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New Body Technologies: Laminated Steel and Foams

New materials being used in car body construction

by Julian Edgar

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At a glance...

  • Laminated steels and structural foam
  • Characteristics
  • Identification
  • Repair
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This material first appeared in the I-CAR Advantage Online, which is published and distributed free of charge. I-CAR, the Inter-Industry Conference on Auto Collision Repair, is a not-for-profit international training organization that researches and develops quality technical education programs related to collision repair. To learn more about I-CAR, and to subscribe to the free publication, visit

Laminated Steels

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Laminated steel is a type of "sandwiched" sheet metal that uses two layers of steel bonded together by a polymer core. Consumer demand for quieter vehicles is the primary reason for using this type of material for automotive parts. One trademarked material, named Quiet Steel®, is used on some of the newer General Motors, DaimlerChrysler, and Ford vehicles. The core of Quiet Steel has a "visco-elastic" property that effectively reduces vibration transferred through the panel. By reducing vibration, noise is also reduced.

  • History

The UltraLight Steel Auto Body (ULSAB) consortium developed a similar type of material in the 1990s. This worldwide consortium consisted of 35 steel producers from 18 different countries with the common goal of designing an all-steel lightweight vehicle while maintaining structural integrity and affordability.

The ULSAB version of laminated steel was developed along with other innovations including tailor-welded blanks, advanced high-strength steels, and the hydroforming processes used to form steel. This material had a polymer core of 0.650 mm between two sheets of steel. It was used for the dash insert panel and spare tyre tub on the ULSAB unibody concept structure that was completed in 1998. Both laminated steel parts were lightweight and had sound-absorbing capabilities, but neither could be welded because the polymer core was too thick. The parts were attached to the structure with bolts, rivets, and adhesive.

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The polymer core of the ULSAB laminated steel was much thicker than the 0.025 mm core of current Quiet Steel panels.

The first body application of Quiet Steel in a production vehicle was the cowl panel of the 2001 Ford Explorer Sport Trac. This type of application of Quiet Steel later won the Premier Automotive Suppliers’ Commitment to Excellence (PACE) Award for the cowl panel on the Cadillac CTS.

  • Benefits

Currently, some of the body parts made using laminated steel include cowl panels, lower plenums, storage tubs, and for other areas where noise, vibration, and harshness (NVH) is a concern. Some mechanical parts, such as the oil pan on the 2004 Ford F-150 Triton V8, are made with laminated steel.

Using this material allows vehicle makers to produce quieter vehicles without adding extra steps during assembly. Another benefit is that the material is 100% recyclable compared to other non-recyclable materials like thick carpeting, cotton shoddy, foam, and mastics. Replacing non-recyclable materials with laminated steel may also increase the amount of interior space in the vehicle.

  • Characteristics

Characteristics of the steel, and total thickness, typically remain the same when a part is made with laminated steel. The laminated material is shipped to stamping plants in a continuous coil or steel sheets. There, the parts are stamped, E-coated, and shipped for assembly. The material can be welded because the core is only 0.025 mm thick. Parts are commonly attached at the factory with squeeze-type resistance spot welding (STRSW). Other attachment methods may also be used.

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DaimlerChrysler uses a windshield urethane adhesive for attaching the laminated steel seat tubs on mini-vans with Stow N’ GoTM seating.

  • Repair Issues

Some repairability issues include identifying parts made of laminated steel, varying recommended repair procedures, and different joining techniques.

Currently, most locations of parts made of laminated steel do not provide adequate accessibility for using STRSW equipment during repairs. MIG plug welds are sometimes recommended, but weld contamination from the polymer core may arise. Achieving adequate penetration through both layers of steel into the backside may be another problem. Practice welds help to identify the proper settings and techniques used to reduce contamination and achieve proper penetration in the weld, but this can only be done if laminated steel is available. A good practice is to keep a piece of this material in the facility for future repairs that require sample welds.

