How to avoid deforming snap rings (4 Easy Tips)

Snap rings are great for fastening components on a shaft or inside a bore. But they can fail easily when deformed. In this article, learn what causes a snap ring to deform and how to avoid it.

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Snap rings or circlips help retain components on a shaft or inside a cylindrical bore. These retaining rings provide great tensile and yield strength to fasten shaft assemblies and keep them from coming off.

Snap rings are so strong that you might think they are indestructible. And to some extent, this is true. It is very hard to deform snap rings when you expand or compress them correctly. But when you mishandle them, you can easily deform or damage them and eventually cause them to fail. In this article, I explore some of the things that cause circlips to deform or break and what you can do to avoid them.

What causes snap rings to deform or break?

deformed snap ring
overstretched snap ring

1. Overstretching or overcompressing

One of the major causes of snap ring deformation is overexpanding or overcompressing them. This can happen when you are compressing internal snap rings or stretching external circlips.

While it is not necessarily easy to apply a precise amount of force on a snap ring, it is more difficult when you are not using the correct tool. For example, it is hard to avoid overexpanding an external snap ring when you use screwdrivers to open it. It is also easy to bend a circlip when you use regular pliers to pull the ends apart or squeeze them.

2. Operating a snap ring the wrong way

Some people operate snap rings the wrong way. Instead of pulling the ends apart or pushing them together in the same plane, they tend to shear them. This causes the snap ring to bend and deform irreversibly.

3. Excess mechanical load on a circlip

Although snap rings reliably retain components on a shaft or inside a bore, there is a limit to the amount of mechanical load they can carry without bending or breaking. This is expressed in terms of thrust load capacity or shear strength.

Ideally, the thrust load must not exceed the snap ring load capacity specified in the technical manual. However, if the material of the circlip is more hardened than that of the shaft, the maximum thrust load must not exceed 1200 lbs. Otherwise, the ring fastener will put so much pressure on the groove and cause it to deform or widen. As a result, this can cause a lot of play in the groove that can cause the circlip to twist, deform, or even snap out due to uneven pressure.

On the other hand, snap rings that go onto shafts made of hardened steel provide different load capacities depending on their thickness. For instance, a circlip thicker than 0.042 inches can withstand a thrust load capacity of up to 150, 000 lbs/square inch. Anything above the limit can cause the ring to fail or deform.

4. Rust and corrosion

Rust or corrosion causes the quality of a snap ring to deteriorate. This makes the fastener lose its shear strength. As a result, when you expand or compress a corroded snap ring it can fail to return to its original state, leading to permanent deformation.

Snap rings that are prone to corrosion are those that are meant for use in high-strength applications. Most of them are forged from carbon steel alloy which is not corrosion-resistant. Therefore, such snap rings need special care to protect them from corrosion. Otherwise, they will not provide the maximum strength in order to ensure they provide maximum strength all the time.

How to prevent snap rings from deforming

1. Avoid overstretching or overcompressing

One way to avoid overextending or overcompressing snap rings is to use a proper tool. The right tool for snap rings is snap ring pliers. These are special types of pliers with pointed tips that go into the holes or ears of a c-clip. The tips are strong and fit nicely to keep the ring fastener from snapping off while under tension. Circlip pliers make it easy to open or compress circlips to the right position. They also give you a bit more control over the amount of force you apply on a retaining ring.

Some snap ring pliers such as the Knipex Precision 48 41 J31 or  49-41-A01 have an integrated overexpansion guard to prevent overexpanding the c-clip rings. The guard ensures that the jaws stretch the ring just enough to put it over the shaft. You can adjust it depending on the size of the ring you are working with. When you set the opening limiter properly, you don’t have to worry about applying too much force on the handles.

2. Operate snap rings correctly

Even if you are using the right tool, you need to ensure that the tips fit snugly into the snap ring holes. This keeps the ring in place and prevents it from snapping off and flying off. When you have a good grip on the snap ring, it is easy to handle it properly.

Moreover, when compressing and expanding snap rings, ensure you are pulling the ends together or pushing them apart on the same plane. This keeps the ring from warping or bending and eventually deforming permanently.

3. Avoid exceeding the mechanical load limit of the circlip

Always avoid exceeding its thrust load capacity. You can consult the technical manual that comes with it or the specifications in the repair manual. Also, be sure to use the proper size snap ring. If it is too thin, it will introduce a lot of play in the assembly and may eventually deform. If the ring is too thick, it might slip out of the groove and cause failure.

4. Lubricate non-corrosion resistant snap ring

Apply a light coat of lube onto the snap ring if it is made of non-corrosion-resistant material. For snap rings in the transmission system or axle boot, you don’t need to lubricate them. The grease in the axle boot and the oil in the transmission or gearbox will protect them.

Wrap up

At the very least, a good snap ring should last as long as the assembly it is retaining. So, if you just observe these simple rules, you will be good to go. However, if you deform the ring fastener by any chance, replace it immediately. This is because a deformed ring won’t hold components in place securely anymore and it can be disastrous when it fails.

Sources

  1. Snap ring load capacities (https://www.rotorclip.com/images/wysiwyg_images/library/LoadCapacityArticle8_10.pdf)
  2. Retaining ring failure: causes and symptoms – https://www.thomasnet.com/articles/hardware/retaining-ring-failure/
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