Controlling NVH the Molykote way

Effective NVH control gets priority attention from vehicle development engineers and Tier suppliers – both global players and local manufacturers – especially as India grows its domestic market and gains strength as a manufacturing hub for vehicle and component exports.

Autocar Pro News DeskBy Autocar Pro News Desk calendar 14 Aug 2012 Views icon21734 Views Share - Share to Facebook Share to Twitter Share to LinkedIn Share to Whatsapp
In India’s dynamic transportation industry, customer satisfaction and impressions of vehicle quality can be directly related to reducing or eliminating noise, vibration and harshness (NVH). Comfort and convenience are not exclusive to luxury-brand passenger cars. Potential buyers and operators of almost every type of vehicle value these attributes. Less noise and more smoothness are important design qualities in upscale saloons to entry-level small cars, in the growing SUV and MPV segments, for all commercial vehicles, and from electric urban transportation to two-wheeler scooters and motorcycles.

Effective NVH control gets priority attention from vehicle development engineers and Tier suppliers – both global players and local manufacturers – especially as India grows its domestic market and gains strength as a manufacturing hub for vehicle and component exports. Meeting global NVH standards is challenging, involving both tactile (smoothness) and audible (quietness) vehicle characteristics. NVH issues can increase service and repair expense and reduce owners’ satisfaction.

Sound solutions for squeaks, rattles and buzzing vibrations

Many manufacturers strive for distinctive sound impressions in their vehicles. Global silicones supplier Dow Corning collaborates with OEMs and their vendors to help meet design objectives for NVH control in cars, trucks, two-wheelers, and even tractors and construction equipment.

Sometimes called ‘miracle lubes’, Molykote brand lubricants were initially based on molybdenum disulfide (MoS2), processed from molybdenite ore that was first commercially extracted for strengthening steel.

For more than 60 years, many of the world’s more demanding lubrication challenges have been met with Molykote solid-lubricant technologies. Lubricating solids – such as MoS2, graphite and polytetrafluoroethylene – are blended with base oils, thickeners, binders, solvents, rust and corrosion inhibitors, and anti-wear and extreme-pressure additives.

Different Molykote lubricant forms offer options and proven solutions to achieve quiet comfort, improve vehicle quality and enhance customer satisfaction. Powders deliver solid-lubricant particles with excellent load-carrying ability, low friction, thermal stability and chemical inertness. Pastes blend powders with fluids for durable lubrication, friction control and corrosion protection. Greases are formulated for heavier-duty lubrication and extended service. Dispersions suspend anti-wear, extreme-pressure solids in lubricating fluids. Bonded lubricants blend lubricating solids with resins or inorganic binder-solvents, and they cure to clean, dry anti-friction coatings.



Powertrain

For years, most attention on NVH prevention centered on vehicle powertrain systems. In many cases, solutions were found with added engine-compartment insulation; beefed-up firewalls; component baffles; and tapes, fasteners or enclosures. However, concealing NVH issues lost out to the need to reduce mass and increase assembly efficiency. OEMs sought solutions to eliminate the root causes of underhood NVH.

Molykote anti-friction coatings (AFCs), applied to piston skirts and rings with a special process, help reduce engine noise, scuffing and wear. Increased fuel efficiency and reduced emissions are added benefits. The process extends to petrol and diesel engines for all vehicle types. AFCs also are used for boosting fuel efficiency while quieting noise on two-wheelers in India.

Other noise-damping Molykote brand Smart Lubrication solutions for powertrain applications include a grease for clutch dual-mass wheels and an AFC for HVAC compressor pistons. These high-performance lubricants also can be used to reduce noise from camshafts and tappets, while coated exhaust manifold gaskets can eliminate the ‘ping’ in exhaust systems.

Chassis and brakes

Good lubrication of steering, suspension and brake components can help improve safety and perceived quality. Yet, material compatibility is important. Many petroleum-based lubricants can soften, swell and cause failure of common sealing elastomers. Lubricants must control friction to reduce noise and excessive wear while preventing corrosion and possible seizure under some of the harshest conditions faced by any vehicle components.

