Tight tolerance and a high surface finish are always desirable in manufacturing, and a grinding wheel is just the right tool to achieve both. But what are grinding wheels? How does it work, and what are the different types of grinding discs? This article will provide a detailed guide on grinding wheels, right from their construction to their intended use.
What are Grinding Wheels? Usage and Application
Grinding wheels are abrasive tools that are used to remove a fine layer of material from the surface of the workpiece. This is done to achieve the desired dimensional tolerance and surface finish.
Using a Grinding Wheel
At high speed, rotate the grinding wheel so it comes into contact with the workpiece and removes the material. This high-speed contact can generate high frictional heat (especially when grinding tough metals like stainless steel). This makes it important to use cutting fluid to prevent overheating of the tool and the workpiece.
When using a grinding wheel, always maintain to-and-fro movement between the grinding wheel and the surface of the workpiece. This is required to ensure a smooth and uniform surface finish. Furthermore, when a high volume of material is to be removed, it is advised to gradually grind the workpiece in multiple passes. This is because grinding at the same spot for a prolonged time can result in overheating. Thus damaging the workpiece and the tool.
Applications of Abrasive Wheels
Common usage of grinding wheels is to grind the workpiece and achieve the desired dimensional accuracy or improve its surface finish. Therefore, it is an important operation that is performed on almost every workpiece before finalizing the machining process.
Common use of grinding is to remove unwanted material or smoothen sharp edges in metalworking industries, and to finish and achieve a smooth surface on jewelry and other intricate works.
Types of Grinding Wheels
Grinding wheels can be classified based on the abrasive and bond type.
Generally, resinoid and rubber are the most commonly used bond types and are used for most general-purpose applications. The vitrified bond provides the strongest adhesion, preventing the abrasive particles from falling off during intense grinding applications.
Similarly, the harder the abrasive, the better the material removal ability of the grinding wheel. Based on the abrasive material, there are four types of grinding wheels:
Aluminium Oxide Abrasives
Aluminium oxide is the most commonly used abrasive on grinding wheels and is best suited for grinding ferrous metals and steel workpieces. These abrasive wheels are colour-coded as grey, white, pink, brown, etc.
Grey and brown are the most widely used wheels for general-purpose grinding applications, as they provide good durability at a low cost. These wheels are ideal for machining low-carbon steel.
Pink and white grinding discs are comparatively harder and are used for grinding tougher grades of steel (such as stainless steel) that generate high frictional heat during the grinding operation.
Apart from these, aluminium oxide grinding wheels are also available in ruby red colour. These wheels are extremely tough and are used for machining tool steel.
Silicon Carbide Abrasives
Silicon carbide abrasives are ideal for grinding non-ferrous metals like aluminium, copper, etc., and non-metals like marble, granite, etc.
These grinding wheels are available in black and green, with green wheels having better sharpness than black wheels. Silicon carbide wheels are also used for grinding stainless steel when a high-quality surface finish is required.
Ceramic Abrasives
Ceramic abrasives are relatively new and are not readily available on the market. These abrasives tend to self-sharpen by breaking the dull grains, attaining a renewed sharp cutting edge.
These types of grinding wheels are ideal for applications where extensive material removal is required while maintaining a long tool life. However, ceramic grinding wheels are comparatively expensive and cost around three times more than aluminium oxide abrasive wheels.
Diamond Abrasives
Diamond abrasives are ideal for grinding extremely tough materials like concrete, asphalt, stones, etc. These grinding discs can be used on almost any material, but their high-cost limits them from being used for general-purpose applications.
Specification of Grinding Wheels
Each grinding wheel has a specific code to identify its specifications. This code provides information about the five basic elements: Abrasive type, grain size, grade, structure, and bond type.
Let us consider an example of a grinding wheel marked as A24S7B. Here, the code can be divided into 5 elements, such as A-24-S-7-B, where each element provides information about the type of abrasive, grain size, grade, structure, and bond type, respectively.
The tables below provide details about the commonly used codes for the specification of grinding wheels:
Different types of abrasives provide different types of material removal capabilities. Similarly, the type of bond determines the ability of the grinding wheel to retain the abrasive particles under the action of the cutting force.
Apart from that, the grain size determines the material removal rate and the surface finish of the final product. The higher the grain size, the lower the material removal rate and the smoother the surface finish.
Buy Grinding Wheels at L&T-SuFin
The type of grinding wheel to be used is based on your application requirements and the type of machine you use. Therefore, when buying a grinding wheel, it is important to consider the abrasive type, bond, bore diameter, size, and thickness of the wheel.
L&T-SuFin provides a wide range of grinding wheels to choose from. They deliver the product all over India. Moreover, you can request a quote based on your order quantity.