DSM cosmetic inspection standard
Applicability
This Cosmetic Inspection Standard applies to all requirements for cosmetic inspection on drawings for sheet metal parts after chemical coating such as chromate conversion and anodizing.
General
Cosmetic inspection shall use the Time and Distance Inspection procedure described below and shall rely on the judgement of trained inspectors and suppliers. The Cosmetic Reference Standard defined in this Specification is to be used for training inspection personnel and may be used to assist in making an accept/reject decision.
Process control
Manufacturing steps that might affect finished part appearance shall be prepared to enable compliance with this cosmetic specification.
Order of inspection
Cosmetic Inspection of finished parts shall be performed as the last inspection by DSM and the first inspection by the customer.
Viewing conditions
Parts and products shall be inspected under the following conditions.
- Uniform, nondirectional illumination between 80 and 150 footcandles. At levels greater than 150 footcandles caution should be used to not over inspect.
- Parts shall not be manipulated to reflect a single light source in order to accentuate surface flaws. View without directly reflecting a light source.
- Magnification is not to be used when inspecting for cosmetic defects.
Cosmetic class codes
The cosmetic class codes used in this Standard use Roman Numerals "II" through "III". Class "I" is reserved for mirrored or optical surfaces and is not considered in this Standard. Class "II" is generally specified for front panels or exterior surfaces of an assembly. Class "III" is generally specified for interior frames and chassis not visible in the final assembly. To refine the cosmetic classes further, a suffix letter "A" through "D" is appended. Class "IIA" would indicate a very critical surface, where "IIC" might be used to indicate an important surface, but less so than "IIA". The lowest cosmetic designation would be "IIID", which is basically "no requirement" for beauty.
Time and distance inspection
"Viewing Time" indicates the duration of the observation. The more critical the cosmetic surface, the longer the inspection period. "Viewing Distance" indicates how far the inspector will be from the parts. The more critical the cosmetic surface, the closer the inspector will be to the parts. Parts shall be inspected in accordance with instructions and codes on the part drawing. If the drawing references this specification the codes will reference Table 1 "Viewing Time and Distance". On drawings referencing this specification, surfaces not cosmetically coded shall be considered IIIC.
Accept/reject
When flaws are observed within the specified time and distance and the accept/reject decision is difficult to make, refer to Table 2 "Cosmetic Reference Standard". Parts are often cosmetically acceptable even though flaws are noticeable.
Repetitive inspection
A flaw that occurs repeatedly in the same surface location becomes more easily noticed. If this same cosmetic flaw was judged acceptable at the beginning of the inspection of the run or lot, it shall also be acceptable at the end.
Reference dimensions
Dimensions locating cosmetic areas designated by phantom lines are "reference" and should not be measured.
Terms and Definitions
(See Table 2)
- Discoloration - Any change from original color or unintended inconsistent color.
- Glossiness - An area of excessive or deficient gloss.
- Lint - Any unintended foreign substance in the coating or on the surface.
- Marks - Pits, sanding or other marks on the base material that remain visible after coating.
- Blisters - Non adhesion. Lack of proper sticking of the coating to the surface.
- Nonuniform coverage - Areas that have an insufficient or excessive coating.
- Runs - Excessive coating that causes drips or nonuniform coverage.
- Scratches - Shallow grooves.
- Specks - Small Particles.
Table 1:
Viewing Time and Distance
Indicates the viewing time and distance to be used for various cosmetic standard codes. "External" applications include front panels, covers, and frames that are readily visible in the final assembly. "Internal" components are generally seen only by assembly and technical personnel and are less important cosmetically. Some components, such as the inside of a door, may have both and internal and external application.
Table 2: Cosmetic Reference Standard
Lists flaws typically found on coated parts. This table constitutes the reference standard of cosmetic acceptability. The total number of allowable mixed flaws shall not exceed the limit specified for the flaw with the largest allowable quantity limit. Table 2 is primarily used to train personnel involved in inspection and may be used to assist in making an accept/reject decision.
Note 1:
As shown in Table 2, if a part surface is coded IIIC, flaws exceeding those allowed under IIIB are permitted; however, when viewed at the specified time and distance, the flaws must not be so obvious as to suggest inferior workmanship or processing.
cosmetics
