No-maintenance isolation technology by Firestone solves problems created by noise and vibration
Dealing with noise, vibration and harshness (NVH) is one of the big challenges of the traditional Christmas-New Year maintenance season.
It's often during these shutdowns that engineers have to contend with the damage caused by NVH to vital components such as bearings, bushings, joints, welds, mountings and springs (not to mention the effects on hearing and workplace health and safety).
"It's a far cry today from the old days when noise and vibration were just something workers and workplaces just had to put up with. Quite apart from the potentially expensive compensation issues of hearing and nerve damage, unchecked harshness and vibration can wreak havoc with production machinery - and with nearby automation and computer technology," says industrial actuation and isolation specialist Mr James Maslin.
Mr Maslin is National Sales and Marketing Manager of Air Springs Supply Pty Ltd, which has more than 30 years experience throughout Australia in solving isolation and actuation challenges, using technologies from world leaders in the field, including the world's foremost producer of Air Springs, Firestone.
One of the simplest and most effective technologies he has employed for suitable applications is Marsh Mellow® rubber springs from Firestone, which are engineered for immense strength and longevity.
Marsh Mellows feature hollow centres surrounded by a solid rubber core and fabric ply reinforced body to deliver constant vibration isolation with changing loads.
Their unique construction delivers low natural spring frequencies to provide excellent isolation of forced frequencies in the range of 13-20-HZ (800-1200 cycles a minute).
This outstanding performance and a maximum load range now extending from 0.64 kN up to 88 kN (on special order) makes them particularly suitable for vibration isolation applications beneath equipment commonly used by the mining, quarrying, primary production, food and beverage processing and manufacturing, where they are used beneath machinery ranging from vibrating screens to stamping presses, mixers, motors, compressors, conveyors, crushers, blowers and bins, motors and generators.
Marsh Mellows also make ideal shock absorbers for conveyor and primary product and other materials handling applications, particularly in situations where their corrosion-resistant durability means they will survive damp and corrosive environments in which standard coil springs may fail.
"Marsh Mellows have no moving parts and require no maintenance or lubrication, so they are ideal of applications in moist, grimy and demanding environments. And because they reduce structurally transmitted noise caused by vibration, Marsh Mellows have considerable OHS and comfort benefits by being quiet in operation unlike coil springs, which often suffer coil chatter and readily transmit high frequency structural noise.
"Their terrifically rugged rubber construction eliminates the problem with coil springs of cracking to allow fragments of metal to damage equipment and cause costly downtime. Additionally, Marsh Mellow springs exhibit exceptionally high overload characteristics and offer some support even during failure," said Mr Maslin.
Because so much bulk handling and materials processing is prone to high levels of damaging impact vibration and noise, plant engineers are giving increasing attention to OHS and reliability issues.
"Not only can excessive vibration cause noise and component failures, but also it can disrupt sensitive computers and electronic equipment now being widely adopted by the industry to automate production," says Mr Maslin.
In addition to eliminating damage to machinery and resultant production interruptions, other advantages of Marsh Mellows include:
- High load carrying capacity because of their superior deflection capabilities and the load carrying influences of the fabric reinforcement. This means they can carry a greater load than an all-rubber part of the same modulus and dimensions at a superior natural frequency.
- Increased stability at higher percentages of compression. As height compresses, the fabric-reinforced rubber plies pantograph and the diameter grows. This supports the rubber core laterally even in an emergency at 30-40 per cent compression.
- Lower cost. Marsh Mellow springs' higher load capability means fewer springs may be needed in an application, resulting in less overall cost.
The spring's components (rubber, bias plies, size of centre) are combined in different ways to meet specific load and performance requirements. This gives them great flexibility and precision, says Mr Maslin, whose Air Springs engineering team experience spans several hundred applications of both solid and hollow (bellows-type) air springs throughout Australia. Details of applications can be researched on Air Springs' website, www.airsprings.com.au.)
Naturally different types of springs have different performance characteristics suited to particular tasks. These should always be discussed with suppliers having wide experience in the particular area of application being considered.