Distributed-Parameter Modeling for Geometry Control of Manufacturing Processes With Material Deposition

1998 ◽  
Vol 122 (1) ◽  
pp. 71-77 ◽  
Author(s):  
Charalabos Doumanidis ◽  
Eleni Skordeli
Keyword(s):  
Solid Freeform Fabrication ◽  
Surface Topology ◽  
Distributed Parameter ◽  
Surface Geometry ◽  
Mass Source ◽  
Freeform Fabrication ◽  
Geometry Model ◽  
Material Deposition ◽  
Solid Objects ◽  
3D Solid

Recent solid freeform fabrication methods generate 3D solid objects by material deposition in successive layers made of adjacent beads. Besides numerical simulation, this article introduces an analytical model of such material addition, using superposition of unit deposition distributions, composed of elementary spherical primitives consistent with the mass transfer physics. This real-time surface geometry model, with its parameters identified by in-process profile measurements, is used for Smith-prediction of the material shape in the unobservable deposition region. The model offers the basis for a distributed-parameter geometry control scheme to obtain a desired surface topology, by modulating the feed and motion of a moving mass source. The model was experimentally tested on a fused wire deposition welding station, using optical sensing by a scanning laser stripe. Its applications to other rapid prototyping methods are discussed. [S0022-0434(00)02301-7]

On the Optimal Robot Manipulator Motion Planning for Solid Freeform Fabrication by Thermal Spraying

1995 ◽  
Author(s):  
J. Rastegar ◽  
Y. Qin ◽  
Q. Tu
Keyword(s):  
Motion Planning ◽  
Robot Manipulator ◽  
Solid Freeform Fabrication ◽  
Thermal Spraying ◽  
Freeform Fabrication ◽  
Novel Approach ◽  
Solid Objects ◽  
Optimal Motion Planning ◽  
Spatial Geometry ◽  
Probabilistic Nature

Abstract A novel approach to optimal robot manipulator motion planning for Solid Freeform Fabrication (SFF) by thermal spraying is presented. In this approach, given the desired spatial geometry of the object, the motion of the spray gun relative to a forming platform is synthesized for minimal masking requirements considering the probabilistic nature of the thermal spraying process. The material build-up rate can be planned to achieve the desired distribution of the physical/material properties within the object volume. Examples of optimal motion planning for the generation of some basic solid objects and computer simulation of the effectiveness of the developed methodology are presented.

A Process Map for Consistent Build Conditions in the Solid Freeform Fabrication of Thin-Walled Structures

2000 ◽  
Vol 123 (4) ◽  
pp. 615-622 ◽  
Author(s):  
Aditad Vasinonta ◽  
Jack L. Beuth ◽  
Michelle L. Griffith
Keyword(s):  
Solid Freeform Fabrication ◽  
Numerical Models ◽  
Thermal Control ◽  
Process Map ◽  
Freeform Fabrication ◽  
Thin Walled Structures ◽  
Melt Pool ◽  
Material Deposition ◽  
Thin Walled ◽  
Net Shaping

In solid freeform fabrication (SFF) processes involving thermal deposition, thermal control of the process is critical for obtaining consistent build conditions and in limiting residual stress-induced warping of parts. In this research, a nondimensionalized plot (termed a process map) is developed from numerical models of laser-based material deposition of thin-walled structures. This process map quantifies the effects of changes in wall height, laser power, deposition speed and part preheating on melt pool length, which is an essential process parameter to control in order to obtain consistent build conditions. The principal application of this work is to the Laser Engineered Net Shaping (LENS) process under development at Sandia Laboratories; however, the general approach and a subset of the presented results are applicable to any SFF process involving a moving heat source. Procedures are detailed for using the process map to predict melt pool length and predictions are compared against experimentally measured melt pool lengths for stainless steel deposition in the LENS process.

Solid Freeform Fabrication by GMA Welding: Geometry Modeling, Adaptation and Control

1999 ◽  
Author(s):  
Yong-Min Kwak ◽  
Charalabos Doumanidis
Keyword(s):  
Shape Control ◽  
Laser Scanning ◽  
Gma Welding ◽  
Solid Freeform Fabrication ◽  
Gas Metal Arc Welding ◽  
Welding Process ◽  
Full Density ◽  
Surface Geometry ◽  
Bead Width ◽  
Freeform Fabrication

Abstract This paper introduces the Gas Metal Arc Welding process with deposition shape control to solid freeform fabrication for large sculpted metal objects and rapid tooling of molds and dies. Besides full density and toughness properties, GMAW deposition must ensure near-net-shape surface geometry. To this end, an analytical model of deposited morphology is derived, based on linearized superposition of ellipsoidal unit deposition globules. The time-varying parameters of these primitives are identified in-process using laser scanning measurements of the bead width. An experimental description of width on the GMAW inputs is also established. On this basis, bead width control through the wire feed is implemented in real time, using Smith prediction to cope with sensor delays, and feedforward to compensate for the predeposited terrain. This controller was validated in the laboratory, in stainless steel deposition in single and overlaid beads.

