Table of Contents

• Introduction
• What is a bench grinding wheel?
• Types of bench grinding wheels
• Factors to consider before choosing
• Conclusion

Introduction

Metalworking is precision and hardness. Each cut, grind, and polish demands the appropriate tool. Among these tools, a bench grinding wheel is important. It shapes, sharpens, and smoothes metal surfaces with ease. However,  selecting the correct wheel is not as easy as it appears to be. The incorrect wheel can ruin both the tool and workpiece. In order to make the correct selection, most workshops tend to bank upon a reputable abrasive tools supplier Dubai for credible and superior grinding solutions.

What is a bench grinding wheel?

Previously, a grinding machine with revolving parts would be fitted with sandstone blocks. The machines would be hand-driven, and water would serve as a coolant. Today, efficiency is all that matters, so grinding wheels are mass-produced. Tens of millions of abrasive particles are compressed in tandem with a bond and bonded onto a backing material.

Mounted on bench grinders and operating at high speeds, these wheels will shape, sharpen, and deburr metal parts on contact. Therefore ,the heat generated by this friction warms up materials and produces sparks.

By selecting the proper quality grinding wheel and grain, you will have the bench grinder perform its task well. However, wear is normal, and it’s important to keep an eye on the profile of the grinding wheel to make sure it is in an acceptable condition. 

Moreover, dressing your bench grinder regularly helps it to maintain an effective grit with an even cutting surface. A grinding wheel will be perfectly flat and even when new. If over time it’s getting out of balance in a big way or creating vibrations, it is wise to replace the wheel altogether. 

Types of bench grinding wheels

There are several types of grinding wheels available with different specifications. There are different uses like sharpening, polishing, cutting, & smoothening of metal.These are based on the type of abrasive used, the size produced, and the finished product. This comprises:

• Straight wheel: They are used in various forms of tools such as chisels. It can be used for grinding of all kinds.
• Cylinder or wheel ring: It is used for the creation of flat surfaces. The grinding is done using the end face of the wheel.
• Tapered wheel: It is used for grinding of thread and gear teeth.
• Straight cup: It is used for cutting off tools and cutter grinders.
• Dish cup: It is used for cutter grinders and jig grinders.
• Saucer wheel: It is used for grinding of miller cutters and twist drills.
• Diamond wheels: These are used in the grinding wheels utilized to finish industrial diamonds.
• Cut-off wheels: These are used in the fabrication of reinforcement bars. It is also used for anything requiring a rapid removal and cutting.

Factors to consider before choosing

1. Abrasive Type

Selecting the proper abrasive grain is important, as it’s the major cutting agent and must be well suited for the material of the workpiece and its properties. 

• Aluminum Oxide (A/WA/PA): The most popular abrasive. Aluminum oxide is the best abrasive for grinding tough tensile strength materials such as steel, stainless steel, and iron. You can stick with White (WA) for general work or use the more durable Pink (PA) and Semi-Friable (FA) types for tougher jobs.
• Silicon Carbide (C/GC): Harder than aluminum oxide. Ideal for low-tensile-strength materials such as cast iron, brass, bronze, aluminum, and non-metallic materials such as stone, ceramics, and rubber.
• Zirconia Alumina (AZ): A durable, self-sharpening grain that is employed for heavy stock removal and heavy-duty rough grinding in alloys and cast iron.
• Ceramic Alumina (SA): The newest and most costly abrasive. Microcrystalline structure enables it to sharpen itself, resulting in a very hard and tough product. It’s employed for precision grinding on the hardest-to-grind steels and alloys.

2. Grit Size

Grit size is a measure of the dimensions of abrasive grains. A lower value equals a larger, coarser grain, whereas a higher value equals a smaller, finer grain.

• Coarse (8-24): For high material removal in applications where surface finish is not essential.
• Medium (30-60): It strikes a balance between aggressive material removal and smooth surface finish.
• Fine (70-220): Used for smooth finishing and for holding precision.
• Very Fine (240+): Applied to polishing and extremely fine finishing operations.

3. Grade

The grade of a grinding wheel defines its hardness and the strength of the bond holding the abrasive grains.

• Soft Grade (A-H): The grains are free to release easily. Most suitable for hard material and aggressive stock removal, since new cutting edges are continually exposed.
• Medium Grade (I-P): A general-purpose, all-around selection for a variety of materials and uses.
• Hard Grade (Q-Z): The grains are more firmly engaged. Most suitable for soft materials and limited contact areas, since the life of the wheel is prolonged.

4. Structure

“Structure” refers to the distance between the abrasive grains.

• Dense Structure (1-7): The grains are tightly packed. Used for precise finishes and holding shape.
• Open Structure (8-14): The grains are more widely spaced. Avoids clogging when grinding soft, gummy, or ductile materials such as aluminum and copper.

5. Bond Type

The function of the bond is to bind the abrasive grains together.

• Vitrified (V): The most widely used bond type. Composed of clays and fired at high temperature, it is strong, porous, and impervious to water or oils.
• Resinoid (B): A resin bond that is synthetic and employed on high-speed cutting wheels and snagging grinders, which need to be strong and impact-resistant.
• Rubber (R): A rubber bond for cutting-off and polishing operations that need a fine finish.
• Metal (M): Used on diamond or CBN (cubic boron nitride) superabrasive wheels.

6. Knowing Grinding Wheel Marking Codes

Grinding wheels are stamped with a standardized code that is a blueprint of the wheel’s contents. The understanding of this code is crucial in ensuring the appropriate wheel is used and a safe and effective grinding process.

Grinding wheels are stamped with a standardized code indicating these five elements. For instance, a symbol such as WA 60 K 7 V reads as

• WA: White Aluminum Oxide (Abrasive)
• 60: Size of Grit (Medium)
• K: Grade (Medium)
• 7: Structure (Open)
• V: Vitrified (Bond)

Conclusion

The selection of the right bench piece wheel will ensure accuracy, safety and equipment durability. Most of the workshops depend on the famous abrasive tools dealers in Dubai to supply them with quality wheels and supply. Appropriate practices, quality materials, and correct wheels make metal smooth, safe, and more efficient.