Surface-Set Diamond

Surface-Set Diamond

Surface-set non-coring bits are set with a single layer of natural industrial drill diamond on the working surfaces of the bit crown in a pre-determined pattern. The diamonds are embedded in a powdered metal matrix body that is fused to a steel tool body. This metal bond is extremely tough and wear resistant as its function is to securely hold the diamonds in place throughout the operational life of the bit.

Surface-set diamond bits are recommended for use when drilling medium-soft to soft formations that are not drilled effectively by impregnated diamond bits or by bits that have been set with polycrystalline (PDC) elements.

Surface-set non-coring bits are available for hole sizes in the range of A-size (Ø 48 mm / 1.875 inch) to P-size (Ø 123 mm / 4.828 inch).

These types of bits are supplied with industry standard thread connections. Other thread connections may be available to suit specific customer needs.

The bits in this range are supplied with a concave face profile.

Diamond Size

The size of diamonds used in surface-set bits is described as the number of stones per carat (SPC). The general rule for selecting the appropriate diamond size is that the harder the rock, the smaller the diamond.

As the diamonds that are used in surface-set bits are naturally occurring, they fall into a broad range of sizes. The SPC sizes that are referred to in describing Dimatec’s surface-set drill bits are actually nominal values that represent a fixed range of SPC sizes. These ranges are defined in the table below:

Dimatec Diamond

Size Range (SPC)

Actual Number of

Stones Per Carat


Stone Size

4 / 5

4 to 5


6 / 8

6 to 8


9 to 12


13 to 20


21 to 35


36 to 60


Diamond Grade

Grade AA

A whole-stone grade of high quality natural drill diamond with stones that are octahedral or dodecahedral in shape with no internal fissures
or cracks. Recommended for use when drilling igneous and harder sedimentary formations.

Grade P2

A processed grade of medium quality natural drill diamond with stones that are approximately spherical in shape. Their surface texture may exhibit some irregularities but are free from any internal fissures or cracks. Recommended for use when drilling sedimentary formations.

Carbonado Grade

These stones are sometimes referred to as “black diamond”. They are an opaque grey/black coloured aggregate of diamond crystals, graphite and amorphous carbon. They naturally occur as relatively large, irregularly shaped crystalline structures that are mechanically split into angular shapes with desired particle sizes. Normally, individual carbonado crystals are sized in the range of 10 stones per carat (SPC) or larger. Bits that are set with carbonado crystals are particularly well suited for use in drilling softer formations or hard/soft blended formations such as Serpentine.

ISO 9001:2015 & ISO/TS 29001:2010

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