Characteristics of the three main categories of abrasive tools

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Abrasive tools, commonly referred to as abrasives, are divided into three main categories: bonded abrasives, coated abrasives, and super abrasives. Each series has its distinct characteristics and advantages, serving different purposes within the industry. In this article, we will explore these three series of abrasive tools and their key features in detail.

1. Bonded Abrasives:

Bonded abrasives are tools made by combining abrasive grains with a bonding agent to create a specific shape and grinding capability. The marking of bonded abrasives typically includes shape, dimensions, abrasive grain size, bonding agent, hardness, and structure. For example, a marking could be 35M/SGB/T2485, where 35M/S indicates the highest operating speed, GB/T2485 represents the standard, and the numbers 300x50x75 denote the shape and dimensions of the abrasive tool.

1.1 Hardness:

Hardness refers to the strength of the bond between the abrasive grains and the bonding agent under external forces. It is measured using methods such as the sandblasting hardness tester and the Rockwell hardness test. Hardness levels are categorized into seven major grades, including ultra-soft (U1, U2), soft (S1, S2), medium-soft (MS1, MS2), medium (M1, M2), medium-hard (MH1, MH2, MH3), hard (H1, H2), and super-hard (SH1, SH2).

1.2 Bonding Agent:

The bonding agent is the material that binds the abrasive grains together in bonded abrasives. The four main categories of bonding agents used in bonded abrasives are ceramics, resins, rubber, and vitrified clay. Among them, ceramic bonding agents are the most commonly used. Ceramic bonding agents are composed of materials such as clay, feldspar, kaolin, and quartz, and their specific composition varies depending on the type of abrasive, intended use, and manufacturing method (casting or pressing). Resin bonding agents are primarily phenolic resins and are divided into powder and liquid types based on their manufacturing method and intended use. Rubber bonding agents include synthetic butadiene rubber, butyl rubber, and liquid rubber. Vitrified clay bonding agents are composed of materials such as magnesium oxide and magnesium chloride and are primarily used for fine-grit abrasives in precision machining applications. The abbreviations for these bonding agents are V (ceramic), B (resin), R (rubber), and MG (vitrified clay).

1.3 Structure:

The structure of bonded abrasives refers to the volume occupied by abrasive grains in the tool and is expressed as a weight percentage. In general, the structure is not explicitly indicated in the marking of the abrasive tool. However, during the manufacturing process, a numerical value is assigned to represent the structure, with smaller numbers indicating a looser structure (less abrasive grain content) and larger numbers indicating a denser structure (higher abrasive grain content). The structure is usually represented by numerical values ranging from 0 to 12.

2. Coated Abrasives:

Coated abrasives, also known as flexible abrasives, are abrasive tools where abrasive grains adhere to a flexible backing material using a bonding agent. Coated abrasives possess nine key characteristics: backing material type, backing material treatment, abrasive grain type, abrasive grain size, grain coating density, bonding agent type, bonding strength, shape, and dimensions.

3. Superabrasives:

Superabrasives are abrasive tools made using synthetic diamonds or cubic boron nitride (CBN) as the abrasive material. They represent another major series of abrasive tools. Superabrasives have the following distinctive features and markings: 3. Superabrasives:

Superabrasives are a specialized series of abrasive tools that are manufactured using synthetic diamonds or cubic boron nitride (CBN) as the abrasive material. They possess exceptional hardness and durability, making them suitable for high-precision grinding and cutting applications. The characteristics and markings of super abrasives include concentration, bonding agent, grain size, abrasive grade, abrasive layer thickness, porosity, total thickness, diameter, and shape code.

3.1 Concentration:

The concentration of a superabrasive tool refers to the percentage of abrasive material contained within a given volume. It is represented as a percentage and indicates the density of the abrasive grains. The concentration codes are as follows:

- 250: 22.5% abrasive content per cm3

- 500: 44.5% abrasive content per cm3

- 750: 66.7% abrasive content per cm3

- 1000: 88.1% abrasive content per cm3

- 1500: 132.1% abrasive content per cm3

3.2 Bonding Agent:

The bonding agent used in super abrasive tools determines the strength and stability of the abrasive layer. Common bonding agents for super abrasives include resin, metal, and ceramic. The bonding agent codes are as follows:

- B: Resin bonding agent

- M: Metal bonding agent

- V: Ceramic bonding agent

3.3 Grain Size:

Grain size refers to the size of the abrasive particles used in super abrasive tools. It influences the surface finish and material removal rate during grinding or cutting operations. Grain sizes are specified using standard industry codes.

3.4 Abrasive Grade:

The abrasive grade indicates the quality and characteristics of the super abrasive material used. It is typically represented by a specific grade or brand name.

3.5 Abrasive Layer Thickness:

The abrasive layer thickness denotes the thickness of the layer containing the super abrasive material. It influences the tool's cutting or grinding performance and is crucial for maintaining precision and stability.

3.6 Porosity:

Porosity refers to the presence of open spaces or pores within the super abrasive tool. It affects coolant flow, heat dissipation, and chip clearance during grinding or cutting processes.

3.7 Total Thickness:

The total thickness of a superabrasive tool includes the abrasive layer thickness and any additional layers or backing materials used. It determines the overall rigidity and stability of the tool.

3.8 Diameter:

The diameter of a superabrasive tool indicates its size and compatibility with different grinding or cutting machines. It is measured in millimeters or inches.

3.9 Shape Code:

The shape code represents the specific shape or profile of the super abrasive tool. It helps identify the tool's intended application and compatibility.

The three series of abrasive tools, namely bonded abrasives, coated abrasives, and super abrasives, each have unique characteristics and are used for various industrial applications. Bonded abrasives are known for their specific shape, hardness, bonding agent, and structure. Coated abrasives offer flexibility and are characterized by their backing material, abrasive grain, and bonding strength. Superabrasives, on the other hand, stand out for their exceptional hardness and include features such as concentration, bonding agent, grain size, abrasive grade, and shape. Understanding the characteristics of these abrasive tools is essential for selecting the right tool for specific grinding and cutting tasks in various industries.