Shaft collars attach to shafts and are used as stop features or targets for devices such as tachometers. They are usually made of aluminum, steel, stainless steel, or alloyed steel and coated with zinc, chromium or black oxide. Shaft collars made from non-metallic materials such as nylon are also available. Generally, these products are used for washdown applications such as food processing.

There are several basic shaft collar designs:

• Setscrew collars are suitable for simple shaft positioning, but are not designed for high axial loads or applications that require repositioning.
• Threaded clamp collars are designed for threaded shafts and provide a relatively high axial loading force.
• One-piece clamp or C-style collars provide a more uniform holding force on the shaft. Like threaded clamp collars, these devices can be repositioned as necessary.
• Two-piece shaft collars provide a stronger and more uniform holding force than one-piece shaft collars. They also accept greater variances in shaft diameter and can be assembled anywhere on a shaft.

Video Credit: Ruland Manufacturing Company, Inc. via YouTube

Specifications

Selecting shaft collars requires an analysis of specifications. Products are measured in English units such as inches (in) or metric units such as millimeters (mm) or centimeters (cm).

Thread types include:

• Unified national fine (UNF)
• Unified national coarse (UNC)
• Acme

Important specifications to consider when specifying shaft collars are:

• Width
• Bore diameter
• Outer diameter
• Axial load capacity

Measured in pounds (lbs) or kilograms (kg), axial load capacity is the maximum load that can be applied along or parallel to and concentric with the primary axis. Typically, acme threaded collars can withstand higher thrust loads than conventional smooth bore collars. Some shaft collars include clamping screws that are all inserted from the same direction. Others include clamping screws that are inserted from opposite directions.

Applications and Industries

Shaft collars are used in a variety of application and industries. Examples include:

• Agricultural implements
• Office machines
• Exercise equipment
• Mixers
• Printing presses

A variety of specialized products are available:

• Knurled shaft collars provide a friction surface for hand gripping and are suitable for conveyors and other applications which require frequent collar adjustment.
• Hexagonal-bore shaft collars are suitable for power transmission and drive applications.
• Heavy-duty shaft collars feature large cross sections and sturdy clamping screws for added holding power. Because heavy-duty shaft collars provide better vibration and shock resistance, they are designed for applications such as off-road, mining, paper and steel mill equipment.

Standards

BS 4185-2 - Specification for Machine Tool Components - Part 2: Collars

Image credits:

Grainger Industrial Supply | MISUMI USA | Stafford Manufacturing Corp.