the smaller drilling pressure should be used in soft to medium soft formations. The drilling pressure should be increased properly in complete, medium hard and hard formations. In broken, cracked and mixed formation, the drilling pressure should be reduced properly accordingly to cracking level of the formations
Greater drilling pressure can be adopted for the bits which have big diameter, thick wall and soft matrix. The bits with small diameter, thin wall and hard matrix, the drilling pressure should be smaller. The drilling pressure for surface set core bit should be higher than impregnated core bit. In order to make the diamonds on surface set core bit to drill into the rock and cause its brokenness.
Drilling pressure should be Giger when diamond quality is good, quality is big and the grain size is large; on the contrary, small drilling pressure should be adopted when the large-size but fewer diamond should be lower than the one on the bits which are with small-sized but more diamonds
The cut area of the rock depends on the bit diameter, wall thickness and waterway quantities. The larger the coring area, the higher, the drilling pressure. Conversely, the drilling pressure should be lower.
