Influence of pulsed and continuous wave emission on melting efficiency in selective laser melting

Caprio, Leonardo; Demir, Ali Gökhan; Previtali, Barbara

doi:10.1016/j.jmatprotec.2018.11.019

Cited by 50 publications

(31 citation statements)

References 51 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Again, the emission zone narrowed as the laser moved further, with a final shape that resembled the real molten pool geometry observed with the external light. In both scanned geometries, the modulation of the laser power led to a reduced emission area, resulting in a greater control over the thermal load especially in the thin geometry, where the melt pool enlargement may prove to be detrimental for geometrical precision and part density [45], [46], [47]. In addition, spatter ejections were detected by the sensor and they were distinguishable from their small size and fast movement from the melt pool to the outside.…”

Section: B Comparison Between Visible and Nir Wavelength Bandsmentioning

confidence: 99%

Real-Time Observation of Melt Pool in Selective Laser Melting: Spatial, Temporal, and Wavelength Resolution Criteria

Mazzoleni

Demir

Caprio

et al. 2020

IEEE Trans. Instrum. Meas.

Self Cite

View full text Add to dashboard Cite

Melt pool monitoring in selective laser melting (SLM) is a key challenge to enhance the understanding of the basic process physics as well as the in-situ identification of drifts. The main issues are related to its fast dynamics and small spatial extent, which require high performance monitoring systems in terms of temporal and spatial resolution, often resulting in unmanageable data rates. Furthermore, the broadband thermal emission from the process can be viewed in different spectral ranges depending on the sensor and optical system employed. Accordingly, a wide range of sensing configurations is possible. The choice of monitoring parameters is crucial to achieve a solution capable of describing process dynamics with industrial applicability in terms of data transport and analysis. This work discusses the design of a coaxial monitoring module to assess melt pool dynamics in SLM using temporal and spatial cues related to the process physics. Restrictions regarding data management were considered to ensure a future inline process control. The system was tested with an external illuminator to reveal the actual melt pool geometry employing an acquisition rate of 1200 fps, 4.3 mm x 4.3 mm field of view and 14 µm/pixel spatial resolution. The process emission in visible (640 nm) and nearinfrared regions (850-1000 nm) was also acquired and the band choice discussed. The proposed solution captured successfully the melting conditions from both a spatial and temporal viewpoint. The monitoring system depicted variations of the melt pool shape when processing different geometries using modulated and continuous wave laser emission. Index Terms-Selective laser melting, process monitoring, thermal emission, infrared imaging, melt pool geometry.

show abstract

Section: B Comparison Between Visible and Nir Wavelength Bandsmentioning

confidence: 99%

Real-Time Observation of Melt Pool in Selective Laser Melting: Spatial, Temporal, and Wavelength Resolution Criteria

Mazzoleni

Demir

Caprio

et al. 2020

IEEE Trans. Instrum. Meas.

Self Cite

View full text Add to dashboard Cite

show abstract

“…An analytical model has been presented to evaluate the impact of pulsed and continuous laser emissions, considering the main spatial and temporal parameters affecting the energy delivering efficiency to the powder bed during the SLM. Process efficiency is assessed by identifying changes corresponding to duty cycle [ 109 ]. To incorporate the generated temperature field by a pulsed wave Gaussian, the solution proposed by Ravi Vishnu et al [ 110 ] has been applied.…”

Section: Numerical Simulation Of Slmmentioning

confidence: 99%

An Overview of Additive Manufacturing Technologies—A Review to Technical Synthesis in Numerical Study of Selective Laser Melting

et al. 2020

View full text Add to dashboard Cite

Additive Manufacturing (AM) processes enable their deployment in broad applications from aerospace to art, design, and architecture. Part quality and performance are the main concerns during AM processes execution that the achievement of adequate characteristics can be guaranteed, considering a wide range of influencing factors, such as process parameters, material, environment, measurement, and operators training. Investigating the effects of not only the influential AM processes variables but also their interactions and coupled impacts are essential to process optimization which requires huge efforts to be made. Therefore, numerical simulation can be an effective tool that facilities the evaluation of the AM processes principles. Selective Laser Melting (SLM) is a widespread Powder Bed Fusion (PBF) AM process that due to its superior advantages, such as capability to print complex and highly customized components, which leads to an increasing attention paid by industries and academia. Temperature distribution and melt pool dynamics have paramount importance to be well simulated and correlated by part quality in terms of surface finish, induced residual stress and microstructure evolution during SLM. Summarizing numerical simulations of SLM in this survey is pointed out as one important research perspective as well as exploring the contribution of adopted approaches and practices. This review survey has been organized to give an overview of AM processes such as extrusion, photopolymerization, material jetting, laminated object manufacturing, and powder bed fusion. And in particular is targeted to discuss the conducted numerical simulation of SLM to illustrate a uniform picture of existing nonproprietary approaches to predict the heat transfer, melt pool behavior, microstructure and residual stresses analysis.

show abstract

“…In L-PBF systems, both continuous wave (CW) and pulsed wave (PW) laser emission have been used as the primary heating source [ 26 ]. Within PW systems, both Q-switching [ 27 ] and power modulation [ 28 , 29 ] are used to achieve pulsing. In Q-switched Nd: YAG lasers, very high peak powers in the megawatt range can be achieved over very short nanosecond pulses.…”

Section: Introductionmentioning

confidence: 99%

Absorption of Nitrogen during Pulsed Wave L-PBF of 17-4 PH Steel

2021

View full text Add to dashboard Cite

In the fabrication of 17-4 PH by laser powder bed fusion (L-PBF) the well-documented occurrence of large amounts of retained austenite can be attributed to an elevated concentration of nitrogen present in the material. While the effects of continuous wave (CW) laser processing on in-situ nitrogen absorption characteristics have been evaluated, power modulated pulsed wave (PW) laser processing effects have not. In this study the effects of PW L-PBF processing of 17-4 PH on nitrogen absorption, phase composition, and mechanical performance are explored using commercially available PW L-PBF equipment and compared to samples produced by CW L-PBF. PW L-PBF samples fabricated in cover gas conditions with varying amounts of nitrogen demonstrated reduced absorption levels compared to those produced by CW L-PBF with no effects on phase composition and minimal effects on mechanical performance.

show abstract

Influence of pulsed and continuous wave emission on melting efficiency in selective laser melting

Cited by 50 publications

References 51 publications

Real-Time Observation of Melt Pool in Selective Laser Melting: Spatial, Temporal, and Wavelength Resolution Criteria

Real-Time Observation of Melt Pool in Selective Laser Melting: Spatial, Temporal, and Wavelength Resolution Criteria

An Overview of Additive Manufacturing Technologies—A Review to Technical Synthesis in Numerical Study of Selective Laser Melting

Absorption of Nitrogen during Pulsed Wave L-PBF of 17-4 PH Steel

Contact Info

Product

Resources

About