The Dip-Forming Process

A cool slab of metal when dipped into the bath of a molten metal first freezes metal from the bath; then—if kept there long enough—the frozen crust and the slab melt out. The same result is obtained in a continuous process where the slab is pulled through the melt. In this paper a theory is developed for the process, assuming that the material properties of bath and slab are the same. The governing partial differential equation is established, and is approximated by four-node (“3-channel”) and two-node (“1-channel”) difference-differential equations. It is shown that when the slab is passed through the bath at a speed exceeding a value 5 of the Peclet number p, it is adequate to regard the slab in the calculations as suddenly dipped into the bath and then kept there for a time equal to the time of travel through the bath. The solutions of the 1-channel equations are presented in the form of dimensionless curves which give the mean temperature of the slab as function of position and show the growth and decrease of the slab thickness. Good agreement is obtained with available test results for dip-formed copper.