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DESCRIPTION
Polmak impregnated bits are made of high quality synthetic diamonds mixed through out the metal bond matrix. With over to 30 years of experience, Polmak’ s impregnated bit technology has developed various matrixes with different hardness and wear characteristics. All Polmak impregnated diamond bits have uniform diamond distribution, ensuring that all diamonds will share the same work load. This results in faster penetration rates and longer bit life.
Impregnated bits and casing shoes are ideal in hard, fractured and abrasive formations where a surface set bit gets polished after a few drill meters.
Polmak impregnated bits and casing shoes are mainly available in five different matrix hardness, symbolized as P1, P2, P3, P4 and P5. P1 is the softest matrix and P5 is the hardest. In this classification there are subdivisions that refer to the customer requirements or rock descriptions. From Polmak’s Impregnated Bit range, one can chose the most appropriate and economical type of bit for their drilling jobs and requirements. Below is a brief guide for selection of the proper matrix hardness.
For higher penetration rates, one grade softer matrix may be chosen (See Bit Selection chart). |
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OPERATIONAL GUIDE
SPEED (RPM): Impregnated Bits work better at higher speeds than commonly used for surface sets bits. Peripheral speeds of 2 – 4 meter per second are recommended for impregnated bits where conditions permit.
PRESSURE: Don’t let the bit be polished. We caution you that it does no good to have high speeds if the bit is not biting into the formation and the bit does not progress. For relatively shallow holes some driller’s experience success at 150 PSI (pressure on the hydraulic gauge of the drill), while others start right out at 200 or 250 PSI. In some instances varying the pressure moderately has been an effective method for keeping the bit sharpen. The pressure should be adjusted according the fracture strength of the formation being drilled.
BIT WEIGHT; Too much weight on the bit can damage the bit or cause the bit to wear out prematurely, while too little weight can cause the diamonds to polish. To maximize the effects of pressure and tool weight a Bit Weight Indicator should be used.
COOLANT; Again it is matter of finding what works best. During the drilling of very hard, fine-grained rocks, keep in mind that softer matrices are more readily subject to wear and can abrade too quickly. It is imperative to use adequate amounts of drilling fluids at proper pressure and viscosity to wash away the cuttings from the face quickly. In cutting fine grained, homogeneous rock, lubricants such as polymers or cutting oils increase bit life, while improving circulation and bit penetration. Below are a few examples of recommended fluid volumes;
SHARPENING; To sharpen the bit in the hole, increase the pressure, reduce the peripheral speed (rpm) , and also reduce the flow of coolant for short periods (about 30 seconds up to a maximum of about one minute).
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