scholarly journals Estimation and Improvement of the Achievable Tolerance Interval in Material Extrusion Additive Manufacturing through a Multi-State Machine Performance Perspective

2021 ◽  
Vol 11 (12) ◽  
pp. 5325
Author(s):  
Natalia Beltrán ◽  
Braulio J. Álvarez ◽  
David Blanco ◽  
Álvaro Noriega ◽  
Pedro Fernández
Keyword(s):  
Additive Manufacturing ◽  
State Machine ◽  
Tolerance Interval ◽  
Manufacturing Strategy ◽  
3D Design ◽  
Dimensional Parameter ◽  
Material Extrusion ◽  
Machine Performance ◽  
Working Space ◽  
Before And After

Dimensional quality is still a major concern in additive manufacturing (AM) processes and its improvement is key to closing the gap between prototype manufacturing and industrialized production. Mass production requires the full working space of the machine to be used, although this arrangement could lead to location-related differences in part quality. The present work proposes the application of a multi-state machine performance perspective to reduce the achievable tolerance intervals of features of linear size in material extrusion (MEX) processes. Considering aspecific dimensional parameter, the dispersion and location of the distribution of measured values between different states are analyzed to determine whether the production should be treated as single-state or multi-state. A design for additive manufacturing strategy then applies global or local size compensations to modify the 3D design file and reduce deviations between manufactured values and theoretical values. The variation in the achievable tolerance range before and after the optimization of design is evaluated by establishing a target machine performance index. This strategy has been applied to an external MEX-manufactured cylindrical surface in a case study. The results show that the multi-state perspective provides a better understanding of the sources of quality variability and allows for a significant reduction in the achievable tolerance interval. The proposed strategy could help to accelerate the industrial adoption of AM process by reducing differences in quality with respect to conventional processes.

In Implementing a Metal 3D AM Machine

2018 ◽  
Vol 786 ◽  
pp. 356-363
Author(s):  
Tero Jokelainen ◽  
Kimmo Mäkelä ◽  
Aappo Mustakangas ◽  
Jari Mäkelä ◽  
Kari Mäntyjärvi
Keyword(s):  
Additive Manufacturing ◽  
Selective Laser Melting ◽  
Dimensional Accuracy ◽  
Acceptance Test ◽  
Aisi 316L ◽  
Laser Melting ◽  
Geometrical Accuracy ◽  
Machine Performance ◽  
Geometrical Features ◽  
Made In

Additive Manufacturing (AM) does not yet have a standardized way to measure performance. Here a AM machines dimensional accuracy is measured trough acceptance test (AT) and AM machines capability is tested trough test parts. Test parts are created with specific geometrical features using a 3D AM machine. Performance of the machine is then evaluated trough accuracy of test parts geometry. AM machine here uses selective laser melting (SLM) process. This machine has done Factory acceptance test (FAT) to ascertain this machine ́s geometrical accuracy with material AISI 316L. Manufacturer promises accuracy of ±0.05 mm. These parts are used as comparison to AT parts made in this study. After installation two AT parts are manufactured with AM machine. One with AISI 316L and one AlSi10Mg. Dimensional accuracy of geometrical features on these parts are then compared to FAT part and to one another. Machines capability is measured trough two test parts done with material AlSi10Mg. Two of the test parts are done at the same time using same model as the FAT. Parts are printed without supports and with features facing same directions. Features of these parts were then evaluated. Another test to find out AM machines capability was to create part consisting of pipes doing 90˚ angle resulting in horizontal and vertical holes. Dimensional accuracy and circularity of holes was measured. Through these tests machines capability is benchmarked.

Material Flow Rate Estimation in Material Extrusion Additive Manufacturing

2021 ◽  
Vol 13 (1) ◽  
pp. 46-56
Author(s):  
G.P. Greeff
Keyword(s):  
Additive Manufacturing ◽  
Flow Rate ◽  
Material Flow ◽  
Fused Deposition Modeling ◽  
Volumetric Flow Rate ◽  
Cost Effective ◽  
Fused Filament Fabrication ◽  
Material Extrusion ◽  
Fused Deposition ◽  
G Code

The additive manufacturing of products promises exciting possibilities. Measurement methodologies, which measure an in-process dataset of these products and interpret the results, are essential. However, before developing such a level of quality assurance several in-process measurands must be realized. One of these is the material flow rate, or rate of adding material during the additive manufacturing process. Yet, measuring this rate directly in material extrusion additive manufacturing presents challenges. This work presents two indirect methods to estimate the volumetric flow rate at the liquefier exit in material extrusion, specifically in Fused Deposition Modeling or Fused Filament Fabrication. The methods are cost effective and may be applied in future sensor integration. The first method is an optical filament feed rate and width measurement and the second is based on the liquefier pressure. Both are used to indirectly estimate the volumetric flow rate. The work also includes a description of linking the G-code command to the final print result, which may be used to create a per extrusion command model of the part.

Kinematic and Acoustic Changes to Vowels and Diphthongs in Bite Block Speech

2021 ◽  
pp. 1-8
Author(s):  
Christopher Dromey ◽  
Michelle Richins ◽  
Tanner Low
Keyword(s):  
Young Adults ◽  
Sentence Context ◽  
Bite Block ◽  
Transition Duration ◽  
Formant Frequencies ◽  
Working Space ◽  
Vowel Space ◽  
Articulation Index ◽  
Before And After

Purpose We examined the effect of bite block insertion (BBI) on lingual movements and formant frequencies in corner vowel and diphthong production in a sentence context. Method Twenty young adults produced the corner vowels (/u/, /ɑ/, /æ/, /i/) and the diphthong /ɑɪ/ in sentence contexts before and after BBI. An electromagnetic articulograph measured the movements of the tongue back, middle, and front. Results There were significant decreases in the acoustic vowel articulation index and vowel space area following BBI. The kinematic vowel articulation index decreased significantly for the back and middle of the tongue but not for the front. There were no significant acoustic changes post-BBI for the diphthong, other than a longer transition duration. Diphthong kinematic changes after BBI included smaller movements for the back and middle of the tongue, but not the front. Conclusions BBI led to a smaller acoustic working space for the corner vowels. The adjustments made by the front of the tongue were sufficient to compensate for the BBI perturbation in the diphthong, resulting in unchanged formant trajectories. The back and middle of the tongue were likely biomechanically restricted in their displacement by the fixation of the jaw, whereas the tongue front showed greater movement flexibility.

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