Repetitive Process Control of Laser Metal Deposition

2014 ◽  
Author(s):  
Patrick M. Sammons ◽  
Douglas A. Bristow ◽  
Robert G. Landers
Keyword(s):  
Process Control ◽  
Dynamic Models ◽  
Open Loop ◽  
Metal Deposition ◽  
Hammerstein Model ◽  
Layer By Layer ◽  
Laser Metal Deposition ◽  
Material Source ◽  
Stabilizing Controller ◽  
Repetitive Process

The Laser Metal Deposition (LMD) process is an additive manufacturing process in which a laser and a powdered material source are used to build functional metal parts in a layer by layer fashion. While the process is usually modeled by purely temporal dynamic models, the process is more aptly described as a repetitive process with two sets of dynamic processes: one that evolves in position within the layer and one that evolves in part layer. Therefore, to properly control the LMD process, it is advantageous to use a model of the LMD process that captures the dominant two dimensional phenomena and to address the two-dimensionality in process control. Using an identified spatial-domain Hammerstein model of the LMD process, the open loop process stability is examined. Then, a stabilizing controller is designed using error feedback in the layer domain.

scholarly journals Repetitive Process Control of Additive Manufacturing With Application to Laser Metal Deposition

2019 ◽  
Vol 27 (2) ◽  
pp. 566-575 ◽  
Author(s):  
Patrick M. Sammons ◽  
Michelle L. Gegel ◽  
Douglas A. Bristow ◽  
Robert G. Landers
Keyword(s):  
Additive Manufacturing ◽  
Process Control ◽  
Metal Deposition ◽  
Laser Metal Deposition ◽  
Repetitive Process

A Model Predictive Repetitive Process Control Formulation for Additive Manufacturing Processes

2015 ◽  
Author(s):  
Patrick M. Sammons ◽  
Douglas A. Bristow ◽  
Robert G. Landers
Keyword(s):  
Additive Manufacturing ◽  
Process Control ◽  
Predictive Control ◽  
Reference Signal ◽  
Deposition Process ◽  
Open Loop ◽  
Two Dimensions ◽  
Manufacturing Processes ◽  
Layer By Layer ◽  
Repetitive Process

Additive Manufacturing (AM) processes are a class of manufacturing processes in which parts are fabricated in a layer-by-layer fashion. The layer-by-layer fabrication method creates layer-to-layer dynamics. Implementing process control that neglects the layer-to-layer dynamics can lead to process instability. While repetitive process controllers which utilize only layer-to-layer feedback are a viable method, their usefulness is limited in that they are not well-suited for tracking non-periodic layer-domain references. However, since the entire reference signal is typically known a priori in AM process fabrications, a predictive control methodology can be useful for controlling fabrications in which the reference signal is non-periodic. In this paper a model predictive control formulation is extended to two-dimensions and utilized for repetitive process control Simulation results comparing open-loop and controlled fabrications for a Laser Metal Deposition process are given.

Height Dependent Laser Metal Deposition Process Modeling

2013 ◽  
Vol 135 (5) ◽  
Author(s):  
Patrick M. Sammons ◽  
Douglas A. Bristow ◽  
Robert G. Landers
Keyword(s):  
Heat Transfer ◽  
Critical Role ◽  
Metal Deposition ◽  
Lumped Parameter Model ◽  
Analytical Models ◽  
Layer By Layer ◽  
Laser Metal Deposition ◽  
Melt Pool ◽  
Solid Region ◽  
Scan Speed

Laser metal deposition (LMD) is used to construct functional parts in a layer-by-layer fashion. The heat transfer from the melt region to the solid region plays a critical role in the resulting material properties and part geometry. The heat transfer dynamics can change significantly as the number of layers increase, depending on the geometry of the sub layers. However, this effect is not taken into account in previous analytical models, which are only valid for a single layer. This paper develops a layer dependent model of the LMD process for the purpose of designing advanced layer-to-layer controllers. A lumped-parameter model of the melt pool is introduced and then extended to include elements that capture height dependent effects on the melt pool dimensions and temperature. The model dynamically relates the process inputs (laser power, material mass flow rate, and scan speed) to the melt pool dimensions and temperature. A finite element analysis (FEA) is then conducted to determine the effect of scan speed and part height on the solid region temperature gradient at the melt pool solidification boundary. Finally, experimental results demonstrate that the model successfully predicts multilayer phenomenon for two deposits on two different substrates.

