March 16, 2020
Vibration and sound transmission create problems for many industries. Combating the noise of a motor engine in cars, boats or planes, silencing disruptions from home appliances such as dishwashers and washer/dryer rooms or reducing the rattle of air conditioning systems are new frontiers in creating more comfortable and peaceful environments. More and more, adhesives and sealants are playing a key role in addressing these issues of vibration and unwanted sounds.
Most adhesives and sealants are naturally viscoelastic and damp sound by absorbing energy. Epoxies, silicones and polyurethane-based adhesives are the most popular products for this task, but many adhesive types can be effective tools for noise and vibration control. These materials fill open spaces to reduce noise leakage while also absorbing energy and dispersing stress across the entire bonded surface. This, combined with insulation, significantly reduces noise, vibration and any harshness (NVH) associated.
NVH is an abbreviation and industry term commonly used in automotive manufacturing when discussing noise, vibration, and harshness. The context is typically to eliminate these nuisances from effecting the occupant’s environment. As such, NVH products are generally designed for vehicles and substrates used in automotive manufacturing from steel to composites, but the same core ideas apply to appliances and other manufacturing segments where there is a desire to minimize noise.
The sound of home appliances may be irritating, impacting a person’s sleeping, concentrating, level of stress and overall health. Anything over 85-decibel scan harm the hearing over time. General home appliances produce around 50 decibels and the loudest ones are in 80-95 decibels range. Noise levels for some common home appliances such as a dishwasher are 55-70 decibels, a refrigerator is 50 decibels, a washing machine or an air conditioner is 50-75 decibels, a coffee grinder is 70-80 decibels, a juicer is 80-90 decibels and a hairdryer is 60-95 decibels. Home appliances like washers and dryers used to be in basements and garages. In order not to create sound problems over time, adhesives and sealants are starting to be used as alternative sound blocking materials.
Aside from physically blocking sound waves as an insulator, some adhesives are specialized to address specific NVH challenges. Structural adhesives, for example, cure into rigid forms to help create firm connections that bond separate pieces into one solid structure. With structural adhesives applied, vibrations are less capable of moving individual pieces which reduces rattling noises and extends a product’s durability. This is particularly important where consistent impacts or shaking is encountered.
Threadlockers also play a role by resisting vibration, leaks, and corrosion when bonding threaded fasteners in place. Washing machines, dryers and other appliances that are subjected to high frequency of vibrations should be protected against loosening fasteners with thread lockers applied to all threaded fasteners. Thread locking adhesives are often pre-applied to lock nuts and bolts against vibration and thermal expansion. As an important side benefit, they protect the fasteners from corrosion and leakage by filling all the voids between the interfacing threads
Any fastener selected for noise reduction must work with the application environment, such as hot and relatively dirty motors. In motor applications, temperature cycling tolerance and chemical resistance will be key, so be sure to review the application with adhesive specialists. Adhesives provide an economical way to control noise and vibration as they are low cost and can be applied simply with minimal alteration to substrates. NVH adhesive products often have high bond strength, easy applications, and complete curing to create strong NVH resistance.
Hernon Manufacturing, Inc.® produces over 5000 adhesives and sealant types. A full in-house chemical laboratory ensures quick turn around on testing and development projects and an on-site machine division allows Hernon® to build, service and integrate unique dispensing systems to even the most exacting specifications. This horizontal integration helps Hernon® to provide customers with a Total Solution for any unique application.
Hernon® Manufacturing is headquartered in Sanford, FL. and maintains an ever-expanding network of over 100 distributor and partner locations around the globe. Already shipping to over 60 nations, Hernon® can provide adhesive solutions to manufacturing operations anywhere in the world.