Products >> Drill Bit >> Surface-Set Diamond Bit

Surface-Set Diamond Bit

The surface set diamond bit is produced from a single layer of natural diamond setting on the surface of bit crown with hard matrix.
Surface set diamond bit is mainly recommended for drilling soft to hard formations. Generally speaking, surface set diamond bit can provide satisfying penetration rate.

In order to confirm the surface-set bit quality, we have to confirm the following information:

Diamond sizes (spc – stones per carat)
As a general rule; the softer formation, the larger the diamonds used i.e. 20 to 25 spc. In hard formation, smaller diamonds 30 to 50 spc are typical

Diamond Size	Formation Drilled
10/20 SPC	Soft formation
20/30 SPC	Soft to medium formation
30/40 SPC	Medium formation
40/60 SPC	Medium to hard formation
60/80 SPC	Very hard formation

Diamond quality
The standard range of natural diamonds for surface set bits is chosen in a special allround grade with special quality. The quality includes selected and processed diamonds with a highly polished surface. These stones have a high impact resistance and may be considered as an universal type. Recommended for soft to medium hard formations.

Diamond Grade	Formation Drilled
A Grade	Soft formation
AA Grade	Sort to medium formation
AA Grade	Hard to very hard formation

Diamond size range (SPC)	Actual number of stone per carat	Diamond size
Diamond size range (SPC)	Actual number of stone per carat	inch	mm
6~8	6~8	0.098	2.49
10	9~12	0.085	2.16
15	13~20	0.071	1.80
25	21~35	0.063	1.56
50	36~60	0.054	1.37
75	61~90	0.044	1.12
100	91~120	0.042	1.07

Profiles
Surface set drill bits are available in different profiles to obtain optimal drilling performance.
Standard profiles for surface set core bits:

	Semi-Round Type (standardized by DCDMA) The most commonly used of non-step core bits and good general-purpose bit, suitable for a wide variety of conditions depending on the diamond grade and size selected. It requires high bit loads and offers good strength especially in very hard broken formations.
	Multi-Step (standardized by DCDMA) Very popular bit for wireline drilling — good penetration and stability in all but very broken formations. Suitable for drilling hard and competent formations, hole deviation can be prevented.
	Semi-round Face Discharges Suitable for drilling sedimentary or metamorphic formations containing some more powder mineral. It can prevent excessive core washing out, so as to get high coring percentage.
	Stepped Face Discharges The face discharge crown features extended ports to minimize sample erosion,thereby increasing core recovery in delicate formations