Hot Dip Galvanization is a form of galvanization is the process of coating iron , steel or aluminum with a layer of zinc y immersing the metal in a bath of molten zinc at a temperature of around 450 ( 0 c). Stabilizing the thickness of the coating and controlling the size of the spangles in continuous hot dip galvanizing line is a major concern in that industry. In recent years, many efforts have been devoted to analyze the effect of different parameters of the air knives (the main part of the galvanizing line which fixes the zinc coating and raises the spangles) on the coating thickness. These parameters include line speed, distance between nozzle to strip, height from the Zinc bath, inlet pressure, geometry of the nozzle and the environment temperature. Some others also focus on simulation of the phenomena and also the bath conditions. The present research is about designing and manufacturing of a mechanism to adjust those parameters and have a control on them. After presenting the background and previous researches on this subject and some basic information, an air knife mechanism is designed and simulated based on the highlighted parameters. Different parts of the mechanism are manufactured and proposed to be assembled. Then a theorical model is proposed to predict and estimate the coating thickness. This equation is retrieved by the real production-line values using multi variable surface-fitting method of regression and suggested to be utilized in different companies. The maximum error between the equation values and the real values is acceptable. An interface is also added to this mechanism to have a real and true understanding of all working conditions and parameters. A vision-base device is also proposed to make the operator have a complete control on the spangles and other coating parameters of the line. This interface divides the parameters into three categories. First category is the fixed parameters such as the strip thickness, height from the zinc bath and strip width. The second category includes strip temperature, input pressure and line speed which are called the local parameters. The last category includes distance to strip and the nozzle angle which are called the changeable parameters. All these values and the coating thickness are saved in a database which not only can used in production line but also enables the operator to use them in an analytical analysis. This analytical analysis is also performed on the mechanism to predict the outlet air pressure of the air knife. This system provides more flexibility and reliability for controlling spangles’ size and shape while better quality can be achieved. Keywords: Hot dip galvanizing, Coating thickness, Air Knife, Spangle, Zinc coating,