High power sine wave generator
This unit converts low frequency (60 Hz) electrical power to high frequency (20kHz) electrical power.
The high frequency electrical signal is transmitted to traducer which converts it into high frequency low amplitude vibration. Essentially transducer converts electrical energy to mechanical vibration. There are two types of transducer used
1. Piezo electric transducer
2. Magneto-stricitve transducer.
Piezo electric transducer: These transducer generate a small electric current when they are compressed. Also when the electric current is passed though crystal it expands. When the current is removed , crystal attains its original size and shape. Such transducers are available up to 900 Watts. Piezo electric crystals have high conversion efficiency of 95%.
Magneto-strictive transducer: These also changes its length when subjected to strong magnetic field. These transducer are made of nickel , nickel alloy sheets.
Their conversion efficiency is about 20-30%. Such transducers are available up to 2000 Watts. The maximum change in length can be achieved is about 25 microns.
Tool holder. OR Horn.
The tool holder holds and connects the tool to the transducer. It virtually transmits the energy and in some cases, amplifies the amplitude of vibration. Material of tool should have good acoustic properties, high resistance to fatigue cracking. Due
measures should be taken to avoid ultrasonic welding between transducer and tool holder. Commonly used tool holders are Monel, titanium, stainless steel. Tool holders are more expensive, demand higher operating cost.
Tools are made of relatively ductile materials like Brass, Stainless steel or Mild steel so that Tool wear rate (TWR) can be minimized. The value of ratio of TWR and MRR depends on kind of abrasive, work material and tool materials.