Specifications and Testing

Kiegle‐Böckler, Gabi; Pausch, Gerhard; Schwarz, Jörg; Streitberger, Hans‐Joachim; Wagner, Gerhard

doi:10.1002/9783527622375.ch12

Cited by 4 publications

(8 citation statements)

References 24 publications

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“…Instead of the approaches that aim at defining tolerance ellipsoids in CIELab‐space, as just described, a different approach is to transform the underlying color space coordinates such that it becomes uniform. This approach was taken by the German Standards Institute DIN, and used by the German automotive industry . By definition, tolerances in the resulting DIN99 space are given by discrimination spheres, instead of ellipsoids .…”

Section: Some Current Issues In Setting Qc Color Tolerancesmentioning

confidence: 87%

“…p. 174, 175, and 225 of Ref. 2) . For example, tolerance in terms of dE CMC (2:1) increases from 0.79 at 110° to 1.32 at +15° aspecular angle according to some studies, and from 1.43 at 110° to 2.75 at 15° according to another .…”

Section: Improving the Process Of Setting Qc Color Tolerancesmentioning

confidence: 90%

“…In these combined equations, color differences measured for geometries close to the gloss angle are found to contribute less than color differences measured for the 25° or 45° geometry . This agrees with the empirical finding that for QC of effect coatings, tolerances for angles close to the gloss angle are substantially larger than for the 45° geometry …”

Section: Improving the Process Of Setting Qc Color Tolerancesmentioning

confidence: 99%

“…Indeed, for QC, dE cmc (2:1) is often used in the automotive industry . Examples are a pass‐fail criterion of dE cmc (2:1) = 1.0 for metallic colors and dE cmc (1:1) = 0.5 for solid colors . Apart from that, additional tolerances are often used for the color coordinates L *, C *, and H *.…”

Section: Some Current Issues In Setting Qc Color Tolerancesmentioning

confidence: 99%

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Setting tolerances on color and texture for automotive coatings

Kirchner

Ravi²

2012

Color Research & Application

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In the automotive industry, color quality control is increasingly done by reflection measurements. We discuss how color tolerances are set in specifications to suppliers of add‐on parts and to paint suppliers. We mention several factors that often lead to unrealistically tight settings, and therefore to incorrect rejections and unnecessary high productions costs. We show that this is likely to occur when the dEab color difference equation is used, or when a strict criterion separating pass from fail is used instead of specifying a “grey area” where instrumental monitoring needs to be followed by visual assessments. Unrealistically, tight tolerances also result from halving tolerances in the supply‐customer chain in an attempt to compensate color variations due to uncontrolled application conditions. Tolerances should be widened further when a gap separates an add‐on part from the car body, making visual discrimination of color differences less critical. Other common situations where tolerances should be widened are the presence of visual texture in effect coatings, the lightness of metallic coatings becoming very high (L*> 100) and measurement geometries close to the gloss angle. Finally, we address the issue that instrumental color tolerances should not be tighter than what is allowed by instrumental reproducibility, repeatability, and inter‐instrument agreement. Accounting for these factors, we provide a set of reasonable values for tolerances on color and on visual texture parameters, based on our own practical experience. But realistic tolerance values depend very much on actual conditions, and should be agreed in tripartite discussions among automotive industry, suppliers of add‐on parts, and paint supplier. © 2012 Wiley Periodicals, Inc. Col Res Appl, 39, 88–98, 2014

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Section: Some Current Issues In Setting Qc Color Tolerancesmentioning

confidence: 87%

Section: Improving the Process Of Setting Qc Color Tolerancesmentioning

confidence: 90%

Section: Improving the Process Of Setting Qc Color Tolerancesmentioning

confidence: 99%

Section: Some Current Issues In Setting Qc Color Tolerancesmentioning

confidence: 99%

See 2 more Smart Citations

Setting tolerances on color and texture for automotive coatings

Kirchner

Ravi²

2012

Color Research & Application

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“…17 In the process, the backscatter behaviour of a light source is looked at and the waviness of the surfaces is quantified in terms of a short-term and a long-term waviness (LW) range. 17,18 The limit values of waviness for Class A surfaces are not precisely defined. However, waviness values based on experience exist which are minimum requirements for painted Class A surfaces (according to Gru¨nberg 19 : Short wave: <30; long wave: <15; according to Schubel et al 18 : Short wave: <20; long wave: <8).…”

Section: Surface Characterizationmentioning

confidence: 99%

Identification and quantitation of processing parameters controlling the surface quality of carbon fibre-reinforced composites

Kunze

Mahrholz

Sinapius

2016

Journal of Reinforced Plastics and Composites

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The paper investigates the effect of essential manufacturing parameters on the surface quality of uncoated carbon fibrereinforced composites used as car body panels with visible surfaces (Class A properties). A series of carbon fibrereinforced composites laminates were prepared by the resin transfer moulding technique varying the fibre volume content (30 to 60 %), reinforcement material (woven fabrics vs. unidirectional fibre reinforcements), curing temperatures (40 C to 120 C), additives (SiO 2 nanoparticles as matrix fillers) and using a surface finish applied as an in-mould coating. Laminate surfaces were characterised by roughness analysis (white-light interferometry) and wave-scan measurement to quantify the influence of the different manufacturing parameters on the surface quality. Especially, the used resins were intensively characterised concerning thermal properties and total resin shrinkage. These results correlate very well with the performed analysis of surface roughness. It is found that the fibre print through effect is significantly reduced by realising low total resin shrinkage and an even distribution of resin and fibres at the surface. Thus, using of unidirectional fibre reinforcement (no weft or sewing threads; very fine filaments), low curing temperatures (slow curing processes) and an in-mould coating are most successful for reduction of fibre print through effect and getting surface similar to Class A properties. In addition, the surface quality is quite positively affected by the application of nanoparticles and also strongly controlled by roughness of tooling.

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Surface Quality of Carbon Fibre Reinforced Nanocomposites: Investigation and Evaluation of Processing Parameters Controlling the Fibre Print-Through Effect

Mahrholz

Sinapius

2021

Acting Principles of Nano-Scaled Matrix Additives for Composite Structures

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Specifications and Testing

Cited by 4 publications

References 24 publications

Setting tolerances on color and texture for automotive coatings

Setting tolerances on color and texture for automotive coatings

Identification and quantitation of processing parameters controlling the surface quality of carbon fibre-reinforced composites

Surface Quality of Carbon Fibre Reinforced Nanocomposites: Investigation and Evaluation of Processing Parameters Controlling the Fibre Print-Through Effect

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