The need to avoid downtime in manufacturing, mining, and materials handling tasks is driving maintenance and engineering operations managers to rethink their options of how to isolate production equipment from the machinery-busting effects of vibration.
"Where once standard metal springs were always the go-to option for dealing with Noise, Vibration, and Harshness (NVH), now the need to achieve better isolation, greater reliability, and quieter operation is prompting a search for alternatives to consider in varied applications," says Air Springs Supply Technical Product Manager, Vinh Lam.
"Avoiding downtime is a major reason for change in highly competitive industries, but also driving a rethink is the fact that staff have to contend with OH&S hazards involved in maintenance and damage caused by NVH to vital components and structures, including bearings, bushings, joints, welds, and mountings. And then there are the long-term effects of crashing and chattering springs on hearing and the nerve damage that can result where NVH is untrammelled," says Vinh.
Air Springs Supply has more than 50 years' experience in solving isolation and actuation challenges. It is national distributor for Firestone Airide products, including Airstroke™ and Airmount™ isolators and the broad range of simple but tough Marsh Mellow™ rubber springs 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 industries. They can be used beneath machinery ranging from vibrating screens to stamping presses, mixers, motors, compressors, conveyors, crushers, blowers and bins, and generators.
"Marsh Mellows also make ideal shock absorbers for conveyor, 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 alternatives may fail," says Vinh.
"Marsh Mellows have no moving parts and require no maintenance or lubrication, so they are ideal for 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.
"Their terrifically rugged rubber construction eliminates any problem with metal cracking to allow fragments to damage equipment and potentially cause costly downtime. Additionally, Marsh Mellow springs exhibit exceptionally high overload characteristics.
"For example, the W22-358-0216 spring (cited in the Air Springs Supply Marsh Mellow Selection Guide) has a normal load capacity of 30kN, (approximately 3 tons) with 16mm of deflection. The same model can handle isolated shock loads up to 200kN (approximately 20 tons) with up to 40mm of deflection."
In addition to curtailing 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 allows them to 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 Vinh, whose Air Springs engineering team experience spans applications of both solid and hollow (bellows-type) air springs, offering isolation efficiencies exceeding 99 per cent in critical applications.
Naturally different types of springs have different performance characteristics suited to particular tasks. No one type of spring is the ideal solution for all NVH issues. Individual applications should always be discussed with suppliers having wide experience in the particular area of use being considered.
About us:
Air Springs Supply Pty Ltd is Australia's leading supplier of air springs and associated pneumatic technology for industrial actuation and isolation and air suspension for heavy truck, bus, rail and hard-working light-to-medium vehicle applications.
