Properties Of Mold Research Articles

Investigation of the Effect of Inoculant and Casting Temperature on Fluidity Properties in the Production of Spheroidal Graphite Cast Iron

Working with liquid metal makes the casting method very advantageous, but also presents some difficulties. One of the common challenges in the casting process is that the liquid metal may not fill the mold cavity completely. This is mainly due to the contact of the liquid metal with the mold surface in the mold cavity, the high heat transfer coefficient of the mold material, and the undercooling and solidification of the liquid metal during liquid movements. For this reason, the fluidity of the liquid metal is important for robust casting production. The fluidity is affected by many factors such as mold properties, casting temperature, and alloying elements. In this study, it is aimed to investigate the fluidity characteristics of GGG60 alloy. For this purpose, the effects of casting temperature, different inoculants, and different inoculant quantities were used in the new mold design, which has different cross-sectional thicknesses. The distance of the alloy in the cavities was also compared with FlowCast Casting simulation software.

Utilization of industrial solid waste as a mold material in the foundry industry

The current Scenario of industrialization leads to the generation of the huge amount of industrial solid waste and the major problem faced by the current industries is the damping of such solid waste, which leads to the clean environmental issue. The aim of this paper is the utilization of industrial solid waste such as Granular blast furnace slag, Red mud and Ferro-Chrome slag in the foundry industries as a mold material. Silica sand is one of the major sources as a mold material in the foundry industries. The mold prepared with a combination of silica sand and solid waste (blast furnace slag, red mud, and ferro-chrome) separately. Physical and chemical characterization of solid waste has done through X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and X-ray fluorescence (XRF) and also mold properties such as hardness, compressive strength, shear strength and permeability were investigated. It was observed that mold having a combination of silica sand and different solid waste shows significant mold properties to replace silica sand in the foundry industry.

ОСОБЕННОСТИ ИСПОЛЬЗОВАНИЯ ОРГАНИЧЕСКИХ ИЛИ ВОДНЫХ СВЯЗУЮЩИХ НА ОСНОВЕ ОКСИДОВ ЭЛЕМЕНТОВ III ИЛИ IV ГРУПП ПРИ ИЗГОТОВЛЕНИИ КЕРАМИЧЕСКИХ ФОРМ ДЛЯ ЛИТЬЯ ОТЛИВОК ИЗ ХИМИЧЕСКИ АКТИВНЫХ СПЛАВОВ (обзор)

The article considers the experience of using organic and aqueous binders based on silicon or aluminum oxides in the manufacturing of ceramic casting molds, and tendencies of world manufacturers in this industry to improve the quality, accuracy and operational reliability of cast products, especially critical parts made of titanium, intermetallic and heat-resistant alloys obtained by investment casting. The paper gives information on the results of studying physical and mechanical properties of ceramic molds and defect zone of the outer surface of castings made of various alloys.

In Situ Microfibrillation of Polyamide 66 and Construction of Ordered Polytetrafluoroethylene Fibers to Significantly Reduce the Friction Coefficient of Polyphenylene Sulfide

Self-lubricating polyphenylene sulfides (PPS) were obtained by in situ construction of the ordered polyamide 66 (PA) microfibrillar structure and polytetrafluoroethylene (PTFE) fibers, as induced by high-shear force fields in thin-wall injection molding (TIM). The average friction coefficient and specific wear rate of PPS/PA/PTFE20 composites reached 0.114 and 7.149 × 10–6 mm3/Nm, respectively, of which the former is 27.4% lower than that obtained from conventional injection molding. The worn surface of PPS/PA/PTFE composites prepared by TIM displayed a much smoother and more stable transfer film coupling with the homo-dispersed F element, which greatly improves the tribological properties of subsequent moldings. This study provides a novel perspective for improving the tribological performance of engineering plastics by systematically tailoring the microstructure.

Improvement on corrosion resistance of gypsum for ceramics molding with soluble salts

Dissolution of dihydrate gypsum and severe chemical corrosion are the principal causes of short working life of gypsum molds in slip casting technology. In this experiment, a new modification method was focused on the improvement of corrosion resistance on the premise of ensuring water absorption and mechanical strength. The effects of three soluble salts (barium chloride, sodium phosphate and sodium oxalate) on various properties of gypsum molds were evaluated using three different methods, which included solution mixing, immersing and coating. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to evaluate the phase transformations, structures and morphologies. Results revealed that immersing hardened sample into sodium oxalate solution effectively enhanced the corrosion resistance at the optimum concentration of 1.8 wt%. The water-saturated flexural strength and softness coefficient were increased by 36.7% and 22.2%, respectively. Calcium oxalate was produced by chemical reaction between dissolved Ca2+, SO42− and sodium oxalate. Calcium oxalate monohydrate (COM) was crystallized after water evaporation and the crystals accumulated on the outer surfaces of hardened pastes forming as waterproof film, which reduced the dissolution of dihydrate gypsum and further improved the corrosion resistance.

