At the turn of the century, automobiles may have felt like a miracle, but the teeth-rattling, hip-displacing reality of riding one was anything but miraculous. Many early machines wore out fast or were replaced entirely because they lacked the technology to control vibration or absorb shock. Complex yet simple solutions are now in place that can protect machinery and the people who operate it.
The elegant machines of the modern age aren’t just vehicles of conveyance. Everything from manufacturing to roboticized equipment benefits when unwanted movement is minimized. The parts that accomplish this are typically made from rubber or metal and expertly manufactured for optimal use.
At RPM, vibration control and shock absorption are part of our standard and custom offerings. There are numerous materials and forms these materials take. Every coupling, mount, isolator or bushing we make is perfectly engineered for optimal use. Read on for a comparison of the common materials and best options for shock and vibration control.
Elastomers v. Metal Springs
Moving parts aren’t a back and forth operation. Machine parts and attached components move in multiple directions and on multiple planes. Even minor misalignments can seriously impair machine function and increase wear and fatigue on components. Two frequently compared options for maintaining integrity and minimizing unwanted movement are elastomers versus metal springs.
There are a few criteria with which to compare these two options.
Machinery is subject to both intermittent shocks and continuous vibration. Vibration issues are transmitted downstream. Flexibility is preferred over stiffness. This can mitigate shock and decrease vibration. Most people are familiar with standard coil springs. You apply a force and the spring compresses by some distance. This is called the spring rate.
Surface motion, over time, can cause damage to this design. Coil springs while good in a lot of applications has one drawback - that is they don't dissipate energy quickly. Meaning the input can resonate for quite some time. The spring rate is often linear.
One of the benefits of elastomers over metal springs is that they dissipate (absorb) energy and the spring rate is variable to some degree. Meaning the elastomer is much better suited to absorb energy from the system without transferring it as a metal spring system would.
Bump compliance is often measured through bump tests, by learning transfer function, intertance, dynamic compliance, or mobility. Knowing the natural frequency and exciting frequency (which results in resonance), damping measures can be correctly applied. The margin or resonance varies from machine to machine. Most commonly, rubber and rubber elastomers outpace coiled metal springs for damping bumps.
The fatigue cycle of elastomers versus metal should be considered. It’s the one area in which metal may have the advantage. Elastomeric polymers do have high thermal resistance, which means they can withstand high heat caused by friction. However, their degradation rate is higher than many kinds of metal. This may mean that they need to be changed out more often to continue the desired function.
Pros and Cons of Elastomeric Isolators
Elastomers effectively isolate vibration by reducing transmission between parts. Elastomeric isolators are an ideal product for most shock and vibration control applications. This is true down to a cellular level. The chemical ingredients that form natural and synthetic rubber materials are connected in a way that provides both durability and elasticity. While they are frequently used and a preferred material, there are some pros and cons.
Pros of Elastomeric Isolators
- Vertical bearing capacity
- Large horizontal allowable displacement
- Small horizontal stiffness
- Variety of static load ranges
- Low natural frequency
Cons of Elastomeric Isolators
- Poor tension properties
- Limited lifespan
- May be sensitive to chemical agents
- Compression loading required
Common Applications for Rubber Isolators
To best control shock and vibration control, the choice of rubber or synthetic rubber and manufacturing must be exacting. Anyone who oversees machines that operate with precision understands what’s at stake. Rubber isolators are commonly used in a variety of industries, from naval ships to automobiles to construction equipment.
It is likely that they will be used for shock and vibration control in:
- Welding machines
- Electronic equipment
- Medical equipment
The precise functions rubbers parts may serve include:
- Isolate vibration
- Absorb shock
- Protect machines from overload
- Extend the life of valuable machines
The best shock and vibration control rubber parts that will achieve these functions best are:
- Vibration isolators
- Rubber mounts
- Bonded mounts
- Machinery mounts or machine feet
RPM Industrial Rubber Parts is a leading manufacturer of best-in-class rubber parts for shock and vibration control.
RPM Rubber Parts
At RPM, we understand that unique challenges need innovative solutions. Whatever type of machinery you use, shock and vibration control are essential for best use. Need more technical information on a specific product? Go here to access a comprehensive library of free downloads on all of our molded rubber and vibration control products.
In addition to expertly manufactured standard shock and vibration parts, we create custom rubber molded parts. Expert engineers oversee our three-step process, where we design, build and ship the perfect part for your application. For specific questions or to learn more, contact our sales team at (888) 842-5668 or click here to contact us online.