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Description / Abstract:
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. 1.1 Material Description. Not
applicable.
Symbols. Not applicable.
Applicability. Electroplated parts of the
copper-nickel-chromium type as used on plastic or metal components
where a bright or low-gloss decorative and/or protective finish is
required.
Remarks.
Deviations. Deviations accepted by GM require,
in every case, GM signed boundary samples that are stored by the
supplier and accepted by both GM Design 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.