Guidelines for Choosing the Particle Size and Hardness of Grinding Tools and Abrasives

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The choice of abrasive material is a crucial factor in grinding operations. Selection is primarily based on the properties of the work-piece material, such as hardness, tensile strength, and toughness. When selecting abrasive materials, the following principles are essential: for grinding harder work-piece materials, opt for abrasives with higher hardness; for materials with high tensile strength, use abrasives with greater toughness; for materials with low tensile strength, select more brittle or higher strength silicon carbide abrasives. This article will delve into the specific applications of different abrasives like brown fused alumina, white fused alumina, black silicon carbide, green silicon carbide, SG, and CBN ceramics, and explore the use of mixed abrasives to enhance grinding efficiency.

Section 1: Abrasive Material Selection

The choice of abrasive material depends on the specific characteristics of the workpiece material. Here are some examples:

1. Brown Fused Alumina: Suitable for grinding carbon steel, cast iron alloy steel, and hard bronze.

2. White Fused Alumina: Suitable for grinding quenched steel, alloy steel, high-speed steel, and tool steel.

3. Black Silicon Carbide: Suitable for grinding non-ferrous metals, rubber, leather, and plastic.

4. Green Silicon Carbide: Suitable for grinding hard alloys, optical glass, and ceramic materials.

5. SG and CBN Ceramics: Widely used for grinding difficult-to-machine materials.

Section 2: Mixed Abrasives

To harness the advantages of different abrasive materials fully, the manufacturing of grinding tools often involves the use of mixed abrasives. This approach aims to enhance grinding efficiency. Here are some examples:

1. A/WA Mixed Abrasives: Commonly used for grinding nodular cast iron, combining the toughness of brown fused alumina with the brittleness and excellent thermal conductivity of white fused alumina. This combination improves the grinding efficiency.

2. Brown and White Fused Alumina Mix: By combining brown fused alumina's high toughness with white fused alumina's certain brittleness and good thermal conductivity, this mixture is suitable for grinding applications like crankshaft grinding wheels (typically using a mix with a grit size of 60#-80# and a hardness ranging from medium-soft 2 to medium 1).

3. Single Crystal and Micro-crystalline Mixed Abrasives: Used for coarse grinding cobalt-based alloy gears.

4. Brown Fused Alumina and Green Silicon Carbide Mix: Suitable for grinding aluminum high-speed steel wheels.

5. Brown and White Fused Alumina Mix for Grinding Ball Bearings: Recommended specifications include GZ/GB80# P600x36x305 for rough grinding the raceway, and GZ/GB80# P600x510x355.6 for the final grinding of the outer diameter, and so on.

The selection of abrasive materials plays a vital role in grinding operations. By considering factors such as the workpiece material's hardness, tensile strength, and other properties, professionals can make informed decisions when choosing abrasives. Understanding the principles of abrasive particle size and hardness selection is essential for achieving efficient and effective grinding processes. Moreover, the use of mixed abrasives allows for tailored grinding solutions by combining the advantages of different abrasive materials. By implementing these practices, industry professionals can optimize grinding performance, enhance productivity, and achieve high-quality results.