B. Ravi

Distributed Manufacturing: scope, challenges and opportunities

This discussion paper aims to set out the key challenges and opportunities emerging from distributed manufacturing (DM). We begin by describing the concept, available definitions and consider its evolution where recent production technology developments (such as additive and continuous production process technologies), digitisation together with infrastructural developments (in terms of IoT and big data) provide new opportunities. To further explore the evolving nature of DM, the authors, each of whom are involved in specific applications of DM research, examine through an expert panel workshop environment emerging DM applications involving new production and supporting infrastructural technologies. This paper presents these generalisable findings on DM challenges and opportunities in terms of products, enabling production technologies and the impact on the wider production and industrial system. Industry structure and location of activities are examined in terms of the democratising impact on participating network actors. The paper concludes with a discussion on the changing nature of manufacturing as a result of DM, from the traditional centralised, large-scale, long lead-time forecast-driven production operations to a new DM paradigm where manufacturing is a decentralised, autonomous near end user-driven activity. A forward research agenda is proposed that considers the impact of DM on the industrial and urban landscape.

Effect of Binder Composition on the Shrinkage of Chemically Bonded Sand Cores

Modern foundries increasingly use chemically bonded no-bake sand cores and molds because they provide ease of molding, good surface finish, and collapsibility. One of the most popular binder systems is alkyd oil urethane no-bake system comprising three parts: alkyd resin, catalyst, and crosslinking agent. Their amounts and ratios can influence mold shrinkage, and thereby dimensional quality of the resulting casting. With rising emphasis on net-shape casting, there is a need to optimize the binder composition to minimize dimensional errors, while achieving the desired bench life, stripping time and hardness. This work investigates the effect of binder composition on the dimensions of chemically bonded sand cores with respect to time. The maximum shrinkage of 0.15% over length was observed when resin content was 2.4% by weight of sand. The rate of shrinkage increased with the amount of catalyst. Measurement of core hardness and reduction in weight, followed by SEM studies, provided a better understanding of the underlying phenomena, especially formation of resin bridges between compacted sand particles and evaporation of solvent. This work is expected to aid in selection of the most appropriate binder composition for a given set of molding process constraints and cast product requirements.

Multi-Gate Systems in Casting Process: Comparative Study of Liquid Metal and Water Flow

Most industrial castings are manufactured by allowing liquid metal to fill the mold cavity through multiple gates. The goal is to ensure smooth, complete, and uniform filling, thereby minimizing related defects such as cold shuts and inclusions. Very few researchers have, however, investigated flow parameters in such systems. In this work, novel experimental setups were developed to study the flow of liquid metal (Al-Si12 as well as Zn) and water through a gating system comprising a vertical sprue at one end connected to four gates through a horizontal runner. The flow sequence, velocity, and discharge through the four gates were observed by video recording and various measurements. It was found that while the first gate (closest to sprue) filled first, the last gate exhibited the maximum volume of discharge. The proportion of flow through the four gates was found to be nearly the same for all three fluids. The results establish the usefulness of water models to investigate mold filling in metal casting. The study provides valuable insight that can help in balancing the flow through multiple gates in industrial castings, as well as benchmarks to verify simulation codes.

Ultra performance liquid chromatographic method for simultaneous quantification of plerixafor and related substances in an injection formulation

Abstract Plerixafor (PLX) injections are administered to patients with cancers of lymphocytes (non-Hodgkin’s lymphoma) and plasma cells (multiple myeloma). The main objective of the current study was to develop a short reverse phase chromatographic method for the simultaneous quantification of PLX and its impurities, in an injection formulation, to reduce the time required for these quality tests. Furthermore, the present work describes the role of nonalkyl branched nonquaternary ion pair reagent in improving the peak shape and reducing column equilibration time. The separation of PLX and its related substances is pH dependent (optimum pH = 2.50) and was achieved on an octadecylsilyl (C18) column. The method was validated for its intended purpose in accordance with the current regulatory guidelines for validation. The proposed method can be applied for quality control, release, and stability analyses of active pharmaceutical ingredient, PLX, as well as finished products, PLX injections.

