Investment Casting Method Research Articles

Analysis of emission of volatile organic compounds and thermal degradation in investment casting using fused deposition modeling (FDM) and three-dimensional printing (3DP) made of various thermoplastic polymers.

The study examined the degradation process of various types of polymers used to form models using the fused deposition modeling (FDM) and three-dimensional printing (3DP) methods and used in the investment casting method. Commercial filaments made of polylactide (PLA), acrylonitrile butadiene styrene terpolymer (ABS), high-impact polystyrene (HIPS), polyamide 12 (PA12), poly(methyl methacrylate) (PMMA), and polypropylene (PP) were used to produce gypsum molds. The assessment included organic volatile compounds (VOCs) released during mold heating and model degradation, which is characteristic of this technological process. The screening qualitative chromatographic analysis of decomposition products sampled from various points of the production hall made it possible to define potential threats related to the processing of selected polymers and the necessary preventive measures. Furthermore, passive diffusion-type samplers were used at the sampling stage of VOCs emitted to the gaseous phase to reduce nuisance and user interference. Studies have been completed to characterize the thermoplastic polymer degradation process. The coupled thermogravimetry (TGA) with analysis of gaseous products by infrared spectroscopy with Fourier transformation (FT-IR) has been used. The presented results are the first to compare and rate the use of this still-developing novel aspect of castings by the method of fused models.

Effect of Composition and Pouring Temperature of Cu-Sn on Fluidity and Mechanical Properties of Investment Casting

The composition and pouring temperature are important parameters in metal casting. Many cast product failures are caused by ignorance of the influence of both. This research aims to determine the effect of adding tin composition and pouring temperature on fluidity, microstructure and mechanical properties including tensile strength and hardness of tin bronze (Cu-Sn). The Cu-Sn is widely used as employed in the research is Cu (20, 22 and 24) wt.%Sn alloy using the investment casting method. Variations in pouring temperature treatment TS1 = 1000°C and TS2 = 1100°C. The mold for the fluidity test is made with a wax pattern then coated in clay. The mold dimensions are 400 mm long with mold cavity variations of 1.5, 2, 3, 4, 5 mm. Several parameters: increasing the pouring temperature, adding tin composition, decreasing the temperature gradient between the molten metal and the mold walls result in a decrease in the solidification rate which can increase fluidity. The α + δ phase transition to β and γ intermetallic phases decreases fluidity at >22wt.%Sn. The columnar dendrite microstructure increases with the addition of tin composition and pouring temperature. The mechanical properties of tensile strength decrease, hardness increases and the alloy becomes more brittle with increasing tin composition.

Investigation of the radiated emission of honeycomb structured aluminum foam/cellular heatsinks at 1–10 GHz

Metal foams or cellular structures like honeycombs, can also be evaluated according to mechanical, acoustic, thermal, and chemical resistance parameters in terms of functionality. However, it is vital to investigate the performance of these cellular structures' radiated emission (RE), which can be used as PCB heatsinks. In this study, the radiated emission (RE) performance of honeycomb-structured aluminum foam (or cellular) heatsinks (AFH), which can be considered as unidirectional regular foam, is examined in the frequency range of 1–10 GHz as a novelty. Also, the effect of four primary variables (the geometry of AFH, honeycomb hole direction, honeycomb cell size, and honeycomb cell wall thickness) on the RE performance of AFH is investigated. Unlike classical honeycomb production methods, the investment flask mold casting (loss wax) method is preferred due to the complex offset strip geometry of designed honeycombs. The original design offset hexagonal honeycomb structures were successfully produced using this investment casting method with additive manufacturing technologies from molten metal. While all simulations are carried out using CST Studio Suite, the RE performance of the proposed AFHs is measured in a standard 3 m fully anechoic chamber using a reference horn antenna and vector network analyzer (VNA). When the results are examined, the measured and simulated results agree with each other quietly. Regarding RE, structures with a CPI value of 14 are better at low frequencies, while structures with a CPI value of 3.5 are better at high frequencies. Secondly, the honeycomb cell thickness value does not significantly affect EMI performance. Lastly, although there is no significant difference in EMI in the low-frequency region, it is better to use a directional structure with vertical holes in the high-frequency region. As a result, in the design of AFH, the RE performances of the heatsinks and their thermal performance should be considered.

