GMW GMW15067 PDF

This specification details the material and performance requirements for heat-fusible (bakeable) and selfadhesive, bitumen-based, vibration damping sheets. These heat-fusible sheets are intended for application in the assembly plant paint shop to provide local vibration and sound damping effects to the body. They are intended to be applied over metal with cured electrocoat (ELPO) and baked in at least one paint shop oven. The materials are intended for use on horizontal, vertical, or negative horizontal (inverted) surfaces.

Material Description. Heat-fusible damping sheets consist primarily of a bitumen-based damping layer. The sheets may be supplied as a single layer or as a multilayer composite. When multiple layers are involved, the following descriptions are typical (see Table 1).

Adhesion to the substrate may be obtained through the use of a hot-melt adhesive or a heat-fusible film, applied to the bottom surface of the damping sheet and activated by the baking process. Prior to the bake, adhesion to the substrate may be enhanced with a magnetic filler in the bitumen-based layer or with a pressure sensitive adhesive (PSA) applied to the bottom surface of the sheet. Additional layers may be applied to the top surface of the sheet to provide anti-blocking or stiffening.

Only the complete system that has been validated as meeting the performance requirements of this standard shall be allowed.

Heat-Fusible Dampers for Standard Process Paint Shops (Types 1 thru 5). Materials designated as Type 1, 2, 3 and 4 are intended for use in GM paint shops utilizing standard low or high bake primer surfacer paints (solvent-based, water-based or powder). The damping sheets are intended for application on the sealer line over metal substrates with cured ELPO and baked in the primer surfacer and topcoat ovens. All performance requirements must be achieved after the first oven and shall not be negatively impacted by subsequent ovens including topcoat reprocess.

Heat-Fusible Dampers for Non-compressed Integrated Process Paint Shops (Types 1A thru 5A). These materials correspond with Types 1 thru 5 described in 1.1.1, but are intended for use in GM paint shops utilizing a non-baked primer process (non-compressed integrated, waterborne). In the non-compressed integrated process, the damping sheets are intended for application on the sealer line over metal substrates with cured ELPO. In a non-compressed integrated process, the damping mats are baked in a short sealer oven, followed by a waterborne (WB) primer, heated flash and then basecoat, 1K or 2K (1 component or 2 component) clearcoat and topcoat oven. All performance requirements must be achieved after the first oven and shall not be negatively impacted by subsequent ovens including topcoat reprocess.

Remarks. These materials are not intended to be applied in body shop (over oily metal) or in general assembly without a bake (except Type 3/3A and Type 5/5A). The materials specified are not intended for use in areas subject to excessive heat such as directly above exhaust components.