Three main questions about diamond stones

1. WHAT IS THE CONCENTRATION OF DIAMONDS IN A STONE?

Concentration is an indicator of the number of diamond grains (carats) in a bond. With increased concentration, the abrasive ability of the stone improves. The higher the percentage of concentration - the faster the stone works, the less time is spent on sharpening, the less abrasive is consumed. The lower the percentage of concentration - the slower the stone works, but it works softer. It is the concentration of diamonds in the powder that is the most important factor in the performance of a diamond stone. It is important to note that to increase the stiffness of the bond, aside from the diamond powder, additional abrasive grinding powders, such as boron carbide, can be added to it, which also affects the quality of the stone.

By definition, the concentration of diamond powder is the weight content of diamonds per unit volume of the diamond layer. The unit of weight of a diamond is a carat, 1 carat (crt) is equal to 0.2 g. Standard diamond stones have a relative concentration of 25%, 50%, 75%, and 100% of the diamond powder.

The content of diamond powder is measured in both weight and volume characteristics.

The weight content of diamonds in the diamond-bearing layer (crt\cm3):

Volume content of diamonds in the diamond layer (%):

2. WHAT TYPES OF BONDS ARE THERE IN DIAMOND STONES?

The diamond layer of the stone includes grains of industrial diamonds, a special bond, and in some cases a filler. The bond is the substance that connects the abrasive grains, bond provides the effectiveness and durability of the abrasive stone. Fillers (in organic bonds) form the physical, chemical, and mechanical properties of the diamond layer: its strength, resistance to temperature changes, wear resistance, speed of grain consumption, etc. Moreover, they serve as a good base for diamonds, securely holding them in their thickness. The granularity of the filler is selected so that it minimally affects the sharpening process, and the main work is done with diamond powder.

There are three main types of diamond abrasive binders:

1) Galvanic bond (diamond plates "Blitz", diamond stones with triple coating). Galvanic bond is a method of application in which diamond particles are attached to the coated base and a layer of the metal bond is deposited from the electrolyte, covering and fixing the diamond grains. The galvanic bond is characterized by the fact that it holds the diamond grains only due to mechanical coupling forces, so the grains must be inserted in the bond to a height of at least 65-70% of the grain size.  The metal that reliably holds the abrasive grain on the steel body is nickel. Diamond plates on a galvanic bond provide intensive metal removal and can be used for the cutting edge of a knife that has significant damage (chips, bends, etc.). They work noticeably more aggressively than stones on organic and metal bonds with similar grain sizes. This is achieved by protruding diamond grains, while in the metal and organic bond, the diamond grains are sunk into the binder and mixed with it. The concentration of grain sizes in the layer is 100%. At the same time, it should be noted that for the duration of work, such stones will be inferior to abrasives on other bonds due to a thin layer of deposition, which is actively erased during the sharpening process. To extend the service life, two or three layers of coating are applied, which also allows you to work faster and longer. It is also important to note that when working with such diamonds on soft steels with a hardness of up to 58 HRC, this type of stone is produced faster than when working on steels with high hardness. Plates on a galvanic bond do not require preparation for work (e.g. leveling). In general, they are effective and inexpensive solutions for fast sharpening.

2) Metal bond (CNB abrasives). It is a solid bond with high metal removal performance. It has no filler and consists of metals and diamonds mixed in a layer. Abrasives on this bond are usually marked with the letter M and have a light gray hue. The M2-01 bond is used for manufacturing diamond tools recommended for grinding hard-alloy products, hard-alloy multi-blade tools, and sharpening them. The structure of the M2-01 bond is a system in which a solid solution of tin is located in copper (copper-tin bond).

3) Organic bond (Venev diamond stones, incl. Premium). The main advantage of the organic bond over metal in that it has a more viscous structure, which means easier processing (e.g., while manually leveling and opening of the silicon carbide powder), it is updated not as quickly glared. The main advantage of an organic bond over a galvanic one is that the diamond is not applied in a thin layer to the surface of the bond, but is located along with its entire thickness. Also, an organic bond has greater plasticity and viscosity, which means that the diamond on such a bond is painted less than on a galvanic one, and as a result, a diamond stone on an organic bond serves much longer. This is a bond with the highest wear resistance. 

The B1-10 bond is made of pulverbakelite (phenol-formaldehyde), containing boron and copper carbide, so it has a reddish color. Intended for processing of hard alloys of various grades; sharpening and finishing of high-speed steels and superhard materials, finishing grinding of hardened steels.

The B2-01 bond is made of liquid bakelite (phenol-formaldehyde), with iron content. Designed for finishing and polishing of hard alloy.

The B2-01M bond is an improved version of the B2-01, which works somewhat softer.

OSB bond is an advanced technology in the production of Venev Industrial Diamonds Inc. for stones on an organic bond. This is a modernized bond, which is not based on a grinding powder, but a micro-powder of the ACM brand, made of synthetic diamonds of normal abrasive ability. The OSB bundle differs from the others in that it does not use boron carbide. Also, the abrasive layer on it is not sintered but is glued to the body of the metal plate. The absence of unnecessary inclusions of other abrasives makes it possible to do softer and finer work. The concentration of diamonds in these bars is 100%. Already out of the box, this stone is ready to work, it does not require leveling on silicon carbide. OSB bond is perfect for hard steels at small angles.

3. WHAT ARE DIAMOND AND MICRO POWDERS?

Diamond powders (АС) are made of synthetic diamonds, in addition to the letter, they are numbered and a digital code, the figure indicates the arithmetic mean of the compressive strength of all grains of a certain brand, expressed in newtons. The compressive strength of synthetic diamonds (static strength) is determined by the load at which a single crystal is destroyed. Diamond powders of the AC4, AC15, and ACM diamond micro powders are obtained by enriching sintering mass (synthesis products) with the lowest-grade synthetic diamond, followed by crushing, sieving and classification.

AC4 diamond powder (Venev diamonds) - grain size from 2500 to 40 microns. It is made of synthetic diamonds, the grains of which are represented by aggregates. It has a high quality of sieving, the content of the main part of diamonds with average grain size is not less than 85%, small grains are not more than 10% and large ones are not more than 5%. This is a synthetic diamond powder of precision quality.

Diamond powder AC-15 (stones with triple diamond coating).

Diamond powder made from synthetic diamonds. Grains are represented by aggregates, as well as elongated crystals with a grain shape coefficient from 1.3 to 3.0. The content of medium-sized grains is 70%, large ones - no more than 15%. Intended for the manufacture of tools on organic, metal, ceramic bonds used in the processing of hard alloy, ceramics, glass, and other brittle materials.

ACM (Venev diamonds) is a micro-powder of the ACM brand made of synthetic diamonds of normal abrasive capacity. It is included in the stones of the Venev Industrial Diamonds Inc.  The grain size of the micro-powder is from 60 to 1 microns.

Micro-powders are obtained by static or centrifugal sedimentation methods from the fine product remaining after the manufacture of AC-type grinding powders. Properties of micro-powders of various brands are provided by the technological process of their production. The mass fraction of impurities in the form of soluble components in the grinding powders of synthetic diamonds should not exceed 1%.