Dr. Martinus Arie
Post-doctorate Researcher, Small Thermal Systems Laboratory (S2TS) & Terrapin Works Center of Additive Manufacturing
University of Maryland, MD

A Review of Recent Progress in Additive Manufacturing of Ni Alloys

Additive manufacturing (AM), also known as 3D printing, emerged nearly three decades ago to be mainly employed for quick prototyping and production of specialized parts. With the advantages of reducing materials use and waste, reducing energy used for manufacturing, and reusing the feedstock due to enabled recycling, AM have been gradually and effectively reserving its place among sustainable manufacturing techniques. In particular, the progress made over the most recent decade has elevated its applicability for broad-reaching current and future applications, with a strong potential to serve as a revolutionary digital manufacturing technique. Significant recent developments include the substantial price drop of polymer-based AM machines, and the advancements in industrial-scale 3-D printers that enables printing various metals, ceramics, and other tough-to-machine materials. Eventually, these AM techniques are applicable not just for prototyping, but also for finished products in the aerospace, biomedical, energy/water, and automotive industries, among many others. For the thermal management of energy/water applications, various breakthroughs have been reported due to the AM enabling for example heat exchanger geometries that were impossible to be conventionally manufactured; among which air-cooled heat exchangers that significantly reduce the reliance on water for power-plants cooling, which emphasize the role of AM in promoting sustainable manufacturing. With the possibility of realizing these complex geometries and expanding the range of targeted applications, the focus has been recently drawn towards gradually extending the material options of 3D printing to include metals of superior properties, such as Ni super alloys. The development of such 3D printed alloys will benefit high-temperature and high-pressure heat exchangers of need to the power production sector for utilization of high efficiency cycles such as high temperature super critical CO2 (sCO2). Such cycles have shown capability to significantly increase the efficiency of power production and electricity generation when compared to regular Bryton or Rankin cycles. One bottle neck to further progress of these cycles is lack of cost affordable high effective high temperature heat exchangers that employ super alloys such as Inconel 718 and 625, which are also used for aerospace parts, gas turbine components, filtration and separation (chemical applications), molding processes, and micro-burners for optimized combustion. In this paper, we will first review the progress made in digital printing of metals, metal alloys, including super alloys. Next, we will report the recent work by our team for successfully developing, optimizing and additively manufacturing an Inconel high temperature novel heat exchanger, with enhanced heat transfer characteristics. The heat exchanger was designed to be 30% lighter than comparable HXs available in the market. To take advantage of the high-temperature capability of this material, we built a test loop capable of testing the heat exchangers at temperatures in excess of 600°C (1112°F) and pressures up to 90 psig (620 kPa), and successfully tested the 3D printed heat exchanger.

George P. Bray
International Pharmaceutical Executive
International Federation of Pharmaceutical Wholesalers, Manassas, VA

An Overview of International Pharmaceutical Distribution and its impact on Sustainability

International pharmaceutical distribution is a vibrant efficient industry dominated by three players in the U.S. However, internationally, and especially in the developing world, supply chains are fragmented and counterfeit medicines generate risks to millions of patients. The International Federation of Pharmaceutical Wholesalers represents the worlds’ largest pharma distributors and in 2012 formed the IFPW Foundation with the goal of improving the availability of quality medicines to patients in need and to support full service pharmaceutical wholesalers in insuring the continuous availability of pharmaceuticals, when and where they are needed.
The Foundation supports efforts of corporate social responsibility(CSR) through its members over the entire globe. These CSR efforts range from teaching supply chain concepts to build capacity for vaccine distribution in East Africa to providing much needed medical supplies to earthquake ravaged parts of Mexico.
The IFPW Foundation, through its members, supports the UNs sustainable development agenda and the 17 Sustainable Development Goals(SDGs) adopted in September 2015. Sustainable cities and communities is one of these SDGs. Walgreens Boots Alliance, an international member of IFPW, is an example of a world class company who has committed to a circular economy. Although not an engineering topic per se the idea of making the world a better place through commitment to the United Nations SDGs is important to the world economy. This contribution will address some of the actions international pharma distributors are making in committing to sustainable development.

