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Shaft collars are simple, versatile components that are commonly used as mechanical stops or to fix components in place on a shaft. They can also be used for spacing or aligning other components. Shaft collars find applications in everything from gearbox assemblies to medical instruments to flagpoles; wherever there is a need to keep mechanical parts in place. However, since they are used so widely and are available in so many varieties, it can be difficult to identify which shaft collar is right for your application.
Shaft collars differ in key variables such as material, holding power, and surface treatment, so it’s critical to check that the type you choose aligns with your specifications to ensure efficiency and effectiveness for your application. In this guide, we’ll cover the key factors that should influence your choice of shaft collar to make sure you choose the right one for your needs.
Holding power is one of the most critical factors when selecting a shaft collar as it determines the amount of load that a shaft collar can withstand without slippage. In general, holding power is based largely on the collar bulk, bore size, and screw size.
A number of application-specific factors also influence holding power, including friction between the shaft collar and the shaft, as well as the quality and tension of the fastening hardware. Friction is based on the surface material of both the shaft collar and the shaft, so materials and surface treatments are especially relevant to holding power in a given application.
Stafford offers several classes of shaft collars that offer different levels of holding power. These include:
Shaft collars are most frequently made from steel. Steel shaft collars often receive a surface finishing treatment to enhance their holding power or corrosion resistance. Although there are multiple finishing options for shaft collars, the two primary options include oven-blackened and zinc plating.
An oven-blackened finish is a non-slip option designed to increase friction and decrease slippage between the shaft collar and the shaft, making it the ideal surface finish for enhancing holding power. In applications exposed to moisture, rust is a primary concern as it can compromise component longevity. Zinc plating offers greater corrosion resistance, making it ideal for this type of application; however, this smooth plating reduces friction, decreasing holding power.
Another key performance consideration is face-to-bore perpendicularity, which refers to the angle between the face of the collar and its bore. This measurement is important in load-bearing applications because a high degree of perpendicularity ensures that pressure is applied evenly across the interface between the collar and the shaft. Deviation from a 90-degree angle can lead to slippage or even premature component failure.
Face-to-bore perpendicularity is more important in certain applications than others, although extreme deviations are never desirable. When shaft collars are used to align components or used for heavy load-bearing, it’s especially important that the bore be as close to perpendicular with the face as possible.
Just as surface finish is an essential factor in shaft collar selection, so is material. The most common material options are steel, stainless steel, and aluminum. Although steel is stronger and tends to offer better holding power, aluminum is lighter and has a favorable strength-to-weight ratio. As such, the choice primarily depends on two factors: corrosion-resistance and strength.
If corrosion resistance is a primary goal, then stainless steel or treated steel is a better choice than aluminum. On the other hand, aluminum is a better option if weight is a primary consideration.
Other material options include titanium and plastic. Titanium is lightweight, extremely strong, and temperature resistant; however, it is only used in applications requiring these attributes due its extremely high cost. Plastic shaft collars are very affordable and lightweight but offer much lower holding power.
The experts at Stafford can help you identify which material will offer the best performance in your application.
Another factor to consider when choosing a shaft collar is how frequently you will need to adjust or disassemble it. There are several styles of shaft collars, some of which are easy to adjust and disassemble, and some that are more permanent. These styles include:
These configurations are available in both heavy-duty and thin-line designs, which differ in profile and holding power. Thin-line designs have a smaller profile and are designed for applications with weight and space restrictions. Heavy-duty collars have a larger outer diameter, screw, and width for applications requiring high holding powers.
The diversity of shaft collar designs means that these components can be used with large and small assemblies across industries such as:
Stafford manufactures quality shaft collars, couplings, and other unique components for a variety of applications across many industries. With our knowledge, expertise, and broad range of product offerings, we can help you choose the right shaft collar for your needs. For more information, or to get started on your shaft collar solution, contact Stafford today.