A. Cleaning Steel Strip Surface
Cold rolled steel strip contains iron fines and lubricant oil on the surface need to be cleaned to optimized cleaning process, CSL utilize 3 cleaning methods :
1. Chemicaly cleaning using alkaline solution.
2. Mechanically cleaning using brush scrubber.
3. Electrically cleaning using electrolytic process.
B. Non Oxidized Furnace (Nof)
CSL has 125 meter length non-oxidized furnace to ensure the homogenous mechanical properties of the product and maximize alloy metal coating adhesion. Non Oxidized Furnace has the ability to perform annealing process which gives lower yield and tensile strength as required by customers. Three stage process at Non oxidized furnace :
1. Heating.
2. Holding / Soaking.
3. Cooling.
C. Coating Process
After cleaning and heating, the steel strip dipped into the 55% Al-Zn alloy molten metal. The hot dipped coating process equiped with :
1. Pot which contains 55% Al-Zn alloy molten metal.
2. "Air knife" to control the thickness (coating mass) of coated alloy metal.
3. 4 stages vertical air cooler and 2 stages horozontal air cooler.
4. Water quenching.
D. Surface Conditioning
Skin Conditioning Mill (SCM) and Tension Leveler are available to make up the conditions of product surface:
1. SCM is applied to get smooth and flat on product surface which is suitable for painting process.
2. Tension Leveler is applied to achieve straigthness and flatness which are crusial for certain application.
E. Surface Finish Treatment
Three applicable alternatives for Saranalume finish product :
Passivation Coating
Prevent 55% Al-Zn coating surface from premature oxidation during storage, which is called "black rust".
Resin coating
Give "anti finger mark" property and also act as lubricant during roll forming.
Oil Coating
Give temporary coating surface protection for certain application.