The slip plane, when positioned against the coil screed, serves a crucial role in ensuring a smooth surface for the refractory lining. This smooth surface is essential for allowing unimpeded reversible movement of the refractory lining, which occurs due to thermal expansion and contraction during the operation of the equipment.

By facilitating smooth movement, the slip plane helps prevent the refractory lining from becoming distorted or damaged due to the stresses induced by thermal cycling. This is particularly important in high-temperature environments such as those found in steelmaking processes.

Moreover, the presence of mica in the slip plane provides an added layer of protection against metal penetration. Mica is known for its resistance to heat and chemicals, making it suitable for use in applications where it acts as a barrier between the refractory lining and the molten metal. This protection helps extend the lifespan of the refractory lining and maintains the integrity of the equipment.

Overall, the combination of the slip plane and mica contributes to the effective performance and longevity of the refractory lining, ensuring smooth operation and minimizing the risk of damage from thermal expansion, contraction, and metal penetration.