6 FACTORS TO CONSIDER WHEN CHOOSING AN ABRASIVE
1. TYPE OF ABRASIVE
Choosing the right type of abrasive is very essential before working on your masterpiece. 4 types of abrasives are popularly used:
- Aluminum oxide – the versatility and low cost of aluminum oxide make it one of the most widely used abrasives. due to its extreme friability, which causes it to break up into smaller pieces as it cuts, the cutting surface is always razor-sharp. you will need to replace aluminum oxide more frequently because it is less durable than other abrasive grains.
- Silicon carbide – due to its even and reliable cut-rate, silicon carbide is frequently used for finishing work. it is more expensive than aluminum oxide because it is stiffer and sharper. however, the improved cut rate cancels out the higher cost. silicon carbide is preferred for low-tensile-strength materials like cast or ductile iron as well as non-ferrous metals like copper, bronze, titanium, aluminum, zinc, gold, etc.
- Zirconium Alumina – Zirconia cuts sharply, making it a superior material for grinding or polishing metal and removing stock from hardwoods. for ferrous metals or high-tensile alloys, a high-torque grinder is an ideal option. in terms of cost and longevity, it is comparable to ceramic and less durable than aluminum oxide.
- Ceramic – one of the toughest abrasives utilized in heavy metal removal applications is ceramic. it's one of the priciest abrasives available, but the cost is balanced by the fact that it lasts the longest.
Another kind you may encounter is garnet (the go-to choice for light-duty smoothing and hand-sanding jobs) and emery (ideal for polishing).
2. GRIT SIZE
The next step is picking the appropriate grit after choosing an abrasive.
The degree of grit, which can range from extra-smooth to extremely coarse, is how abrasive manufacturers describe their products. The quantity of distinct abrasive grains in the wheel is known as the grit size. The grain is coarser the lower the number (10, 16, 24, etc.). For more difficult jobs like heavy removal or quick cuts, finer grains are ideal. Higher count, finer grains (70, 100, 180, etc.) are suitable for smaller, more accurate applications like delicate finishing and defined areas.
3. SHAPE OF A WHEEL
For applications involving abrasive grain type, choosing the proper wheel shape will be beneficial.
- Cylinder, Cup, Or Dish Wheels - Although each of these has a different name based on its shape, they all generally feature cutting faces on their sides.
- Recessed Wheel - is similar to a straight wheel, but has a recessed center to fit on a machine spindle or flange assembly.
- Straight Wheel - The most popular kind of grinding wheel is the Straight wheel. The abrasive area, or grinding face, is positioned on the outer edge of the device.
- Mounted Wheels - These wheels often come in smaller sizes and unique designs like plugs or cones.
4. TYPE OF COATING
The term coating describes how tightly the abrasive grain is pressed against the backing material. The abrasive grains are held together by a bond or coating, which makes them cut more effectively and progressively wears away to reveal younger, sharper grains. There are three distinct varieties: closed, open, and semi-open/closed, each with a specific function.
- Closed Coating - An abrasive with a closed coat ensures that the grain is equally distributed throughout with no free spots. It is frequently employed in metalworking applications; for instance, closed-coat aluminum oxide is the preferred abrasive for weld removal and metal grinding.
- Open Coating - In open-coat abrasives, the backing is only partially covered with grains, which lessens loading in coarser grits. Coverage is typically between 50 and 70 percent, making it easier to remove material accumulation from the grain. To plane, strip, and finish wood, open-coat aluminum oxide is widely employed.
- Semi-open Coating or Semi-closed Coating - These abrasives provide a coat that is halfway between an open and closed coat by reducing grit by an average of 30%.
5. GRADE
The grade, which ranges from A for gentle to Z for hard, designates how firmly the abrasives are bound together and can have an impact on the wheel's speed, depth of cut, feed rates, and other factors. Tougher grades are preferable for softer materials, according to the usual rule of thumb, whereas softer grades are excellent for harder materials.
6. TYPE OF BACKING
An abrasive's suitability for your application may depend on its backing. The types of backing are as follows:
- Cloth - Due to these materials' strength and flexibility, many high-end abrasives items feature cloth or synthetic backing. Polyester is particularly waterproof, making it suitable for wet tasks like maritime repairs.
- Paper - Paper-backed abrasives offer more consistent cutting during sensitive procedures like smoothing and polishing because they are lighter in weight and less expensive than other backing types. Although it can be infused with other materials (like latex) for more flexibility, it is not as durable as synthetic or fabric. In specific applications including woodworking, metal polishing, and plastics, paper-wide belts are particularly prevalent.
- Foam & Sponge - Foam and sponge backings provide the adaptability required to accommodate contours and particular shapes if veneers and moldings must be hand-sanded.
- Plastic Film - The strength, flexibility, and water resistance of plastic film backing contribute to its popularity as a common abrasive backing for wet sanding. It also offers a fantastic uniform finish.
