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Noise from delivery carts in an industrial setting has always been a problem. Have you ever walked a manufacturing facility and been passed by empty carts and experienced the noise equivalent of a jet plane taking off? It is not only unpleasant but hazardous to your hearing health. Noise reduction in an industrial setting continues to be a challenge when the origin of the noise is the moving of carts used for material handling.

There are many expensive ways to design or retrofit carts to minimize noise but finding adequate funds in a budget is always a challenge. The occurrence of ”noise pollution” has become a serious concern for many safety engineers. Not only are workers unable to hear other sounds in their environment but they also risk long-term hearing loss from constant exposure.

Let me share with you the most cost-effective ways to decrease cart noise and improve environmental quality in a manufacturing facility.

1. Wheel Composition (Poly Wheels)

Certainly the harder the wheel material the more sound and vibration that will be transmitted from the floor through the wheel assembly and into the cart. The material the wheel is made of should be firm enough to support the load without causing premature failure while soft enough to minimize the vibratory effects of the wheel traveling across a less than perfect floor. Polyurethane treaded wheels are commonly used. They are able to carry industrial loads as well as provide higher pitch ”noise reduction.”

Common durometers range from 70A to 70D. It is important to note that while softer treads do a better job of reducing noise, they provide less wear resistance and are also more difficult to roll manually.

2. Spring Loaded Casters (Vertical Mounted Spring Casters)

Spring-loaded casters are designed with a cantilevered spring mechanism that supports the load while dampening shock coming from the interface of the floor with the wheel surface. Spring configuration can be in a vertical or a horizontal orientation which impacts the space that the caster consumes. A wide variety of combinations of spring capacity can be designed into the caster to provide varying load capacity while providing degrees of noise reduction at predetermined weights. Pre-load on the spring can also be determined and designed into the final product. Spring loaded casters can carry loads from a few hundred pounds to over 20,000 lbs.

3. Shock Absorbing Wheels (CasterShoX®)

New to the industrial scene is patented technology that houses a specially designed flexural spring within the hub of a wheel and encases the spring with an elastomer. With this design there is significant sound dampening (70% of cart noise) without the need to change the design or the ”space” that the caster must live in. This has proven to be the most cost effective means to decrease cart noise without significant design changes and budget over-runs. This wheel can also be fit into existing caster rigs.

4. Dampening of the Axle

These include mechanism that suspends the axles within a formed polymer. This is seldom used today due to poor performance and premature failure.

5. Combination

In very difficult applications the combination of two or more of the above suggestions can be combined to maximize the sound deadening effect. Many applications will utilize the best wheel material for a particular application and combine it with the Spring Loaded Caster and or the Shock Absorbing Wheel.

The five suggestions above provide the reader with a great place to begin when designing a cart application when noise in a manufacturing operation is an issue. Caster Concepts, Inc. has the expertise and engineering support to meet the most difficult noise problems.

Spring loaded casters have long been the gold standard when it comes to reducing noise and protecting payload in the manufacturing environment. When the proper caster and spring configuration are chosen the outcome will be very predictable, achieving the planed noise reduction. If the spring loaded caster is not properly designed and the spring configuration is not properly engineered the result will be less than desirable and may even increase noise levels in the manufacturing operations.