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Diamond Core Bits used for exploration drilling

Diamond Core Bits used for exploration drilling are almost always mounted with diamonds.

A diamond is the hardest known naturally occurring mineral. In fact it is the hardest material that we all know. Diamonds can thus cut in almost any other material from earth.

Diamonds do also have another quality which makes them suitable for use in core bits.

They do have a very high coefficient of thermal conductivity.

When the diamonds cut the rock a large amount of friction heat is produced. Thanks to the very good thermal conductivity of the diamonds this friction heat can be removed by means of the flushing fluid.

TC Bit is also a way, but it does not have the same good thermal conductivity and thus it can only be used for drilling in soil and other very soft formation which does not create anywhere near the amount of friction heat created when drilling hard formations.

There are two types of diamond core bits i.e. surface set diamond core bit and impregnated diamond core bits. Only natural diamonds are used for surface set bits. With natural diamonds we mean diamonds that are mined. For impregnated core bits only synthetic diamonds are used. With artificial diamonds we mean man-made synthetic diamonds.

The technique for manufacturing synthetic diamonds has had a fast development during the last decades. Today the synthetic diamonds are superior to the natural diamonds both in terms of life length and cutting ability.30 Another advantage with the synthetic diamonds is that these can be give special qualities required for core drilling. The synthetic diamonds can thus be “tailor made” to suit drill bits intended for different types of rock. Brittleness, grain size and geometry are three important characteristics that can be “tailor made”.

Diamonds are a form of carbon. Unlike graphite, which also is a form of carbon, they are very hard and this is due to the strong bonds between the carbon atoms. Diamonds have a thermal stability up to around 800 degrees Celsius. At higher temperatures a gradually graphitization will take place provided that air is present.

A diamond drill bit consists of diamonds, a matrix and a steel body. The matrix is a metal powder i.e. a mixture of different metals grains. The composition of the metals is depending on which physical properties the matrix should have i.e. soft, hard, wear resistance, ……..

Diamond Core Bits

When manufacturing impregnated diamond core bits the diamonds and the matrix are mixed together. The mixture is poured in a graphite mould and pressed together. The graphite mould, together with the steel body and a bond, are placed in a furnace and is heated to high temperatures. The bond will solder the mixture of the diamonds and the matrix to the steel body.

In order to prevent graphitization of the diamonds the heating takes place in a controlled atmosphere.

During this metallurgical process the metals in the matrix are sintered and infiltrated to a homogeneous structure with a very high wear resistance.

When manufacturing surface set diamond core bits natural diamonds are set on the inner envelope surface of a graphite mould which then is filled with a matrix. The graphite mould together with the steel body are then placed in the furnace and are heated in the same way as the impregnated diamond core bit.

A surface set diamond bit cuts the rock whereas an impregnated diamond bits works on the rock by means of a grinding or a wearing action. The axial motion of the diamond bit, which is called the penetration speed, is depending on several factors. Some of these factors can be controlled by the driller while others can not.

The driller can for example control the flushing, the choice of drill bit and the drilling parameters but he has no control over the geology, the hole diameter and the hole depth.One of the most important keys to successful and productive core drilling is to create a balance between the factors that the driller does have an influence on. We will look closer into this in the chapter Drilling Technique.

Welcome anyone to share us with your idea for diamond core drilling.

The diamond core bit we can provide:

NQ diamond core bit

HWL core bit impregnated

PQ imp diamond bit

HW casing shoe diamond

HWT diamond case shoe bit

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Contact with our technical person for getting further supports for diamond core drilling.

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Knowlege For Diamond Core Bit for Mineral Exploration Drilling