Foam might be the ultimate problem-solving material. It's what auto industry engineers reach for to eliminate squeaks and rattles, to prevent fretting, absorb noise and seal interfaces. No driver ever boasted about the foam used in their car or truck, but without it the vehicle wouldn't feel as good, perform as well or last as long. As a leading fabricator of flexible foam, Merryweather is positioned to help automotive OEMs, Tier 1's, and beyond solve their problems. Read on to learn how precision-cut foam components and materials help build high quality vehicles.
Auto Industry Challenges
The auto industry is on a roll right now. 2015 saw record sales, and some are predicting an even better 2016, but car companies aren't getting complacent. It's a highly competitive industry facing an array of challenges, from EPA gas mileage mandates to customer satisfaction scores, warranty costs and recalls. Here are three issues keeping automotive engineers awake at night, and what foam can do to help.
- Perceived Quality - Squeaks, rattles and vibrations might seem minor, but they have a big impact on how buyers feel about their vehicle and reflect in Consumer Reports and J.D. Powers rankings. Foam used between mating surfaces absorbs relative movement and prevents irritating noises. It can dampen vibrations and absorb transmitted sound, helping give occupants a sense of riding in a quality vehicle.
- Fuel Economy Mandates - Refining engine technology and launching hybrids and pure electrics isn't going to be enough. Lightweighting is essential and automakers are moving as fast as they can, but risk reducing structural stiffness. More flex means more squeaks and rattles, and greater likelihood of water ingress. Correctly selected foam compresses and springs back, filling variable gaps and sealing effectively. Plus, foam is inherently a lightweight material.
- Cost Control - Foam helps manufacturers address cost in three ways. First, by preventing problems like water ingress it helps bring down warranty costs and avoid recalls. Second, its ability to accommodate variable gaps grants designers greater freedom in tolerancing components, in turn reducing tooling costs and increasing yields. And third, used as a contact material in dunnage, it helps prevent scrap due to damage to Class A surfaces.
In cars and trucks foam is used primarily for comfort and cushioning, gasketing and sealing, and noise attenuation. Cushioning applications tend to be more form-in-place than foam fabrications. It's a specialized area with the materials being formed to shape and sometimes integrally bonded to surface materials. Although technically a foam application, the focus here is on flexible foam fabrications.
In terms of piece count, gasketing and sealing probably represents the largest usage category. Foam gaskets of various types are used on external body surfaces, under the hood and in the passenger compartment.
Around headlamp, tail lamp and CHMSL clusters foam gaskets prevent water ingress by filling gaps that vary as a result of manufacturing tolerances. Under mirrors, door handles and latches, and antenna mounts they stop hard plastic or metal components rubbing against paint and forming sites where corrosion can start. Under the hood foam locates and shields sensors and fluid reservoirs, reducing the transmission of vibration and providing EMI shielding. Internally, foam seals joints in HVAC ducting and insulates it from body structures. Airbag components are sealed with foam gaskets, as are occupant sensors and instrument or gauge clusters. It also makes an ideal gap filler between trim pieces.
Noise attenuation is the third usage category. By stopping parts from rubbing together, foam fabrications can deaden squeaks and rattles. Foam can also absorb noise transmitted through the structure and prevent it reaching the cabin.
Another big automotive use for foam is in dunnage. Custom formed foam dunnage, as described in "Polyethylene Foam: An Excellent Material for Automotive Dunnage Racks," is a great way of reducing losses due to marking of Class A surfaces in transit or while moving dunnage lineside.
Foam Properties and Selection
Perhaps foam was once selected on a trial and error basis – the engineer squeezing a piece into a gap and if it stopped the rattle, moving on to the next job – but it's not done that way today. Modern foams are as highly engineered as every other part of the vehicle, and come in a wide range of properties.
Density is a major concern, because that drives weight and influences performance. Denser foam is usually more robust and gives higher compression force deflection numbers, although density correlates poorly with firmness. In some applications feel is the primary concern, in others it's natural frequency.
Then there are the material properties. Foam used externally must resist water ingress, endure the rigors of the carwash, and withstand UV exposure without crumbling or cracking. Closed cell foams are generally selected when sealing is a priority, although the increased compression resistance can raise clamping loads. Inside and under the hood high temperatures can be a huge challenge, yet the same vehicle could also see bitter winter lows, so temperature ranges will be important.
When selecting foam for a particular application, it's essential to remember that it's not all the same. The decision should be made based on science and engineering, not "poke and hope!"
Foam Manufacturing Processes at Merryweather
Merryweather has foam fabrication equipment suitable for both low volume or sample production as well as long runs and high quantities.
Water jet and digital knife cutting are ideal processes for prototype development and pre-production samples. With no special-purpose tooling lead times are minimized and the machines can be programmed direct from the CAD files.
For volume production of gaskets it's hard to beat the efficiency and consistency of die cutting. Steel rule dies slice through thin foam sheets, producing excellent dimensional repeatability and good edge quality. Nesting gives excellent material utilization and "kiss-cutting" allows gaskets to be delivered on a roll for easy storage and peeled off when needed. Foam sheets can be given a pressure sensitive adhesive coating that eases application.
A Problem-Solving Material
Auto companies face an array of challenges, from lightweighting to improving perceived quality. What engineers need is a robust yet inexpensive material that takes up manufacturing tolerances, stops water penetration and prevents squeaks and rattles.
Flexible foam fabrications are ideal for addressing all these problems. A conversation with Merryweather will highlight the many ways in which carefully selected and shaped foam pieces can help. To learn more about Merryweather's automotive capabilities, contact us today!