Destructive and non-destructive testings of 304 austenitic stainless steel produced by investment casting method

ABSTRACT In this study, the properties and structures of 304 austenitic stainless steels produced by investment casting methods and stages through destructive and non-destructive (NDT) testing methods are examined. First, the model mould was created from recycled wax containing 5–25% water, 15–35% filler and 0.5% ceramic for the production of a water pipe armature by investment casting method. Then, the ceramic coated mould was sintered at 1350°C, and 304 austenitic stainless steel was melted in the induction furnace at 1150°C at a speed of 1.36 kg/min and poured into this mould. The hardness value of the 304 austenitic stainless steel water pipe armature was obtained as 86.16 HRB and the tensile strength value was 518.76 MPa. As a result of examination with an optical metal microscope, ferrite and austenite structures were observed. Linear and round defects were detected in the liquid penetrant test, and third level (RT-3) shrinkage-delta defects were detected in the radiography test. These results showed that the armature part was acceptable in terms of mechanical strength, corrosion and leakage.

Effect of temperature and pressure on shrinkage in wax injection molding

Abstract In precision casting, many model materials can be used to make complex, accurately sized molds. Model material is an important key for successful production. Wax models are widely used in model manufacturing because they allow economical production. In the wax injection method, some undesirable situations occur during the production of the model such as shrinkage, collapse, warpage, weld marks, surface defects, air marks, and burr formation that the manufacturer does not want. In this study, it is aimed to examine the effect of temperature and pressure parameters on shrinkage of the wax model in injection molding. The study was carried out at wax temperatures of 65 °C, 70 °C, and 75 °C and injection pressures of 0.1 MPa, 0.15 MPa, 0.2 MPa, and 0.25 MPa. In the experiments, the flow of the parts was observed during the filling of the plexiglass mold, and the shrinkage ratio of the obtained wax model was determined and evaluated. It is assigned that some of factors which affect quality of the final product produced by investment casting method are product shrinkage and surface quality of wax model.

Mechanical and Degradation Behavior of Zinc‐Based Biodegradable Metal Foams

Zinc has gained interest as a biodegradable material due to its adequate degradation behavior under physiological conditions and acceptable biocompatibility. However, during the use of zinc as a degradable orthopedical implant, the mechanical properties are expected to change while the implant needs to maintain its function and mechanical support for 12–24 months with the load gradually transferred from the degrading implant to the healing bone. For such investigation, six different kinds of open‐cell zinc foams are fabricated by a modified investment casting method displaying different pore densities and strut thicknesses. Compressive properties and corrosion behavior in simulated body fluids are studied to determine the map of the most relevant parameters that influence the degradation properties. After 4 weeks of immersion in Hank's solution, changes in the slope in the “plateau” region and strain localization are observed. These changes can be explained by supposing microcrack propagation into the depth of the struts due to the progressing corrosion attack.

Crushing response of triply periodic minimal surface structures fabricated by investment casting and powder bed fusion method

Cellular materials, serving as alternatives to solid materials in applications demanding high mechanical efficiency and versatility, bring significant advantages to industries like automotive and aerospace. With attributes such as impressive strength-to-weight ratios, noise dampening, thermal shielding, and energy absorption, these materials are valuable assets. This study focuses on probing the energy absorption and deformation behavior of gyroid based triply periodic minimal surface (TPMS) structures under quasi-static compression. These gyroid structures, produced using AlSi10Mg through both investment casting and powder bed fusion (PBF) techniques, were designed at varying relative densities (7.5%, 11.2%, and 14.8%), adjusting cell wall thickness and cell numbers. Crushing response of these structures was also analyzed numerically using a commercial LS-DYNA finite element software. The study's findings indicate that gyroid structures printed through the PBF technique display around 150% greater specific energy absorption (SEA) capacity than those created using the investment casting method. However, the crush force efficiency of casted gyroid structures surpasses that of printed gyroid structures by 25%, owing to reduced peak stress values at the onset of crush dam

Experimental and Simulation Investigation on Energy Absorption of Cu Casting Lattice Structure during Compression

This investigation aims to assess the mechanical behavior and energy absorption properties of the Cu lattice structures made by investment casting method experimentally and by finite element method (FEM) simulation. The casting pattern of lattice structures is additively manufactured with 2.0, 2.5, and 3.0 mm diameters and the lattice structures produced by investment casting of Cu. Then a uniaxial compression test is applied to measure maximum compressive strength, energy absorption density, efficiency, and specific energy absorption. The simulation and the experimental results indicate that the abovementioned properties of the lattice structures have a significant improvement and properties developments will rise by increasing the diameter of the struts. The mechanical characterization has done for Cu lattice structure with 3.0 mm strut diameter, which endures a stress of 242 MPa at the densification strain and the maximum tolerated stress of 404 MPa. The energy absorption density of this lattice structure is 67 MJ m−3 and has a specific energy absorption of 28 J g−1 followed by an energy absorption efficiency around 70%. The simulation result shows a mathematical connection between the unit cells and the final lattice structures in terms of maximum tolerated stresses, which can help the prediction of the mechanical behavior of these structures.

