Identifying Organic Contaminants in Sub Tier Castings Using FTIR Fingerprinting
Attenuated total reflectance FTIR identifies organic parting agents on raw castings before expensive coating processes fail on customer lines.
Paint Delamination
Meaning
Failure of the adhesive bond between a coating layer and its substrate or between two subsequent layers of paint. This separation appears as peeling, flaking, blistering, or cracking of the protective film, exposing the underlying material to environmental degradation. In industrial manufacturing, paint delamination is a critical defect that necessitates the complete removal and reapplication of the coating.
Contamination Cause
Poor adhesion usually results from the presence of oils, waxes, or moisture on the surface of the part before painting. If the pre-treatment cycle fails to remove these residues, the paint cannot form a mechanical or chemical bond with the substrate. Siloxane compounds from nearby molding operations are a common source of such failure.
These substances lower the surface energy, preventing the liquid paint from wetting the surface.
Intercoat Failure
Problems also arise when the time interval between the primer and the topcoat is too long. The base layer may become too hard or contaminated by dust, preventing the next layer from sticking. If the chemistry of the two layers is incompatible, they will separate under thermal stress or physical impact.
Cross hatch testing is used in the lab to verify the strength of the bond between the layers.
Operational Consequence
Repairing delaminated parts requires abrasive blasting or chemical stripping, which increases production costs. Parts that fail in the field are susceptible to rapid corrosion, leading to warranty claims. Ensuring a clean environment and correct curing temperatures is the primary way to prevent this defect.