Various Alternative Sources for Silica Sand, Binders and Additives in Sand Casting and their Properties – A Review

Foundries all over the world consume silica sand, clay binders and additives to some proportion for production of green sand castings. Silica sand apart from being used for mould making and core making, it is also used in many areas such as glass making, and construction etc., Consumption of silica sand in large quantities will lead to the depletion of these resources. If an alternative source is identified, the demand on single source will be avoided and the cost of the sand can be lowered drastically. Apart from conventional binders and additives for sand moulding different organic binders and additives are also available by which the sand mould properties can be improved according to the material cast like cast iron, steel, aluminum, brass etc. The search for different alternative sources in sand moulding can lead to good quality sand casting at reduced production cost.

Effect of Chopped ZrO2 Fiber Content on the Microstructure and Properties of CaO-Based Integral Ceramic Mold.

A chopped ZrO2 fiber (ZrO2 (f)) reinforced CaO-based integral ceramic mold was successfully fabricated by stereolithography (SLA) and tert-butyl alcohol (TBA)-based gel-casting, and the effect of chopped ZrO2 (f) content on properties of the ceramic mold was investigated. The results show that the ZrO2 (f) content had a significant effect on the viscosity of CaO-based ceramic slurry, which directly affects the filling ability of slurry in complex structures of the integral mold. The tiny structures of the ceramic mold cannot be filled completely with a ZrO2 (f) content exceeding 3 vol %. The sample fabricated with 3 vol % fiber content showed a harmonious microstructure and exhibited an excellent comprehensive performance with 25 °C bending strength of 22.88 MPa, an 1200 °C bending strength of 15.74 MPa, a 1200 °C deflection of 0.86 mm, and a sintering shrinkage of 0.40%, which can meet the requirements of casting very well.

Utilising Flowability Sensor for Green Sand Mould Characterisation

In this work, an attempt has been made to improve the sand casting process by reducing the percentage of casting defects. The enhancement of the sand casting process is based on producing green sand castings with good pattern profiles and no failures at any complex ‎points during the separation process, handling and transportation. This work ‎introduces modified, non-destructive, direct tests for measuring sand mould ‎properties using sensor readings. ‎A new flowability sensor has been used to measure the time-dependent density, ‎distance-dependent mould hardness, and distance-dependent mould strength. The ‎sensor is able to detect sand motion at the desired points during the mould-making process. The live characterisation of the green sand mould is used to determine the optimum ‎parameters for the compaction process, reduction of the moulding time, and spent ‎energy, so that the cost of the moulding and casting process will be reduced.‎ It has been found that there is a linear relationship between the properties of the green sand samples and the sensor signals. The new method facilitates the measurement of sand properties and determines the most effective moulding parameters based on the flowability sensor readings. The resultant increases in both compactibility and compaction pressure improve mould hardness and mould strength.

Modelling selection of structure and properties of monolayer electrophoretic shell molds during investment casting

The paper presents a mathematical model for optimizing shell mold (SM) material selection process to ensure the greatest crack resistance during liquid metal pouring. Minor elastoplastic deformation theory and heat conductivity equations as well as approved numerical methods are used to solve this problem. Objective function “min–max” has been developed based on control variables characterizing shell mold material properties. The paper considers axially symmetrical SM heating process during liquid metal pouring. SM resistance is evaluated based on occurring stress. An algorythm for solving this problem has been developed.

Changes in Properties of Pulp Mold Depending on the Forming Conditions of Wet Pulp Mold Manufacturing

In this study, the effects of process conditions of wet pulp mold manufacturing on the properties of the pulp mold were analyzed with a pilot wet pulp mold simulator. Two kinds of pulp stock, HwBKP and ONP pulp, were used in this study. The mesh hole size of the forming wire and the stock concentration were also changed. The results showed that the higher stock concentration led to a higher grammage pulp mold. The ONP pulp stock resulted in a lower grammage pulp mold which could be originated from the lower freeness of the ONP pulp. The grammage of pulp mold was not significantly affected by the mesh hole size of the forming wire. However the mesh hole size had influence on the pulp mold bulk was and the smaller hole size of the mesh resulted in the higher bulk of the pulp mold, which could be caused by changes in the retention of the small components such as ash.

