As a result of the harsh stress abrasive grains are subjected to during grinding, especially by machine grinding, the grains must be glued to the backing material in two stages. In the first stage, grains are glued onto the backing material, while in the second stage; the "gaps" between the abrasive grains are filled to make them more stable. This strengthens the attachment of the grains and the grinding effect of the grains as they do not detach so easily from the backing material. Below is a list of the most commonly used bonding agents in today's products:
GLUE. Normally vegetable or animal glue varieties are used. There are many trade terms in use like starch, bone glue, technical gelatin, hide glue etc.Glue products are best suited for hand processing and should be protected from moisture as they will dissolve over time.
- To facilitate grinding
- Resistant to moderate stress / strain
- Withstands moderate friction heat
- Some are odorless
UREA RESIN Urea resin is a much stronger bonding agent compared to glue and is a chemical combination of urea and formaldehyde. It is found everywhere and used in many manufacturing processes due to its useful properties and relative economical price. Examples include decorative laminates, textiles, paper, foundry sand molds, wrinkle resistant fabrics, cotton blends, rayon. corduroy, etc. It is also used to glue wood together (e.g. MDF).
- Good tensile strength
- Can withstand high friction heat
- Water resistant
- Suitable for both hand and machine slip
PHENOLIC RESIN. Phenolic resin is a mix of chemical compounds: aldehyde and phenol. From this mix, it is then later called as phenolic resin. Phenolic resins can be found in a myriad industrial products such as bearings, wear strips, terminal boards, switches, washers, industrial lamination, gaskets, transformers, machining parts, and gears. Phenolic laminates are made by impregnating one or more layers of a base material such as paper, fiberglass or cotton with phenolic resin and laminating the resin-saturated base material under heat and pressure. The resin fully polymerizes (cures) during this process.
- Extra high strength
- Withstands high load and high friction heat
- For all types of grinding jobs, particularly well-suited for machine sanding