scholarly journals In-Line Observation of Laser Cladding Processes via Atomic Emission Spectroscopy

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4401
Author(s):  
Malte Schmidt ◽  
Philipp Huke ◽  
Christoph Gerhard ◽  
Knut Partes
Keyword(s):  
Laser Beam ◽  
Emission Spectroscopy ◽  
Base Material ◽  
Optical Emission ◽  
Type A ◽  
Atomic Emission ◽  
Process Conditions ◽  
Monitoring And Control ◽  
Melt Pool ◽  
Process Monitoring And Control

Direct metal deposition (DMD) can be used for the cladding of surfaces as well as repairing and additive manufacturing of parts and features. Process monitoring and control methods ensure a consistent quality during manufacturing. Monitoring by optical emission spectroscopy of the process radiation can provide information on process conditions and the deposition layer. The object of this work is to measure optical emissions from the process using a spectrometer and identify element lines within the spectra. Single spectra have been recorded from the process. Single tracks of Co-based powder (MetcoClad21) were clad on an S235 base material. The influence of varying process parameters on the incidence and intensity of element lines has been investigated. Moreover, the interactions between the laser beam, powder jet, and substrate with regard to spectral emissions have been examined individually. The results showed that element lines do not occur regularly. Therefore, single spectra are sorted into spectra including element lines (type A) and those not including element lines (type B). Furthermore, only non-ionised elements could be detected, with chromium appearing frequently. It was shown that increasing the laser power increases the incidence of type A spectra and the intensity of specific Cr I lines. Moreover, element lines only occurred frequently during the interaction of the laser beam with the melt pool of the deposition layer.

scholarly journals From Black Box to Machine Learning: A Journey through Membrane Process Modelling

Membranes ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 574
Author(s):  
Claudia F. Galinha ◽  
João G. Crespo
Keyword(s):  
Machine Learning ◽  
Process Modelling ◽  
Model Membrane ◽  
Point Of View ◽  
Personal Perspective ◽  
Process Conditions ◽  
Monitoring And Control ◽  
Membrane Processes ◽  
Mechanistic Modelling ◽  
Process Monitoring And Control

Membrane processes are complex systems, often comprising several physicochemical phenomena, as well as biological reactions, depending on the systems studied. Therefore, process modelling is a requirement to simulate (and predict) process and membrane performance, to infer about optimal process conditions, to assess fouling development, and ultimately, for process monitoring and control. Despite the actual dissemination of terms such as Machine Learning, the use of such computational tools to model membrane processes was regarded by many in the past as not useful from a scientific point-of-view, not contributing to the understanding of the phenomena involved. Despite the controversy, in the last 25 years, data driven, non-mechanistic modelling is being applied to describe different membrane processes and in the development of new modelling and monitoring approaches. Thus, this work aims at providing a personal perspective of the use of non-mechanistic modelling in membrane processes, reviewing the evolution supported in our own experience, gained as research group working in the field of membrane processes. Additionally, some guidelines are provided for the application of advanced mathematical tools to model membrane processes.

scholarly journals Analysis of Melt Pool Characteristics and Process Parameters Using a Coaxial Monitoring System during Directed Energy Deposition in Additive Manufacturing

Materials ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 308 ◽  
Author(s):  
Christian Kledwig ◽  
Holger Perfahl ◽  
Martin Reisacher ◽  
Frank Brückner ◽  
Jens Bliedtner ◽  
...  
Keyword(s):  
Stable Process ◽  
Base Material ◽  
Industrial Applications ◽  
Process Conditions ◽  
Melt Pool ◽  
Temporal Variance ◽  
Laser Deposition Welding ◽  
Working Distance ◽  
Melt Pool Characteristics ◽  
Pool Area

The growing number of commercially available machines for laser deposition welding show the growing acceptance and importance of this technology for industrial applications. Their increasing usage in research and production requires process stability and user-friendly handling. A commercially available DMG MORI LT 65 3D hybrid machine used in combination with a CCD-based coaxial temperature measurement system was utilized in this work to investigate what information relating to the intensity distribution of melt pool surfaces could be appropriate to draw conclusions about process conditions. In this study it is shown how the minimal required specific energy for a stable process can be determined, and it is indicated that the evolution of a plasma plume depends on thermal energy within the base material. An estimated melt pool area—calculated by the number of pixels (NOP) with intensities larger than a fixed, predefined threshold—builds the main measure in analysing images from the process camera. The melt pool area and its temporal variance can also serve as an indicator for an increased working distance.

scholarly journals In-process Monitoring and Control of Robotized Laser Beam Welding of Closed Square Butt Joints

2018 ◽  
Vol 25 ◽  
pp. 511-516 ◽  
Author(s):  
Morgan Nilsen ◽  
Fredrik Sikström ◽  
Anna-Karin Christiansson ◽  
Antonio Ancona
Keyword(s):  
Laser Beam ◽  
Process Monitoring ◽  
Laser Beam Welding ◽  
Monitoring And Control ◽  
Butt Joints ◽  
Process Monitoring And Control ◽  
And Control

scholarly journals The Use of Machine Tool Internal Encoders as Sensors in a Process Monitoring System

