{"id":12967,"date":"2025-03-16T17:07:51","date_gmt":"2025-03-16T08:07:51","guid":{"rendered":"https:\/\/mirror-polish.com\/uncategorized\/polishing-basics\/"},"modified":"2025-11-27T10:11:24","modified_gmt":"2025-11-27T01:11:24","slug":"polishing-basics","status":"publish","type":"post","link":"https:\/\/mirror-polish.com\/en\/faq\/knowledge-of-polishing\/polishing-basics\/","title":{"rendered":"What Is Polishing\uff1f| Basic Knowledge and Processing Methods"},"content":{"rendered":"\n

This page provides an overview of the basic knowledge and processing methods related to polishing.<\/p>\n\n\n\n

For information about TDC\u2019s ultra-precision polishing and machining services, please refer to “Ultra-Precision Polishing and Machining Services<\/a><\/strong>“.
To learn more about the specific polishing processes carried out at TDC, see “Precision Polishing Service<\/a><\/strong>“.<\/p>\n\n\n\n

What Is Polishing?<\/h2>\n\n\n\n

Polishing is a process that removes surface irregularities from a product by using abrasive grains\u2014tiny, hard particles.<\/p>\n\n\n\n

There are various types and materials of abrasive grains used in polishing. By selecting the appropriate abrasives and processing methods to suit the target material, it is possible to achieve surface adjustments at the micrometer (\u03bcm) or nanometer (nm) scale. For this reason, polishing is often used as a final finishing step in product manufacturing.<\/p>\n\n\n\n

The Difference Between Polishing and Grinding<\/h3>\n\n\n\n

While both polishing and grinding involve removing unwanted material from a product\u2019s surface, they are technically distinct processes.<\/p>\n\n\n\n

Grinding is commonly used to ensure dimensional accuracy and is well-suited for applications such as shape refinement and flatness correction. Polishing, on the other hand, is positioned as an ultra-precision process that aims for even higher levels of accuracy. It is employed to achieve exceptional surface smoothness and to eliminate extremely fine irregularities\u2014often at the nanometer scale. Polishing also plays a vital role in enhancing the overall quality and finish of a product.<\/p>\n\n\n\n

Selecting the most appropriate method based on the specifications and required precision is essential for achieving optimal results in any manufacturing process.<\/p>\n\n\n\n

At TDC, we combine polishing, grinding, and cutting processes as needed to deliver ultra-precision finishing services, specializing in surface roughness levels as fine as Ra 1 nanometer.<\/p>\n\n\n\n

Types of Polishing Processes<\/strong><\/h2>\n\n\n\n

Polishing processes encompass a wide range of methods and techniques, selected according to specific objectives such as dimensional accuracy, shape, and surface finish requirements.<\/p>\n\n\n\n

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Lapping<\/h3>\n\n\n\n

Lapping polishing is a machining method that uses a device known as a lapping machine. It is generally classified into two types: double-sided lapping, in which the workpiece is held between two flat plates, and single-sided lapping, where the workpiece is placed on a single flat plate.<\/p>\n\n\n\n

In both cases, pressure is applied from above to rub the product against an abrasive compound containing free abrasives. This process enables highly precise planar finishing and is commonly used for products where flatness is critical, such as plano lenses, molds, precision jigs, and cutting tools.<\/p>\n<\/div>\n\n\n\n

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Polishing<\/h3>\n\n\n\n

Like lapping, polishing also uses a polishing plate and abrasive compound; however, it differs in that softer materials\u2014such as cloth or felt\u2014are used during the process.<\/p>\n\n\n\n

By selecting the appropriate polishing pad and type of abrasive, it is possible to achieve a more delicate and refined surface finish. Polishing is commonly used as a final finishing process, such as for gloss enhancement or creating a mirror-like surface.<\/p>\n<\/div>\n<\/div>\n\n\n\n

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Barrel Polishing<\/h3>\n\n\n\n

Barrel polishing is a method in which products are placed into a large container along with polishing media and a compound\u2014a polishing agent that also provides cleaning and lubricating effects. The container is then vibrated or rotated to gradually polish the surface of the products.<\/p>\n\n\n\n

A major advantage of this process is its ability to handle the polishing of large quantities of items simultaneously.<\/p>\n<\/div>\n\n\n\n

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Electropolishing<\/h3>\n\n\n\n

Electropolishing is a method in which a product is immersed in an electrolyte solution and subjected to a direct electric current to achieve a polishing effect. This technique is often used when other polishing methods are not suitable.<\/p>\n\n\n\n

However, it has some limitations\u2014only certain types of metals are compatible, and the process tends to be relatively costly.<\/p>\n<\/div>\n<\/div>\n\n\n\n

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Electrical Discharge Machining (EDM)<\/h3>\n\n\n\n

Electrical Discharge Machining (EDM) is a method of metal processing that utilizes thermal energy generated by electrical discharges. Unlike cutting with tools or blades, EDM removes material by melting it through high-temperature sparks generated between an electrode and the workpiece.<\/p>\n\n\n\n

Because this method relies on a fundamentally different approach from other material removal processes, it is often used for machining extremely hard materials that are difficult to process using conventional techniques.<\/p>\n<\/div>\n\n\n\n

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Coated Abrasive<\/h3>\n\n\n\n

Coated abrasive polishing\u2014commonly understood as polishing with sandpaper\u2014involves using a belt made of cloth or paper, on which abrasive grains are evenly distributed. This belt, often referred to as an abrasive belt, is shaped into a loop and rotated. The workpiece is then brought into contact with the moving belt to perform the polishing.<\/p>\n\n\n\n

This method is categorized as a type of fixed abrasive processing.<\/p>\n<\/div>\n<\/div>\n\n\n\n

Everyday Examples of Polishing<\/h2>\n\n\n\n

Polishing is not limited to industrial settings or specialized machinery.
There are also many familiar forms of polishing found in everyday life.<\/p>\n\n\n\n

Whetstone Polishing (Manual)<\/h3>\n\n\n\n

Polishing with whetstones is also commonly found in everyday life.
A familiar example is sharpening kitchen knives using a whetstone. While high precision is generally not required, the choice of whetstone and the sharpening technique may vary depending on the item being worked on.<\/p>\n\n\n\n

Sandpaper Polishing<\/h3>\n\n\n\n

Anyone who has done DIY or craft projects has likely used sandpaper at some point.
Though simple, sanding with sandpaper is a legitimate and widely used method of polishing.<\/p>\n\n\n\n

Lens Polishing<\/h3>\n\n\n\n

In the manufacturing of camera and microscope lenses, the final stage often involves manual polishing to complete the surface.
This is another example of polishing that we can relate to in everyday life.<\/p>\n\n\n\n

For more detailed information on different polishing methods, please refer to the “Types of Polishing Processes<\/a><\/strong>” page.<\/p>\n\n\n\n

What Are Abrasive Grains?<\/h2>\n\n\n\n

Abrasive grains are hard particles used in polishing and grinding processes. They serve as the actual “cutting edges” that remove material from a workpiece. Unlike conventional cutting tools, abrasive grains continuously renew their cutting edges through microscopic fracturing during use.<\/p>\n\n\n\n

Abrasives are broadly classified into two categories: conventional abrasives and superabrasives. Conventional abrasives can be further divided into alumina-based and silicon carbide-based types.<\/p>\n\n\n\n

Alumina abrasives (also known as alumina or aluminum oxide) are commonly used for materials such as steel and hardened steel, while silicon carbide abrasives (carborundum) are suitable for stone and cast iron.<\/p>\n\n\n\n

Below are examples of typical abrasive grains.<\/p>\n\n\n\n