Wednesday, 29 May 2013

Diamond Grades


All surface-set diamond bits manufactured by IDP are available with one of eight standard grades of natural drill diamond set on the cutting surfaces of the bit face. The diamond grades are described as follows:
AAA Grade
Premium quality natural drill diamond. These stones are round to octahedral and dodecahedral in shape and may have small amounts of internal inclusions with no cracks or fissures.
AA Grade
High quality natural drill diamond. These stones are mainly round with a small percentage of off-shaped stones and somewhat spotted as well as crystal shaped stones.
A Grade
Medium quality natural drill diamond. These stones have a generally blocky shape with somewhat broken surfaces and sharp edges. Many have fissures, inclusions and minor surface cracks.
Physical Properties of Natural Diamond Grades

Physical Properties of Natural Diamond Grades

Application of Natural Diamond Grades
The general rule for selecting the appropriate diamond grade is that the harder the rock, the better the diamond toughness and crystal geometry should be. For example, the selection of the “AAA” or “AA” grade would be appropriate for use in a hard, consolidated granite formation while the selection of the “P2” or “P3” grade would be appropriate for use in a limestone or sandstone formation.
Kicker Grade
This is a special grade of diamond that is applied exclusively as gauge diameter setting below the bit face on surface-set diamond bits and casing shoes. The inherently low crystal strength of Kicker grade diamond makes it unsuitable for bit face setting but is more than adequate for use in wear protection applications on the set diameters of drill bits where there is little load on the diamonds. Kicker grade diamonds range in shape from angular or elongated to completely amorphous. Their coloring is variable and they frequently possess fissures, cracks and inclusions.

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