Today, most metalworkers and seasoned welders understand that the process of welding is much more than laying a bead to join pieces of metal so that the final product is created. The step of post-processing is required once the welding is completed, which varies according to the requirements of the end customer.
Most often the post-processing involves the use of a grinder that has some abrasive product which is mounted. There are several abrasive products available which vary in terms of the hardness of the wheel grit size, shape of the wheel or disc, backing material, etc. There are essentially 4 types of abrasives to select from – coated abrasive fibre discs, bonded abrasive thin wheels or grinding wheels, coated abrasive flap discs and non-woven abrasive discs.
Differences Between the Abrasives
Bonded Abrasive Thin or Grinding Wheels
These are made of 2 parts i.e. abrasive and bond. The abrasive and the bond, which is in the powdered form are mixed and compressed in a mould and baked to get a stiff wheel. While adding more bond causes the wheel to be harder and improves its life, lesser bond causes the wheel to be softer, which produces a free cutting action. Using a coarse grit abrasive helps to improve the life and the rate of the cut, whereas using a fine grit abrasive requires lesser pressure and also produces a good surface finish.
Coated Abrasive Fibre Discs
These comprise a backing material which is coated with 2 layers of resin and the 2 layers contain abrasive grains in between. The coarse and fine grit abrasive produce the same effect as the above; however, in this case, the grains have more of an effect on the weld. The grain type must be selected according to the type of material getting ground. The lifespan of the product and the cutting are affected by the backing material. The cut rate and lifespan are improved when the backing material is thick and rigid, whereas, a much thinner and flexible backing produces a better surface finish.
Coated Abrasive Flap Discs
These are essentially coated abrasive pieces that are overlapping and are arranged along the external rim of the hub and stuck with an adhesive. The overlapping improves the disc life as it lets more abrasive to be loaded onto the hub and allows greater grain exposure. Just like the fibre disc, you can change the type of grain and sizes of the grit as per the surface finish and cut rate requirements.
Non-Woven Abrasive Discs
These are made of fibrous materials and the abrasive is stuck to the fibres by resin. The disc has an easy cutting action due to the random assortment of the fibre and the grain. This results in a good surface finish. While the coarse non-woven abrasive discs are not quite aggressive compared to fibre discs, grinding wheels or flap discs can deliver aggressive cuts required for the particular application.
The abrasives discussed in the article are sure to provide a starting point where you can determine the best abrasive product to use for a particular application. However, what will work best for you will really be determined by trial and error and understanding each of the products can help you make the decision of the best product for you.