2013 ◽  
Vol 7 (4) ◽  
pp. 410-417 ◽  
Author(s):  
Tomas Beno ◽  
◽  
Jari Repo ◽  
Lars Pejryd ◽  
Keyword(s):  
Tool Wear ◽  
Machine Tool ◽  
Process Monitoring ◽  
Low Frequency ◽  
Machining Process ◽  
Process Conditions ◽  
Monitoring And Control ◽  
Signal Features ◽  
Process Monitoring And Control ◽  
Cutting Force Components

Tool wear in machining changes the geometry of the cutting edges, which affects the direction and amplitudes of the cutting force components and the dynamics in the machining process. These changes in the forces and dynamics are picked up by the internal encoders and thus can be used for monitoring of changes in process conditions. This paper presents an approach for the monitoring of amulti-toothmilling process. The method is based on the direct measurement of the output from the position encoders available in the machine tool and the application of advanced signal analysis methods. The paper investigates repeatability of the developed method and discusses how to implement this in a process monitoring and control system. The results of this work show that various signal features which are correlated with tool wear can be extracted from the first few oscillating components, representing the low-frequency components, of the machine axes velocity signatures. The responses from the position encoders exhibit good repeatability, especially short term repeatability while the long-term repeatability is more unreliable.

The Start-Up, Operation and Monitoring of High-Rate Anaerobic Treatment Systems: Discusser's Report

1991 ◽  
Vol 24 (8) ◽  
pp. 257-277 ◽  
Author(s):  
P. Weiland ◽  
A. Rozzi
Keyword(s):  
Process Control ◽  
Warning Signal ◽  
Anaerobic Treatment ◽  
High Rate ◽  
Process Conditions ◽  
Physical Parameters ◽  
Monitoring And Control ◽  
Start Up ◽  
Process Monitoring And Control ◽  
And Control

The reduction of the duration of start-up and the improvement of process control are important factors in order to increase the competitiveness of anaerobic high-rate reactor systems. This paper discusses and reviews the specific similarities and differences of UASB, filter and expanded/fluidized bed reactors with respect to start-up, operation, parameter monitoring and process control. The influence of microbial, biochemical and physical parameters upon reactor start-up and process performance is evaluated and methods for process monitoring and control are described. The different role of stability indicators, which give an early warning signal of oncoming unstable process conditions, and control variables, which must be kept constant during operation, is discussed with respect to process control and reactor start-up. The merits and weak points of each reactor system are presented and all systems are qualitatively compared.

scholarly journals Study of optical emission from laser-produced plasma expanding across an external magnetic field

2003 ◽  
Vol 21 (1) ◽  
pp. 65-71 ◽  
Author(s):  
VIRENDRA N. RAI ◽  
JAGDISH P. SINGH ◽  
FANG Y. YUEH ◽  
ROBERT L. COOK
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Emission Spectroscopy ◽  
Line Emission ◽  
Optical Emission ◽  
Atomic Emission ◽  
Laser Induced Plasma ◽  
Steady Magnetic Field ◽  
Three Body ◽  
Body Recombination

The laser-induced plasma obtained from the liquid target and expanding across a steady magnetic field has been studied using atomic emission spectroscopy. The line emission from the plasma was enhanced (>1.5 times) in the presence of a magnetic field, whereas background emission decreases. Enhancement in line intensity was found to be mainly a function of plasma beta (β). An increased rate of three-body recombination in plasma particles due to the cooling of the plasma during its expansion and an increase in effective plasma density as a result of its confinement seems to be the reason behind this enhancement.

Ultratrace Analyses by Optical Emission Spectroscopy: The Stray Light Problem

1976 ◽  
Vol 30 (4) ◽  
pp. 384-391 ◽  
Author(s):  
G. F. Larson ◽  
V. A. Fassel ◽  
R. K. Winge ◽  
R. N. Kniseley
Keyword(s):  
Inductively Coupled Plasma ◽  
Emission Spectroscopy ◽  
Large Fraction ◽  
Optical Emission ◽  
Atomic Emission ◽  
Stray Light ◽  
Measured Signal ◽  
Inductively Coupled ◽  
Light Effects ◽  
Total Composition

When atomic emission spectroscopy is employed for the determination of trace elements at concentrations near the detection limit, the spectral background will normally be a large fraction of the total measured signal. Precise background corrections are therefore required if accurate analyses are to be achieved. Experimental evidence is presented to document the fact that stray light may produce substantial shifts in the background signal measured with some spectrometers when the total composition of the sample changes. The data presented have been obtained with the inductively coupled plasma as an excitation source; similar effects can be expected with other excitation sources as well. Examples of various forms of stray light originating from grating defects (ghosts, near and far scatter) and defects in the design of spectrometers are presented. Various methods for the reduction, elimination or correction of stray light effects are also discussed.

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