The abrasive belt is a very important type of abrasive product, usually classified into three major categories: hard cloth sanding belts, soft cloth sanding belts, and paper abrasive belts. As an abrasive belt, it generally consists of four major elements: base material, bonding agent, abrasive, and structural formation. The structural form of the abrasive belt refers to two forms: "seamless abrasive belt" and "seamed abrasive belt".
The seamless abrasive belt is a type of abrasive belt that is made from cylinder cloth as the base material, and processed through a series of processes such as original fabric treatment, glue coating, sand planting, and solidification to form a seamless abrasive belt. This type of abrasive belt is an early product, and to this day, only Japan and China still have this product, with a small quantity of products. Due to the limitations of the cylinder cloth base material and production equipment in this process, it cannot meet the requirements of many specifications, especially the wide abrasive belt, and also has low production efficiency and complex processes. Therefore, it has been eliminated in the development of modern abrasive belts and replaced by seamed abrasive belts.
In the international standard for abrasive belts, the term "abrasive belt" actually refers to the seamed abrasive belt. Seamed abrasive belts are divided into two categories: lap joint and butt joint, and the joint has shifted from lap joint to butt joint as the main type. Butt joint abrasive belts account for more than 75% in Europe and the United States, and the biggest advantage of butt joint abrasive belts is to avoid the directional requirements for lap joint abrasive belts during use.
The lap joint method is to sand the sand surface and cloth surface into inclined edges (usually 67 degrees) at the two joints according to the predetermined width requirements, then coat them with joint adhesive, overlap and press them together. The thickness of the overlap at the joint cannot be greater than 0.1mm than the non-joint thickness. This joint method can be used for cloth base, paper base, and composite base.
The butt joint abrasive belt first sands the front (sand surface) or back (cloth surface) of the two joint edges to remove thickness equivalent to that of the joint liner, and then affixes an abrasive belt made by pressing a PVC polyester film on the joint. This film not only has high strength but also extremely low elongation. Butt joint is a widely used joint method, which is simpler in process, more stable, and has better flatness than lap joint method, but is slightly more expensive. The PVC films currently used in abrasive belt factories are available in five colors: yellow, red, white, blue, and green. They have specific technical properties, different directional angles, and different film thicknesses to meet the needs of different abrasive belt uses.
Butt joint methods can be further divided into two forms: one is regular end-to-end butt joint, where the two joint edges are directly spliced together (ordinary flat joint); the other is S-shaped butt joint, where both joint edges are processed into an S-shape and the two edges are interlocked like gears, and then pressed into an abrasive belt with a PVC polyester film (S-shaped flat joint).