Design Theories & Methods

Engineering Design 

Integrated Function Modelling

This project focuses on Integrated Conceptual Design Methodologies in automated modular construction manufacturing systems. Applications range from Machine Learning techniques, such as Principal Component Analysis, Forward Orthogonal Search, and Self-organizing Map Neural Network, as feature selection techniques in optimally reducing product design complexity at the customer requirement definition stage of conceptual design. Moreover, integrating controller design with Quality Function Deployment (QFD) of multiple-input and multiple-output (MIMO) robotic systems is studied as well.

Sustainable Design – Environmental Impact of AM

The focus of this project is on the “Life Cycle Assessment (LCA) of Metal Additive Manufacturing (AM)”. AM is a process of creating parts layer by layer, just as making a layered cake, instead of reducing a chunk of material from a bulk part (conventional manufacturing, CM). LCA of a product or a service answers a simple question: How does a product or service affect the environment? The effects involve the study of environmentally hazardous greenhouse gases, energy consumed, effect on the ecosystem, and many other factors, which are studied by analyzing the product/service from cradle (initiation) to grave (end of life). LCA is critical in creating a sustainable environment, as it promotes the manufacturing of products, processes or services, which are environmentally friendlier. It can be applied to almost anything, for example, a very famous study analyzed using tissue papers and the latest hand dryers to see which is more environmentally friendly. The study acknowledges the work done so far in this field, analyzes the various forms of additive manufacturing processes, and aims to propose a process of bridging and standardizing the gap between the current studies performed for evaluating and comparing the environmental impacts and sustainability studies of AM technologies and processes with CM.

LCA Flowchart

Advanced Manufacturing Systems

Metal AM

Geometric Quality Assessment Framework for Metal AM Processes

For metal AM, the geometric quality is a function of various parameters throughout the process stages, which lead to specific geometric deviation modes and an overall geometric effect on the final printed part.

The total geometric deviation is the sum of the individual deviation modes, and it could be characterized based on Geometric Dimensioning and Tolerancing (GD&T). The GD&T-based characterization enables a complete and standardized quantification of any mechanical part with respect to ISO 1101. This research is aimed at developing a framework to assess the total geometric quality of a metal AM part based on GD&T standards. The framework will include modeling deviation modes at each stage of the process. Integration of various modes will be conducted in order to calculate the total effect on the geometric quality and will be characterized in terms of GD&T standards.

Closely related to this project is a sub-project which will provide a framework to systematically estimate the geometric process capability of a SLM AM process. The framework is based on experimentation on a GBTA created through normative benchmarking techniques. The GBTA used in this study was manufactured through a SLM process on a Renishaw AM 250 machine using SS-316 material. This project focuses on defining the measurement strategy undertaken to measure the different tolerance bands of the Geometric Dimensioning and Tolerancing (GD&T) characteristics. ISO 1101:2017 standard is referred to understand the definitions and the implications of different tolerancing characteristics in GD&T. A basic statistical analysis is performed on the output measurement results of these tolerance bands. Moreover, any relationships between the tolerance band value of any GD&T characteristic of the features with respect to the location on the GBTA, and geometric properties such as surface area, volume, aspect ratio, characteristic length, and diameters of the features are analyzed.

GBTA CAD File
Metal GBTA

Robotized Metal AM

This project is concerned with metal AM, “also known as 3D printing, where computer-aided design is used to build objects layer by layer” (American Society for Testing and Materials). Today, AM is already used in the industry for rapid prototyping, legacy part manufacturing, and part repairs. Various AM systems are currently commercially available. These systems are, however, only suitable for small-scale printing (e.g., 200×200 mm footprint). In our research, we aim to develop a system that uses an industrial robotic arm to deposit layers of metal utilizing technologies such as wire-and-arc welding or laser-based direct energy deposition. The large reach of the robotic arm (for example 2000 mm) allows for large-scale parts to be printed (e.g., 1000×1000 mm footprint). Another limitation of the current state of AM is the need for support structures for overhanging features. We are also developing methods for multi-directional material deposition where the dexterity of the robotic arm in addition to a tilting and rotating build platform are leveraged to eliminate this limitation. Moreover, we are conducting research in in-situ process monitoring, and process modeling and control, in order to facilitate process optimization and automation such that a desired quality of the finished part with respect to metallurgical and material strength requirements can be achieved.

Plasma Transferred Arc (PTA) AM

This project is focused on summarizing the developing research in the AM of metal parts using PTA technology. A particular focus is paid to the need for real-time, closed-loop processes control in order to ensure quality, consistency, and reproducibility through utilizing real-time strategies and machine learning techniques. Preliminary results of two printed test parts can be found here.

The preliminary work was conducted using an outdated PTA System without remote control adapted to it. Therefore, the three-axis table and the Starweld System worked independently and synchronized. A new PTA System is now installed with new technology in its controller. This allows for the possibility of seamlessly integrating it with the PTA-AM Table.

The integration of both platforms is conducted using Virtual Instruments in the main control station. Standardized communication protocols are used to read and write information in the PTA System. Now, the main control station is able to read and modify real-time process parameters. Current work attempts to generate a Human Machine Interface (HMI) used as a SCADA systems. By now, the HMI can communicate with 35 process variables in the PTA and transfer/receive information through script commands.

