which perform the cutting action, come in many different sizes and spacing configurations, depending on the part that is being broached. There are quite a few generalized spline styles on the market today as well.
An involute spline works much like an involute gear works, with the uniform pattern of teeth that when rotating, intersect perfectly with each other and cause the torque that powers a vehicle or machine. Most splines and gears utilize the involute equation.
A parallel key spline has parallel, equally spaced groves in both the radial and axial directions. Serrations are spline shafts that have a “V” formed by their equally spaced grooves. Crowned splines are basically involute splines, except with slightly modified teeth that allow for misalignment.
A helical spline is going to look a lot like a screw, with helical grooves all around the side that are either parallel or involute, which allows for beneficial movement between the parts. One more well known style is the ball spline, which involves a ball bearing on the end of the teeth for a varied amount of motion.
These specific spline styles are most commonly used as bicycle gears, mounts for the propellers in engines, drive shafts and cassettes.