Industrial Collar Bolts

Product Description

An industrial collar bolt (also known as a shoulder bolt or striker bolt) is a specialized fastener with an unthreaded, precision-ground section called a "collar" or "shoulder" located between the head and the threaded portion. Unlike a standard bolt that clamps components together, the collar bolt is designed to act as a pivot point, a guide, or a spacer.

The Anatomy of a Collar Bolt

1. Head: Typically a hex or socket head (Allen drive) used for installation.

2. Collar (Shoulder): The smooth, enlarged part of the shank. This part is usually manufactured to very tight tolerances ($ISO$ h7 or g6) because it often serves as a bearing surface for moving parts.

3. Threaded Section: Located at the end of the bolt, the threads are smaller in diameter than the collar. This allows the collar to sit flush against a surface while the threads secure the bolt in place.

4. Undercut: A small groove between the collar and the threads that allows the shoulder to seat perfectly square against the workpiece.

Primary Functions

• Rotation Axis: In machinery, these bolts often serve as an axle for bushings, rollers, gears, or linkages, allowing them to rotate freely around the collar while the bolt remains stationary.

• Linear Guides: They are frequently used in "stripper plates" in die sets or injection molds to guide the movement of plates back and forth along a precise path.

• Clamping Limitation: Because the collar is larger than the threads, it creates a "stop." This allows you to tighten the bolt completely without crushing the component being held, maintaining a specific gap or clearance.

Common Standards and Materials

Industrial collar bolts must withstand high shear stress and repeated friction. They are typically governed by:

• ISO 7379: The international standard for hexagon socket head shoulder screws.

• ANSI/ASME B18.3: The American standard for socket head shoulder bolts.

Installation Considerations

• Fitment: Because the collar is a precision surface, the hole in the moving part (the gear or linkage) must be slightly larger than the collar diameter to allow for smooth movement without excessive "play."

• Alignment: The mounting hole for the threaded end must be perfectly perpendicular to the surface. If the bolt is tilted, the collar will not provide a true axis for rotation, leading to premature wear or mechanical failure.

• Lubrication: If the bolt is being used as a pivot, the collar should be lubricated with grease or oil, especially in high-cycle automated machinery.