Theoretical Analysis of Roll-Over-Web Surface Thin Layer Coating

Tareq Manzoor,Kashif Nazar,Sanaullah Manzoor,Muddassir Ali,Mahmood Saleem,Muhammad Zafar,Woo Young Kim,Shaukat Iqbal

doi:10.3390/coatings10070691

Abstract

This study presents the theoretical investigation of a roll-over thin layer formation under the lubrication approximation theory. The set of differential equations derived by lubrication approximation is solved by the optimal homotopy asymptotic method (OHAM) to obtain precise expressions for pressure and velocity gradients. Critical quantities such as velocity, pressure gradient, and coating layer depth are numerically estimated. The impact of parameters affecting the coating and layer formation is revealed in detail. Results indicate that the transport properties of the higher-grade fluid play an essential role in regulating velocity, pressure, and the final coated region. Moreover, couple stress effects on the properties of fluid particles to be coated on roller-surface have also been studied.

Highlights

Roll-coating is a technique in which liquid is allowed to flow over a sheet/web to form a micro-nano scale thin layer coating over a surface
Optimal homotopy asymptotic method is a semi-analytical approximate approach to solve non-linear problems [15,16,17,18,19,20]
The movement of plate considered is with uniform velocity U1∗ and in the direction of positive x-axis H0 is the width called as nip-region between plate and roll

Summary

Introduction

Roll-coating is a technique in which liquid is allowed to flow over a sheet/web to form a micro-nano scale thin layer coating over a surface. Zahid et al [11] investigated the roll coating process using a third-grade fluid lubrication approximation and numerically estimated all the important properties. Ali et al [13] studied the web-coating technique for a couple stress fluid by using the lubrication approximation theory. They measured all the essential properties such as pressure gradient, pressure, velocity, roll-separating force, power input, and velocity. Optimal homotopy asymptotic method is a semi-analytical approximate approach to solve non-linear problems [15,16,17,18,19,20] This technique is independent of any large/small parameters as compared to other method of perturbation.

Materials and Methods

Results

Conclusions