Archive: Mar 2021

What Is a Threaded Shaft Collar?

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A shaft collar is a simply-designed machine component composed of a plastic or metal ring fitted around a rod to act as stops, spacers, or for mounting components.  The collar can be loosened or tightened around the shaft using a clamp screw or multiple screws. They are used for tasks ranging from bearing loads to holding components in place along a rod. Among the many types of shaft collars are threaded shaft collars, which offer unique features that make them suitable for various applications. 

What Is a Threaded Shaft Collar?

Threaded Bore Shaft Collars

A threaded shaft collar is a type of shaft collar defined by the threaded 

pattern on the inside of the ID. While the standard shaft collar has a smooth interior, threaded shaft collars employ this textured interior to provide superior grip to the rod it is attached to. 

Threaded shaft collars are paired with a threaded rod, making them fasten together much more securely than a smooth shaft collar on a smooth rod. This provides higher axial holding power with less chance of damaging the rod. Additionally, threaded shaft collars allow for precise positioning and easier adjustments along the rod’s length.

In terms of variants, threaded shaft collars are typically manufactured in two distinct styles. The one-piece clamp collars are designed as a singular piece of equipment, which are fastened by being pressed together and then tightened once in position. Two-piece split collars consist of two separate halves of a single collar held together by a pair of screws that can be used to loosen and tighten the ring. Threaded shaft collars are typically made from steel or hard plastics. HInged threaded collars are also available for a simple, all-in-one assembly style.

Applications of Threaded Shaft Collars

threaded shaft collar

Due to the various advantages threaded shaft collars have over smooth 

shaft collars, they are typically used in applications where additional precision or strength are required. In machinery, threaded shaft collars are most frequently used for load-bearing applications and as spring tensioners. Their holding power and durability allow them to survive longer when placed under high stress than other similar parts. They are also used as end stop positioners and as limiters in repetitive operations.

Hospitals and other medical facilities make use of threaded shaft collars in places ranging from surgical equipment to beds and equipment stands. Other applications include:

  • Automation machinery
  • Mechanical stops
  • Locating components
  • Sprocket hubs
  • Bearing holders
  • Shaft protectors
  • Measuring and testing equipment

Stafford Manufacturing’s Threaded Shaft Collars

Stafford Manufacturing produces a variety of threaded shaft collars, all made with quality materials and designed to be non-marring to the rods they attach to. In addition to the previously touched upon UNF/UNC one-piece and two-piece clamps, Stafford also makes hinged collars that combine the ease of use of the one-piece collars with the quick assembly and disassembly of the two-piece collars. Our other offerings include ACME threaded collars featuring left- and right-hand threading as well as custom manufacturing options. 

Partner with Stafford Manufacturing

The many beneficial features of threaded shaft collars make them useful in many industries. Their superior grip strength and reliability compared to other types of shaft collars make them the optimal choice for a variety of applications. At Stafford Manufacturing, we manufacture superior threaded shaft collars and other types of shaft collars, and we can work with you to create a custom solution for your needs. For more information, or to get started on your next shaft collar solution, contact us today.

What Is Shaft Coupling Windup and Backlash?

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Rigid shaft couplings connect two separate shafts by clamping onto their adjacent faces. When installed properly, the shaft coupling connects the shafts in a precise line that transfers rotary motion between the shafts without causing misalignment or breakage. However, there are two main obstacles to the perfect transfer of rotary motion:

  1. This occurs when the application of torque results in greater shaft rotation at one end compared to the other.
  2. Backlash is the unwanted reactive motion between connected mechanical parts that can break couplings or cause mechanical stress.

This blog explores the causes and effects of windup and backlash in shaft couplings.

What Is Torsional Rigidity in Shaft Couplings?

Windup, otherwise known as torsional rigidity, torsional deflection, or torsion stiffness, occurs when torque is applied and the rotation of one end of the shaft is greater than the other end. This creates unequal torsional deflection that engineers have to consider as they set up feedback mechanisms. The varying load on the gears causes unequal wear. Torsional rigidity can also put stress on the coupling, leading to deformation, breakage, and a more frequent need for parts replacement.

What Is Backlash in Shaft Couplings?

Backlash occurs whenever mating parts in a system aren’t precisely aligned. In shaft coupling systems, the coupling may have a poor grip on each of the shafts, resulting in slight angles and unequal wear and stress on the system.

Shaft couplings can accommodate some degree of backlash, but it’s important to ensure that any backlash is well within the system’s threshold. For example, angular movements greater than 2° past the preferred angle are considered excessive backlash, and this can cause extreme wear, stress, and even breakage. When the backlash is too great, it will result in erratic dial indicator and laser alignment readings. Operators should always reduce the backlash to within the 2° threshold before alignment begins.

There are different types of misalignment based on the resulting misalignment angle. These include:

  • Angular misalignment. When the shafts of two coupled units form a wide ‘V’ or obtuse angle
  • Parallel misalignment. When the shafts are parallel but one is slightly higher than the other
  • Skewed misalignment. Involves both parallel and angular misalignment

Any type of misalignment can cause backlash on the mechanical parts. It can also reduce the overall efficiency of the rotary motion transfer. It’s important to choose the right type of coupling that can prevent misalignment in the first place. Rigid shaft couplings, along with precise installation and setup, can reduce the risk of parts slippage and skew during operation of the system.

Choose Stafford Manufacturing for Shaft Couplings and Mechanical Components

At Stafford Manufacturing, we specialize in manufacturing rigid shaft couplings and other types of specialty mechanical components for energy transfer, motion control, automation, and other systems. Our rigid shaft couplings are designed to optimize the transfer of rotary motion. Browse our selection of one-piece split clamp, two-piece split clamp, three-piece split clamp, and precision sleeve couplings, or contact our team to learn more about our capabilities and inventory.