Page 35 - Diamond Products Catalog

Quick Tip:
• Penetration rates vary anywhere form 2 ipm (5cpm) to 12 ipm (30 cpm) based on bit and formation.
• In extremely broken, hard, ground, run at half RPM and weight on bit sufficient to reach 1 to 2 ipm.
• The penetration rate to prevent polishing mode may be higher in UMXTM bits.
Quick Tip:
• Decreasing torque and penetration rate indicates bit polishing.
• Maximum bit torque occurs during bit sharpening. Only be concerned with torque rise when restricting water or in lost circulation.
• Fluctuation in torque, particularly during sharpening is caused by unstable rock fragmentation and/or insufficient rock penetration. Weight on bit needs to be maintained to establish secondary fracturing and stable cutting.
• If the head stalls under normal operation, then reduce speed to produce more torque and maintain steady rotation.
• UMXTM bits can drop or stall RPM when sharpening. If RPM drops during sharpening, then a lower gear or speed should be used to increase available torque.
Quick Tip:
• High penetration and/or rotation rates require additional flow.
• There is no maximum water flow rate. At high pressures, the bit can be lifted off the rock face, causing it to polish.
• Free-cutting bits, especially UMXTM bits, obtain maximum life and penetration using plenty of water.
5. The bit torque can be measured in a similar fashion by comparing the “off bottom” hydraulic pressure of the rotation unit to the hydraulic pressure while drilling.
Torque
Torque generated by the bit is a function of sharpness of the bit and weight on bit, and results from the diamonds cutting the formation. As such, torque should be viewed as beneficial and an indication of drilling effectiveness. Minimum torque occurs just after bit sharpening has completed and as bit weight is reduced. Maximum bit torque occurs during bit sharpening due to the bit matrix coming into contact with the rock. A simultaneous decrease of torque and penetration rate
indicates that the bit is polishing and needs to be sharpened. Torque increases due to sharpening should only be a concern in lost circulation or when sharpening requires water restriction. Due to its wear-resistant matrix and large diamonds, UMXTM bits can drop or stall RPM when sharpening. If RPM drops during sharpening then a lower gear or speed should be used to increase available torque.
Penetration Rate
The cutting rate varies as a result of weight on bit, sharpness, bit formula, and ground conditions. Typical penetration rates vary anywhere from
2 ipm to 12 ipm depending on bit formula and formation. As formations become harder, the penetration rate should be reduced to achieve good bit life. In extremely broken, hard, ground, drill at half RPM and weight on bit sufficient to reach 1 to 2 ipm (3 to 5 cpm).
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Water Flow
The flow of drilling fluid in the drill hole serves many purposes including the essential cooling of the diamonds, removal of cuttings, and attainment of good bit life. High penetration rates require additional flow to keep cuttings off the bit face,
as do higher rotation rates. There is no maximum water flow rate, though at high-flow rates, the
bit can be lifted off the rock face, causing it to polish. Free-cutting bits, especially UMX, obtain maximum life and penetration using plenty of water.