Analysis of Abrasive Machining Tools and Materials

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Abrasive tools are widely used in various industries for grinding, polishing, and finishing operations. They are available in both natural and synthetic forms, with the majority being manufactured using synthetic abrasives combined with binders. Apart from metalworking and manufacturing industries, abrasives find applications in sectors such as food processing, paper production, and the processing of non-metallic materials like ceramics, glass, stone, plastics, rubber, and wood.

Historical Background:

The use of natural grinding stones for shaping stone tools, bone tools, and other implements dates back to the Neolithic period. In 1872, ceramic grinding wheels made by combining natural abrasives with clay were introduced in the United States. Around 1900, synthetic abrasives were developed, leading to the production of various types of abrasive tools and facilitating the rapid advancement of grinding and grinding machines. Since then, the proportion of natural abrasives in abrasive tools has gradually decreased.

Types of Abrasive Tools:

Abrasive tools can be categorized into two main types based on their raw material source: natural abrasive tools and synthetic abrasive tools. In the mechanical industry, the commonly used natural abrasive tool is oil stone. Synthetic abrasive tools are further classified into five categories: grinding wheels, abrasive heads, oil stones, abrasive bricks (collectively known as bonded abrasive tools), and coated abrasive tools. Grinding powders are also considered a type of abrasive tool.

Bonded Abrasive Tools:

Bonded abrasive tools consist of abrasive grains bonded together with a binder, forming a tool with a specific shape and strength. The three essential components of bonded abrasive tools are abrasive grains, binders, and pores. The abrasive grains perform the cutting action, while the binder holds them together. Inorganic and organic materials are used as binders, with ceramics, magnesite, and sodium silicate being common inorganic binders, and resin, rubber, and shellac being organic binders. Pores in the abrasive tools facilitate chip removal and cooling during grinding and can be impregnated with fillers such as sulfur and paraffin to improve tool performance.

Key Characteristics of Bonded Abrasive Tools:

Several factors define the characteristics of bonded abrasive tools, including shape, size, abrasive grain size, hardness, structure, and binder properties. Hardness refers to the ability of the abrasive grains to resist detachment under external forces, reflecting the strength of the binder in holding the grains. Hardness levels are categorized into seven major grades: super-soft, soft, medium-soft, medium, medium-hard, hard, and super-hard. Measurement methods for hardness include the handheld cone method, the mechanical cone method, the Rockwell hardness test, and the sandblasting hardness test.

Applications and Selection of Abrasive Tools:

The choice of abrasive tools depends on the hardness of the workpiece material. For hard work-piece materials, abrasive tools with lower hardness are preferred, while for softer materials, abrasive tools with higher hardness are selected. The structure of the abrasive tool also plays a crucial role in its performance. Tools with a looser structure exhibit less blunting and heat generation during grinding, reducing the risk of work-piece deformation and burn damage. In contrast, tools with a tighter structure retain abrasive grains better, enabling them to maintain their geometric shape. The structure of abrasive tools is controlled during the manufacturing process, and various levels of looseness or tightness can be achieved.

Abrasive processing plays a vital role in various industries, providing efficient and precise grinding, polishing, and honing capabilities. The selection of appropriate abrasives and the careful design and manufacturing of abrasive tools are essential to achieve optimal performance and desired results in different applications. With continuous advancements in materials and manufacturing techniques, abrasive processing continues to evolve, offering improved efficiency, durability, and versatility to meet the ever-growing demands of modern industries.