Dr. Changqing Cheng
Assistant Professor, Department of Systems Sciences and Industrial Engineering
State University of New York at Binghamton, NY

Process Monitoring of Ultra-Precision Machining Towards Sustainable Manufacturing 

As the production processes in semiconductor, automotive, and aerospace manufacturing industries are moving towards expensive, large part sizes (e.g., > 300 mm wafer size, integrally machined, as opposed to welded aerospace and automotive panels) with stringent quality requirements (e.g., defect-free sub-20 nm feature sizes, with surface finish Ra ~ 1nm). Consequently, the cost of quality loss is becoming increasingly prohibitive, which has posed an enormous challenge to sustainable manufacturing. As such, in-situ monitoring and control of process variations are becoming essential for quality assurance in advanced manufacturing including ultraprecision machining (UPM) processes. An effective process monitoring and control approach will reduce rework and consequently the cost, echoing the theme of sustainable manufacturing. Remarkably, recent leap forward in sensor, computing, and communication technologies and the consequent availability of abundant data sources has transformed the way real-world complex systems are monitored and controlled, and it therefore has provided an unprecedented way for anomaly detection and quality control in such advanced manufacturing process. However, conventional approaches are limited in their ability to address the complex dynamics hidden in the nonlinear and nonstationary processes. As a result, it is difficult for them to effectively capture the process variations of UPM. This paper presents a new heterogeneous recurrence monitoring approach to detect dynamic transients in UPM processes. First, a high-dimensional state space is reconstructed from in-situ sensing signals. A Dirichlet process (DP) driven clustering approach is then developed to automatically segment the state space into local recurrence regions. Furthermore, a fractal representation is designed to characterize state transitions among recurrence regions and extract novel measures to quantify heterogeneous recurrence patterns. Finally, we integrate a multivariate control chart with heterogeneous recurrence features for in-situ monitoring and predictive control of the UPM process. Experimental results showed that the proposed approach effectively detects transitions with a small magnitude, and identifies the shift from stable cutting (Ra = 35 nm) to unstable cutting (Ra = 82 nm) in UPM processes with an average run length of 1.0. This paper presents a novel data-driven DP clustering approach to characterize heterogeneous recurrence variations and link with the quality of surface finishes in UPM processes. This new DP recurrence approach circumvents the need to empirically define local recurrence regions and is shown to have strong potentials for manufacturing process monitoring and control that will increase the surface integrity and reduce rework rates.

Dr. Muhammad Jahan 
Assistant Professor, Department of Mechanical & Manufacturing Engineering
Miami University – Oxford, OH

Investigating the Wear Mechanisms of Uncoated and TiAlN-coated Carbide Tools in Conventional Flood Coolant and Sustainable Dry and MQL Machining of Ti-6Al-4V  

Ti-6Al-4V is commonly known as a difficult-to-cut material due to its poor thermal conductance, strong alloying tendency and work-hardening characteristics. Among various approaches to improve machining of titanium alloys, dry and minimum quantity lubrication (MQL) machining are being increasingly approached. Both dry and MQL machining processes are considered as sustainable processes as they reduce the costs associated with the coolant supply, filtration, and circulation, reduce the waste associated with coolant, and eliminate its adverse effect on operator health and environments. In recent years, the application of tool coating was found to be an effective approach for machining difficult-to-cut materials.

The objective of this study is to investigate and explain the tool wear mechanisms that dominate during machining of titanium alloy Ti-6Al-4V in conventional flood coolant and sustainable dry and MQL machining. In addition, this study aims to investigate the effectiveness of titanium-aluminum-nitride (TiAlN) coating on the tungsten carbide tools during conventional and sustainable machining of Ti-6Al-4V.

In this context, milling experiments were carried out on Ti-6Al-4V with three different conditions namely dry, flood coolant, and MQL using uncoated and coated carbide tools. The cutting feed rate and depth of cut were varied keeping the cutting speed constant at comparatively higher setting. While investigating the cutting tools after a series of experiments, it was observed that tool wear mechanisms differ based on the type of coolant used and with the tool coatings. It was found that abrasion was the dominant tool wear mechanism for all dry, flood coolant and MQL machining, although MQL and flood coolant machining had fewer abrasion occurrences compared to dry machining. Edge chipping and tool nose wear were the second most dominated tool wear mechanisms in conventional flood coolant machining, which may be associated with the thermal fatigue caused by the sudden cooling of tool tip from the high temperature generated during machining. On the other hand, adhesion was the second dominant tool wear mechanism observed in the dry machining. Both the edge chipping and adhesion of chips to the cutting tools were reduced significantly in MQL machining. Delamination of coating film was observed when TiAlN-coated carbide tools were used. The delamination was more significant in wet and MQL machining compared to dry machining, indicating the effectivity of coated tools in dry machining compared to wet and MQL machining. There were some cases of plastic failure of tool flutes and edges, with again dry and flood machining having more occurrences of tool failure than MQL. The abrasion wear was dominant on the rake and flank face of the cutting tools, whereas, the adhesion occurred mostly on the secondary cutting edge. The chipping was found in both primary secondary cutting edges.