Composite AM

Development of Magnetically Loaded Polymer Composites for Electromechanical Applications using AM

AM allows for the production of complex parts with less tooling and minimum material wastage. In this context, magnetically loaded polymer composites with isotropic and anisotropic properties are promising for many electro-mechanical and electromagnetic applications. The fundamental goal of this research work is to offer an effective AM technique for manufacturing magnetic composites which involve critical rare earth materials. Two different AM techniques namely, stereolithography and material jetting are being utilized to make both isotropic and anisotropic magnetic composites respectively. This research work is multidisciplinary and involves the utilization of finite element methods, image processing, rheological analysis, X-Ray Diffraction, thermogravimetry, and FTIR spectroscopy to derive material and process characteristics. Novel AM equipment’s, materials are developed, validated and characterized.  This research work is significant from both an academic and industrial point of view, for example, Flywheel Energy Storage Systems (FESS). FESS has received considerable attention in the field of industrial energy storage, light rail transit vehicles, and space applications. Present Flywheel technology employs a separate electrical machine that functions as a motor-generator for the Flywheel system. An emerging design approach is to integrate the electrical machine functionality into the Flywheel rotor by incorporating magnetic particles into the composite polymer matrix. This approach will enable the composite rotor to function both as a motor and generator eliminating the need for a separate electrical machine. Additionally, AM will enable engineering both magnetic and mechanical properties suitable for the FESS systems.

Particle Settling Control
X-Ray Diffraction Results of Manufactured Composites
Optical Micrographs for Real-time Optical Microscopy
FEMM Simulation – Two Cube System, Separation Distance Influence, and Flux Density Map
Image Processing Analysis of Optical Micrographs for Process Optimization

Polymer AM

Tolerance Control of Parts Manufactured by µSLA

3D printing manufacturing technology has been utilized in various applications due to its promising manufacturing advantages. Desktop Digital Light Processing (DLP) printers provide high-resolution products with a moderate price range. DLP uses an array of micromirrors to transmit UV light from the light projector in order to perform selective curing of a prepolymer resin and turn it in to the required geometry. The CAD file is transformed into several slices according to the layer thickness. Each slice is then converted to an image of black and white pixels, in which each white pixel actuates a corresponding micromirror to transmit the UV light to cure a corresponding voxel, while a black pixel corresponds to no actuation, which means no curing for the corresponding voxel. The micromirror’s size determines the resolution of the printer. Although a theoretical voxel size can be determined as a function of the micromirror’s dimensions and layer thickness, the actual voxel volume depends on several parameters such as the layer thickness, UV exposure time, and UV exposure intensity. Controlling these three parameters would result in more accurate 3D printed parts and more control over the dimensional tolerance. In this project, the effect of variable light intensity in terms of grayscale pixels is studied along with the exposure time and layer thickness to manipulate the voxel horizontal dimensions. This enables printing with voxel dimensions below the size of the micromirrors in the DLP, which improves the geometric dimensioning and tolerance of the printed parts.

Layout of the used Manufacturing System
Assessing the Cylindricity Error and Tolerance of Manufactured Cylinders using CMM

Optimization of 3D Structures Manufactured by a Constrained Surface Mask Protection µSLA System

With the advancement of micro-stereolithography (µSLA) based AM systems, the manufacturing cost of microfluidic devices drops significantly. The implementation of mask projection devices, as Digital MicromirrorsDevices (DMD), in µSLA enables higher resolution at lower manufacturing times. The vertical resolution of the constrained surface mask projection µSLA is affected by the minimum layer thickness achievable by the control system and the light penetration through the material, which is determined based on the overall absorbance of the resin used.

On the other hand, the horizontal resolution depends on the size of the micromirrors in the DMD and the curing light diffraction, which is represented by point spread functions. The currently available DMD provide the individual modulation of irradiance reflected from each micromirror, which facilitates a controlled variable irradiance per each layer and improves the horizontal resolution with pixel blending algorithms. In this study, a geometric simulation algorithm including both the vertical and horizontal distortions is presented, and an optimization algorithm is proposed to enhance the current resolution.

Electron Microscope Image of a Micro 3D Pyramid Structure Manufactured by µSLA
Confocal Microscopy of a Microstructure Manufactured by µSLA
3D Profile Analysis of the Confocal Microscope Scanning

Systems Engineering

CNC Router

The goal of the project is to design and construct a multi-axis gantry system which can be used in different applications, including the application of a CNC router.

Hybrid Manufacturing Processes

Investment Casting with SLA 3D Printing

One of the processes used to make complex shapes in a shorter time span than AM is Selective Laser Sintering (SLS). Although this process has proven to be useful in terms of dimensional accuracy and surface finish, it is also rather expensive for producing a lower number of units in a given span of time(<500). Investment casting with Stereolithography (SLA) 3D printing for the pattern manufacturing is an alternative which can be used to manufacture complex objects. This proposed method is currently used by jewelers to create personalized jewelry out of gold and silver. 

Stereolithography is a 3D printing technology where liquid resin in a resin tank is converted into a solid pattern with the help of layer-by-layer deposition of the material, this process is known as photopolymerization. 

Investment Casting, also known as lost wax casting, is an old process where a wax pattern is used to make a ceramic mold. A mold cavity is created when a mold is developed around the wax pattern and it is heated at high temperatures to evaporate the wax pattern. The impressions of the pattern leaves behind a cavity inside the mold into which the molten metal is poured to obtain the product of desired shape and size. In this particular process, resin was used instead of wax for creating the pattern of the object for casting due to the cost advantage of resin over wax.

(1) CAD Design
(2) Preform (STL File)
(3) SLA 3D Printed Part
(4) Final Object

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