Some companies encounter a peculiar phenomenon when using casters.

After the device has been parked for a while, when you push it again, the wheels always seem to jerk and stutter, as if they’re not rolling but “hopping.”

Upon closer inspection, it becomes apparent that the wheel is neither cracked nor visibly worn; however, a flat area has emerged on its surface.

This is what the caster industry often refers to as… “Flat Spot” , also called Indentation deformation 。

Many people mistakenly assume that this is due to poor wheel quality; in fact, most flat spots are not a manufacturing defect but rather the result of prolonged compression combined with operating conditions.

Today, we’ll discuss an issue that’s often overlooked yet directly affects caster lifespan and the smoothness of pushing.

What is a “flat spot”?

Under normal circumstances, the wheel surface of a caster is circular.

When a device is parked for an extended period and the wheels remain under constant pressure in the same direction, the contact area between the wheel tread and the ground may experience slight compression.

If this compressive stress persists for an extended period, the wheel tread may fail to fully regain its original shape, eventually resulting in a flat spot.

As the device moves again, this flat surface continuously contacts the ground, resulting in a “jerk-and-stop” rolling sensation.

This is the fundamental principle behind the formation of flat spots.

Which devices are more likely to experience flat spots?

Not all casters exhibit this issue.

The following categories of equipment have a relatively higher probability of experiencing flat spots:

Heavy-duty equipment parked for extended periods

For example, large equipment bases, mold transport carts, and storage racks.

When equipment remains stationary for several months or even longer, the weight is constantly concentrated on the same spot, and the wheel tread is continuously subjected to stress, making it more prone to developing compression marks.

Transport vehicle stored at full load for an extended period

Many logistics trolleys are not moved every day.

Sometimes, after being loaded with goods, they remain parked for several days or even longer.

When weight is continuously concentrated on a single point on the wheel rim, flat spots are also likely to develop.

High-temperature operating environment

Some wheel rim materials become softer at elevated temperatures.

If subjected to significant stress simultaneously, the likelihood of permanent deformation also increases.

Therefore, in high-temperature environments, greater attention should be paid to the proper parking of equipment.

What impacts will a flat spot have?

Many people think that as long as the wheel is only slightly flattened, it won’t affect its continued use.

In fact, a flat spot could trigger a series of cascading effects.

Resistance to implementation has increased.

With each rotation, the flat bearing makes a single impact with the ground, resulting in noticeable jerky motion when the equipment is pushed.

Increased equipment vibration.

The wheel tread no longer maintains a perfect circular shape, leading to periodic vibrations during equipment operation.

For precision instruments, testing equipment, and the like, such vibrations may impair normal operation.

Noise has increased.

The flat tip repeatedly strikes the ground, producing a regular rolling sound, which is especially pronounced on hard surfaces.

Accelerates wear on other components.

Continuous vibration increases the stress on components such as bearings, brackets, and fasteners, which over time may shorten the service life of the entire caster assembly.

What is the difference between flat spots and wheel tread wear?

Many users tend to confuse the two.

Wheel tread wear It occurs gradually as rolling proceeds, and the entire wheel surface is typically fairly uniform.

And Flat point It is a deformation caused by localized compression.

It often appears consistently in the same location, creating a distinct rhythmic feel when scrolling.

Therefore, if the equipment exhibits slight vibrations at a fixed frequency when in motion, it is advisable to carefully inspect whether flat spots have developed on the wheel tread.

How can the occurrence of flat spots be reduced?

Although flat spots cannot be entirely avoided, they can be effectively reduced in occurrence through proper management.

Do not leave it fully loaded and stationary for extended periods.

If the equipment is to be stored for an extended period, and conditions permit, some of the load may be appropriately removed to reduce continuous pressure on the wheel tread.

Regularly move the device

Even when the equipment is not in use, it’s recommended to gently reposition it at regular intervals to shift the load distribution on the wheel surface, preventing prolonged pressure on a single point.

Select the appropriate wheel material based on operating conditions.

The compressive resistance varies depending on the wheel rim material.

For equipment that remains stationary for extended periods and is subjected to heavy loads, the choice of wheel material should be based on the actual operating environment, rather than focusing solely on load‑carrying capacity.

Regularly inspect the condition of the wheel tread.

If you notice slight indentation on the wheels, promptly inspect the equipment’s load and parking conditions to prevent the issue from progressing into a noticeable flat spot.

A detail that is easily overlooked

Many companies believe that casters experience no wear as long as the equipment remains stationary.

In fact, for equipment that remains stationary for extended periods, The greatest losses occur precisely during periods of “stasis.”

Continuous compression, ambient temperature fluctuations, and the gradual deformation of the wheel tread material all subtly affect caster performance.

Therefore, casters must consider not only “how to move” but also “how to park.”

Written at the end

The service life of a caster depends not only on the distance it rolls each day, but also on how long it endures static loads.

An inconspicuous flat spot may not immediately render a caster inoperable, but it will gradually compromise pushing efficiency, equipment stability, and the overall operational experience.

For equipment that is parked for extended periods or operated under heavy loads, proper storage, regular inspections, and appropriate component selection are often far more critical than replacing casters after the fact.