Among three conditions, MQL provided the least occurrences of tool wear, indicating suitability of sustainable machining process for effective machining of Ti-6Al-4V. It was also concluded that TiAlN coating was more effective in dry machining of Ti-6Al-4V compared to MQL and wet machining.

Dr. Lai Jiang
Assistant Professor, Mechanical Engineering Department
Prairie View A&M University, TX

A New Manufacturing Process for Biocomposite Sandwich Parts Using a Myceliated Core, Natural Reinforcement and Infused Bioresin

A new approach to manufacture biocomposite sandwich structures from purely natural constituents and the corresponding analysis useful for process design are fully demonstrated in this thesis. The constituent materials include agricultural waste (agri-waste) bound together with fungal mycelium as core, natural textiles bound to the core surfaces with mycelium as reinforcement skins, and a bioresin, if needed, to stiffen and strengthen the skins for high performance applications. Based on a series of preliminary experiments, an optimized seven-step manufacturing approach is proposed including: (1) die cutting of skin reinforcement; (2) natural glue impregnation using a nip roller system to allow preforming of the skins; (3) forming/sterilizing of the preform skins with matched and heated molds to serve as integral tools; (4) filling the tools with agri-waste inoculated with mycelium vegetative tissue; (5) allowing the mycelium to grow and bind all constituents together; (6) convectively and conductively drying the workpiece to drive off water and inactive the mycelium; and (7) infusing skins with bioresin and allowing them to cure.
Key aspects, process parameter effects and sensitivities and design models of the seven manufacturing steps were investigated and developed further. It was determined that the number of reinforcement plies should be maximized when cutting with steel rule dies to reduce the number of cutting defects. The resulting skin layups can be rapidly impregnated using a nip roller system with an starch-based glue that is continuously circulated, and an analytical model is available for designers to use. Forming, sterilizing and setting of the glue occur simultaneously using heated tooling coated with a ceramic-polymer composite where molding pressure and temperature play a key role. Integral tooling with preformed skins, although potentially offering significant manufacturing cost reductions, loses shape fidelity during the growth process in a high humidity environment. Conductive drying helps to bring the part back into shape conformance, although convective drying is still required to achieve the low moisture levels required by the industrial collaborator. Resin transfer molding with a soy-based bioresin is demonstrated to complete the process cycle. Finally, a manufacturing system model involving all seven steps is developed for system optimization purposes, and a case study to maximize profit is demonstrated.

Dr. Sojung Kim
Assistant Professor, Department of Engineering and Technology
Texas A&M University-Commerce, TX

Real-Time Energy Cost Reduction System for Sustainable Manufacturing

For decades, the energy cost reduction issue in manufacturing has been received nationwide attention due to its multiple negative effects, particularly, on environment and human sustainability. Thus, to resolve the issue, both government agencies and international organizations have motivated the manufacturing industry with monetary or taxation benefits (e.g., energy tax). In addition, as a part of efforts for the energy consumption reduction, utility companies in U.S. offers two major demand response (DR) options such as time of use (TOU) and real-time pricing (RTP) so that their industrial customers can track and adjust their electricity usage by participating DR program. To be more specific, if the companies only use electricity during load off-peak periods, there will be significant energy cost reduction given by the DR program. The goal of this study is to introduce a simulation-based machine shop operations scheduling system for energy cost reduction without causing any negative effects on productivity of a facility. Two major modules have been considered in the proposed system: (1) real-time energy consumption monitoring module and (2) simulation-based machine shop operations scheduling module. The first module utilizes power meters installed in CNC machines so that it is able to track energy consumption of an entire manufacturing facility in real-time. Moreover, mobile application is developed to provide the real-time electricity consumption to a machine shop floor manager or other engineers at different location. The second module develops a shop operations schedule (i.e., turn off machines or adjust operations schedule) via simulation with AnyLogic® software. To this end, an electricity consumption model is devised for each individual machine via the additive regression technique. Then, the developed model is plugged in the simulation model to estimate electricity consumption of an individual CNC machine based on various machining parameters (e.g., feed rate, spindle speed, and depth of cut) under two DR programs: (1) TOU with difference electricity costs for on-peak and off-peak time periods and (2) RTP with different base and guaranteed electricity loads. The simulation model conducts what-if analysis to evaluate the performance of various operations schedules involving multiple CNC machines. In addition, there is the optimization function to find the (near)optimal operations schedule considering potential machine statuses and turning on sequences to minimize the total electricity cost of the entire facility. The devised system is implemented at a manufacturing company in Tucson, Arizona, U.S. This study will demonstrate performance of the proposed system in terms of electricity cost savings and productivity of a subject facility under multiple scenarios of machine shop operations.

