I.P.S. Ahuja

Application of fusion deposition modelling for rapid investment casting – a review

The rapid prototyping technologies are being used in the various fields of engineering. The ability of producing very small and intricate details makes the rapid prototyping technologies suitable for making patterns for investment casting. Moreover, by using rapid prototyping technologies the patterns can be produced without the necessity of costly hard tooling. The rapid prototyping technologies are considered very useful when only limited numbers of pieces are promptly required as in making prototypes, design iterations and design optimisations. The fusion deposition modelling (FDM) is a rapid prototyping technology that can use a number of materials which can be effectively used for making patterns for investment casting. Different non-wax materials are available which can be used for making patterns and can be burnt easily during autoclaving/firing. This paper reviews the suitability of FDM for making patterns for investment casting. The direct and indirect methods of producing casting patterns along with different approaches have been discussed. Different available FDM materials and their properties have been presented. The pattern accuracy depends upon a number of FDM process parameters. Various process parameters have been identified to obtain the desirable dimensional accuracy and surface finish of the casting patterns.

Investigations for Mechanical Properties of Hybrid Investment Casting: A Case Study

Conventional investment casting is one of the old manufacturing processes. It involves expensive tooling for making sacrificial wax patterns to make ceramic moulds. However, with the emergence of rapid prototyping technologies, now it is possible to make and use plastic patterns instead of wax patterns along with some advantages. In this paper, plastic patterns have been prepared by using fused deposition modeling and used for investment casting process. A case study has been discussed to make a biomedical implant by the hybridization of fused deposition modeling with investment casting. Dimensional accuracy, surface finish and hardness of the casted biomedical implants have been tested and reported.

Execution of rapid prototyping technology – an Indian manufacturing industry’s perspective

Since independence, India has endeavoured to bring economic and social change through science and technology. While India’s economic growth in the recent years has been impressive, many challenges remain to be met to create a strong and vibrant innovation eco-system. This requires a culture and value system which supports both basic and applied research and technology development. One of those technologies, rapid prototyping (RP) technology, is the automatic construction of physical objects using additive manufacturing technology. It can be defined as an automated and patternless process which allows solid physical parts to be made directly from computer data in a short time. RP acts as the ‘manufacturing middle’ to link up the computer-aided design (CAD) process and manufacturing processes. It includes the making of prototypes for design verification and even the making of tooling for production. With the trend towards concurrent engineering and the widespread use of CAD, RP has quickly become a booming business in the past few years. This paper aims to provide a comprehensive overview of the execution of RP technology in India and the critical decision factors in executing RP for the Indian manufacturing industry.

Multi-objective optimization of dimensional accuracy, surface roughness and hardness of hybrid investment cast components

Purpose The purpose of this paper is to optimize the process parameters to obtain the best dimensional accuracy, surface finish and hardness of the castings produced by using fused deposition modeling (FDM)-based patterns in investment casting (IC). Design/methodology/approach In this paper, hip implants have been prepared by using plastic patterns in IC process. Taguchi design of experiments has been used to study the effect of six different input process parameters on the dimensional deviation, surface roughness and hardness of the implants. Analysis of variance has been used to find the effect of each input factor on the output. Multi-objective optimization has been done to find the combined best values of output. Findings The results proved that the FDM patterns can be used successfully in IC. A wax coating on the FDM patterns improves the surface finish and dimensional accuracy. The improved dimensional accuracy, surface finish and hardness have been achieved simultaneously through multi-objective optimization. Research limitations/implications A thin layer of wax is used on the plastic patterns. The effect of thickness of the layer has not been considered. Further research is needed to study the effect of the thickness of the wax layer. Practical implications The results obtained by the study would be helpful in making decisions regarding machining and/or coating on the parts produced by this process. Originality/value In this paper, multi-objective optimization of dimensional accuracy, surface roughness and hardness of hybrid investment cast components has been performed.

Process capability study of three dimensional printing as casting solution for non ferrous alloys

Purpose The purpose of this paper is to investigate the process capability of three-dimensional printing (3DP)-based casting solutions for non-ferrous alloy (NFA) components. Design/methodology/approach After selection and design of benchmark, prototypes for six different NFA materials were prepared by using 3DP (ZCast process)-based shell moulds. Coordinate measuring machine has been used for calculating the dimensional tolerances of the NFA components. Consistency with the tolerance grades of the castings has been checked as per IT grades. Findings The results of process capability investigation highlight that the 3DP process as a casting solution for NFA component lies in ±5sigma (s) limit, as regards to dimensional accuracy is concerned. Further, this process ensures rapid production of pre-series industrial prototypes for NFA. Final components prepared are also acceptable as per ISO standard UNI EN 20,286-I (1995). Originality/value This research work presents capability of the 3DP process supported with experimental data on basis of various process parameters for the tolerance grade of NFA castings. These statistics can help to enhance the application of 3DP-based NFA casting process in commercial foundry industry.

