Retaining rings are a type of metal fastener installed into a groove on a shaft or in a housing or bore. They hold components or assemblies and are designed for one-time use only. The retaining ring grooves feature a compact design that allows for fewer machining operations compared to other fastening techniques. Read on to learn all about retaining rings grooves and understand why they are important.
What Are Retaining Rings?
Retaining rings gained popularity thanks to their compact and more functional design than their traditional counterparts. These metal fasteners eliminate the drilling, threading, tapping, and other machining operation typically associated with standard alternatives like nuts, screws, and bolts. What is more, retaining rings can significantly reduce manufacturing costs as they can be machined using other manufacturing processes.
According to engineers, retaining rings can be specified based on an application’s installation and removal requirements, conditions and operating environment, rotational speed, expected force loads on the ring, and cost.
The diameter of retaining rings can be from 1 millimeter to 1 meter. The different combinations of shape, size, style, and material result in designs that work in a wide variety of industries. Retaining rings can be used in wind turbines, bicycles, gas pumps, fitness equipment, office equipment, doorknobs, and more.
Types Of Retaining Rings
There are four types of retaining rings, and each can be broken down into sub-types depending on the application’s needs.
Tapered Section Retaining Rings
Tapered section retaining rings decrease from the center to the free ends symmetrically. They remain circular when contracted or expanded within the normal use limits, thus ensuring contact with the groove along the ring periphery. The tapered section retaining rings can be installed axially or radially.
Constant Section Retaining Rings
Constant section retaining rings, also known as snap rings, are made of flat or round wire. The material used is the same width at any point along the ring’s circumference. When contracted or expanded, these rings are deformed elliptically, and as a result, they contact the groove at three or more isolated points. That said, they never contact the groove continuously around the periphery.
Spiral Retaining Rings
Spiral retaining rings are axially installed externally onto shafts or internally into housing or bores. Manufactured by coiling flat wire into the shape of the retaining ring, they make a 360-degree contact with the groove. Spiral rings usually come with a removal notch to simplify the removal process.
Circular Push-On Rings
A circular push-on ring mirrors a toothed washer. They are installed by pressing onto the end of a grooved shaft until the inner teeth of the nut snap into the groove. The use of push nuts helps cut costs of threading the nut onto the shaft’s end during the manufacturing process.
Why Are Retaining Ring Grooves Important?
The retaining groove determines how good retaining rings are. If the groove doesn’t properly install the fastener retaining ring, the assembly’s capacity would be less than the retaining ring’s rated capacity. This is why the groove shouldn’t be neglected when developing assemblies held by a retaining ring. Quite the contrary, you should put a lot of consideration when designing the grove so that you can decrease the chance of assembly failure and boost thrust load capacity.
The Ideal Width of a Ring Groove
The groove shouldn’t be as thick as the ring, or else the ring will never install correctly. And if the ring isn’t correctly placed, it will work itself out of the groove. It’s recommended that the groove is wider by a few thousandths of an inch than the ring’s thickness to ensure proper installation. Axial tolerance will allow for slight dishing when the load is applied and properly seated in a groove.
The Ideal Depth of a Ring Groove
The groove’s depth defines how much the retaining ring extends beyond it. So, a too shallow groove will cause a lever-arm effect where axial forces cause the retaining ring’s dishing, which could result in premature assembly failure. Ideally, the groove’s depth should be one-third of the retaining ring’s radius.
In Conclusion
A retaining ring is most likely to fail due to deformation of the ring, which would prevent the ring from searing correctly. So, design engineers shouldn’t overlook the importance of the groove when developing a retaining ring. The integrity of the groove and the material it’s made out of are the two crucial things for building a solid retaining ring.
