Manufacturing Process II

Unit: 5 Grinding

According to WBSCTE revised syllabus of 2022

Basic Concept

• Grinding is a conventional finishing operation.
• Finishing operation means a machining operation where very little amount of material is removed from the exterior surface of the work piece.
• This process is generally used to accurate the dimension (where a very little amount of material has to be removed) of a work piece after any other conventional machining process like turning, shaping, planning, milling etc.
• Each Abrasive particle acts as a single point cutting tool whereas the grinding wheel, with full of abrasives called a multi-point cutting tool.
• Abrasive particles of square or rectangular cross-section are embedded in the body of the grinding wheel.
• These abrasive particles cut through the metal surface of the work piece to perform the finishing operation.

Classification of Grinding Operation & Machines

Mechanism of Grinding & Self-Sharpening Behaviour

During Grinding only the outer layer of abrasive particles wears out & they are further pulled off from the wheel. Due to the rubbing action between the wheel and the grinding wheel.
When one layer of abrasive pulled out of the grinding wheel, then a fresh layer of abrasive comes out ready for material removal, this is known as self sharpening behaviour of the Grinding Wheel.

Loading of Grinding Wheel

During Grinding soft work piece materials like Aluminium, Copper, Lead etc., after sometime of grinding, work piece particles gets clogged between the abrasive particles, this condition is called Loading.

Glazing of Grinding Wheel

If a hard grinding wheel is taken for grinding a hard work piece, the rubbing force increases & abrasive particles wears out quickly. Since, the grinding wheel is also hard, it will not allow the abrasive particles to be pulled of & also no material removal will takes place, only rubbing action will persist.

This phenomenon is called Glazing.

Dressing of Grinding Wheel

After glazing occur, the worn out abrasive particles are forcefully removed to pull out new layer of fresh abrasives, with the help of single point tipped tool. This phenomenon is known as Dressing of Grinding Wheel.

So, rember that, dressing is a process of sharpening of grinding wheel.

Tool Life of a Grinding Wheel = Time period between two successive wheel dressing.

Dressing Tool

Grinding Wheel Dressing

Truing of Grinding Wheel

The process of making a new grinding wheel a concentric circle with respect to the spindle axis is called Truing.

Truing is sometimes, necessary after dressing of a used grinding wheel.

So, remember that, truing is also a process of sharpening of grinding wheel, just like dressing.

Balancingof Grinding Wheel

The process of checking and correcting a grinding wheel for its equal distribution of mass around its axis of rotation, is called Balancing of a Grinding Wheel.

Balancing is done generally, after truing a new grinding wheel.

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Unit 5: Grinding