Mini-spanglizer - Galvanizing

Mini-spanglizer - Galvanizing - Coating defects

Figure 1: Circular dents induced by the impingement of liquid droplets from the spangle-minimizer.

Defect name: Mini-spanglizer
Record No.: 2002
Type of defect (Internal/Surface): Internal, surface
Defect classification: Coating defects
Steel name: Steel
Steel composition in weight %: No data.
Note: Although the science and technology of continuous galvanizing have improved significantly over the years, it is still a challenge to produce defect-free coatings. Studies indicate that poor substrate surface quality, insufficient strip cleaning, mechanical damage to the substrate surface due to handling, and inadequate process control are the main causes of coating defects. The recent introduction of high strength steels makes the production of galvanized coatings for applications such as exposed autobody panels even more challenging. To produce high quality zinc-coated strip, galvanizers need to improve quality control of the incoming strip as well as the continuous galvanizing process.

The operation of a mini-spanglizer may introduce coating defects. Shown in Figure 1 are circular dents apparently caused by the impingement of liquid droplets from the spanglizer. If spangles are minimized through the spray of zinc dust to the coating, residual zinc dust may accumulate on rolls down the stream, causing coating defects.
Reference: Not shown in this demonstration version.