When making test welds, it is important to use a piece of laminated steel that closely matches the thickness of the intended repair. The total thickness of laminated steel can range from 0.8 mm to 3.0 mm and the polymer core can be specifically "tuned" for the type of noise the part is designed to absorb. Differences in thickness or composition may affect the welding characteristics of the part.

To avoid these concerns, General Motors recommends rivet bonding for repairs that involve laminated steel parts. When repairing laminated steel Stow N’ Go seat tubs, DaimlerChrysler recommend that the repaired or replaced tubs be reattached with a urethane adhesive. MIG welds are recommended for attaching the apron to the laminated steel cowl panel on the 2004 Ford F-150.

  • Identification

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At first glance, laminated steel parts may look identical to parts made of non-laminated steel. A closer look at the edges of the panel may show two separate pieces of steel sandwiched together – as pictured. To confirm, a firm tap on the part may also help identify that the part is laminated steel. Of course, vehicle maker service information is the best method to identify and determine proper repair processes for this new material.

  • Conclusion

Laminated steel is a sandwich-type material designed to reduce vibration and noise. Laminated steel has helped vehicle makers design quieter vehicles without adding additional assembly steps. It is a recyclable material and can reduce the amount of other non-recyclable sound-absorbing materials added to a vehicle. Repair technicians should be aware of the proper joining techniques to use when working with laminated steel. Vehicle makers may also have different recommendations for repairing these parts.


Foams seem to be the latest innovation used throughout the vehicle for the ultimate benefit of the occupants. Foam materials used during vehicle repairs are typically two-part materials that can change in state and shape after they are dispensed.

  • NVH Foam Categories

Some of the first foam materials were used for NVH control. NVH foam materials are currently broken into four categories: sound-dampening material, flexible, rigid-type, and structural. Rigid-type foam is broken into three sub-categories.

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Sound-dampening material is an NVH foam used for covering or sealing small openings that are easily accessible, and for reattaching existing foam. This is a two-part product that is black, heavy bodied, and non-expanding, much like windshield urethane or seam sealer when compared to common two-part expanding NVH foam.

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Another NVH material is flexible foam. Flexible foam is soft, compressible, and returns to its original shape without retaining permanent deformation.

Rigid-type foam is the NVH material that currently has three sub-categories. These sub-categories include rigid, semi-rigid, and pillar foam.

Each material has distinct characteristics as an NVH control product. Rigid foam reacts differently than flexible foam when compressed. Rigid materials have a much lower compression rate when a force is applied and may remain permanently deformed when the force is removed. The main difference between rigid and semi-rigid is the strength of the material. Pillar foams are typically rigid foams with unique foam times and flow rates. This allows them to be used in situations where foam placement is difficult.

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The latest material introduced to the foam family is referred to as structural foam. Structural foam is used for stiffening parts of a vehicle chassis/body and for increasing occupant protection in the event of a collision.

  • Foam Replacement Considerations

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Along with identifying the material originally used in the vehicle, there are other considerations that affect installing replacement foam. These include determining the amount of material to be installed, how to get the material to a specific location, and how to get the foam to adhere in a specific location. Expansion rate, viscosity, and foam time are among the variables that must be considered.

The expansion rate of a foam product is typically given as a maximum amount. Products may have expansion rates listed as "up to ten times." The actual expansion rate of the foam may change based on many variables, some of which technicians can control. To determine how much material should be installed in a part, the volume of the void to be filled should be calculated. After determining the volume of the void, and matching that to the approximate expansion rate of the material being used, the proper amount of two-part foam can be determined.

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Knowing the viscosity and foam time of different foams can be helpful when determining how to place the foam in specific areas. Sometimes, due to location and access, it is difficult to hold foam in specific areas. When this is the case, dams can be used. Depending on where the dam is to be placed, it can be installed either before or after parts are assembled. There are many different acceptable materials that can be used as dams. The most important consideration for using a dam is determining its ability to retain moisture. Do not use materials that have the ability to retain moisture.

  • Conclusion

Overall, there are six different classifications of foam, along with a variety of application techniques that may be required for positioning the material. Choosing the correct replacement material is important, as is using the proper amount of foam and properly filling the specific area.

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