PENGARUH TEMPERATUR CETAKAN TERHADAP STRUKTUR MIKRO DAN KEKERASAN PISTON HASIL PENGECORAN MENGGUNAKAN 3D PRINTING

Motorcycle users in 2019 reached 133,617,012 units in Indonesia. The impact of a large number of motorcycle certainly attracts the interest of the industry to produce two-wheeled automotive vehicles. The piston is part of the engine that functions as a compression barrier in the combustion chamber, the piston material is aluminum alloy. Therefore, research was carried out on making pistons with investment casting methods, physical and mechanical patterns from 3D printers on pistons. This research starts from drawing the piston using CAD (computer-aided design), making a printed pattern from a 3D Printer machine with PLA (polylactide acid) material. The mold pattern is coated with a mixture of gypsum cement and silica powder. The casting process with a pouring temperature of 750ᵒC and a mold temperature of 200 ᵒC, 250 ᵒC, 300 ᵒC, 350 ᵒC, and 400 ᵒC. The results showed the largest grain size at a mold temperature of 400ᵒC. The highest hardness at 200 ᵒC mold temperature is 47.00 HRB and the lowest hardness at 400 ᵒC mold temperature is 40.56 HRB. The higher the temperature of the mold used, the level of porosity of a material will decrease. This is due to the temperature difference when pouring the molten metal and the lower mold temperature. This makes the metal solidification time longer. The higher the mold temperature, the slower the solidification time, the larger the grain structure, and the decreased hardness.

Investigation of Microstructure and Mechanical Properties of AlSi7Mg0.3Cu0.5 Alloy with Addition of Zr, Ti and Sr

The main objective of this paper is to investigate the effect of Zr and its synergistic effect together with the addition of an inoculant (Ti) and a modifier (Sr) in terms of structural analysis and mechanical characteristics of AlSi7Mg0.3Cu0.5 alloy. In accordance with the objectives of the paper, in the experimental part, eight material variants were cast by the investment casting method. The presence of Zr in the experimental alloys was manifested by the crystallization of phases with different chemical compositions mainly (AlSi)3(TiZr) and (AlSi)2(TiZr). The graded addition of Ti in the alloys resulted in a higher number of nucleation grains of Zr-rich phases, and alloys with a combination of Zr and Sr were characterized by the formation of (AlSi)2(TiZr) phases. Various types of precipitates based on Zr (Al3(ZrTi)) and Cu (Al2Cu) were observed in the substructure of the alloys. The addition of Zr and its synergistic effect with Ti and Sr led to an increase in the conventional yield strength, hardness and partly tensile strength with reduced elongation of the experimental alloys.

Study of Solidification Process of Ni-Based Superalloy Castings Manufactured in Industrial Conditions with the Use of Novel Thermal Insulating Module Technique

The solidification process of IN713C Ni-based superalloy rod castings made by the investment casting method without and with the use of novel insulating module applied on the ceramic mold was studied in this article. The design of the cone-shaped insulating module was developed based on numerical simulations of the distribution of local solidification parameters, ensuring the lowest centerline shrinkage porosity along the castings. The effectiveness of the design of the insulating module was tested in industrial casting trials. It was found that the use of a novel insulation module increases temperature gradient G and decreases cooling rate v, thus leading to a favorable increase of the Niyama criterion value (Ny = G/√v) and also ensuring directional solidification of the casting rod compared to the process where thermal insulation was not used. In this way, the centerline shrinkage porosity was removed, maintaining the equiaxed grain structure of the castings. The presented results show that it is possible to use the same insulating module multiple times, in the subsequent manufacturing processes, to control the solidification of Ni-based superalloy precision castings in industrial conditions.

