In the 1930’s hollowcore machines used slipformers or machines featuring the “tube pull” method to extrude the cores.
Vibrating extruders, currently used by our competitors, were introduced in the 1970’s using an electric motor to rotate the eccentrics at a vibration frequency of 50 – 250 Hz. This method offered easy production with improved efficient compaction but inconsistent quality due to the vibration. The vibration caused high noise levels and machines prone to breakdowns.
The first shear compaction extruder was introduced by Elematic in 1985.
How does the shear compaction work?
The concrete is compacted at a vibration frequency of approximately 10 Hz by the means of a controlled three-dimensional motion. The efficient feeding screws play a dual role pushing the Extruder forward on the casting bed while compacting concrete.
Less vibration and moving parts creates consistent casting of exact required dimensions and smoother surfaces left behind.
When making concrete no two batches are the same as it is impossible to 100% control the exact inputs of stone, powder, cement and water (temperature) and friction from the strands that create changes in resistance when casting. The Elematic E9 extruder’s automatic compaction control senses the consistency of the concrete by measuring the resistance from the screws and based on this information the casting parameters are adjusted in real time: braking, “pulling” – assisting movement, shear compaction movement frequency and screw speeds.
This ensures constant compaction, improved adhesion to the strands and cohesive quality of the produced slabs.
The Elematic E9 extruder is the 4th generation integrating 30 + years of experience, research and development from the market leader in hollowcore equipment technology.
Shear compaction significantly reduces the cement required to fill the spaces between the aggregates while providing a stronger product. Our E9 extruder provides flexible strand height placement within the slabs offering Fritz-Alder design flexibility on fire ratings, spans and strength. Fritz-Alder Precast cores are optimally designed to offer customers maximum product flexibility and improved load capacity with consistent casting efficiency.