Dr. Gul E. Kremer
Professor and C.G. “Turk” & Joyce A. Therkildsen Department Chair of Department of Industrial and Manufacturing Systems Engineering
Iowa State University, IA

Design for REMADE: Opportunities & Barriers to Economic and Environmental Sustainability

Sustainable manufacturing efforts have been initiated, but are incomplete without simultaneous consideration of manufacturing process and the supply chain costs and environmental impacts during conceptual design of components. Currently, manufacturing and supply chain perspectives are primarily considered during detail design – the final phase of product design when much of the design flexibility has been removed. These shortcomings motivate an integration of cradle-to-gate life cycle decisions to optimize component production and supply chain alternatives early in design. A summary of lessons learned will be provided resulting from a collaborative work that undertook: (1) Automated modular architecture generation and analysis, (2) Development of models of manufacturing and supply chain processes through industrial and experimental process investigations, and (3) Optimization to balance cost and environmental sustainability metrics from procurement through end of life. Our results point to the importance of the product architecture as a customization platform to supply globally while optimizing different performance measures for different contexts. Inspired by these results, Design for REMADE concept will be introduced to discuss related opportunities and barriers to economic and environmental sustainability.

Dr. Prahalada Rao
Assistant Professor, Mechanical and Materials Engineering Department
University of Nebraska-Lincoln, NE

Qualify-as-you-Build: A Paradigm for Sustainability in Additive Manufacturing Through Big Data Analytics

This talk concerns the following research question in the context of metal Additive Manufacturing (AM): how to reduce waste and defects in additive manufacturing (AM) through in-process monitoring and prognosis?
The advent of AM allows unprecedented flexibility of design and manufacturability, for instance, recent studies in the aerospace industry have demonstrated that metal AM processes, such as powder bed fusion (PBF) can drastically reduce the so-called buy-to-fly ratio, which is the ratio of the material that is required to make a part to the final weight of the part. The buy-to-fly ratio is typically 20:1 for traditional subtractive and formative processes, in the case of PBF this ratio is as small as 2:1. Simultaneously, the lead time for delivering a new part design or concept can be shortened from 5 months to less than a week.
Despite these possibilities, the poor consistency of AM parts hinders their wider adoption in mission-critical components; typically, 2 in 5 parts fail to build. In the context of quality assurance in AM, the current practice is to examine the part after it is built using X-ray computed tomography (XCT), which is exceedingly expensive and cumbersome. However, if a sensor data record exists to attest the integrity of every layer, and if this data can be correlated back to the XCT for a few test parts, then this recorded sensor data, instead of XCT scanning, can be used to rapidly qualify the part quality and thereby avoid waste and scrap through closed-loop control. This is the first-step towards a paradigm called qualify-as-you-build in AM.
The success of qualify-as-you-build is rooted in information synthesis and decision-making based on the high volume, variety and velocity of data acquired by the sensors – a Big Data problem. For example, detecting failure of overhang features of AM parts using signals from infrared, high-speed imaging, and photodetector sensors. An approach to answer this question is through newer signal analysis techniques from the domain of spectral graph theory. The efficacy of this approach is demonstrated based on data generated and shared by collaborators at NIST, Penn State, and Edison Welding Institute.

Dr. Ziteng Wang
Assistant Professor, Industrial and Systems Engineering
Northern Illinois University, IL

Inventory Sharing in Supply Chains with Scarce Resource: Decisions, Benefit and Optimization

To reduce waste in manufacturing, retail and energy industries, inventory transshipment is conducted between locations with excess demand and surplus materials. This practice is generally shown to be beneficial to supply chain participants (e.g., newsvendors) by matching their excess demand with surplus inventory. We investigate the profit maximization strategies of two newsvendors in a realistic but not yet fully studied scenario where the total amount of resource is limited and inventory transshipment is conducted after demand realization. Taking a game theoretic approach, we derive the best ordering decision and Nash equilibrium solution for each newsvendor. The existence and uniqueness conditions derived clearly unveil the joint effects of having limited total supply and inventory transshipment. In particular, we show that the benefit of employing inventory transshipment may vanish due to the limited supply capacity. Some decision criteria are provided for the news-vendors to determine if they will be benefited from the exercise of inventory transshipment. Numerical study indicates that a carefully chosen transshipment price plays an important role in keeping inventory transshipment beneficial to both news-vendors. Subsequently, a coordinating mechanism is designed for the newsvendors to negotiate a transshipment price that maximizes the total profit of the two news-vendors while keeping each of them in a beneficial position. This study can be used to guide mechanism design and strategic planning regarding scarce resource allocation and utilization.