Fabrication of PLA-HAp-CS Based Biocompatible and Biodegradable Feedstock Filament Using Twin Screw Extrusion

In this chapter, detailed procedure for development of biocompatible and biodegradable composite material based feedstock filament, by using twin screw extrusion (TSE) process has been highlighted. The poly lactic acid (PLA) has been selected as a polymer matrix with hydroxyapatite (HAp) and chitosan (CS) as osteo-conductive filler for potential use in medical applications. The feedstock filament of PLA-HAp-CS can be used in fused deposition modelling (FDM) open source 3D printer (without change in any hardware or software of system) for printing of functional/ non functional prototypes. The results are supported by tensile testing; thermal analysis; and scanning electron microscope (SEM) based photomicrographs. Finally the feasibility of fabrication of functional prototypes for medical applications by using in house prepared feedstock filament on the FDM has been ascertained.

Effect of SiC/Al2O3 particle size reinforcement in recycled LDPE matrix on mechanical properties of FDM feed stock filament

ABSTRACT In this research work, an effort has been made to develop fused deposition modelling (FDM), feed stock filament wire from recycled low-density polyethylene (LDPE) with different particle sizes (i.e. single particle size (SPS), double particle size (DPS) and triple particle size (TPS) in different proportions) of SiC/Al2O3 as reinforcement. After evaluation of melt flow index (MFI), the best combinations were selected and used for filament wire preparation on twin screw extruder. The results of the study highlight that Al2O3-based DPS reinforcement resulted in better mechanical properties of the feed stock filament. Finally, the non-functional prototypes have been printed with feed stock filament prepared on open-source FDM. The Al2O3-based DPS reinforcement in LDPE resulted in better dimensional stability with improved surface hardness. The results have been supported by SEM-based photomicrographs and differential scanning calorimetry (DSC).

On Development of Functionally Graded Material Through Fused Deposition Modelling Assisted Investment Casting from Al2O3/SiC Reinforced Waste Low Density Polyethylene

The recycling of packaging materials such as low density polyethylene (LDPE) into useful product is one of the challenging tasks. Since waste LDPE has some issues like low mechanical strength and thermal degradation; some studies have been reported in recent past to improve these properties with ceramic/metallic reinforcements. In this work reusability of LDPE has been ascertained as functionally graded material (FGM) through aluminum (Al) matrix based investment casting (IC). This study highlights the use of SiC and Al2O3 as reinforcement in LDPE for IC applications as a novel method for development of FGM. The master patterns for IC were prepared from reinforced LDPE based feed stock filament (prepared on conventional screw extruder) on open source fused deposition modelling setup. The in-house prepared filament wire was subjected to mechanical and thermal testing to ensure recyclability and stability of the material. The photo micrographs and SEM images were collected to ensure the dispersion of SiC and Al2O3 reinforcements in Al based FGM.

Investigating the Polymeric Composites for Online Repair and Maintenance

Polymers are one of the most commonly used materials in engineering applications (such as structure, pipelines, etc.). Infield practices, whenever a crack/leakage develops in polymeric pipelines, there is need of quick online repair/maintenance. In such cases, replacement of the whole pipeline section can lead to high downtime and cost. The online repair/maintenance of those cracks/leakages can be performed with the application of friction/friction stir welding but it needs the development of polymeric composite material that is compatible with substrate (pipeline) materials. This study outlines the development of such polymeric composites on the basis of maintaining rheological properties. In this chapter, an experimental investigations have been reported for two differently characterized polymers (namely, acrylonitrile butadiene styrene (ABS) polyamide (PA)6), which were reinforced with Al metal powder by twin screw extrusion process. The results suggested that ABS reinforced with 15% Al metal powder by weight (ABS–15Al) and PA6 with 50% Al (PA6–50Al) resulted in similar range of melt flow index (MFI) as 11.57 g/10 min and 11.97 g/10 min, respectively, and confirmed the compatibility for joining of both polymer by friction/friction stir welding. The functional prototypes have been printed on commercial fused deposition modeling (FDM)-based 3D printer, (by using feedstock filament prepared with standard twin screw extrusion process). The mechanical properties of composite feedstock filaments were investigated for optimization of extrusion parameters. Additionally, friction stir welding has been performed to check the feasibility of joining of developed composite parts (prepared as functional prototypes) on FDM.

Thermomechanical investigations of SiC and Al2O3–reinforced HDPE

This research work highlights the thermomechanical investigations of silicon carbide (SiC) and aluminum oxide (Al2O3)–reinforced high-density polyethylene (HDPE)–based feed stock filament of commercial fused deposition modeling (FDM) setup. The recycled HDPE waste was collected (from domestic waste) and washed with water jet for removal of contamination in the first stage. After contamination removal, rheological and thermal behavior (melt flow index, melting temperature, decomposition and enthalpy, etc.) of the unreinforced and reinforced polymer matrix was observed. The SiC and Al2O3 reinforcements in the HDPE matrix have been controlled by twin-screw extrusion process, followed by its processing on single-screw extrusion for preparation of FDM feed stock filament. The feed stock filament prepared by single-screw extruder was subjected to tensile test for mechanical properties (such as peak strength, peak load, and Young’s modulus). After ascertaining mechanical properties, multifactor optimization has been performed. Finally, scanning electron micrographs were obtained to understand the distribution of ceramic particles. This study highlights the detailed procedure for managing the polymer waste with improved mechanical properties by considering multifactor optimization. This will enhance the sustainability and also helps to develop low-cost, in-house FDM filament for possible applications as rapid tooling.