Heat treatments for improved quality binder jetted molds for casting aluminum alloys

The objective of this paper was to investigate the most suitable heat treatment for casting molds manufactured by binder jetting. For this purpose, the printed molds were subjected to different heat treatments and the properties of the molds were analyzed. Tests were performed at different temperatures and times to investigate their effect on the water and volatile substances content; the joining among particles; and the porosity, roughness, and compression strength of the printed molds. Moreover, to relate the properties of the mold with the quality of the castings, aluminum alloy specimens were cast and the dimensional accuracy, surface roughness, mechanical strength, and porosity were evaluated. This research leads to the conclusion that the binder jetting process, using calcium sulfate powder, is useful for manufacturing molds for casting aluminum alloy. To improve the mold quality and, consequently, the casting quality, heat-treatment is necessary. The best mold properties were obtained at 250 °C for 1.5 h.

Product Design & development of High-Pressure moulding machine and analysis of various mould properties

Although there are many advanced technologies for metal casting, green sand casting is one of the most commonly used casting processes today due to its low cost of raw materials, and ability to produce a variety of castings both in size and composition, and the ability to recycle the moulding sand. The green sand-casting process is one of the most versatile processes in manufacturing because it is used for most metals and alloys even with high melting temperatures such as iron, copper, and nickel. Understanding the conventional and modern green sand moulding method can help redesign for manufacturability and utilize processes for modernization of foundry; that meet specific requirements. The flexibility of moulding is demonstrated by the number of moulding processes currently available. This wide range of choices offers design engineers and component users’ enormous flexibility in their metal forming needs. Each process offers distinct advantages and benefits when matched with the proper product application. This project is to design a high-pressure moulding machine and study, compare mould properties achieved by different moulding methods, that help improve product quality.

The influence of coating sand materials on shell mold properties of Investment casting process

Abstract The investment casting process is well known for the production of accurate complex casting products. The time of shell mold production is remarkable. It plays an important role on shell mold properties in the post treatments after shell production. It decides the quality of casting. In present work, Fused silica and Alumina-silicate based ceramic sand materials selected as a backup coat to understand its effect on properties. Shell drying time, Modulus of Rupture (MOR) and thermal expansion of mold is observed in the work. Drying time of shell varies from 84 to 86 h in the shell mold production. Modulus of rupture results 94 kg/cm2 strength in Alumina-silicate type materials compared to 49 kg/cm2 strength of Fused silica sand shell. In the firing of shell, thermal expansion observed up to 1200 °C temperature. Fused silica provides stable nature against thermal expansion from highest 0.054 to lowest −1.139 with increasing temperature upto 1200 °C.

Molding Binder Influence on the Porosity and Gas Permeability of Ceramic Casting Molds.

The investment casting process is widely used in the aerospace industry to produce complex engine parts. The article determines the properties of quartz powders, nanosilica dioxide binders, and multilayer samples of ceramic casting molds. The properties of spherical molds obtained using an alcohol-water system derived from hydrolyzed ethyl silicate (ZKE) and LUDOX PX-30 (type Q1) were compared with those obtained in water systems derived from Remasol Plus and Remasol Premium binders (type Q2). The spherical samples are composed of seven layers made with the use of an immersion-sprinkling method. To assess the properties of the molds, X-ray microscopy (µCT), scanning electron microscopy (SEM), and gas permeability analysis over a temperature range of 20–950 °C were utilized. The binder type is proven to affect the properties of the casting mold samples. The material obtained in the water system, Q2, has advantageous properties such as a high porosity and gas permeability.

Evaluating Silicon Carbide-Based Slurries and Molds for the Manufacture of Aircraft Turbine Components by the Investment Casting

Silicon carbide (SiC) is a promising material for the fabrication of ceramic shell molds due to its high mechanical strength, hardness, thermal shock resistance, and thermal conductivity compared with commonly used slurries. This article describes the test results of casting materials, i.e., SiC-based powders and aqueous binders with aluminum oxide nanoparticles, as well as the parameters of slurries used for prime coats and structural layers. Tests were also performed to evaluate the physical and mechanical properties of SiC-based shell molds for the manufacture of aircraft turbine components. Two SiC-based slurries with solid concentrations of 65 and 70 wt.% were prepared, and their viscosity, density, pH, quantity, thickness, and copper plate adhesion (plate weight test) were investigated. Fourteen days were required to prepare and evaluate the slurry parameters. The results showed that SiC-based slurries had a Zahn cup #4 outflow time of 33.1 s to fabricate the first two coats and 14.8 s to fabricate the shell mold structural layers. Three series of SiC-based shell mold samples were prepared: after dewaxing (PW1), after burnout preheating at 700 °C (PW2), and after annealing at 1200 °C (PW3). The bending mechanical strength, Young’s modulus, and Weibull’s modulus of the samples were calculated, and the roughness (Ra and Rq) and microstructures of samples were also analyzed (SEM). Inner defects were evaluated by CMT (µCT). The Ra and Rq values of the prime coat of the SiC-based shell mold did not exceed 5 µm. The fabricated SiC shell molds had bending mechanical strengths from 1.21–2.28 MPa, Young’s modulus of 102.97–207.66 MPa, and a Weibull’s modulus from 5.36–9.94. The shell molds fabricated on the technical scale met the requirements specified for industrial shell molds.