Additive Manufacturing

2019 ◽  
pp. 165-183 ◽  
Author(s):  
Kamardeen Olajide Abdulrahman ◽  
Esther T. Akinlabi ◽  
Rasheedat M. Mahamood
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Titanium Aluminide ◽  
Three Dimensional ◽  
Physical And Mechanical Properties ◽  
Processing Parameters ◽  
Metal Deposition ◽  
Layer By Layer ◽  
Laser Metal Deposition ◽  
Additive Process

Three-dimensional printing has evolved into an advanced laser additive manufacturing (AM) process with capacity of directly producing parts through CAD model. AM technology parts are fabricated through layer by layer build-up additive process. AM technology cuts down material wastage, reduces buy-to-fly ratio, fabricates complex parts, and repairs damaged old functional components. Titanium aluminide alloys fall under the group of intermetallic compounds known for high temperature applications and display of superior physical and mechanical properties, which made them most sort after in the aeronautic, energy, and automobile industries. Laser metal deposition is an AM process used in the repair and fabrication of solid components but sometimes associated with thermal induced stresses which sometimes led to cracks in deposited parts. This chapter looks at some AM processes with more emphasis on laser metal deposition technique, effect of LMD processing parameters, and preheating of substrate on the physical, microstructural, and mechanical properties of components produced through AM process.

Control Module of Laser Metal Deposition Shaping System

2011 ◽  
Vol 480-481 ◽  
pp. 644-649
Author(s):  
Kai Zhang ◽  
Xiao Feng Shang ◽  
Wei Jun Liu
Keyword(s):  
Motion Control ◽  
Computer Control ◽  
Processing Parameters ◽  
Metal Deposition ◽  
Layer By Layer ◽  
Laser Metal Deposition ◽  
Control Module ◽  
Software Structure ◽  
Shaping System ◽  
Rapid Prototyping And Manufacturing

The Laser Metal Deposition Shaping (LMDS) is a state-of-the-art technology which correlates the Rapid Prototyping and Manufacturing (RP&M) and laser processing. During this process, a certain alloy is fused onto the surface of a substrate. Laser deposition devices, namely powder feeder, CNC worktable, and laser shutter, are integrated to automatically make any cladding profile possible. Material is deposited by scanning the laser across a surface while injecting metallic powders into the molten pool at the laser focus. The metal part is then fabricated layer by layer. The LMDS system consists of four primary components: energy supply module, motion control module, powder delivery module, and computer control module. These modules of LMDS system individually perform the specified functions, but coordinate with each other. One of them, the control module plays an important role in causing the LMDS system automatic and intelligent. The control module can be divided into hardware and software components. The hardware structure mainly includes industrial computer, motors, and motion control card, which build the overall framework, and are driven by software structure. The software structure, namely the system application program with GUI, can instruct every module of LMDS system to finish the motion cooperatively adjust the processing parameters freely, and fulfill the LMDS technology automatically and intelligently. The hardware and software structures work in harmony with each other, thus flexibly controlling the LMDS system.

scholarly journals Additive Manufacturing of H11 with Wire-Based Laser Metal Deposition

2017 ◽  
Vol 22 (4) ◽  
pp. 466-479 ◽  
Author(s):  
Stella Holzbach Oliari ◽  
Ana Sofia Clímaco Monteiro D’Oliveira ◽  
Martin Schulz
Keyword(s):  
Additive Manufacturing ◽  
Travel Speed ◽  
Metal Deposition ◽  
Parameters Optimization ◽  
Layer By Layer ◽  
Laser Metal Deposition ◽  
3D Cad ◽  
Deposition Parameters ◽  
Commercial Applications ◽  
Functional Components

