GMW 17408 Flexible Expanded Rubber and Rubber-Like Materials for Automotive Sealing Applications

The “GMW 17408 Flexible Expanded Rubber and Rubber-like Materials for Automotive Sealing Applications” standard, developed by General Motors Worldwide (GMW), is a material specification for flexible expanded rubber and rubber-like materials used in automotive sealing and insulation applications. This standard covers materials used in air and dust seals, water seals, gaskets, insulators, rattle protection, and gap sealing applications.

The GMW 17408 standard is particularly important because sealing materials must maintain their functional performance over a wide range of temperatures, environmental conditions, compression levels, and service conditions. This standard establishes a common framework for the classification and evaluation of these materials for General Motors vehicle applications.

The GMW 17408 standard applies to flexible expanded rubber and rubber-like materials that can be supplied as sheets, strips, die-cut components, or sliced ​​products. A pressure-sensitive adhesive may also be added to one side when required by the application. Typical applications include:

• Air and dust seals
• Water seals and gaskets
• Noise and rattle isolators
• Gap fillers
• HVAC sealing components
• Instrument panel gaskets
• Door and closing seals
• Side mirror seals
• Sunroof seals
• Other insulation and sealing components

Commercial automotive foam products certified according to the GMW 17408 standard are used in applications such as instrument panels, HVAC modules, door locks, sunroofs, side mirrors, and NVH seals.

One of the key features of the GMW 17408 standard is its classification system. This specification categorizes materials into different classes and types, allowing engineers to select a material based on its intended function and compression behavior. For example,

• Class I materials can be used in air, dust, and vibration isolation applications and may include open-cell, semi-open-cell, semi-closed-cell, or closed-cell structures. The material type is related to its compression-stretch properties.
• Class II materials are associated with applications requiring waterproofing and therefore their performance is particularly important where moisture ingress needs to be prevented.

Commercial material data shows a classification from Type I to Type V, with progressively different foam properties such as ultra-soft, extra-soft, soft, medium, and hard grades.

The GMW 17408 standard is not limited to a single polymer family. Depending on the application, the engineering drawing or material specification defines the required polymer base. Examples include:

• EPDM: Ethylene propylene diene terpolymer
• NBR: Acrylonitrile butadiene rubber
• PVC: Polyvinyl chloride
• CR/SBR: Chloroprene/SBR blends
• Other approved rubber or rubber-like materials

The specification specifically requires the identification of the polymer base material when the standard is stated in the engineering documents.

It is important to note that this standard does not cover all types of automotive foam. This standard specifically excludes silicone, polyurethane, and polyolefin foams because these material families are addressed in other General Motors specifications.

Some sealing components require an adhesive backing to hold their position during assembly. The GMW 17408 standard allows the use of the “ADH” suffix when an adhesive is specified. In such cases, the adhesive material must meet the requirements of the GMW 16443 standard.

Low-friction coatings may also be specified when the sealant needs to slide against another surface. This is identified using the suffix “CO”. Such coatings can help reduce friction and prevent undesirable behavior between the sealant and the mating substrate.

The GMW 17408 standard evaluates sealing materials through a range of physical and functional requirements. Depending on the material class, type, and application, the evaluation may include the following areas:

• Compression-elasticity: Compression-elasticity behavior is fundamental to sealing performance. The material must generate sufficient sealing force when compressed while avoiding excessive assembly forces.
• Waterproofing performance: For applications where waterproofing is required, the material must exhibit suitable waterproofing properties. This is particularly important for Class II materials.
• Air and dust tightness: Materials used around openings, joints, instrument panels, and other vehicle interfaces must prevent unwanted air movement and dust contamination.
• Environmental resistance: Automotive sealants can be exposed to temperature variations, humidity, weather conditions, and other environmental influences. Their properties must remain suitable throughout their intended service conditions.
• Physical properties: Material classification is supported by physical property requirements that help ensure consistent behavior across production batches and approved material sources.
• Flammability: Depending on the application and material composition, flammability requirements may also be relevant. For example, commercial foam products marketed according to the GMW 17408 standard often also specify compliance with the FMVSS 302 standard.

One of the greatest strengths of the GMW 17408 standard is that it does not treat every sealing application the same way. Engineering documentation should include essential application information, including:

• Polymer-based material
• Class and type
• Interior, exterior, or engine compartment application.
• Required adhesive or coating
• Surface appearance
• Dimensions
• Other application-specific requirements

Specific tests are selected according to the intended interior, exterior, engine compartment, or exterior lighting application. This approach helps to avoid over- or under-specificating the sealant.

The GMW 17408 standard is important because although sealing components may seem simple, failures can cause significant vehicle problems. An inadequate seal can lead to:

• Water leak
• Dust inlet
• Rüzgar sesi
• Creaks and clicks
• Loss of sealing pressure
• Component movement
• Corrosion-related problems
• Reduced NVH performance
• Negative customer perception

The GMW 17408 standard helps General Motors and its suppliers select materials with predictable sealing properties by defining material classifications and performance requirements. It also provides a common technical language among vehicle manufacturers, material suppliers, component manufacturers, and testing laboratories.

The GMW 17408 standard has replaced the earlier GMW 15473 standard.

In conclusion, the GMW 17408 standard is primarily designed for flexible expanded rubber and rubber-like materials used for sealing, insulation, and void management functions. It addresses applications involving air, dust, water, noise, and rattling control and provides a classification system based in part on material compression behavior and intended application.

Compliance with the GMW 17408 standard is important for automotive suppliers because it provides a controlled method for the selection and verification of sealants. The correct class, type, polymer, adhesive/coating configuration, and application-specific requirements must always be confirmed.

For many years, our organization, with its competent and experienced staff, has been understanding the needs of its clients, providing the advanced testing services they require, and assisting them in the establishment, implementation, and improvement of management systems. Within this framework, we also provide testing services in accordance with the GMW 17408 standard.