Non Conventional Machine

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  • Topic: Abrasive, Fracture, Machining
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  • Published : November 4, 2012
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Module
9 Non-conventional machining
Version 2 ME, IIT Kharagpur

Lesson
36 Ultrasonic Machining (USM)
Version 2 ME, IIT Kharagpur

Instructional Objectives
i. ii. iii. iv. Describe the basic mechanism of material removal in USM Identify the process parameters of USM Identify the machining characteristics of USM Analyse the effect of process parameters on material removal rate (MRR) v. Develop mathematical model relating MRR with USM parameters vi. Draw variation in MRR with different process parameters vii. Identify major components of USM equipment viii. State the working principle of USM equipment ix. Draw schematically the USM equipment x. List three applications of USM xi. List three limitations of USM

1. Introduction
Ultrasonic machining is a non-traditional machining process. USM is grouped under the mechanical group NTM processes. Fig. 9.2.1 briefly depicts the USM process. Force, F Slurry of abrasive and water Horn Vibration frequency f ~ 19 - 25 kHz Amplitude, a ~ 10 – 50 μm Tool

Work

Fig. 9.2.1 The USM process In ultrasonic machining, a tool of desired shape vibrates at an ultrasonic frequency (19 ~ 25 kHz) with an amplitude of around 15 – 50 μm over the workpiece. Generally the tool is pressed downward with a feed force, F. Between the tool and workpiece, the machining zone is flooded with hard abrasive particles generally in the form of a water based slurry. As the tool vibrates over the workpiece, the abrasive particles act as the indenters and indent both the work material and the tool. The abrasive particles, as they indent, the work material, would remove the same, particularly if the work material is brittle, due to crack initiation, propagation and brittle fracture of the Version 2 ME, IIT Kharagpur

material. Hence, USM is mainly used for machining brittle materials {which are poor conductors of electricity and thus cannot be processed by Electrochemical and Electro-discharge machining (ECM and ED)}.

2. Mechanisms of...
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