The role of additive manufacturing in the investment casting process

The aim of this study was to systematically describe the additive manufacturing (AM) technologies used for various casting technologies and how rapid investment casting (RIC) is changing the field of casting. The capability and effectiveness of additive manufacturing to provide investment casting production solutions has been investigated. The traditional investment casting method is less efficient in terms of cost and time to develop new wax models of solid tooling for low volume production or prototypes. To overcome this problem, it is proposed to introduce additive manufacturing to these processes to produce investment casting models. This paper discusses specific applications of rapid prototyping in this area. The study concluded that the use of additive manufacturing for investment casting instead of the traditional method is more cost- and time-efficient. Terms and designations: RP – Rapid Prototyping, IC, RIC –(Rapid) Investment Casting, PM – Project Manager, AT – Additive technologies, AM – Additive manufacturing

Achieving ultra-high strength in Be/Al composites by self-exhaust pressure infiltration and hot extrusion process

Beryllium particle reinforced aluminum matrix (Be/Al) composite with exceptionally high strength was fabricated from Be debris by self-exhaust pressure infiltration and hot extrusion process. The microstructures characteristics and mechanical properties of the Be/Al composite at as-cast and as-extruded state were systematically investigated in the current study. It was found for the as-cast composite that uniform distribution of beryllium particles with average size of 2.2 μm were achieved, the microcracks in beryllium particles were repaired in situ by infiltrating liquid aluminum into these microcracks under external pressure. The Be phase and Al phase were well bonded despite the presence of nano BeO at the interface. After hot extrusion, the beryllium particle deformed and elongated along the extrusion direction. The average grain size of Al was refined from hundreds of microns to 450 nm, and the dislocation density increased significantly. The tensile strength and yield strength of Be/Al composite reached 595 MPa and 494 MPa by hot extrusion, respectively. The ultra-high strength was mainly related to grain boundaries strengthening, dislocation strengthening, precipitation strengthening and load transfer strengthening. Compared with the composites prepared by the investment casting and powder metallurgy methods, the Be/Al composite showed more than 100% increment in strengthening efficiency and 80% increment in yield strength. It indicated that the self-exhaust pressure infiltration technology combined with hot extrusion process was a feasible and successful method to prepare high performance Be/Al composites.

Experimental and Simulation Analysis on the Mechanical Behavior of 3D‐Enhanced Al‐Based Tetrahedral Lattice Materials

Herein, the compressive mechanical behavior of novel 3D tetrahedral lattice materials is investigated by ways of experimental, numerical, and analytical methods with a good performance of accuracy. Samples with varied length–diameter ratios are fabricated through 3D printing combined with investment casting method. The compressive behavior, deformation characteristic, and energy property of the lattice materials are comprehensively recorded and analyzed with respect to the geometric parameter and compression directions. It is observed that the length–diameter ratio exhibits a significant influence on the mechanical performance and energy absorption of the materials, that is, the lower the length–diameter ratio, the higher the relative density, strength, and energy absorption. Good agreements are observed among the experimental, numerical, and analytical results within a relative acceptable error. Moreover, the mechanical properties and deformation characteristics of lattice materials depend on compression directions to a great extent. In addition, the novel tetrahedral lattice materials with reasonable relative density present superior performance features compared with the other cellular materials.

Investigation of the Biocompatibility of Laser Treated 316L Stainless Steel Materials

In this study, 316L stainless steel materials, which are widely used in the industry, were produced by investment casting management. Depending on the microstructure, the hardness values constitute an important stage of the properties that can be developed and controlled. For this purpose, the differences between the microstructure and hardness properties of 316L stainless steel, which is produced by the investment casting method, and 316L stainless steel, which is currently used commercially, were examined. The changes caused by the fiber laser on the surface of 316L materials produced with two different production methods were examined. It was observed that the laser used made different changes in the surface structure of the 316L material produced by both methods. Since the surface of the material is a buffer between body fluids and biomaterial, it is known that there is a relationship between surface properties and biocompatibility. In this study, the L929 cell growth test, one of the cytotoxicity tests, was applied and thus, how laser surface treatment affects the biocompatibility of 316L materials produced by both methods was comparatively examined.

Experimental simulation of volumetric compacts formation from spherical waxy elements

The growth in metal intensity of industrial production and the volume of consumption of finished metal products determine the relevance of development and research of energy efficient technological processes aimed at reducing costs by reducing the number of operations while maintaining product performance. In mechanical engineering, the problem of obtaining blanks with increased dimensional and geometric accuracy and complex configuration is solved by using a common method of investment casting. Expansion of the use of such technological approach to produce blanks in mechanical engineering is hindered by a number of physical phenomena associated with the thermal expansion of investment and ceramic materials, which leads to an increase in the product final cost. A significant number of defect-forming factors can be eliminated by applying an innovative solution consisting in the formation of porous removable models by compacting mixtures based on waxy materials. This solves the problem of material shrinkage and increases the crack resistance of ceramic molds, which significantly reduces the share of machining in the overall volume of technological operations. Technical tests of the new method have revealed the reason why the machining of castings cannot be completely eliminated at present. The problem mainly lies in elastic response of compacted material of the model mixture, which, in some cases, affects the increase in the compacts size. This paper considers the effect of initial packing of spherical-shaped elements simulating one- and two-component model mixtures on the stress-strain state of a powder body subjected to unilateral compaction in a rigid cylindrical matrix to technologically justified density values. The results of the experiment are presented in the form of stress-strain relations. Preferable conditions of compact formation with minimal values of elastic response of the compacted material are considered.

