The bond strength of the bronze bond is high, and this can help to make better use of diamonds. Its wear resistance is good, it can withstand a larger load, and its thermal conductivity is also good. Bronze-bonded diamond tools are mainly used to process non-metallic brittle materials, such as ceramics, glass, stone, concrete as well as gemstone and semi-conductor materials. They are suitable for coarse grinding, half-fine grinding and profile grinding, and are suitable for cutting and edge grinding.

Bronze bonds also have some shortcomings. Its self-sharpening capability is not good. Bronze-bonded diamond tools’ grinding efficiency is lower than the resin-bonded ones’. If they are not properly used, block and heat may be caused, and their dressing is difficult.

The bronze bond has high strength and hardness. Its shrinkage is small and it is easy to generate dispersed shrinking holes. In addition, the thermal conductivity of Cu is only lower than the expensive Ag and is higher than other metals. This helps to decrease the temperature generated in the diamond tools’ working process and avoid burns on the workpiece.

The often adopted metal materials in the bronze bond are the powders of Cu, Sn, Zn and Ag. Sometimes some non-metal materials, such as graphite, are also added. As the objects to be processed and their processing requirements vary, the composition of the bronze bond may also be different. According to the number of metal elements in it, bronze bonds can be categorized into binary-alloy series, ternary-alloy series and multi-alloy series.

1) Binary-Alloy Series: In this series, the Cu-Sn alloy is the most common used. Some graphite is also added into the bonds of this kind.

2) Ternary-Alloy Series: This series is composed by adding a third metal element into the binary-alloy series bonds. The third metal element can be Ag, Ni, Zn, Fe, Pb, etc.

3) Multi-Alloy Series: This series bonds base on the Cu element, and have 3 or more other metal elements, such as Sn, Zn, Pb, Ag, Ni, Co, Fe, Cd, Mo, etc.

The transition layer should have good weldability. For if not, the diamond segment will fall from the steel core when receiving high alternating forces in cutting, and this may cause safety issues.

The bond materials used in the transition layer normally do not contain low melting-point metals, for example, Sn and Zn, for under high temperatures, these metals tend to be evaporated and gasified, and then produce air-holes. The transition layer often adopts Cu, Ni and some other alloy materials.

WC (tungsten carbide) can improve the wear resistance of the weld and the transition layer, but if its content is too high, welding defects such as holes and slag will be caused, and when this is serious, the transition layer may break. To solve this problem, a few Mn and Cr can be added. This will not only generate solid-solution-strengthening and increase wear resistance, but also reduce air-holes.

The compositions of the working layer and the transition layer should not be very different. Otherwise, the junction of the two layers will tend to break because of uneven heat and forces they receive when the diamond blade is sawing.

There are various kinds of diamond tools, and because of their superb sharpness, they have been widely applied in many domains, including construction, electronic information, geological mining, medical devices, etc. According to their bond types, manufacture methods and uses, diamond tools can be categorized to the following types:

1) Metal Bonded Diamond Tools: They are made via the steps of mixing diamond grains with metal powder (e.g., Cu, Sn, Fe) evenly, applying powder metallurgy methods to press the mixtures to some shapes and sinter them, and mechanical processing. This type diamond tools are the most often sighted. They include the common diamond saw blades, diamond cup grinding wheels, diamond core drill bits, etc.

2) Resin Bonded Diamond Tools: They are made via the steps of mixing diamond grains with resin powder and some proper fillers (e.g., copper powder), cold pressing or hot pressing them to some shapes, curing, and mechanical processing. This type diamond tools have characteristics of good elasticity, good impact tolerance, good self-sharpening capability, and high grinding efficiency. An example of this type diamond tools is diamond polishing pads.

3) Plated Diamond Tools: They can be made by using electroplating methods to plate the tool’s surface with one or several metal layers, in which diamond grains are distributed evenly. Another method is using CVD (Chemical Vapor Deposition) method to deposit a layer of dense polycrystalline diamonds on the tool’s surface. Plated diamond tools include some diamond cutting tools, drilling tools, etc. They have characteristics of high efficiency, long life and high grinding precision.

4) Ceramic Bonded Diamond Tools: They are made via the steps of mixing diamond grains with glass and ceramic powder, pressing the mixtures to shapes, sintering, dressing, and sharpening. This type diamond tools include some diamond grinding tools. Their characteristics are: good chemical stability, small elastic deformation, high brittleness, etc.

5) Polycrystalline Diamond (PCD): They are normally made by sintering many micro-size single diamond crystals in high temperature and high pressure. The crystals in PCD are arranged disorderly, so the hardness and wear resistance of PCD in all directions are almost the same. PCD also has good fracture toughness and good thermal stability. It can be applied in geological drill bits, machining tools, etc.

6) Polycrystalline Diamond Composite or Compacts (PDC): They are made by combining some layers of polycrystalline diamonds (PCD) with a layer of cemented carbide liner in high temperature and high pressure. PDC has the advantages of diamond’s high wear resistance and carbide’s good toughness.

1) Resin Bond: This bond itself has good elasticity and polishing function, but is subject to being burnt under high temperatures. The resin bond diamond tools have good self-sharpening capacity, and are not easy to be blocked. They seldom need several times’ repair . Their grinding/cutting efficiency is high, roughness is low, and the temperature generated in the processing is also low. As their these advantages, the resin bond diamond tools are widely used in half-fine or fine grinding for carbide cutting-tools or workpieces. Resin bond CBN tools are mainly used for the cutting edge’s grinding of high-vanadium HSS cutting tools, and half-fine or fine grinding for workpieces of tool steel, mold steel, stainless steel and heat-resisting steel.

2) Ceramic Bond: Ceramic bond has higher toughness and good heat-resisting performance. The ceramic bond diamond tools can cut/grind sharply and their efficiency is high. Over-heating and blocks seldom happen in the cutting/grinding process. Their thermal expansion is small, so the processing precision can be easily controlled. They can be repaired easily. They are normally used in coarse or half-fine grinding, profile grinding with broad contact area and grinding for superabrasive sinter.

3) Metal Bond: There are two kinds of metal bonds: bronze and electroplate. Bronze bond has good rigidity, high toughness, good wear resistance and long service life. It also has good shape-keeping performance and can withstand larger workload. However, its self-sharpening performance is bad. It is subject to block and is difficult to be repaired. The bronze bond diamond tools are mainly used in cutting and coarse or fine grinding for non-metal materials, such as glass, ceramic, stone, concrete, semiconductor materials and super-hard materials, and a few of them are used in the coarse grinding for carbide alloy, profile grinding and honing. Bronze bond CBN tools can be used in profile grinding for metal materials and honing for various alloy steel.

Electroplate bond has an even higher toughness. The electroplate bond diamond tools have a thin abrasive layer in which the density of the abrasive grains is high. The tool is sharp and its cutting/grinding efficiency is high. It is economical and does not need repair, but its service life is short. Electroplate bond is suitable to be used to manufacture profile grinding tools with complicated forms, small grinding heads, trepanning tools, saw blades and electroplated reamers, and can be applied in high speed grinding manners.