Appearance Standard for Decorative Chrome-plated Metals and Plastics
|Publication Date:||1 February 2020|
Note: Nothing in this standard supercedes applicable laws and regulations.
Note: In the event of conflict between the English and domestic language, the English language shall take precedence.
This standard describes the surface appearance and quality requirements for evaluating the appearance of production-level, chrome-plated, interior and exterior metal and plastic parts.
Criteria is established for the determination of allowable appearance criteria based upon the significance of the chrome-plated surface as outlined in standard specifications for electrodeposited coatings for plastic and metal parts (ASTM B604 and ASTM B456, respectively). This specification defines appearance definitions for chromeplated parts covered under GMW14668, GMW14672, GMW15613, and any other decorative chrome-plated performance specifications. ASTM B456 and ASTM B604 define significant surfaces as those surfaces normally visible (directly or by reflection) that are essential to the appearance and/or serviceability of the component when assembled in normal position, or that can be the source of corrosion products that have the potential to deface visible and significant surfaces on the assembled component.
If, after field exposure or accelerated corrosion testing, product corrosion is experienced but not previously considered for degree of visibility, surfaces are permitted to be redefined on the drawing. Contact GM Materials Engineering or the part Subsystem Management Team (SMT) if assistance is needed in defining part surfaces.
Table 1 defines minimum appearance criteria for surfaces based upon degree of visibility. These significant surfaces are to be defined by degree of visibility and indicated on the part drawings.
Note: When defining these visible surfaces, the appearance of corrosion as a result of accelerated testing or field performance can affect the degree of visibility of that surface and is also considered as part of the criteria defining the significance of that surface.
Electroplated parts of the copper-nickel-chromi
Deviations accepted by GM require, in every case, GM signed boundary samples that are stored by the supplier and accepted by both GM Appearance Quality and the respective assembly plant. The visual comparison to accepted boundary samples is always the most decisive method. For evaluating appearances that are subject to interpretation, pick master and boundary samples that are acceptable to all parties involved through assembly. The supplier and GM assembly plant should agree on target, upper limit, and lower limit boundary samples. Appearance Approval Report (AAR) samples should be used for standard reference and initial part submissions. The effects of potential corrosion need to be taken into account for any deviation consideration.