How to Select the Right Grinding Wheel

November 16, 2020

How to Select the Right Grinding Wheel?

How to Select the Right Grinding Wheel

Choosing the proper grinding wheel for a specific application is often challenging. There are several types of spins, and therefore the differences between the various sorts of used abrasives can be confusing.

What is a Grinding Wheel?

The grinding wheel is an abrasive cutter. In a grinding wheel, the abrasive grains are distributed on the wheel's edges to perform the cutting function. Thousands of those hard, chewy grains move against the workpiece to chop away tiny chips of fabric.

These abrasive grains stick together by a bond, a mixture of selected clays, and separated by pores.

While the grinding wheel is operating, the abrasive grains dig the fabric by removing the unwanted surface material in small chips.

The abrasive type, the dimensions of the abrasive grains (or grit), and the bond are the three most vital characteristics to think about when choosing a grinding wheel.

How to Select the Right Grinding Wheel?

These five factors affect the type of grinding wheel:

Table The Five Factors of Grinding Wheel

Grain

Grain Size

Grade

Structure

Bond

Nature of abrasive grain

Size of abrasive grain(F or #)

Retention strength of abrasive grains

Proportion of grains to the entire wheel

Nature of bonding agent


To offer you a touch more clarity, we've mentioned all the characteristics that differentiate grinding wheels.

  • Abrasives
  • There are four primary types of abrasive grains available for grinding discs. Each class has unique properties when it involves hardness, strength, fracture toughness, and resistance to impact. The selection of the abrasive is inevitably associated with the fabric of the workpiece.

    • Aluminum Oxide

    Aluminum Oxide is the most common abrasive utilized in grinding wheels. It's generally recommended for grinding materials like chrome steel and gear steels, but it is the right choice for cutting high tensile aluminum and bronze alloys.

    • Silicon Carbide

    Harder than standard alumina with a sharp abrasive grain, it's mostly used for grinding gray iron, chilled iron, brass, soft bronze, aluminum, and stone, rubber, and other non-ferrous materials.

    • Zirconia Alumina

    Zirconia Alumina is mainly used for rough grinding applications where high stock removal is required. This grain is related to high-tech resin bonds.

    • Ceramic Alumina 

    Often mentioned as just "Ceramic," it is the foremost modern sort of abrasive. This ceramic grain features a unique microcrystalline structure that's self-sharpening. This abrasive is exceptionally hard and powerful. It's primarily used for precision grinding in demanding applications on steels and alloys that are the foremost difficult to grind.

  • Grit
  • As we mentioned above, grit is said to the abrasive grains' dimensions distributed on the wheels. The more the grit size, the finer the abrasive is. The essential descriptions of abrasive types range from coarse to medium to fine. Here's a basic table of the various sorts of grit sizes.

    • Coarse Grain - 8, 10, 12, 14, 16, 20, 24
    • Normal Grain - 30, 36, 46, 54, 60, 70
    • Fine Grain - 80, 90, 100, 120, 150, 180, 220
    • Very Fine Grain - 240, 280, 320, 400, 500, 600, 700, 800, 1000, 1200, 2500

    Grinding wheels with a coarse grit size are commonly utilized in applications where the fabric finish isn't essential, and therefore the focus is on material removal. On the opposite hand, fine grit wheels are preferred when finish may be a fundamental aspect of the project.

  • Bond
  • The material that holds the abrasive grains together so that they can cut effectively is called a bond. Most grinding wheels are developed with vitrified bonds, which contains a mix of carefully selected clays. These wheels are strong and porous and aren't suffering from water, acid, oils, or variations in temperature.

    An essential factor to consider about the bonds is their strength or grade.

    Grinding wheel bond type:

    • Strong bonds - Such bonds are recommended for soft materials, small or narrow areas of contact, or longer wheel life. 
    • Weak bonds, or soft grades - Such bonds are preferable for hardened materials, like hardened tool steels or carbides, giant areas of contact, or rapid stock removal.
  • Wheel Shapes
  • The wheel itself comes in a variety of shapes. The grinding face—a part of the wheel that addresses the work—is on the straight wheel's periphery. The following are the commonly used grinding wheel shapes:

    • A standard variation of the straight wheel design is that the recessed wheel is so-called because the middle of the wheel is recessed to suit a machine spindle flange assembly.
    • On some grinding wheels, the cutting face is on the side of the wheel. These wheels are usually named for their distinctive shapes, as in-cylinder wheels, cup wheels, and dish wheels.
    • Mounted wheels are small grinding wheels with unique shapes, like cones or plugs, that are permanently mounted on a steel mandrel. They're used for a spread of off-hand and precision internal grinding jobs.

    Grinding Wheel Composition

    The grinding wheel consists of the main five parts: abrasives type, bond, grain size, structure, and grade.

    The Five Factors of Grinding Wheel

    Grain

    Grain Size

    Grade

    Structure

    Bond 

    Nature of abrasive grain

    Size of abrasive grain(F or #)

    Retention strength of abrasive grains

    Proportion of grains to the entire wheel

    Nature of bonding agent



    Grinding Wheel Marking

    Grinding wheel marking makes the identification of the wheel type easier. The grinding wheel specifications are mentioned in the following manner:

    Grinding Wheel Marking Codes:

    table

    Example

    Marking

    Marking Codes

    WA

    Abrasive Material

    A – regular aluminium oxide

    WA – white aluminium oxide

    19A – mixture of A and WA

    SD – synthetic diamond

    ASD – synthetic diamond, metal coating

    FA – semi-friable aluminium oxide

    PA – pink aluminium oxide

    SA (HA) – single crystal aluminium oxide

    23A – mixture of A and SA

    AZ – zirconium oxide

    C – black silicon carbide

    GC – green silicon carbide

    RC – mixture of C and GC

    60

    Grit Size

    (Coarse) 10, 12, 14, 16, 20 etc. to 600, 800, 100, 1200 (Fine)

    K

    Grade

    (Soft) A, B, C, D, E etc. through to V, W, X, Y, X (Hard)

    7

    Structure

    (Dense) 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 (Open)

    V

    Bond Type

    V – vitrified

    B – resinoid

    R – rubber

    O – MgO

    E – epoxy

    M – metal

    EP – electroplated


    In the end, selecting the grinding wheel may be a process that needs tons of your time and careful analysis, but if done right, it can cause significant results.