In the late 1800s, engineers faced a growing challenge: how to reduce friction and ensure efficient torque transfer between motors and their connected shafts. The solution came in the form of keyed shafts—a simple yet effective mechanical design that revolutionized power transmission systems.

A keyed shaft system works by using a "key" that fits into a corresponding groove (called a keyway) on the shaft. This design allows for a secure connection without requiring excessive tightening, which helps reduce wear and improve performance. The motor's key slides into the keyway, transferring rotational force through direct contact with the walls of the groove, minimizing slippage and maximizing efficiency. This setup became known as a keyed joint.

Keyshafting is a variation of sprocket drive technology, where each tooth or cog on a driven shaft is linked to a matching component on another shaft or belt to transmit torque. This method ensures precise and reliable motion transfer, especially in high-speed applications.

Common Types of Keyed Shafts:

• Woodruff Keys: These are semicircular in shape and fit into a corresponding pocket on the shaft. They are often used in high-speed motor applications due to their balanced design and reduced vibration.
• Parallel Keys: The most commonly used type, these keys have a rectangular profile and are inserted into a precision-cut keyway. A set screw is often used to secure the hub against the shaft.
• Scotch or Dutch Keys: Simpler to manufacture, these keys are inserted by hammering them through a hole drilled into the motor and the shaft. They act as pins and are typically used in less demanding applications.

How Keyed Shafts Are Made:

Creating a keyed shaft involves several precise machining methods, all aimed at ensuring a perfect fit between the key and the keyway. Here are some of the most common techniques:

• Keyseaters: These machines cut keyways into shafts using a rotating cutter. They can be either stationary or mobile, depending on the setup.
• Wire EDM: Ideal for small-scale or high-precision work, this process uses electric discharges to erode material from the shaft, creating very accurate keyways.
• Broaching: This method involves pushing a broach tool through the shaft to create the keyway. It's more labor-intensive but offers excellent results.
• Milling Machines: Can be used to produce parallel, Woodruff, or tapered keyways, offering flexibility in design.
• Chiseling: One of the oldest methods, it's rarely used today due to its time-consuming nature and lack of precision compared to modern techniques.

Pre-Keyed Shafting: Convenience and Standardization:

Over time, the sizes and configurations of shafts have become increasingly standardized. Pre-keyed shafts are now available in standard diameters ranging from 3/8 inch to 2.5 inches, and lengths from 3 feet to 24 feet. They are typically made from carbon steel or stainless steel, and can also be customized for specific equipment needs.

The availability of pre-keyed shafts saves time and money by eliminating the need for on-site keyseating. Many models come with collars that help connect the shaft to machinery, featuring set screws for a secure fit.

The Big Bearing Store has been providing top-quality power transmission solutions for over a decade. As one of the leading distributors of bearings and related components, we're here to help you find the right products for your application. Contact us today to learn more about our extensive range of pre-keyed shafts and other essential components.