Author: Ryan Stebbins Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Casting is one of the oldest manufacturing methods, dating to 5000 B.C. Its influence can still be seen today, accounting for a $110 billion impact on the US economy in 2019. Sand casting, is the most popular casting process due to its ability to produce relatively complex parts with almost any alloy at comparatively low costs, as well as manufacture both large components and small precision castings. Despite its prominence, casting has design limitations such as required draft angles and parting lines due to required tooling and patterns, which has led to the exploration of new manufacturing methods, such as additive manufacturing (AM). AM allows for increased part complexity, reduced material usage, part consolidation, usage of lattices, and decreased lead time between design and production. The rise of this novel technology is reflected in the large influx in publications and patents involving AM within in the past couple decades. However, its limitations in part size, cost, and available alloys prevent it from fully replacing casting. The merger of both sand casting and AM binder jetting into a hybrid manufacturing method is called 3D sand printing (3DSP), and it offers the benefits of both methods. With the advent of 3DSP, more complex geometries and castings are possible, allowing for the redesign and optimization of gating and rigging systems for defect reduction and improvements in casting quality. Despite research having already explored redesigning gating components like pouring basins, sprues, and runners using more complex mold geometries realizable through 3DSP, no research has considered the use of 3DSP for runner extensions. This thesis investigates various runner extension designs for the purpose of defect reduction. Out of the six different runner extension designs, three required 3DSP due to complexity. All designs were evaluated using simulation and experimental validation to ascertain their impact on casting quality. Designs were derived from literature review of gating system concepts. Simulations were completed using Flow-3D Cast v5 CFD software, comparing the resulting entrained air, tracer particles, and void particles present in the casting cavity. Results indicated difference between designs but required additional experimental comparisons to conclude runner extension impact. Designs were tested on manually poured Al319 cast plates, using a hybrid mold making method of both green sand and 3DSP extension molds. A total of eighteen plates were cast, three per design, all of which were scanned with computed tomography (CT) to determine the defect volume fraction present in the final castings. Three-point bending bars were machined from cast plates and tested to compare extension designs impact on mechanical properties. Statistical analysis of both mechanical performance and defect volume fraction showed no differences between runner extension designs. The results obtained in this thesis aid for the further optimization of gating systems and helping foundries reach zero defect casting.
Author: Santosh Reddy Sama Publisher: ISBN: Category : Languages : en Pages :
Book Description
In recent years, Additive Manufacturing (AM) technologies are fueling a paradigm shift in the advanced manufacturing landscape across all industrial sectors. The metal casting industry is also taking advantage of the wide variety of rapid manufacturing solutions offered by AM processes. The metal casting industry supports about 90% of total manufactured goods and is expected to reach a market size of about 40 billion USD by 2025. Sand casting is the most widely used metal casting process and utilizes expendable molds that demand expensive tooling, high lead time and limited flexibility in their fabrication. In addition, limitations in process control and feasible gating and feeding systems, traditional sand casting experiences higher scrap rates. AM offers an alternative mold fabrication technology known as 3D Sand-Printing (3DSP) process that enables direct digital manufacturing of complex expendable sand molds and cores without any tooling requirements. Ever-growing interest in this indirect metal AM process is attributed to its ability to rapidly produce cores and molds for complex metal castings that are otherwise impossible to manufacture using conventional techniques. Knowledge-based design rules for this process are currently very limited and are progressively realized in an ad-hoc basis to produce economic low-volume castings. Despite the wealth of knowledge in metal AM, no work to date has been reported to take advantage of design complexity offered by 3DSP in developing optimal gating and feeding designs to mitigate casting defects. This thesis provides the first known investigation into the application of design freedom offered by 3DSP to transform and monitor sand casting performance. Non-conventional design rules for gating and risering (also known as rigging) systems are developed to reduce surface turbulence, oxide films, air entrapment, bubble damage and several other casting defects, and improved metallic yield. Several case studies are presented to illustrate the improved casting performance through systematically reengineering elements of the rigging system viz. pouring basin, sprue, runners and risers. Their efficacy is validated through computational simulations and experimental procedures. Of the various components of gating system, innovative sprue design provides the highest opportunity to improve casting quality. Numerical models for novel parabolic and conical-helix sprue profiles can be developed through constrained optimization algorithm based on principles of casting hydrodynamics to reduce surface turbulence. Computational flow simulations, computed tomography scanning, microstructure and mechanical characterization experiments are performed to validate that incorporation of 3D Sand-Printing featured mathematically optimized gating systems (particularly conical-helix sprues) to significantly improve the performance of sand castings.Finally, existing foundry technologies have very limited capabilities to monitor real-time flow conditions of liquid metal during mold filling. Two approaches for novel non-intrusive real-time mold fill monitoring by embedding inexpensive miniature Internet of Things (IoT) sensors into 3d sand-printed molds are proposed. These sensor technologies are based on the electrical properties of molten metals, the former measuring the magnetic flux generated by the conductive liquid and the latter measuring the interference of electric fields by modifying dielectric near the sensor. Experiments are conducted to evaluate the efficacy of both these concepts. Results from experiments validate that IoT sensors can be embedded into 3DSP molds to successfully monitor flow fields that can be used to benchmark simulation results and optimize gating systems.
