ZhongCheng Drill Bit Manufacture 1> Drillers always drill a smaller hole at first, then enlarger it with hole opener, it is a type of regular drilling technology when the drilling machine is lower power or the end-hole is too big. 
2>We can make the hole opener and solutions according to the hardness of rocks, drilling depth, size of pilot hole, size of end-hole. 

3> If fix the tricone bits as the pilot bits, the hole opener will be a rock bits, hole opener with tricone bits as pilot bits is always applicable in special sizes well drilling.

The reamer mainly consists of four or more cones. Cutting Structure with premium tungsten carbide hardfacing or premium tungsten carbide insert of formulas and new techniques is utilized, and increases wear-resistance capability of reamer. The pilot is tricone bit. 
Seal and Lubrication 
High performance HNBR O-ring for bearing seal and advanced grease for lubrication. 
Product Application 
It is suitable for the large size well, mining and infrastructure applications. 
Recommended Drilling Parameter