A full 360° contact gauge ring on a PDC drill bit centralizes the bit reducing or eliminating lateral vibration. This produces a smoother drilling bit vital in directional applications and harder formations.

The chart shows laboratory test results for a conventional gauge design and exactly the same bit with a 360° gauge ring. The chart above shows that the gauge ring restricts lateral movement and therefore improves bit stability. This built in stabilization leads to a reduction in torque fluctuations, generating a much smoother drilling bit.
Both bits were evaluated under identical operating conditions. The RPM was incrementally increased from 60 to 250 RPM. The maximum lateral acceleration reached with the gauge ring bit was only 10 m/s2 (approximately 1g), which is within the noise range of the system.
This in turn improves the bit life, downhole tool life and directional performance by virtue of a smoother bore hole which provides a more predictable weight transfer to the bit and enhanced dogleg severity.
Additionally, the full contact gauge ring helps to protect the gauge cutters from radial vibrations and ensures that the "back corner" of the gauge is always in contact with the formation leading to more predictable steering characteristics on motor.

Tests with an identical bit with no 360° contact gauge ring confirm that low WOBs and higher RPMs exaggerate bit vibration.
On motor it has been noted that directional drillers tend to use lower WOB’s during the sliding mode. This technique reduces the risk of losing tool face as well as the motor stalling. Thus in consequence the PDC bit is at its most unstable condition during the sliding mode, which in turn exacerbates any sliding problems.
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