The impregnated diamond core bit has emerged as the most commonly used type in the mineral exploration industry. The advantages of using impregnated diamond core bits over bits manufactured with other cutting media include:

• An extremely wide range of application.
  
• A simple crown geometry that makes them less susceptible to in-hole damage than bits produced with other types of cutting media and as such are more tolerant of changing or banded geological formations.
  
• Their multi-layered cutter arrangement results in better overall bit life than bits produced with other types of cutting media. They are particularly well suited for drilling in hard, consolidated, non-abrasive formations.
  

D-Series Impregnated Diamond Core Bits

Dimatec manufactures the D-Series range of impregnated diamond matrices with matrix layer metal bonds that range from hard, abrasion resistant types to soft, ductile types. In general, a hard, abrasion resistant matrix such as the Dimatec “D2” or “D3” would be used to drill a soft, abrasive, unconsolidated formation while a soft, ductile matrix such as the Dimatec “D10” would be used to drill an extremely hard, non-abrasive, consolidated formation. The idea is to match the bit matrix hardness to the formation hardness in order that the metal bond of the matrix layer will erode at a controlled rate during normal drilling operation. This controlled erosion of the matrix layer metal bond will in turn continually expose new layers of sharp synthetic diamonds until the matrix layer of the bit crown is totally consumed.

HR-Series Impregnated Diamond Core Bits

In addition to our standard range of D-Series impregnated diamond core bit matrices, Dimatec also offers our high performance HR-Series range of impregnated diamond matrices.

Dimatec’s HR-Series impregnated diamond core bits have been specifically designed for use in Hard Rock drilling applications where formation conditions are generally consolidated and fine grained with high compressive strengths and Mohs hardness values in the 6 to 8 range. Traditionally, it has been necessary to apply higher bit loads when drilling under these conditions in order to achieve acceptable rates of penetration – usually at the expense of overall bit life and premature wear on drill string components.

After conducting extensive field tests with the HR-Series range of impregnated diamond core bits, several performance benefits have been identified. These include:

• Very smooth cutting characteristics throughout the life of the bit when drilling through even the hardest formations.
• A relatively low weight-on-bit is required to maintain a high rate of penetration. In some cases, a reduction in bit load of as much as 30% has been realized with HR-Series bits while achieving or exceeding the penetration rates of competitive products. The application of lower bit loads results in less wear and tear on drill string components as there is less potential for flexure or over-tightening of the thread connections.
• Under most conditions, HR-Series bits are self-sharpening. Very little intervention by the drill operator is required to keep the bit cutting steadily.
• HR-Series bits have demonstrated an ability to drill through fractured formations with significantly fewer core blocks than competitive products.
• Improved overall bit life and exceptional production rates in harder, consolidated and fine grained formations.

Inside the Impregnated Diamond Bit Crown

The basic construction of these bits features a sintered powdered metal crown that is fused to a steel tool body or shank. The powdered metal crown is composed of two layers: the “matrix” layer which cuts the rock and the “backing” layer which connects the matrix layer to the steel tool body and serves to support the gauge diameter protection hard materials.

The cutting media that is used in impregnated bits is synthetic diamond. The material has a distinct advantage over the natural mined industrial diamond that is used in surface-set bits in that it is an engineered material that has measurable, controlled physical properties, particularly in the areas of crystal friability and crystal geometry.

The matrix layer of the bit crown contains a uniform distribution of these synthetic diamond crystals that are embedded in a powdered metal bond. The grit size and concentration of the synthetic diamond crystals as well as the relative hardness of the metal bond materials in which they are suspended are all functions of the matrix type designation.

Unlike the matrix layer, the “backing layer” does not contain synthetic diamond distributed throughout its volume. The backing layer is also composed of a powdered metal bond material - usually a bond type with good wear resistance properties. Normally, the exposed outside and inside gauge diameter surfaces of this layer are set with a combination of natural mined “kicker” grade diamond and tungsten-carbide wear pads. These materials assist in maintaining the critical gauge diameters throughout the life of the bit. Optional setting is available whereby the natural mined “kicker” grade diamond is replaced with synthetic materials and is intended for use on drilling projects where potential contamination by natural diamond crystals is objectionable.