The caster is a wonderfully forgiving caster concerning the range you can work with and not have catastrophic problems. Armco, Trico, and other steelmakers are installing refined mold-level control to reduce breakouts. Among the improvements, computer software today is better at recognizing the effects of changing casting speeds. The oscillation is a key element of the Armco and Ipsco casters. Both casters have molds that are lighter-weight for improved oscillation, and both have hydraulic oscillators.
Oscillators basically vibrate the steel shell out of the mold.
Stroke is the magnitude of the oscillation. Hydraulic oscillators are becoming more popular. They're a motor driving a gear box which is turning a cam or short lever. But hydraulic oscillators allow quick-changing of both stroke and frequency. This greater control over oscillation can improve surface quality because the mill can tailor oscillation for each grade.