Abstract Laser additive manufacturing (LAM) is a near-net-shape production technique by which a part can be built up from 3D CAD model data, without material removal. Recently, these production processes gained attention due to the spreading of polymer-based processes in private and commercial applications. However, due to the insufficient development of metal producing processes regarding design, process information and qualification, resistance on producing functional components with this technology is still present. To overcome this restriction further studies have to be undertaken. The present research proposes a parametric study of additive manufacturing of hot work tool steel, H11. The selected LAM process is wire-based laser metal deposition (LMD-W). The study consists of parameters optimization for single beads (laser power, travel speed and wire feed rate) as well as lateral and vertical overlap for layer-by-layer technique involved in LMD process. Results show that selection of an ideal set of parameters affects substantially the surface quality, bead uniformity and bond between substrate and clad. Discussion includes the role of overlapping on the soundness of parts based on the height homogeneity of each layer, porosity and the presence of gaps. For the conditions tested it was shown that once the deposition parameters are selected, lateral and vertical overlapping determines the integrity and quality of parts processed by LAM.

Two-Dimensional Modeling and System Identification of the Laser Metal Deposition Process

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Patrick M. Sammons ◽  
Douglas A. Bristow ◽  
Robert G. Landers
Keyword(s):  
Metal Deposition ◽  
Dynamic Evolution ◽  
Layer By Layer ◽  
Two Dimensional ◽  
Laser Metal Deposition ◽  
Modeling Framework ◽  
Dynamic Component ◽  
Linear Dynamic ◽  
Dimensional Modeling ◽  
Am Processes

Additive manufacturing (AM) processes fabricate parts by adding material in a layer-by-layer fashion. In order to enable closed-loop process control—a major hurdle in the adoption of most AM processes—compact models suitable for control design and for describing the layer-by-layer material addition process are needed. This paper proposes a two-dimensional modeling framework whereby the deposition of the current layer is affected by both in-layer and layer-to-layer dynamics, both of which are driven by the state of the previous layer. The proposed framework can be used to describe phenomena observed in AM processes such as layer rippling and large defects in laser metal deposition (LMD) processes. Further, the proposed framework can be used to create two-dimensional dynamic models for the analysis of layer-to-layer stability and as a foundation for the design of layer-to-layer controllers for AM processes. In the application to LMD, a two-dimensional linear–nonlinear–linear (LNL) repetitive process model is proposed that contains a linear dynamic component, which describes the dynamic evolution of the process from layer to layer, cascaded with a static nonlinear component cascaded with another linear dynamic component, which describes the dynamic evolution of the process within a given layer. A methodology, which leverages the two-dimensional LNL structure, for identifying the model process parameters is presented and validated with quantitative and qualitative experimental results.

Laser additive manufacturing of copper– chromium–niobium alloys using gas atomized powder

2020 ◽  
Vol 111 (7) ◽  
pp. 587-593
Author(s):  
Dora Maischner ◽  
Udo Fritsching ◽  
Anoop Kini ◽  
Andreas Weisheit ◽  
Volker Uhlenwinkel ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Rapid Solidification ◽  
Elevated Temperatures ◽  
High Strength ◽  
Copper Matrix ◽  
Metal Deposition ◽  
Raw Material ◽  
Layer By Layer ◽  
Laser Metal Deposition ◽  
Niobium Alloys

Abstract Copper-chrome-niobium alloys exhibit excellent thermal and electrical properties combined with high strength at elevated temperatures. Additive manufacturing techniques such as laser metal deposition using powder as raw material offer the potential for rapid solidification as well as a high freedom of design to manufacture parts layer by layer. Powder samples of copper- chrome-niobium alloys were produced by gas atomization. Via laser metal deposition, bulk volumes without cracks and with a very low porosity can be built up. Rapid solidification leads to the formation of fine precipitates which are likely to be (Cr,Fe)2Nb. The precipitates are distributed homogeneously in the copper matrix. The copper crystals grow across the layers due to epitaxial nucleation on the preceding layer.

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