The Significance of Air Pockets for Modelling Thermal Errors of Machine Tool

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

It is well known, especially with the prevalence of compensation for geometric errors, that thermal error represents the most significant proportion of the total volumetric error of the machine tool. Thermal error in machine tools originates from changes to internal and external heat sources that vary the structural temperature of the machine tool resulting in the non-linear deformation of the machine structure. The ambient conditions inside and around the machine vicinity are varied not only by the external heat sources but, equally importantly but less well understood, by the machine itself when local air pockets are warmed inside the voids of the machine during the machining process. Air pockets are areas within the machine structure where the localized heat convection rate is reduced by the heat confined within them causing the temperature to vary slowly relative to the other places of the machine. This results in a relatively slower response of the associated structure. Consideration for this effect is an important, yet often ignored element of thermal modelling which deteriorates the prediction capability of many thermal models. This paper presents a case study where FEA (Finite Element Analysis) is used for the thermal modelling of a machine tool and the issue of air pockets is addressed by measuring and considering the temperature in voids. It was found that the consideration of the most significant air pockets improved the prediction capability of the FEA thermal model in the Z-axis direction from 50% to 62% when compared with the experimental results Z-axis. This paper highlights the significance of air pockets with regard to the thermal modelling and it is believed that the consideration of the temperature measurement inside voids of the machine structure and inclusion of their effect may significantly improve the performance of any thermal model.

Original languageEnglish
Title of host publicationProceedings of the 10th International Lamdamap Conference 2013
Subtitle of host publicationLaser Metrology and machine performance
Publishereuspen
Pages189-198
Number of pages10
ISBN (Electronic)9780956679017
Publication statusPublished - 2013
Event10th International Conference and Exhibition on Laser Metrology, Coordinate Measuring Machine and Machine Tool Performance - Buckinghamshire, United Kingdom
Duration: 20 Mar 201321 Mar 2013
Conference number: 10

Conference

Conference10th International Conference and Exhibition on Laser Metrology, Coordinate Measuring Machine and Machine Tool Performance
Abbreviated titleLAMDAMAP 2013
CountryUnited Kingdom
CityBuckinghamshire
Period20/03/1321/03/13

Fingerprint

machine tools
Machine tools
air
voids
Air
heat sources
heat
predictions
machining
temperature
temperature measurement
proportion
thermal analysis
convection
Hot Temperature
inclusions
Finite element method
Heat convection
Error compensation
Temperature measurement

Cite this

Mian, N., Fletcher, S., Longstaff, A., & Myers, A. (2013). The Significance of Air Pockets for Modelling Thermal Errors of Machine Tool. In Proceedings of the 10th International Lamdamap Conference 2013: Laser Metrology and machine performance (pp. 189-198). euspen.
Mian, Naeem ; Fletcher, Simon ; Longstaff, Andrew ; Myers, Alan. / The Significance of Air Pockets for Modelling Thermal Errors of Machine Tool. Proceedings of the 10th International Lamdamap Conference 2013: Laser Metrology and machine performance. euspen, 2013. pp. 189-198
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Mian, N, Fletcher, S, Longstaff, A & Myers, A 2013, The Significance of Air Pockets for Modelling Thermal Errors of Machine Tool. in Proceedings of the 10th International Lamdamap Conference 2013: Laser Metrology and machine performance. euspen, pp. 189-198, 10th International Conference and Exhibition on Laser Metrology, Coordinate Measuring Machine and Machine Tool Performance, Buckinghamshire, United Kingdom, 20/03/13.

The Significance of Air Pockets for Modelling Thermal Errors of Machine Tool. / Mian, Naeem; Fletcher, Simon ; Longstaff, Andrew; Myers, Alan.

Proceedings of the 10th International Lamdamap Conference 2013: Laser Metrology and machine performance. euspen, 2013. p. 189-198.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

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N2 - It is well known, especially with the prevalence of compensation for geometric errors, that thermal error represents the most significant proportion of the total volumetric error of the machine tool. Thermal error in machine tools originates from changes to internal and external heat sources that vary the structural temperature of the machine tool resulting in the non-linear deformation of the machine structure. The ambient conditions inside and around the machine vicinity are varied not only by the external heat sources but, equally importantly but less well understood, by the machine itself when local air pockets are warmed inside the voids of the machine during the machining process. Air pockets are areas within the machine structure where the localized heat convection rate is reduced by the heat confined within them causing the temperature to vary slowly relative to the other places of the machine. This results in a relatively slower response of the associated structure. Consideration for this effect is an important, yet often ignored element of thermal modelling which deteriorates the prediction capability of many thermal models. This paper presents a case study where FEA (Finite Element Analysis) is used for the thermal modelling of a machine tool and the issue of air pockets is addressed by measuring and considering the temperature in voids. It was found that the consideration of the most significant air pockets improved the prediction capability of the FEA thermal model in the Z-axis direction from 50% to 62% when compared with the experimental results Z-axis. This paper highlights the significance of air pockets with regard to the thermal modelling and it is believed that the consideration of the temperature measurement inside voids of the machine structure and inclusion of their effect may significantly improve the performance of any thermal model.

AB - It is well known, especially with the prevalence of compensation for geometric errors, that thermal error represents the most significant proportion of the total volumetric error of the machine tool. Thermal error in machine tools originates from changes to internal and external heat sources that vary the structural temperature of the machine tool resulting in the non-linear deformation of the machine structure. The ambient conditions inside and around the machine vicinity are varied not only by the external heat sources but, equally importantly but less well understood, by the machine itself when local air pockets are warmed inside the voids of the machine during the machining process. Air pockets are areas within the machine structure where the localized heat convection rate is reduced by the heat confined within them causing the temperature to vary slowly relative to the other places of the machine. This results in a relatively slower response of the associated structure. Consideration for this effect is an important, yet often ignored element of thermal modelling which deteriorates the prediction capability of many thermal models. This paper presents a case study where FEA (Finite Element Analysis) is used for the thermal modelling of a machine tool and the issue of air pockets is addressed by measuring and considering the temperature in voids. It was found that the consideration of the most significant air pockets improved the prediction capability of the FEA thermal model in the Z-axis direction from 50% to 62% when compared with the experimental results Z-axis. This paper highlights the significance of air pockets with regard to the thermal modelling and it is believed that the consideration of the temperature measurement inside voids of the machine structure and inclusion of their effect may significantly improve the performance of any thermal model.

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Mian N, Fletcher S, Longstaff A, Myers A. The Significance of Air Pockets for Modelling Thermal Errors of Machine Tool. In Proceedings of the 10th International Lamdamap Conference 2013: Laser Metrology and machine performance. euspen. 2013. p. 189-198