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Subject: Re: Chatter. Where is the source?
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Date: 03/11/03 at 12:24 AM
Posted by: Prof. Y. Altintas
In Reply to: Chatter. Where is the source? posted by Team Player on 09/20/02 at 11:01 AM:
You can detect the frequency of chatter vibrations by either placing acceloremeter on the headstock and fizture, or simply by using a microphone. The vibration or sound are measured using a A/D card, and apply Fourier Spectrum analysis which will lead to a peak at the chatter frequency. Make sure that the frequency is different than the spindle speed times number of teeth on the cutter, which corresponds to forced vibrations but not chatter.
Which part of the machine is vibrating? You need to conduct modal testing of the machine using an acceloremeter attached to the spindle nose, and apply hammer blows at the different marked positions of the machine. There are software programs which will lead to weak connection spots on the machine. The software systems range from costly but very advanced systems (Structural Dynamics Corp., LMS,..) or low cost simple to use machine tool modal analysis kits (http://www.malinc.com). When one of the mode becomes close to the chatter frequency, you know which part of the machine is chattering during machining.
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