Without center or guide teeth the conical bottom structure change the cutting/crushing sequence.The slag inlet is large, the base plate and tooth plate are integrated, and slag entry resistance is low. These improves the drilling capacity.
The open type drilling tools are stronger than double bottom drilling tools in drilling. So open type drilling tools are not only used in plastic formations with small pile diameters but also used in dense layer of gravel and cobbles, sedimentary rocks of lower strength completely/highly weathered rock strata as well as pile diameters range from 0.6 m to 1.5 m etc.
Due to the open-body structure, the strength of the barrel and base plate is reduced the barrel wall thickness increases to ensure barrel strength.