Author: Ram A. Gullapalli Publisher: ISBN: Category : Metal castings Languages : en Pages : 156
Book Description
Sand casting has long been known to be an effective manufacturing method for metal casting and especially for parts of large dimensions and low production volume. But, for increasing complexity, the conventional sand casting process does have its limitations; one of them mainly being the high cost of tooling to create molds and cores. With the advent of additive manufacturing (AM), these limitations can be overcome by the use of a 3D sand printer which offers the unique advantage of geometric freedom. Previous research shows the cost benefits of 3D sand printing molds and cores when compared to traditional mold and core making methods. The line of research presented in this thesis introduces the idea of additive manufacturing at different stages of the sand casting process and investigates the decision-making process as well as the cost-based effects. This will enable foundries and manufacturers to integrate the use of AM machines more smoothly into their production process without the need for completely re-engineering the existing production system. A critical part of this thesis is the tooling cost estimation using a casting cost model that is significantly accurate to industry standard quotes. Based on these considerations, this thesis outlines three approaches for achieving this goal apart from traditional mold and core making methods. The first approach integrates 3D Printing at the pattern making level where the patterns and core-boxes are "printed" on an FDM printer. This eliminates the tooling costs associated with a traditional sand casting method. The second approach integrates 3D Printing at the core-making level by "mixing" traditional mold-making process and 3D sand printing process for core-making. The third approach, the 3D sand printer is used to create both the molds and the cores, thereby eliminating the need for traditional methods. An initial hypothesis is created which states that, for a given production volume, with increased complexity of the casting, additively manufacturing only the cores and conventionally manufacturing the molds is cost-feasible when compared to traditional manufacturing or 3D sand printing. It is finally concluded that the initial hypothesis is valid when part geometries are highly complex and production volumes range between medium to high. It is also concluded that a decision making tool based on the methodology provided can help determine a specific mixed manufacturing method for the manufacturer.
Author: Md Moinuddin Shuvo Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
For the past few decades, additive manufacturing (AM) has revolutionized manufacturing industries with seven different process categories. While offering features that subtractive manufacturing lacks, AM has also facilitated the sand casting industry through the binder jetting process. 3D sand printing (3DSP) is a type of binder jetting that fabricates complex sand molds and cores layer upon layer without requiring pattern plates, core boxes, and flasks. While the traditional mold-making techniques lacked design freedom due to draft, parting lines, and pattern issues, 3DSP is free from these obligations and capable of making sand molds with complex shapes and intricate features incorporated within the mold. Based on the ad-hoc, knowledge-based, and steel alloy-dominated design rules, improper gating and feeding system design have always contributed to various casting defects and generated high scrap rates. Available gating and feeding system design features are structured upon the traditional mold-making process and do not consider the complex design freedom 3DSP offers. This dissertation is focused on studying different novel riser (feeder) shapes, riser neck, and vortex chambers (slag traps) in comparison with the benchmark design used in the industry in order to reduce shrinkage and slag/surface defects and utilize the design flexibility of 3DSP. Three different alloys- nickel aluminum bronze (NAB), low carbon steel (WCB/ASTM A216), and Aluminum alloy (A319), were studied, which accounted for different freezing ranges. Solidification modeling and experimental validations show up to 45% yield improvement. The results are discussed in terms of computational flow and solidification simulations. Experimental validation of the computational results includes statistical analysis, Ultrasonic testing (UT), computed tomography scanning (X-ray CT), and mechanical characterization of the cast parts. To the best of the author's knowledge, this is the first effort to develop a computational solidification and experimental validation-based framework to claim the design freedom provided by 3DSP in terms of casting's feeding mechanism.
