The melting rate of a solid, subjected to a heat flux at its surface, changes with time. When a fresh unmelted surface is first exposed to a heat source, the melting isotherm moves quickly inside the solid. Then its motion slows down: this decrease in melting rate is obviously because of increasing thermal resistance of the growing liquid layer that separates solid-liquid interface from the heat source. If the liquid layer is not removed, the melting rate approaches zero. The resultant melting rate depends on the manner in which the melt is removed. In a number of cases of practical interest, the melt is removed not continuously but periodically, in the form of drops. For example, during arc welding with a consumable electrode, these drops are accumulated at the tip of the electrode. When the drop becomes big enough, it is detached from the electrode under action of gravity or electromagnetic force the melt is removed not continuously but periodically, in the form of drops. A simple approximate method is suggested to calculate the melting rate of a solid in the case when melt is removed periodically in form of drops. The method allows one to consider separately the heat transfer in the solid and in the liquid and, thus, to include different heat processes in both phases. Good agreement was demonstrated for exact and approximate solutions for a wide range of parameters.