On the Rapid Prototyping Technologies and Applications in Product Design and Manufacturing

2012 ◽  
Vol 710 ◽  
pp. 101-109 ◽  
Author(s):  
Pulak M. Pandey
Keyword(s):  
Rapid Prototyping ◽  
Material Removal ◽  
Solid Freeform Fabrication ◽  
Functionally Graded ◽  
Layer By Layer ◽  
Data Preparation ◽  
Freeform Fabrication ◽  
Material Deposition ◽  
Design And Manufacturing ◽  
Graded Material

Material removal, forming, casting and joining are the established manufacturing approaches and processes based on these approaches are being practiced even in modern industries with appropriate automation. Layer by layer material deposition method to produce prototypes from a solid model is relatively new and was developed during last 10-15 years of 20th century. These processes were named as Rapid Prototyping (RP) or Solid Freeform Fabrication (SFF). Today there are many commercial RP system and most of these able to deposit liquid or solid/powder polymer based materials. Some systems are also able to deposit blends of polymer and metal or ceramic. Latest trend in this area is to deposit metals or alloys with variable composition and hence to produce functionally graded material. This paper describes in general the details related to RP processes, data preparation, and various commercial RP technologies. The article also discusses applications these processes.

Thermo-Geometrical Design Models for Solid Freeform Fabrication With Material Transfer

1998 ◽  
Author(s):  
Charalabos Doumanidis ◽  
Yong-Min Kwak
Keyword(s):  
Fused Deposition Modeling ◽  
Solid Freeform Fabrication ◽  
Heat Transfer Analysis ◽  
Material Structure ◽  
Process Conditions ◽  
Transfer Model ◽  
Material Transfer ◽  
Surface Geometry ◽  
Freeform Fabrication ◽  
Fused Deposition

Abstract In thermal solid freeform fabrication of layered products, simultaneous quality assurance of the part geometry and material structure requires concurrent design of the process conditions with the product features. For a heat transfer analysis yielding the material structure, an analytical, distributed-parameter quasi-linear thermal model is developed and tested in scan welding. This is based on Green’s field, identified in-process by infrared temperature sensing to reflect thermal nonlinearities. Similarly, a mass transfer model of the layer surface geometry is established on an analogous concept of the material deposition field, approximated by an ellipsoidal shape and identified in-process by Laser 3D scanning of the part topology in fused deposition modeling tests. The invertibility and computational efficiency of both models provide a basis for design of adaptive feedback control strategies for the thermogeometrical characteristics of rapid prototypes.

Process and Properties Control in Laser Aided Direct Metal/Materials Deposition Process

Manufacturing ◽  
2002 ◽  
Author(s):  
J. Choi
Keyword(s):  
Solid Freeform Fabrication ◽  
Laser System ◽  
Deposition Process ◽  
Cad Model ◽  
Metal Powders ◽  
Influence Of Process Parameters ◽  
Freeform Fabrication ◽  
Material Deposition ◽  
Nc Machine ◽  
Metallic Parts

Laser aided direct metal/material deposition (DMD) process, one of the technologies based on laser cladding, has demonstrated the ability to make a metal component directly from a 3-D CAD model. DMD process is achieved with a laser system combined with a NC machine tool or laser-robot system. Making metallic parts directly, designer can reduce unnecessary steps such as mock-up and molding. In the sense, DMD process is rather a rapid production technique than a rapid prototyping process. With continued advancement, DMD process, one of the leading solid freeform fabrication techniques, has demonstrated the ability to make a metal part with heterogeneous components directly from a CAD model. One unique advantage of the process is that building different metallic parts in same object can be achieved alternating metal powders. The advantage gives designers better quality of products than others can offer. Another attractive point is that some features such as cooling channel, heat sinks, sensors, fibers, and even hard phases for composites can be embedded during the process. This paper summarizes the fundamentals of the process, process control and influence of process parameters, and reports some examples produced utilizing the technique with the characteristics of fabricated parts.

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