Orthodontic Bracket Friction Affected by Design Selection Material and Manufacturing Process

One of the problems in orthodontic treatment is friction. Some of the factors that support friction are archwire material, archwire dimensions, bracket material, surface roughness, type of ligation, environmental humidity, and bracket position, angulation angle between bracket and wire, changes in the surface of the archwire and bracket. The aim of this study is to analyse the difference in friction between the two branded bracket designs and a new patented bracket (patent no. IDP000069597). The production method for this new bracket is different, however, uses the same material of 17-4 PH stainless steel. There are three groups in this research, one sample of bracket each from two different branded and one sample of a new bracket design. All three groups were tested for microstructure, then tested for measurement of friction between bracket slots and archwire. The microstructure of the two branded brackets has a martensitic phase that is not as dense as the new bracket, which is due to the different manufacturing method processes. The two branded brackets use the metal injection molding method, while the new brackets use the investment casting method. The friction test results show that there are significant differences between the three groups of brackets. One of the branded brackets (A) has the lowest friction, but branded bracket (B) does not have different friction with the new bracket. Differences in design and manufacturing methods of orthodontic bracket affect the friction between orthodontic brackets and archwires even though they use the same material.

Performance Analysis of Micro Francis Turbine Manufactured Locally in Nepal

The manufacturing of micro-hydro turbines, especially Cross-Flow, Pelton, Propeller turbine, has been carried for more than 50 years in Nepal. A prominent opportunity in the manufacturing of Francis turbines has been perceived in recent years as the requirements of turbines for future installations falls on the Francis turbine range and are above 60%. However, none of the manufacturers step forward to accept the challenges of manufacturing Francis turbines which may be due to the lack of know-how in design and the manufacturing technology of Francis Turbine as a whole. Nevertheless, many attempts have been put forward with the initiation of the Turbine Testing Laboratory, Kathmandu University, for the development of both the design and manufacturing methodology. In this paper, the performance analysis of two different Francis runners, manufactured using local technology of investment casting and pressing-welding method, was conducted. For making the manufacturing, installation and, operations of the turbine as simple as possible, the trapezoidal spiral casing with fixed guide vanes was implemented. In addition the leading and trailing edge modification had not been carried out so as to observe the efficiency rise after these modifications. A comparison of the efficiency for both the turbines indicates Francis turbines with fairly good efficiencies can be manufactured using locally available tools and technology.

Mechanical properties characterization of Ti6Al4V for artificial hip joint materials prepared by investment casting

The Investment Casting (IC) process is a type of casting that can produce the suitable shape and size of components by minimizing porosity and defects. However, research on ICs for the manufacture of artificial hip joints made from Ti6Al4V is still lacking. Therefore, the purpose of this study is to determine the mechanical properties of an artificial hip joint made from Ti6Al4V casted using the investment casting method. The stages of the investment casting process used in this research are wax injection, ejection of wax pattern, tree assembly, slurry coating, final sand mould, dewaxing, preheating, pouring, and final product. The characterization of IC products was carried out by tensile test, hardness test, and impact test. The yield strength, Ultimate Tensile Strength, Elongation (%), Hardness (HRC) and Impact Strength obtained in this study were 636 MPa, 687 MPa, 17%, 29 HRC, and 5.3 J, respectively. The lower oxygen content in Ti Alloy after IC resulted in a decrease in yield strength, ultimate tensile strength, hardness, and impact energy. However, the low oxygen content in Ti Alloy after IC resulted in increased ductility (% elongation).

Systematic Review on Investment Casting

Abstract: The Investment casting (IC) method is now used to make all precision components in the medical, hydropower, defence, car, and other sectors. IC has a wide range of applications and is well-known for its ability to make complex near-net form items with great dimensional precision and surface polish. Various scholars are making ongoing efforts to investigate the topic of investment casting. This publication offers a comprehensive survey of the studies in this vast topic. It emphasises improvements in the earliest stages of the investment casting process. It focuses on pattern creation improvements, mould composition, casting materials, and typical flaws, as well as preventative actions. Keywords: Investment casting, Pattern modelling, Mould, TiAl alloys, defects