GMW17408

Description / Abstract: This standard describes the requirements of flexible expanded rubber and rubber-like materials to be used as air and dust seals or water seals and gaskets. These materials may also be used as isolators, rattle protection, covers for gaps and other suitable applications. These materials are typically die cut or slit to width from sheet stock, and may have pressure sensitive adhesive applied to one (1) side.

Material Description. Materials meeting the requirements of this specification will be comprised of four (4) classes and several types.

Class l: Expanded rubber and rubber-like materials to be used for air, dust and rattle isolators. Materials in this class can be open cell, semi-open cell, semi-closed cell, or closed cell materials.

Class II: Expanded rubber and rubber-like materials to be used for water sealing at low compression (30%), and must meet the water sealability requirements of this document. Materials in this class are closed cell materials.

Class III A through E: Expanded rubber and rubber-like materials to be used for water sealing, but at greater compression than Class II materials, and must meet the water sealability requirements of this document. Materials in this class can be open cell, semi-open cell, semi-closed cell, or closed cell materials.

a. Class IIIA: Meets water sealability at 40% compression.

b. Class IIIB: Meets water sealability at 50% compression.

c. Class IIIC: Meets water sealability at 60% compression.

d. Class IIID: Meets water sealability at 70% compression.

e. Class IIIE: Meets water sealability at 80% compression.

Class IV: Expanded rubber and rubber-like materials to be used for lighting applications, and must meet the lighting requirements of this document. Materials approved to Class IV must be sulfur-free. Materials in this class shall be closed cell materials. These materials shall meet water sealability at 40% compression.

Per Table 1 below, Class specific approved materials can be used in applications where there are lesser water sealability requirements. For example, an application requires water sealability at 50% compression (Class IIIB); materials approved to Class II and Class IIIA are permitted to be used in this application.

All materials approved to this specification shall be listed in in the GM Materials Approved Source List. After a material has been granted approval, the required testing for annual material certification shall be all properties listed in Table 3.

Materials are divided into several types, depending on the stiffness (compression deflection).

Materials covered in this specification are resistant to +70 °C continuous and +100 °C excursion. Depending on the base material of the sponge rubber, higher temperature resistance (up to +100 °C permanent) can be obtained. Temperature resistance shall be verified on each foam material, shall be part of the data submitted for approval, and must be specified on the drawing or math data file.

Note: This specification does not cover silicone foams, polyurethane foams, or polyolefin foams. These families of foams have individual GMW specifications. Contact GM Materials Engineering for the appropriate foam specification for these materials.

Material Type shall be identified according to the range of compression deflection. See Table 2.

Certain applications may require the use of an adhesive. If an adhesive (ADH) is required, an ADH suffix shall be added after the basic specification and type number (e.g., GMW17408 Class II Type II – ADH). If an adhesive is specified, the adhesive backed material shall meet the requirements of GMW16443. See Table 7.

Other interior parts may require a low friction coating (CO) to reduce friction between the seal and the substrate. When this coating is required, a CO suffix shall be added after the specification, class, and type numbers (e.g., GMW17408 Class II Type II – CO). See Table 8.

Symbols. Not applicable.

Applicability. Typical applications include: air and dust seals, water seals and gaskets, isolators and rattle protection, covers for gaps, and other suitable applications.

Remarks. To properly use this specification, the information in 1.4.1 through 1.4.4 must be added to the engineering drawing or math data file.

Specify polymer base material, e.g., Acrylonitrile Butadiene Copolymer (NBR), Ethylene Propylene Diene Terpolymer (EPDM), Polyvinyl Chloride (PVC), Polychloroprene/Styrene Butadiene Blend (CR/SBR), etc.

Indicate the ADH or CO suffix if an adhesive or low friction coating shall be used.

Identify application such as interior, exterior, underhood, or exterior lighting. Specific tests are required for each use (see Table 4, Table 5, and Table 6).

Specify surface appearance and dimensions using current requirements as agreed upon between engineering and the supplier.