Abrasive

Abrasives are of natural or synthetic origin. They are distinguished mainly by their degree of hardness. It is said that one material is able to abrade another when one touches the other at their contact. Their degree of hardness is measured using special scales (Knopp, Mohs, etc).

The hardest abrasive material present in nature is the diamond. There are also other materials of both natural and synthetic origin, such as silicon carbide, corundum and zirconium. These do not reach the same hardness as the diamond, but they are very close to it.

To make an abrasive, a support is needed to adhere the abrasive powder. The most used supports are paper or canvas. Resin or glue is then used to fix the abrasive. The main abrasive tools are made this way. Examples are abrasive paper sheets (also known as sandpaper), abrasive strips and more. To create complex instruments such as discs and flap wheels, slightly more complex procedures are required which involve the use of industrial machinery. 

The precision of the abrasive is key and there are main characteristics that need assessing to get the perfect finish.
 

Quality of the backing material
The backing material needs to be strong enough to be stable but at the same time flexible enough to move as you need it to. A good quality backing material will have the right combination of flexibility, stability and tear resistance.
A. Flexible abrasive
● Easily to cut and fold to the required size
● Greater flexibility
● The grit and coating doesn't crumble
B. With a harder backing
● Scratches to the worksurface
● More brittle and breaks more easily
 

What does the actual sanding sheet look like
Poorer quality sanding sheets will often have a marked difference in appearance to their more expensive counterparts. Look at the quality of the edge of the disc. Is it frayed, cracked or peeling away? Bosch make a point about the precision of the holes in their sanding discs as even poorly punched holes can affect the quality of the finished product.
A. Precision punching advantages
● Better extraction
● Consistent quality
● Burr free holes without grit loss
B. Standard hole disadvantages
● Uneven edges create defects when sanding
● Extraction performance is reduced
● Loss of grit on the edges can scratch the surface
 

How good will the extraction be
When sanding with power tools, good extraction is crucial as not only does it prevent you breathing in harmful material but it will also extend the life of the abrasive. You also gain better visibility of the work surface for a more precise finish.
● Dust free sanding
Perforations over the whole area of the disc allow for better dust extraction as the airflow can pull material from the entire surface area. This helps to prevent build up on the disc which prolongs its working life and is safer as less dust is deposited in the air.
Produce a multi hole abrasive which allows better dust extraction and a smooth finish without swirl marks caused by build up. Another key advantage of these discs is that you can use them with different types of sander as you don't have to match the holes to those on your machine. They'll work with different sanders so there's no fiddling around getting the holes to align.
 

Bonding agent
The bonding agent used to bind the abrasive substances to the backing material is a key component in creating an effective abrasive. The grit needs to be held in place securely without being overly hard. There needs to be a balance between flexibility and hardness as a harder bonding agent means the abrasive will be more aggressive and able to remove more material. If it's too hard however it will be brittle and crack more easily resulting in areas needing to be redone.
 

Abrasive grit
Aluminium oxide is one of the most common minerals used for abrasive grain due to its versatile qualities. It's tough and maintains its sharp edges as it fragments when heat and pressure are generated during sanding. The scientific parlance for this is the friability. When sanding this is beneficial as the fragmentation means the cutting edges renew so you're able to use it for longer before having to replace the disc.
There are many different kinds of aluminium oxide which vary in quality and therefore performance. It is difficult to determine the type on the paper alone so often it's a question of trying different types and seeing which works best for you. In addition to aluminium oxide there are other abrasive minerals that are suited to different tasks.
How the abrasive grit is distributed on the sheet is also important for a good finish. A quality sheet will have an even distribution which is carefully monitored during the manufacturing process. Abrasives with an uneven distribution, the material collects on the pad and this can cause it clog and even burn the surface.
 

Coatings
Certain abrasives are also fitted with an additional coating such as stearate which is best used for sanding paint and varnish. On varnish this prevents heat build up and also works to bind varnish dust together for easier extraction and significantly prolonging the life of the abrasive.
● Electrostatic coating
Abrasives that have an electrostatic coating applied ensure that the grain is distributed evenly and the sharpest edge is facing outwards ready to sand the material. 

Followings are the typical applications of abrasive:

Buffing: The buffing is polishing & smoothening a workpiece surface using an abrasives wheel or Buffing products. Buffing removes roughcasting, pits, and solemn or slight scratches, on any type of metal.

Honing: Honing is an abrasive machining process that provides a sharp surface on a metal (example: Knife) by scrubbing an abrasive grinding stone or grinding wheel.

Drilling: Drilling is a cutting method that uses a drill bit to cut a circular cross-section hole in solid (metal, wood) materials.

Grinding: Grinding is an abrasive machining process that uses a grinding wheel as the cutting tool. A Grinding wheel is an abrasive tool with thousands of cutting points on its surface to achieve precise finishes.

Polishing: Polishing is a finishing process for smoothing a workpiece's surface using an abrasive wheel or a leather strop. Mainly polishing refers to methods that use an abrasive that is glued to the polishing wheel.

Cutting: The cutting tool is used in machining technology for cutting operations. A cutting tool is a sharp-edged device to shear off the excess material layer from the workpiece to give it the perfect shape and finishing.

Sharpening: Sharpening creates a sharp edge on a tool using abrasives of finishing or designed for cutting. 

Ningbo Dahua Grinding Wheel Co.,Ltd. Is a well known Chinese company specialized in Researching and producing resin abrasive products. It was found in 1996, mainly produce fiber reinforced resin cutting and grinding wheel, rail cutting and grinding wheel, ordinary resin grinding wheel, fiber glass etc. The factory has Industrial Production License and Independent Exporting License. In the past 20 years, it sales to more than 70 countries in the world and the quality of products is universally recognized.
The company passed ISO9001 Quality Management System and has perfect quality assurance system. The equipment are all advanced and reliable. Also, it has perfect raw material inspect, finished product inspection center and quality assurance team to assure the stability of products.
The company awarded National high-tech enterprises in 2012 and awarded Provincial Engineering Technology Center in 2017. It has more than ten Independent intellectual property invention patent and professional R&D team to provide technical support to offer suitable product to the customers. Based on many years accumulation of industrial insight, produce experience, innovate ability and service network in abrasive industry, the company can not only offer high quality customized products, but also study, design and choose new material for new products together with other factory.
The company will go on struggle as always, renew and improve the quality of products constantly, maintain good services and competitive prices. Warmly welcome you to negotiate cooperation and create better business value.