BASIC PRINCIPLE OF GRINDING

One of my readers has suggested me to write one article about basic of grinding. We have discussed in our previous post about the working principle of milling operation, today we will see the basic of grinding in this post.

What we will understand at the end of this post? We will secure following information here

1. Understanding the fundamental concept of grinding: Process of grinding
2. Abrasives materials
3. Advantage of grinding
4. Types of grinding
5. Application of grinding  

Process of grinding

Grinding is the most common type of material cutting and surface generation process. Mostly grinding process is used to shape and to provide better finishing parts of metals. Grinding process uses one abrasive tool to make controlled contact with workpiece surface. 

Normally grinding wheel is used as abrasive tool in process of grinding. Grinding wheel will have grains of abrasive materials and these grains of abrasive material will be termed as grit. Size of abrasive materials plays a very important role in grinding process as larger size grains will remove material faster from workpiece surface but will not provide better surface finish, whereas smaller grain size will remove material slowly from workpiece surface but will provide better surface finish.

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These grains of abrasive material i.e. grits will have sharp edges or points with enough hardness as compared to workpiece surface hardness and wear resistance and these grits will act as cutting tool in process of grinding to remove small-small particles from workpiece surface.

Image courtesy: Google

According to society of manufacturing engineers, Surface finishing and precision secured by grinding process will be approximate ten times better as compared to milling or turning process of machining.

Abrasive materials

Let us see the types of abrasive materials used for making the grinding wheel, which is key component in grinding process.

1. Aluminum oxide grinding wheel is commonly used in making the grinding wheel and will be best suited for grinding the ferrous metals having high tensile strength  e.g. hard steel, wrought iron etc.
2. Silicon carbide grinding wheel is used to grind the softer, low tensile strength, high density and non-ferrous materials such as brass, aluminum and softer bronze.
3. Cubic boron nitride (CBN) grinding wheel is used to grind hard ferrous material, CBN grinding wheel is used approximate 5% of grinding operation.
4. Diamond grinding wheel is also used rarely and best suited for hard non metal and non ferrous materials.

Performance of grinding wheel will be dependent on grain size, pore structure and bond type. Service life of grinding wheel will also depend on the application of coolant. Application of coolant in grinding process will reduce the power requirement of grinding machine as well as will provide the better quality of grinding also.

Normally it is considered that material removal rate in grinding process is lower while better surface finish and precision will be secured in grinding process, but these days with advancement in technology for development in grinding wheel and grinding machine, we are introduced with abrasive machining where better precision and surface finish with high material removal rate could be secured during grinding process of unhardened surface of workpiece.

Factor affecting the quality of workpiece surfaces prepared by grinding process

Let us see following points where we will come to know about the various factors that influence the workpiece surfaces prepared by process of grinding.

1. Type of grinding wheel: Grinding wheel with smaller grain size will provide the better surface finish, while material removal rate will be low.
2. Feed rate: Slower feed rate will provide the precise surface finishing
3. Material of workpiece: Material with much hardness will yield the precise surface finishing
4. Grinding wheel condition: Damaged grinding wheel will never provide the quality surface finishing.
5. Quality of lubricant: Quality coolant in grinding process will reduce the power requirement of grinding machine as well as will provide the better quality of grinding also.

We will continue to our next post where we will see the various types of grinding process, advantage of grinding process and finally we will see the application of grinding process.

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