CNC machine tool monitoring by AE sensors: Difference between revisions

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'''CNC machine tool monitoring by AE sensors'''. Machine Tool monitoring system is flow of information and system processing in which the information selection, obtaining data,processing of information and decision making on the refined information are integrated. The aim of tool condition monitoring is to detect early the disturbances in the machining process and wear of machine tool components. The condition of tool has been researched extensively in the past and have focused on detection of tool wear, tool breakage and the estimation of remaining tool life.It is very important for on-line identification of tool condition in machining process for enhanced productivity, better quality of parts and lower costs for unmanned, automated manufacturing systems.<ref>{{cite web|url=http://www.eng.nus.edu.sg/EResnews/0310/rd/rd_7.html|website=www.eng.nus.edu.sg}}</ref>

== Techniques of Machinemachine tool Monitoringmonitoring ==

Machine Tooltool monitoring can be done with or without additional sensors.

Using additional sensors, monitoring can be done by measuring:

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== Acoustic emission sensor ==

Machine tool monitoring is explained with Acoustic Emission (AE) Sensorssensors. AE Sensorsensor is commonly defined as the sound emitted as an elastic wave by a solid when it is deformed or struck, caused by the rapid release of localized stress energy. Therefore, it is an occurrence phenomenon which releases elastic energy into the material, which then propagates as an elastic wave. The detection [[frequency]] range of acoustic emission is from 1&nbsp;kHz to 1&nbsp;MHz. Rapid stress-releasing events generate a spectrum of stress waves starting at 0&nbsp;Hz and typically falling off at several MHz. AE can be related to an irreversible release of energy. It can also be generated from sources not involving material failure including friction, cavitation and impact.<ref>{{cite web|website=http://www.tms.org.}}</ref> The three major applications of AE sensors phenomena are: a) Source ___location - determine the locations of occurrence of an event b) Material mechanical performance - evaluate and characterize materials/structures; and c Health monitoring – monitors the safety operation.<ref>{{cite web|website=http://www.tms.org.}}</ref>

=== How an AE Sensorsensor Monitorsmonitors Machinemachine Tooltool===

An acoustic emission (AE) sensor works on principle of measuring the high-frequency energy signals produced during cutting process. It also measures the AE energy resulting from the fracture when a tool breaks. It is best suited to applications where the level of background AE signal is low compared to the sound of tool breakage. This makes the [[AE sensor]] ideal for breakage detection of small drills and taps. It is easy to install on both new and existing machines. AE sensor detects force proportional monitoring signals even in machining operations, which generate very small cutting forces. In combination with true power, it increases the reliability of breakage monitoring.<ref>{{cite book|last1=arbor|first1=ann|title=MTC tool and process monitoring|date=1997|publisher=Artiscompany|___location=USA}}</ref> It is used especially with solid carbide tools, or very small tools on large machines and multi spindles. Most of the sensors have to be attached to the machine tool surface.<ref>{{cite book|last1=hur|first1=Winter|title=Piezo-instrumentation|date=1997|publisher=Kistler company|___location=Switzerland}}</ref> However, there are alternative methods of AE wave transmitting. A rotating, wireless AE sensor consists of a rotating sensor and a fixed receiver.<ref>{{cite book|last1=Aachen|title=Wireless AE sensor AEL 200|publisher=Prometec company|___location=Germany}}</ref> An AE sensor can also receive the acoustic waves via a jet of cooling lubricant, which can be connected directly to the tool or workpiece.<ref>{{cite book|first1=nordmann|title=Nordmann sensor technology|date=1997|publisher=Nordmann company|___location=Germany}}</ref><ref>{{cite book|title=Fluid sound sensor WAE 100|publisher=Prometec company|___location=Aachen, Germany|edition=Aachen, Germany: Prometec company}}</ref>