Author: Daniel Martinez Lepp Publisher: ISBN: Category : Languages : en Pages :
Book Description
Additive manufacturing (AM) has been demonstrated to be a transformative technology for rapid manufacturing from three-dimensional digital models. Due to the disruptive nature of the technology, its integration into manufacturing settings is still difficult to assess. Factors like the large upfront investment required and limited number of certified materials (specially for metal components) available represent challenges for its adoption in industry at a larger scale. One manufacturing sector where these difficulties are lessened is the metal casting industry. The American Foundry Society (AFS) estimates that the metal casting industry amounts to 33.7 billion USD and within the United States, employs directly about 200,000 people. Binder jetting technology and specifically 3D sand-printing (3DSP) offers the possibility of leveraging the freedom of design of AM using comparatively low-cost materials (i.e., silica sand vs. metallic powders) to enhance casting performance. By printing the sand mold, the full range of metals and alloys already qualified for conventional casting applications can continue to be used without any need for further certification. Two important opportunities for reducing casting defects arise when using 3DSP. In the first case, the ability to manufacture complex mold geometries previously unfeasible using conventional methods, means that the flow of liquid metal or alloy circulating through the mold can be controlled by designing rigging components that direct the flow in accordance with predetermined conditions. These design criterions can be set by running numerical simulations of the filling process. In this thesis, the effectiveness of novel sprue geometries designed mathematically for alloys of different flow and solidification behavior is examined. The use of these sprues is simulated and experimentally tested for alloys at separate ends of the freezing range (i.e., gray cast iron Class 30, a very short-freezing range alloy and aluminum alloy 319, a very long-freezing range alloy). Computed tomography (CT) scanning, scanning electron microscopy and three-point bending tests are used to characterize the results in each sprue case.The casting mechanical properties can also be altered by controlling cooling behavior of the casting. Due to the layer-by-layer nature of binder and sand deposition in the 3DSP process, precise control on the thermo-physical properties of the mold such as thermal conductivity, thermal diffusivity, permeability and mechanical strength can be achieved. The second part of this thesis presents experimental procedures used to characterize 3DSP samples obtained from different printing conditions. Permeability and mechanical properties of the mold are examined using AFS standards. Thermal properties are obtained using laboratory techniques to determine thermal conductivity and diffusivity. Casting experiments are monitored to obtain thermal properties using a linear model to solve the backward heat conduction problem. The mechanical and microstructural properties of pure aluminum samples casted using the 3DSP molds are examined using three-point bending and microscopy of etched samples. A framework for integrating these thermomechanical properties into a design loop for metal casting mold design is proposed.Finally, 3DSP samples are examined using micro computed tomography scanning. This technique allows for the creation of a 3D model of the sand mold to determine void spaces and pore interconnectedness. An understanding of the pore network properties of 3DSP samples and how printing conditions affect mold permeability are essential to creating defect-free castings. During mold filling, air present in the mold and gasses generated by the binder burn-out must be evacuated through the mold. Insufficient void space and pore interconnectedness will lead to the appearance of a backpressure within the mold. If this happens, then volumes within the mold will remain unfilled, creating serious casting defects. Samples printed using different printing parameters are examined via CT scanning and permeability simulations are performed to create an understanding of how air flow through the mold occurs.
Author: Eyad S. Almaghariz Publisher: ISBN: Category : Manufacturing processes Languages : en Pages : 140
Book Description
The additive manufacturing industry has the potential to transform nearly every sector of our lives and jumpstart the next Industrial Revolution. Engineers and designers have been using 3D printers for more than three decades but mostly to make prototypes quickly and cheaply before they embark on the expensive business of tooling up a factory to produce the real things. In sand casting industries, a growing number of companies have adopted 3D sand printing to produce final casts. Yet recent research suggests that the use of 3D sand printing has barely begun to achieve its potential market. It is not surprising that executives are having difficulty adopting additive manufacturing; the technology has many second - order effects on business operations and economics. One of the most important factors is the lack of awareness of additive manufacturing's applications and values in the sand casting manufacturing process. The lack of awareness is significantly slowing down the adoption rates. This research will help executives to optimize their adoption decision by answering the question of "At what level of part complexity should sand printing be used instead of the conventional process in molds and cores manufacturing?" Moreover, this thesis defines and analyzes the geometric attributes which influence the parts' complexity. As known in the conventional sand casting process, the high level of complexity leads to higher manufacturing cost. On the other hand, in the additive manufacturing process, the manufacturing cost is fairly constant regardless of the level of complexity. Therefore, 3D sand printing provides a unique advantage that the increasing in geometric complexity of the part has no impact on the molds and cores manufacturing cost or what is known as "complexity for free."
