S-EMS Box Type
for slab caster strands
INTRODUCTION
S-EMS Box Type is Rotelec’s external strand electromagnetic stirring solution for slab casters. Mounted in a box configuration behind the rollers of a strand segment, it acts on internal solidification structure by generating a strong horizontal through-thickness AC magnetic field.
As with In-Roll strand stirring, the main objective is not mold-flow control, but internal quality improvement along the strand through better thermal homogenization and a larger equiaxed zone. This type of strand stirring is mainly used in applications where increased equiaxed structure helps reduce ridging and roping, especially on ferritic stainless and high-silicon steels.
HOW IT WORKS
The system uses a linear inductor mounted behind the rollers of a slab caster segment. Its function is to generate a strong horizontal, through-thickness AC magnetic field that induces circulating liquid-steel movement in the strand. In slab applications, this creates the characteristic butterfly stirring pattern that mixes hot and cold liquid-steel regions and promotes a more uniform internal solidification structure.
Box Type stirrers are especially suitable in the upper part of the caster, where the distance between stirrer and slab can remain short. Beyond about 250 mm, very high electrical power is required, making the configuration more expensive and more space-demanding. Segment modification is required, a manipulator is needed for removal, and the coils together with a dedicated heat shield are cooled by demineralized water.
ROLE IN THE PROCESS AND PLANT INTEGRATION
S-EMS Box Type is particularly strategic when a slab caster needs a strong external strand-stirring effect in the upper part of the machine and when the process goal is a larger equiaxed zone rather than mold-flow correction. Compared with S-EMS In Roll, the Box Type concept is more space-demanding and requires segment modification, but it remains very effective when geometry allows a short slab-to-stirrer distance and strong stirring force is required.
From a plant perspective, successful integration depends on segment design, stand-off distance, power availability, water-cooling layout, manipulator arrangement and the targeted steel grades. The system has to be engineered as a process-specific external solution rather than treated as a generic strand add-on.
For slab casters producing ferritic stainless or high-silicon grades and looking to reduce ridging and roping through stronger equiaxed-zone development, S-EMS Box Type is a proven option. Contact Rotelec to assess whether the machine layout and strand position make the Box Type concept the right choice for your caster.
KEY BENEFITS
- A powerful butterfly liquid flow that significantly mix the hotter and colder liquid-steel regions during solidification, resulting in a better temperature homogenization.
- Enhanced equiaxed zone and improved internal structure.
- Reduction of ridging and roping in ferritic and silicon grades where internal structure strongly influences downstream product quality.
- Low maintenance thanks to a design in which the heat shield is the only consumable part.
- Rapid payback through quality improvements, with return on investment typically achieved in under one year.
- A strong external strand-stirring option for applications where short stand-off distance and high stirring force can be achieved.