Effect of Modularity on the Fatigue Performance of Tibial Tray Designs in TKA Prostheses.

Fatigue performance of tibial tray in total knee arthroplasty (TKA) is of critical importance in terms of longevity of the prosthesis. Standards have been proposed by American Society for Testing and Materials (ASTM) and International Organization for Standardization (ISO) to ensure its long-term structural integrity. The aim of the current study is to evaluate the effect of modularity in the tibial tray following the testing standards, using finite element analysis. Goodman and Sines criteria were used to compare the fatigue safety factor (FSF) of four modular designs versus the two conventional designs. Cruciate-retaining (CR) type modular tibial tray designs were better than posterior-stabilized (PS) type tibial tray designs. More cutouts in the tray and absence of keel were reasons for poor fatigue performance.

Comparison of Stresses in Four Modular Total Knee Arthroplasty Prosthesis Designs

The current study, compares the mechanical performance of four modular TKA prostheses based on von Mises stress distribution in the tibial insert. Three-dimensional finite element (FE) models of a cruciate retaining type modular prosthesis and three posterior stabilized (PS) type modular prostheses namely: anterior slide, modular post and double cam, were developed. A compressive load of 2600 N was applied to the FE models at flexion angles of 00, 150, 300, 600 and 900. Von Mises stress was evaluated on all the modular parts of the prostheses and compared with the yield strength of the corresponding material. Von Mises stress in all the parts were below the yield strength of their corresponding material except for tibial insert of anterior slide design at high flexion angle. Von Mises stress above the yield strength in the tibial insert of anterior slide design, was due to edge loading in the post and it demonstrates the likelihood of mechanical failure by delamination type of wear. KEywoRDS Cruciate Retaining, Cruciate Sacrificing, Loosening, Posterior Stabilized, Tibial Post, Total Knee Arthroplasty, UHMWPE, Von Mises Stress

Indigenous Development and Industrial Application of Metal Casting Simulation Software

Metal casting is a multi-physics process involving many physical phenomena like fluid flow, phase transformation, heat transfer, microstructure evolution, defect formation and thermal stresses. Virtual casting based on process modeling and computer simulation of the above phenomena enables foundry engineers to reduce physical trials, and optimize various process parameters to achieve the desired quality and yield. A multi-disciplinary team of researchers from IIT Bombay and CSIR-NIIST combined their work in casting design and simulation, respectively, and teamed up with 3D Foundry Tech to create an integrated software package called AutoCAST FLOW+. Foundry engineers are able to visualize mold filling, temperature profiles during casting solidification and cooling curves; predict related defects like air blow hole, cold shut, shrinkage porosity and hard zones; and optimize the feeding and gating design. Two industrial case studies demonstrating its successful application for quality improvement are presented. The software has been implemented in several engineering institutes, raising the awareness and interest among students as well as teachers in metal casting field. These efforts are expected to lead to indigenous capability in casting simulation technology suitable for the local requirements.

Effect of Orientation, Thickness, and Composition on Properties of Ductile Iron Castings

In this work, the effects of casting orientation (horizontal, side, and vertical), section thickness (4–16 mm) and composition (Cu, Mn) were investigated on the cooling rate, microstructure, and mechanical properties (tensile strength, yield strength, elongation, hardness) of hypereutectic ductile iron castings. Overall, horizontal castings were found to cool faster than side and vertical castings. Thermal analysis (using cooling curves) showed a wide difference among the four sections. Thinner sections exhibited significant undercooling and thereby carbide formation, leading to poor ductility. The combined effect of Cu and Mn showed an increase in the amount of pearlite to 82% and nodularity to 94% along with a reduction in nodule count to 323 and the amount of ferrite. Also, increased tensile strength (659 MPa) and hardness (264 BHN) were observed along with a drop in ductility to 2.5% in 4 mm thin section, helping offset carbide formation. Thermal analysis was found to be a useful tool in understanding the combined effect of orientation, thickness variations and processing parameters.