| 1. |
- Deisenroth, David C., et al.
(author)
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Measurement Uncertainty of Surface Temperature Distributions for Laser Powder Bed Fusion Processes
- 2021
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In: Journal of research of the National Institute of Standards and Technology. - : NATL INST STANDARDS & TECHNOLOGY-NIST. - 1044-677X .- 2165-7254. ; 126
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Journal article (peer-reviewed)abstract
- This paper describes advances in measuring the characteristic spatial distribution of surface temperature and emissivity during laser -metal interaction under conditions relevant for laser powder bed fusion (LPBF) additive manufacturing processes. Detailed descriptions of the measurement process, results, and approaches to determining uncertainties are provided. Measurement uncertainties have complex dependencies on multiple process parameters, so the methodology is demonstrated on one set of process parameters and one material. Well-established literature values for high-purity nickel solidification temperature and emissivity at the solidification temperature were used to evaluate the predicted uncertainty of the measurements. The standard temperature measurement uncertainty is found to be approximately 0.9 % of the absolute temperature (16 degrees C), and the standard relative emissivity measurement uncertainty is found to be approximately 8 % at the solidification point of high-purity nickel, both of which are satisfactory. This paper also outlines several potential sources of test uncertainties, which may require additional experimental evaluation. The largest of these are the metal vapor and ejecta that are produced as process by-products, which can potentially affect the imaging quality, reflectometry results, and thermal signature of the process, while also affecting the process of laser power delivery. Furthermore, the current paper focuses strictly on the uncertainties of the emissivity and temperature measurement approach and therefore does not detail a variety of uncertainties associated with experimental controls that must be evaluated for future generation of reference data.
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| 2. |
- Gao, Wei, et al.
(author)
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Machine tool calibration : Measurement, modeling, and compensation of machine tool errors
- 2023
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In: International journal of machine tools & manufacture. - : Elsevier BV. - 0890-6955 .- 1879-2170. ; 187, s. 104017-
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Research review (peer-reviewed)abstract
- Advanced technologies for the calibration of machine tools are presented. Kinematic errors independently of their causes are classified into errors within one-axis as intra-axis errors, errors between axes as inter-axis errors, and as volumetric errors. As the major technological elements of machine tool calibration, the measurement methods, modeling theories, and compensation strategies of the machine tool errors are addressed. The criteria for selecting a combination of the technological elements for machine tool calibration from the point of view of accuracy, complexity, and cost are provided. Recent applications of artificial intelligence and machine learning in machine tool calibration are introduced. Remarks are also made on future trends in machine tool calibration.
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| 3. |
- Szipka, Karoly, et al.
(author)
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Identification of machine tool squareness errors via inertial measurements
- 2019
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In: CIRP annals. - : Elsevier BV. - 0007-8506 .- 1726-0604. ; 68:1, s. 547-550
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Journal article (peer-reviewed)abstract
- The accuracy of multi-axis machine tools is affected to a large extent by the behavior of the system's axes and their error sources. In this paper, a novel methodology using circular inertial measurements quantifies changes in squareness between two axes of linear motion. Conclusions are reached through direct utilization of measured accelerations without the need for double integration of sensor signals. Results revealed that the new methodology is able to identify squareness values verified with traditional measurement methods. The work supports the integration of sensors into machine tools in order to reach higher levels of measurement automation. behalf of CIRP.
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| 4. |
- Vogl, Gregory, et al.
(author)
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Diagnostics for geometric performance of machine tool linear axes
- 2016
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In: CIRP annals. - : Elsevier. - 0007-8506 .- 1726-0604. ; 65:1, s. 377-380
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Journal article (peer-reviewed)abstract
- Machine tools degrade during operations, yet knowledge of degradation is elusive; accurately detecting degradation of linear axes is typically a manual and time-consuming process. Manufacturers need automated and efficient methods to diagnose the condition of their machine tool linear axes with minimal disruptions to production. A method was developed to use data from an inertial measurement unit (IMU) for identification of changes in the translational and angular errors due to axis degradation. A linear axis testbed, established for the purpose of verification and validation, revealed that the IMU-based method was capable of measuring geometric errors with acceptable test uncertainty ratios.
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| 5. |
- Vogl, Gregory W., et al.
(author)
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Root-cause analysis of wear-induced error motion changes of machine tool linear axes
- 2019
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In: International journal of machine tools & manufacture. - : Elsevier BV. - 0890-6955 .- 1879-2170. ; 143, s. 38-48
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Journal article (peer-reviewed)abstract
- Manufacturers need online methods that give up-to-date information of system capabilities to know and predict the performance of their machine tools. Use of an inertial measurement unit (IMU) is attractive for on-machine condition monitoring, so methods based on spatial filters were developed to determine rail wear conditions of linear guideways of a carriage from its IMU-based error motion. Rail wear-induced changes in translational and angular error motions as small as 1.5 mu m and 3.0 microradians, respectively, could be resolved. A corresponding two-part root-cause analysis procedure was developed to determine the rail locations of error motion degradation as well as the most probable physical location of damage that causes the detected error motion changes. Another analysis method determined the root cause of non-localized damage along each rail. These approaches support the development of smart machine tools that provide actionable intelligence to manufacturers for early warnings of system degradation.
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| 6. |
- Yague-Fabra, Jose A., et al.
(author)
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Scalability of precision design principles for machines and instruments
- 2021
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In: CIRP annals. - : Elsevier BV. - 0007-8506 .- 1726-0604. ; 70:2, s. 659-680
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Journal article (peer-reviewed)abstract
- The implementation of precision engineering principles in the design of precision systems is fundamental to achieve high accuracy. Although these principles may be independent of the system working range, their implementation is not. The working range, the accuracy, and the load of the system limit, for instance, the selection of materials, the structural design, or the positioning system. This article analyzes the applicability of precision engineering design principles depending on the working range of the system in order to establish their scalability or lack of it in small, medium, and large range machines and instruments.
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