Why Do Casters “Fall Off”?

Why do casters “fall off”? Behind the broken edge of the wheel surface, it may not be a simple quality issue。

During the use of casters, there is a very obvious fault: the originally intact wheel surface suddenly loses a corner, the edge has a notch, and in severe cases, small pieces of material may even fall off continuously.

Seeing this situation on site, it is easy to conclude that the material of the wheels is too brittle

But the broken edges and falling pieces on the surface of the casters are not necessarily just a problem with the material itself. Ground foreign objects, lateral collisions, local stresses, wheel surface conditions, and equipment operation modes may all be involved.

Especially for industrial wheels such as polyurethane and nylon, to determine why there is a “missing piece”, the first thing to do is to figure out how this piece fell off.

1. First, distinguish whether it is “worn off” or “broken off”
Normal wear and tear is usually a relatively slow process.

As the running time increases, the wheel surface gradually becomes thinner and the contact area changes, but the overall contour usually does not suddenly lose a large piece.

Broken edges are different.

It often manifests as obvious gaps appearing locally, with relatively concentrated cross-sections, and the surrounding wheel surface may still be relatively intact.

Therefore, the inspection step is not to look at how long the wheel has been used, but to observe the shape of the damage.

If only one position suddenly becomes missing, local abnormal effects should be prioritized instead of simply classifying it as normal wear.

2. Sharp foreign objects may be the direct cause
The floor of industrial workshops is not always clean and flat.

There may be iron filings, scraps, screws, and other hard debris in the metal processing area.

When the fully loaded equipment presses over these foreign objects, the contact area of the wheel surface will experience a highly concentrated effect.

Some foreign objects may even leave incisions on the wheel surface first.

Subsequently, as the wheels continue to run, this small gap may become a location where the damage continues to expand, eventually forming a visible edge fracture.

So after discovering a falling block, don’t just check the wheels.

It is often equally important to take the route that the device passes through every day.

3.  Side collision is more worthy of vigilance than rolling over directly
When the caster is working normally, the wheel surface mainly contacts the ground through rolling.

But on-site operations are not always ideal.

When the trolley approaches equipment, shelves, tracks, or corners of the wall, the wheels may directly hit hard objects on the side; When passing through narrow areas, the wheel rim may also be scratched.

This mode of operation is completely different from normal scrolling.

Especially after repeated lateral collisions on the edge of the wheel surface, local gaps may first form and then gradually expand.

Therefore, if falling blocks always occur at the edge of the wheel surface, it is important to investigate whether the equipment frequently experiences lateral impacts.

4. Why did only one wheel of the same car fall off?
This phenomenon has great diagnostic value.

If the specifications and usage time of the four casters are similar, but only one fixed position is repeatedly damaged, do not immediately suspect the entire batch of materials.

You can observe whether the position where this caster is located is more prone to hitting obstacles, whether it often passes over the edge of the route when the equipment turns, and whether this position is responsible for different actual working conditions.

Sometimes, the real reason is not in the caster factory, but in a certain action that the equipment repeats every day.

5. Changes in material condition may also increase the risk of falling blocks
After being exposed to a specific environment for a long time, the material condition of the wheel surface may change.

For example, material properties may differ from their initial state due to long-term exposure to temperature, chemical media, light, or other environmental factors.

At this point, encountering sharp foreign objects or strong local impacts makes it easier to expose the problem.

That’s also why failure analysis can’t just look at the back.

Seeing a piece of wheel surface collapse does not necessarily mean that all damage was caused by that collision.

The last impact sometimes only reveals the existing damage completely.

6. Can I still use a small piece that has fallen off?
It is necessary to judge based on the degree of damage and the intended use of the equipment, rather than simply looking at whether it can still function.

If only minor surface gaps are found, the deteriorating working conditions can be stopped first and the damage status can be observed.

If the defect has significantly affected the integrity of the wheel surface, or if there is continuous expansion or cracks extending inward, it should be dealt with in a timely manner.

For wheels with large loads, high operating frequencies, or bearing important equipment, it is not recommended to wait until the wheel surface is extensively damaged before replacing them.

Because as the gap widens, the wheel will repeatedly pass through this discontinuous area with each revolution, and the operating state will also change accordingly.

7. Reducing edge collapse and on-site management are equally important
To reduce wheel breakage, we cannot rely solely on “replacing with better materials”.

Keep the transportation channel clean and promptly remove metal shavings and hard foreign objects;

Improve obvious sharp steps and damaged floors;

Avoid the wheel rim of the trolley directly hitting the equipment foundation or shelf;

Check the wheel surface incision promptly after discovery, rather than waiting for it to continue expanding.

These seemingly simple measures are often very important for the long-term operation of casters.

Write it at the end
The wheel surface of the caster falls off, which looks like a typical “product failure”, but the real reason may lie in the route that the equipment passes through every day.

The edge collapse is the result, and finding where the damage started is the key to failure analysis.

Next time you encounter a sudden missing piece of the caster wheel, don’t rush to ask ‘why is this wheel so brittle?’ Instead, look at the position and shape of the gap, and then check the ground and equipment’s running trajectory.

Sometimes, an inconspicuous piece of metal debris, or a repeated lateral collision every day, is the real starting point of the problem.

For  more information, please feel free to contact GLOBE Team!