Development of an Online Measurement of Cleanliness on the Zodiac Galvanising Line

The project scope is to develop a test method for measuring contamination films on the steel surface at the Zodiac galvanising line in Tata, which supplies galvanised thin strips to Automotive Customers for pressing into body panels. The Zodiac galvanising line is the final process in a production process that takes several weeks from liquid steel to a coil that is ~0.7mm thick; so the need to achieve a good zinc coating for the required corrosion performance is critical.The strip comes into Zodiac and is welded to the previous coil and then cleaned, annealed and then coated with Zinc before being despatched to the customer. Before the strip is coated in Zinc the surface of the steel is cleaned to remove all contamination; if any minute levels of contamination is left on the steel then the subsequent Zinc coating will not adhere to the steel surface.
To achieve this the cleaning section is complex and involves chemical application and agitation, surface brushing, sprays and drying operations; to optimise the removal of any contamination left on the strip from the previous rolling processes.

It is important to the manufacturing line to be able to measure the surface cleanliness in real time i.e. on the processing line itself. This will enable responsive problem solving to correct any discrepancies with surface cleanliness.

This project is to develop an effective online measurement device with the capability to reliably measure the cleanliness level of the steel surface ahead of coating operations.

The environment poses a few challenges;

The online device would need to continuously measure throughout the length of a steel 20T coil
Identify levels of organic and metallic particles
Quantify the level of residue
Test over a reasonable test area
Ability to accommodate the moving strip surface
Detect very low levels of contamination ie thin layer or isolated particles.