Abrasive processing is a manufacturing process that involves scraping the surface of metal or wood to make it smooth and shiny. Abrasives are the materials used in this process, and there are several types depending on the desired outcome. This article will explain the different types of abrasives and how to choose the right one.
What is an abrasive?
Abrasives are particles used to scrape and polish the surface of an object. Sometimes, abrasives also include solutions containing particles.
There are two patterns for abrasive processing, one is to use a power tool with a disc grinder or sander, and the other is to use a polishing sheet or file with a human hand, so we will introduce them below.
Types of abrasives and how to choose them
Abrasive materials can be used in a wide range of applications by changing the number of grinders depending on the purpose of use and the processing conditions. You can improve work efficiency by selecting an abrasive with a shape suitable for the workpiece you want to deal with and then fine-tuning the abrasive count.
In general, abrasive processing requires a hardness equal to or greater than that of the object to be processed. In addition, the processing speed varies depending on the size of the grains contained in the abrasive.
Select by abrasive grain size and abrasive count
Abrasive materials and grinding stones contain abrasive grains to polish the object, and the grain size of the abrasive material refers to the size of the abrasive grains.
The abrasive grain size is expressed as a number, with a higher number indicating finer grains. In other words, a grain size of 100 is finer than a grain size of 0. This grain size is also called a count (bante), and is sometimes expressed with a # (sharp) suffix, such as #400.
Since the size of the grain size is directly related to the roughness of the final finish, it is important to select the appropriate grain size and count. For example, if you want the final finish to have a grain size of 4000, be aware that no matter how much you polish with a smaller grain size and count, you will not achieve a roughness of 4000.
Select by shape
Also called ‘sandpaper’, abrasive sheets are widely used in household hobbies and Sunday carpentry. There is a wide variety of types, including those made of ordinary paper, water-resistant paper, and cloth, and they are also available in finer abrasive counts. The abrasive sheet is generally a consumable item and must be replaced when the abrasive bonded to the paper becomes clogged or peeled.
Abrasive materials are mainly used for surface processing / dimensioning, and glazing. It has a wide range of applications and is used for metals such as iron and copper, wood, and plastics. The most common types include diamond processing, ironworking, and woodworking files, as well as commonly used paper files.
Solid abrasives are solid tools containing abrasive grains, etc., and are used for processing and finishing by shaving the object. Since solid abrasives are basically used to process by shaving the object, abrasive grains with high hardness are used. Generally, materials such as diamond, silicon oxide, aluminum oxide, and cubic boron nitride are used.
Belt abrasives are used by connecting abrasive paper and other materials in the form of strips, which are attached to a belt and rotated. There are lap joints where abrasive belts are overlapped and butt joints where the joints are reinforced by backing or other means, but both can cause defects due to joints, and many of them do not have abrasive grain processing applied to those areas.
Endless abrasive belts without joints are also available, but are usually classified in a separate category from abrasive belts.
It is a disc-shaped abrasive that can be attached to sanders and grinders. There is a variety of types, such as disc wheels (vertically planted type) that can be applied perpendicularly to the workpiece to facilitate corner work, multi-discs that are suitable for soft processing, and three-sided discs that can be used to work on a wide range of surfaces.
Holder-mounted type (band)
This type is used by attaching an abrasive drum. The cylindrical abrasive drum rotates at high speed to polish contact surfaces. It can be used to polish the inside of structures or objects with a rounded edge.
How to select abrasives for manual polishing
The following is an explanation of the different types of abrasives and how to select the right one for manual polishing.
Select by application
There are two main types of abrasives: coarse abrasives for rust removal and woodworking, and fine abrasives for fine corrections.
Abrasive materials suitable for coarse grinding include abrasive sheets, files, dressers, and solid abrasives. Abrasive sheets are used to remove rust from metal-painted surfaces and to polish wood fabrics. Files have a wide range of applications and can be used on metals such as iron and copper, wood, and plastics. There are various types of dressers, such as manual types and machine-installed types, but the tips and surfaces used are often made of diamonds, whose hardness allows for polishing. Solid abrasives are often used for medium finishing of stainless steel, aluminum, and chrome plating.
Make minor corrections
Abrasives suitable for making minor fixes and finishing are steel wool, whetstones, and handrappers. Steel wool is a pad made of special steel shaved to about 0.025 mm and processed into a wool shape, which is soft and has a free shape, and can remove rust and dirt and polish evenly. Grindstones are commonly used to sharpen knives, scissors, and other cutting tools. A hand wrapper is a tool shaped like a toothbrush with a whetstone at the end, and is one of the tools used for correcting by grinding.
Select from compatible materials
Here are the three main materials and the abrasives that fit each.
Speaking of abrasives, it may be easy for you to come up with woodworking. Many of you may have done it in the past at school or in other places. Abrasive materials suitable for woodworking are abrasive sheets and files. They are durable and can be polished with relatively light force.
A file is suitable for polishing iron. Since iron is a metal, the surface must be polished more delicately. Since iron is incompatible with diamond polishing, it is not suitable for polishing with a dresser installed on a machine.
Familiar stainless steel items include kitchen sinks. Solid abrasives and liquid abrasives are suitable for polishing stainless steel. Depending on the particle size and the degree of polishing, you can choose whether to pour the abrasive like a conveyor belt or to buff and polish.
How to choose abrasives when using power tools
By using a power tool such as a sander or grinding machine and using an abrasive material or polishing liquid according to the object to be polished, a smooth polished surface can be obtained speedily.
Disc type, roll type, sheet type, wheel type, etc. are available, and make sure to use the appropriate one for the polishing machine, the object to be polished, and the polishing process. All processes such as deburring, cleaning, film removal, finishing, and polishing can be performed efficiently.
Select by material
The alumina type is mainly composed of alumina oxide and is used for high-hardness polishing. It is one of the most widely distributed abrasives with high adaptability and is suitable for various metals and woodworking.
Zirconia, also known as imitation diamond, is the main component of this material. It has a sharp and pointed structure and is used for polishing stainless steel and other hard metals.
This abrasive specializes in impact and friction resistance. It has high cutting power and can be used for a wide range of steel materials such as stainless steel, titanium, and nickel.
Silicon carbide type
It is also known as carborundum type. This abrasive has the next highest hardness after diamond and is resistant to thermal shock, making it a powerful tool for delicate work. Often used for glass, stone, and other objects that are prone to loss.
Each abrasive has its own strengths and weaknesses, so it is necessary to select the correct abrasive. For efficiency, it is also important to select the most suitable count of abrasives according to the final polish you want to achieve.