Dr. Joshua Werner
Assistant Professor, Department of Mining Engineering
University of Kentucky, KY

Hydrometallurgy as a Driver for Adding Value for Sustainable Manufacturing

Hydrometallurgy is the processing metals aqueously to increase their value. In terms of closing the loop in the circular economy Hydrometallurgy provides unique opportunities both economically and environmentally to make this possible. There are several processes unique to this field which are of great interest in increasing the volume and diversity of feed stocks available to secondary metals producers in competing with primary raw materials feedstocks. These methods include: leaching, solvent extraction, ion exchange, electrorefining, electrowinning, precipitation reactions and speciation via equilibrium thermodynamics as it relates to metal recovery and recycling to list a few.
This work will focus on 3 aspects related to hydrometallurgical recovery of metals. The first will discuss some of the opportunities and challenges facing secondary market metals producers (recycling) in light primary metals producers (mining) and market concerns as it relates to the development and adoption of hydrometallurgical processes. The second will discuss specific technologies applicable to the secondary market such as the techniques of leaching, solvent extraction, electrowinning and electrorefining. Specific examples will be given such as the processing coal by products and non-ferrous wastes from recyclers. Lastly, the challenges facing the utilization and implementation of hydrometallurgical processes will be discussed. These include designing for feed material stability, the role and need of testing and piloting processes and that of modeling and analysis. This presentation will focus on the broad application of Hydrometallurgy as a technology driver to enable a circular economy.

Dr. Hao Zhang
Assistant Professor, College of Integrated Science and Engineering
James Madison University, VA

 A Systems Sustainability Assessment Method of Additive Manufacturing with Biomimicry Structures

High value material products (e.g. stainless steel, titanium, copper) suffer from high raw material cost and expensive end-of-life management plans. One solution for reducing cost and environmental impact is designing high value parts with complex structure (i.e. biomimicry structures) to reduce material use and meanwhile support the functionality of the part. However, machining complex geometry parts with traditional manufacturing processes faces tremendous challenges as it involves multiple processes and human intervention processing. Additive manufacturing provides a unique way to create such complex geometries. Research on creating and sustainability assessment of biomimicry geometry products and parts with additive manufacturing is limited. The objective of this research is to present a system method for economic, environmental, and social impact assessment of using biomimicry geometries for additive manufacturing product design. The method aims to assist product design engineers identify biomimicry geometric structures for product applications, assess the functionality, economic, and environmental impacts of the selected biomimicry geometric structures, and make decisions on design alternatives. The method integrates concurrent considerations of multiple additive manufacturing design and bioinspired design factors including raw material quality (e.g. size, shape, internal porosity), processing parameters (e.g., laser power, roller speed), and functionality of the product (e.g., stress, strain, displacement). Sustainability assessment methods (e.g. life cycle costing, life cycle assessment) have been used for evaluating cost and environmental impact for processing different geometries. Finite element analysis is used for product functionality testing. A case study is conducted on making a unit Titanium spine implant product with selective laser sintering process. Three structures were examined: diamond structure, honey comb structure, and lattice structure. Cost assessment considered material, labor, energy, and equipment components. A cradle to grave life cycle assessment was conducted to assess environmental impact along life cycle. The results show that lattice structure yields lowest cost ($160 compared to $178 for diamond structure and $172 for honey comb structure) and environmental impact (30 CO2e compared to 34 kg CO2e for honeycomb structure and 36 kg CO2e for diamond structure). Other assessed environmental impacts include acidification, eutrophication, ozone depletion, resource depletion, fossil fuel depletion. The results differences are due to different process times and material use in different structures. This study reveals that the method can be applied in additive manufacturing early product design and it assists researchers and engineers explore new bioinspired geometries that could be used in manufacturing. Future research will be focused on more geometries and conduct static and fatigue analysis at various temperature conditions. Sensitivity analysis and uncertainty analysis can be conducted based on new testing results. Surface finish of the product also needs to be studied with prototypes.