A verification of thermophysical properties of a porous ceramic investment casting mould using commercial computational fluid dynamics software

Defects in cast metals remain a common problem in many areas of the foundry industry, particularly in the investment casting of large area, thin-walled components for aerospace applications. During previous research, the thermophysical properties, density and porosity of a fibre reinforced ceramic investment casting mould were determined using several experimental techniques. Without verification, these experimental results remain nothing more than educated guesswork. The purpose of this study is to verify previous results and to more fully characterise the ceramic mould material with complementary measurements. A commercially available computational fluid dynamic (CFD) simulation package, Flow-3D®, was used in conjunction with a full-scale Ni-superalloy (IN718) casting to assess the accuracy of these results. By placing thermocouples strategically across the mould thickness, temperature profiles were determined and compared directly to predicted profiles extracted from the simulation by a custom-written Python script.

Organic–Inorganic Hybrid Replica Molds with High Mechanical Strength for Step-and-Repeat Ultraviolet Nanoimprinting

Abstract In this study we demonstrate that organic radical photopolymerized resins hybridized with inorganic silica nanoparticles improve the mechanical strength of replica mold materials and that organic-inorganic hybridization prolongs mold lifetime independently of mold linewidth during step-and-repeat UV nanoimprinting over 100 cycles. Silica nanoparticles with polymerizable methacryloyl groups (NPMC) were added to 1,10-decanediol dimethacrylate (MC10) and diacrylate (AC10) base monomers to enhance the mechanical properties of the replica molds. Heterogeneous combination of polymerizable groups, such as AC10 and NPMC, maintained a fluidity suitable for molding in UV nanoimprinting, and enabled the preparation of hybrid replica materials with a high inorganic silica content of 56.9 wt% (37.0 vol%). Nanoindentation measurements revealed that the hybrid replica materials with 37.0 vol% silica showed a Young’s modulus of 4.4 GPa. Only the 45-nm-linewidth patterns of AC10-based replica molds without NPMC showed line-collapse defects after imprint cycle tests, while the 45- and 100-nm-linewidth shapes of the hybrid resin materials with NPMC remained intact after 128 step-and-repeat imprint cycles and nanoindentation measurements.

Effect of process parameters on flexure strength and gas permeability of 3D printed sand molds

3D printed sand molds for the casting industry play a vital role in manufacturing intricate parts using a computer model. The possibility of producing fairly significant structural castings using a small job-box 3D sand mold printer is another advantage compared to the direct metal 3D printing processes. It is important to identify the relationship between the process parameters and the properties of the sand mold to produce a mold with the required strength, permeability and stiffness; to reduce gas emissions during casting and minimize the mass of combustible materials in the mold. Hence, it is possible to create an excellent casting by improving the design of such molds for liquid alloy filling and solidification. The relationship between the printing parameters and the properties of the mold can be a great tool for foundrymen, primarily to optimize the strength and permeability properties of these molds and therefore to provide exact boundary conditions for the solidification simulation prior to a casting trial. This paper reports on a study of a basic outline to quantify the role of the sand mold printing process parameters, particularly the recoater speed and print resolution, on the mold strength and permeability, and their impacts on the anisotropic behavior of the printed sand molds.

Multi-objective optimization of western bentonite (Al2H2Na2O13Si4)-blended green sand casting process parameters to improve mould quality

The quality of the mould in the green sand casting process plays a vital role in achieving good quality castings. In this research work, the mould properties permeability and hardness are focused on to improve the quality of the mould. These properties are improved by optimizing the process parameters such as degrees of ramming, mould wall thickness, and weight percentage of western bentonite using Taguchi-based grey relational analysis. The optimal level of these process parameters is experimentally validated by producing castings in a modern jobbing foundry. In the validation experiments, the moulds are produced with nominal hardness (92) and the mould wall thickness is reduced by creating cavities for storage of gases at a distance of 30 mm from the mould cavity. An interesting result found is that the nominal mould hardness and reduced wall thickness improve the quality of the mould by increasing the permeability value from 80 to 120. The improved mould quality reduces the mould-related casting rejection rate in pressure plate casting from 40% to 30%.

Molding and Mold Properties of Spherical Artificial Sand Coated with Inorganic Binder

In recent years, molds made by additive manufacturing (AM) are increasingly applied to build prototypes and small-quantity casting products. Technological development aiming to use mass-produced castings is advancing with the emergence of high speed AM molding technology. Mass production is expected to improve the potential of the entire casting product, such as the realization of complicated internal structures, thinness, and weight reduction by the improvement of cavity accuracy.