Bottom-hole mill MB

Designed for emergency response in the borehole and are divided into three types:
– light (specified in the index 1)
– average (specified in the index 2)
– heavy (specified in the index 3)
In specific situations that occur in the wells, bottom-hole mills are divided into three types:
– regular or light
– average
– special or heavy
Regular is used for the destruction of any sediment, cement, metal pieces of pipes and strings of heavy-walled production and casing strings, or other devices of tubular construction made of ordinary steel and not reinforced hardly with solid materials. Under these conditions, high-speed milling is provided.
Average is designed to perform the same work as a regular mill, but under more complicated conditions, such as milling of drill pipes with joints, particular, not very massive devices and parts.
Special is designed to destroy large and solid items and devices, such as drill bits, joints, adapter subs, calibrators, and stabilizers, various emergency tools, etc.
Each type of the mills is used due to the characteristics of the well in which to work: in the casing string – K, in an open hole – O and according to the type of working surface: a flat (not identified) and wavy (add the letter “B”).
The connecting thread for all bottom-hole mills – tool-joint threads as defined in the standard GOST 5286-75 right and left.
With the help of special devices (heads of centering devices), bottom-hole mills can be equipped with top mill shoe.