The 220×1200 Circular Hole Hollow Slab Equipment​ is a heavy-duty, long-line pretensioned concrete extrusion machine launched by Shuangli Building Materials Machinery Factory (Est. 2005, Ningjin, Shandong) for the large-span precast component market. The designation "220×1200" refers to a finished slab thickness of 220 mm and a width of 1200 mm, configured with 6 circular cores. It is a flagship model within the 1200 series, known for its high load-bearing capacity and exceptional span performance. It is widely used for floor and roof systems in industrial plants, schools, hospitals, shopping malls, office buildings, and large-bay residential structures.

This equipment has been delivered in volume to overseas markets including Iraq, Uzbekistan, India, Russia, and Myanmar, and is compatible with ISO-standard bed production lines.

The machine operates on a long-line prestressing bed​ where high-tensile, low-relaxation steel strands have been pre-tensioned:

1. The main motor drives a spiral auger​ via V-belt pulleys and a heavy-duty horizontal reducer.
2. Dry-mix concrete from the hopper is continuously fed into the forming chamber defined by side plates, a vibrating base plate, a screeding plate, and the bed surface.
3. A medium-frequency vibration system (~100 Hz)​ works in tandem with the auger to plasticize the concrete, expel air, and ensure high density.
4. The reaction force from the compacted concrete propels the machine forward along the prestressed strands at a uniform speed (1.0–1.2 m/min).
5. A rear screeding plate finishes the slab surface as it exits. After approximately 48 hours of natural curing, the continuous slab is cut to length (up to 10.5–11 m).