Full Non-Magnetic Screw Motors for Directional Drilling & MWD
Full non-magnetic screw motors are specialized downhole tools used in directional drilling applications, converting hydraulic energy from drilling fluid into mechanical torque to drive the drill bit. Unlike conventional mud motors, these motors are constructed entirely from non-magnetic materials (μr ≤ 1.005), ensuring no interference with measurement-while-drilling (MWD) systems.
By integrating the probe system directly into the motor housing, our patented design minimizes signal attenuation and accelerates data feedback, enabling real-time adjustments during drilling operations. This makes them ideal for horizontal and directional drilling where precise control over borehole trajectory is critical.
Components Overview
l Bypass Valve Assembly: Located at the top of the motor, it automatically opens when pumping stops, allowing drilling fluid to bypass and preventing damage due to pressure differentials.
l Motor Assembly (Stator & Rotor):
Stator: A helical chambered outer shell typically lined with rubber for sealing.
Rotor: A metal helix that fits precisely within the stator, forming sealed chambers as it rotates.
l Universal Shaft Assembly: Connects the rotor to the drive shaft, converting eccentric motion into concentric rotation while handling significant radial and axial loads.
l Drive Shaft Assembly: Positioned at the bottom of the motor, directly driving the drill bit.
Working Principle
The working principle of a screw motor relies on positive displacement. High-pressure drilling fluid enters the sealed chambers between the stator and rotor, causing the rotor to rotate eccentrically. This motion is then translated into concentric rotation by the universal shaft assembly, driving the drill bit.
l Torque and Speed Relationship: Increased flow rate results in higher torque and RPM, making these motors highly versatile for various drilling conditions.
l Low-Speed, High Torque: Designed for optimal performance at lower RPM, delivering high torque suitable for controlled directional drilling.
Technical Specifications
|
Specification |
Value |
|
Material |
High-strength austenitic non-magnetic steel (P650 grade) |
|
Relative Permeability (μr) |
≤ 1.005 |
|
Torque Output |
Up to 5000 Nm (depending on size and configuration) |
|
RPM Range |
50–300 RPM |
|
Flow Rate |
200–600 GPM |
|
Pressure Rating |
Up to 5000 PSI |
|
Certification |
API 7-1 compliant (optional MA certification for mining applications) |
Note on Material Grades:
The standard offering uses P650-grade non-magnetic steel, which ensures superior mechanical properties and minimal magnetic interference. For specific applications requiring moderate load conditions, P550-grade variants are available upon request—providing an optimal balance between performance and cost efficiency.
Manufacturing Process & Quality Control
l Forged using advanced techniques to achieve uniform microstructure and minimal hardness variation.
l Every batch includes material traceability documentation and third-party permeability/test reports (SGS/BV available).
l Our motors have been successfully deployed in hundreds of directional drilling projects, demonstrating reliability and performance in challenging environments.
As an OEM supplier for national mine safety programs, our full non-magnetic screw motors provide reliable power transmission without compromising the accuracy of MWD systems. They are trusted by drilling teams worldwide for their precision, durability, and seamless integration with modern drilling technologies.