Unit 6 Nontraditional Machining Processes

6.1 Introduction

Traditional or conventional machining, such as turning, milling, and grinding etc., uses mechanical energy to shear metal against another substance to create holes or remove material. Nontraditional machining processes are defined as a group of processes that remove excess material by various techniques involving mechanical, thermal, electrical or chemical energy or combinations of these energies but do not use a sharp cutting tool as it is used in traditional manufacturing processes. [1]

Extremely hard and brittle materials are difficult to be machined by traditional machining processes. Using traditional methods to machine such materials means increased demand for time and energy and therefore increases in costs; in some cases traditional machining may not be feasible. Traditional machining also results in tool wear and loss of quality in the product owing to induced residual stresses during machining. Nontraditional machining processes, also called unconventional machining process or advanced manufacturing processes, are employed where traditional machining processes are not feasible, satisfactory or economical due to special reasons as outlined below:

1. Very hard fragile materials difficult to clamp for traditional machining;

2. When the workpiece is too flexible or slender;

3. When the shape of the part is too complex;

4. Parts without producing burrs or inducing residual stresses.

Traditional machining can be defined as a process using mechanical (motion) energy. Non-traditional machining utilizes other forms of energy; the three main forms of energy used in non-traditional machining processes are as follows:

1. Thermal energy;

2. Chemical energy;

3. Electrical energy.

Several types of nontraditional machining processes have been developed to meet extra required machining conditions. When these processes are employed properly, they offer many advantages over traditional machining processes. The common nontraditional machining processes are described in the following section.