MolykoteLubolid powder additives for semi-metallic and non-asbestos organic brake pads and linings can help control friction to reduce noise, vibration and wear. Proven success is found on cars, trucks, two-wheelers and even railcars. Such friction-control additives are important to meeting OEM standards for quiet-running brakes in India’s growing export markets. In other examples of reducing brake NVH with synthetic lubricants, a global small-car OEM uses a Molykotecaliper pin grease to reduce friction and noise, and a Tier 1 supplier specifies a Molykote AFC for brake-pad retainer clips used on several car and light-duty truck programmes. More noise-damping Molykote specialty lubricants are used on back plates, shims, boosters, and pedal bearings and pivots to help control NVH.

Proper lubricants also can add a smoother feel to adjustable steering columns, steering gears and racks, and pedal-positioning systems. They can help eliminate squeaks, rattles and buzzing vibrations from suspension components and add smoothness and durability to wheel bearings and U-joints. They can enhance performance of handle thrust bearings and shock absorbers on two-wheelers.

Body and lighting

Initiatives for reducing body system NVH have focused on improved aerodynamics to quiet wind noise, soundproofing insulation to muffle road noise, smooth-running tyre technologies, and better sealing around doors and windows. Advanced windshield glass technology, sleeker outside mirrors and relocated antennas also are noise-reduction techniques.

As wind and road noise are quieted, Molykote specialty lubricants are used to eliminate noises possibly unheard above the previous roar. Noise-damping greases are applied to window-lift cables and arms and slider guides for sunroofs and panoramic roofs. Colorless, non-staining anti-friction coatings are used on seals for doors and retractable rooftops. Even heavy-duty commercial vehicles now feature cabin comforts and less outside noise. Other Smart Lubrication solutions enhance tactile quality and help deliver smooth-operating outside mirrors; antennas; and door, trunk and liftgate latching mechanisms. Adaptive front lighting system actuators and guides also benefit.

Interior

As the volume of engine, road and wind noise has been lowered, the need to control buzzes, squeaks and rattles inside the vehicle has soared. With more interior comfort-and-convenience content in cars and trucks alike, along with a myriad of newer, lighter-weight materials, unwanted and unexpected noises can become owner irritants and costly warranty-repair problems.

Molykote solutions for NVH control are used throughout the smart-looking, custom-tailored interiors of today’s vehicles. They help eliminate noise and add a velvety touch to sunroof guides, cupholders and media controls.

Some Molykote greases enhance operation of airbag modules, plastic gears, seating components, window-lift regulators and cable systems. Anti-friction coatings help eliminate stick-slip squeaks from materials used for door and seat trims, instrument panels, consoles, glove boxes, and clips and fasteners. Colorless, non-staining lubricating films stifle noise and add smoothness to sun visors; mirrors; headrest sliders; and window, sunroof and seat guides. Silicone compounds are used on HVAC vents, parking brake cables and wiring harness routing.

Electrical/electronics

Today’s vehicles are electrified as never before. Yet, this is a case where the ‘unseen force’ also may be accused of adding to the challenge for preventing NVH. Molykote lubricants have been quieting various electrical components such as starters, alternators and the small motors used in a number of systems. But, that may have gone unnoticed.

As vehicles of all types have become rolling computers, with new switches for fingertip convenience and smart actuators for system and component control, even a simple click above a whisper is cause for concern. As a result, Molykote solutions are being applied to the full range of multimedia controls and rocker-, toggle- and slider-switch technologies. They are especially effective for quieting noise and smoothing operation of miniaturised motors with plastic gear sets.

Advanced testing and coating expertise

Dow Corning has Application Engineering and Technical Service expertise available in each global region – including India – working on Smart Lubrication solutions for quieting noise and adding smoothness. For drivers, passengers, truckers and open-air riding enthusiasts, the mission is the same: quiet, smooth and lasting – inside and out, regardless of size, weight or cost.

Future challenges

The majority of today’s transportation vehicles are powered by internal combustion engines, and these gas- or diesel-fueled power plants will be with us for some time. The need for high-performance, heat-withstanding, noise-damping lubrication will not soon lessen.

At the same time, rising shares of electric, hybrid and other alternate-power vehicles will not reduce the need for controlling NVH. The challenge for vehicle development engineers to solve NVH issues will only increase. Emerging sounds will include ventilator fans, power electronics, electric motors, battery ventilation and gear noise during regenerative braking.

All said and done, with their experience, ingenuity and problem-solving collaboration, Dow Corning’s NVH experts are helping the transportation industry meet critical needs for less noise and added smoothness.

MATT HAGEMEYER
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