There are several varieties of sanding paper and sanding discs available on the market. Some sandpaper is designed for wood, while others are designed for automobiles. There are also hand sandpaper and sanding discs for orbital sanders. Here is the main process of sandpaper produced.
- apply primer to backing
- apply abrasives to manufacturing coat
- apply dimensional coating
- curved reel
- Apply primer to backing
Typical abrasive belts are derived from the manufacture of sanding jumbo rolls of coated abrasive containing an “X” weight cotton fabric backing, 100 grit alumina, and a resin binder. Production begins when the primer is applied to one side of the backing material.
- Apply abrasives to manufacturing coat
The next step, applying the abrasive mineral, is the most important step in the manufacturing process because it determines the orientation and density of the mineral. In the past, the backing with the first layer of adhesive was passed under a controlled abrasive flow, which applied a thin layer of randomly oriented grit. Today, the backing is passed, adhesive side down, through a disc of electrostatically charged abrasive – given an opposite charge to the backing. The opposite charge causes the abrasive to adhere evenly to the backing, resulting in a very sharp, fast-cutting coated abrasive with maximum service life. Controlling mineral density on flexible backings can lead to two important changes in product design: open and closed-coated abrasives. Open-coated sanding discs contain abrasive particles that cover 50% to 70% of the surface area of the backing. This lower density makes the finished product flexible and prevents it from clogging or loading small amounts of work material. In closed-coated products, minerals cover 100% of the available surface area, making the finished product more suitable for finishing applications and for rougher handling than open-coated products.
- Apply Dimensional Coating
Once the particles are embedded in the primer, the rollers are dried and continued to be coated. After application of the size, the roll is dried again and cured under carefully controlled temperature and humidity conditions. The finished sanding disc is then wound on a large spool, Ship to a company that converts it into a belt or other item. May include additional materials and processes to impart special characteristics to the converted product. One such treatment is the addition of grinding aids to the gel coat to improve the grinding of certain metals in high pressure applications. Another treatment is to apply a pressure sensitive adhesive to the non-abrasive side of the backing to create certain types of abrasive discs. Materials can also be added to reduce static electricity when using belts on wood. The rolls pass through two closely spaced steel rolls to crush the protruding minerals in a process called buffing and leave a product of uniform thickness, designed for fine machining applications.
- Curved reel
Coated abrasive rolls are systematically bent or bent to break a continuous layer of adhesive before being converted into a tape or other product. This bending is necessary because the newly manufactured rolls are very stiff and otherwise would not function properly when converted to other products. Bending can be applied in a single direction or in multiple directions. One-way bending usually breaks the bond at a 90-degree angle to the bead. For special applications where the belt must precisely conform to the surface contour of the part, apply a unidirectional bend along a line parallel to the sides of the belt. Multiple bends break the bond from the sides of the belt in a criss-cross pattern or at a 45-degree angle in a combination of 90- and 45-degree orientations. Although the latter produces a very flexible belt, this bending greatly reduces the product’s lifespan.
Converting Coils to Belts First cut the coated abrasive bars to the desired width. Then cut each strip to the appropriate length and join the ends together. The joints for normal belts are 45 degree overlapping joints. Narrow bands are spliced at sharper angles, and wide bands are spliced at larger angles. Various splicing techniques can be applied depending on the significance of the thickness variation of the tape at the slice and the amount of stress the tape is subjected to during use. A common practice in preparing a splice for connection is scraping, a process that removes a layer of abrasive or backing from the end of a belt. To minimize joint thickness in products intended for finishing applications, both ends are turned. Coarse-grained sanding discs for less precise applications are turned on one end only. The conversion process for other products is similar. For example, a sanding disc starts with an appropriately sized coil section, and then a single wheel is machined out with a hole punched in the center.
Now that you know how the sandpaper is produced, we also shared how to choose the right sandpaper grit size and abrasive, if you are interested, you can contact us. Binic- coated abrasive manufacture.