Author: Philip King Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Metal casting is an old but important manufacturing technology, with an estimated 90% of durable manufactured products containing a casting. While traditional metal casting has existed for thousands of years, it remains a complex process under controlled conditions that suffers from variable casting outcomes, where the same casting design can have on casting run be defect free, and another casting run that must be scrapped. This variability has long been considered unavoidable, and even acceptable by the metal casting community. However, this outlook is no longer feasible, as nations across the world try to improve sustainability and reduce energy consumption. This dissertation presents original research to improve the performance of sand casting, the most widely used metal casting process, so that the industry can improve its sustainability. Leveraging additive manufacturing (AM) via 3D sand-printing enables us to reimagine the design principles of 3D mold geometry to improve casting quality and reduce casting variation. In this research, 3D sprue geometries were systematically studied for the naval alloy nickel aluminum bronze (NAB). When compared to the straight sprue geometry traditionally used in industry, the optimized 3D sprue geometries increased the ultimate flexural strength by 28% with while also reducing the variation with statistical significance. In addition to 3D sprue geometries, this dissertation studied 3D runner geometries for both AM and traditional molds. The optimized 3D runner geometries improved casting consistency by reducing the variance of the ultimate flexural strength by a statistically significant 74%. To accelerate our understanding of melt filling in sand molds, this dissertation also investigated new process monitoring techniques that can be integrated with IoT sensors (internet-of-things) with the potential to rapidly identify defective castings. Computer vision tracked the melt head in the runner system of open molds to extract its velocity, while ultrasonic sensors provided a means to measure in-gate velocity that previously could not be measured. This novel process measured the liquid metal surface height as the mold filled and then calculated the in-gate velocity using the surface height data. Overall, the innovations presented in the dissertation have made original contributions to the science of 3D mold design via 3D sand-printing to improve casting performance and in-process monitoring capabilities.
Author: John Campbell Publisher: Elsevier ISBN: 0080476414 Category : Technology & Engineering Languages : en Pages : 218
Book Description
Each chapter of Professor Cambell's new book Castings Practice will take a look at one of his 10 rules. It is to be expected that the Rules wil one day be taken as an outline or blueprint for an international specification on the methods for making reliable castings.John Cambell has over two decades of experience in the casting industry and is the author of over 40 technical papers and patents. He has become well-known in the foundry industry as the originator of the Cosworth casting process, which is becoming accepted throughout the world as a new production process for the casting of cylinder heads and blocks. He is now Federal Mogul Professor of Casting Technology at the University of Birmingham.* Must-follow rules of castings, from one of the world's leading experts* Companion volume to the renowned book 'Castings' * Accessible and direct, provides essential information for students of metallurgy and foundry professionals alike
Author: Muhammad Azhar Ali Khan Publisher: Springer ISBN: 331946633X Category : Technology & Engineering Languages : en Pages : 49
Book Description
This book provides an overview of metal casting technologies starting from its historical evolution to casting design strategies that are being followed today in foundries and other metal casting industries. The details of most of the casting processes and their applications are also included for completeness. Foundry practices such as mold materials and molding techniques, pattern making and cores, furnaces, pouring, cleaning and heat treatment etc. are discussed in detail. Finally, current practices in casting design are demonstrated. Further developments in the field through computational methods and virtual reality are also described.
Author: Nick Brooks Publisher: Crowood ISBN: 1847977308 Category : Crafts & Hobbies Languages : en Pages : 418
Book Description
Mouldmaking and Casting is a technical manual of the many techniques of this ancient craft and art form. With step-by-step illustrations, it explains the materials required and the processes involved to create reproductions of a range of pieces. The book covers traditional techniques as well as today's more advanced technical methods.
Author: Ryan Stebbins
Author: Santosh Reddy Sama
Author: Ram A. Gullapalli
Author: Md Moinuddin Shuvo
Author: Daniel Martinez Lepp
Author: Eyad S. Almaghariz
Author: Philip King
Author: John Campbell
Author: Muhammad Azhar Ali Khan
Author: Nick Brooks