Design, Simulation and Optimization of an Additive Laser-Based Manufacturing Process for Gearbox Housing with Reduced Weight Made from AlSi10Mg Alloy

The gas turbine engine's (GTE) development aims for the increasing the efficiency, strength, reliability and safety of its components. To create competitive engines, housing parts and components with high functionality and reduced weight are needed. Especially difficult in the design and production are the gearboxes for aviation GTE. Traditional technologies based on precision casting or material forming operations have significant limitations due to the complexity of fulfilling multiple different requirements. Nowadays, one of the progressive production techniques is additive manufacturing. The article presents the results of computational and experimental studies that substantiate the applicability of laser additive technology to reduce the mass of body parts by up to 15% while ensuring their strength properties. The physical and mechanical characteristics of aluminum alloys acceptable for the manufacturing of housing parts were analyzed. The necessary characteristics of the powder alloy of the Al-Si system and the technological parameters of the L-PBF of the modified housing of the gear reducer are established. Using the finite element method (FEM) the L-PBF process was numerically simulated and the technological modes for synthesis of the AlSi10Mg alloy powder were optimized. With the help of a serial 3D printer ProX320DMP, the prototype of a gear housing was manufactured.

Numerical Simulation and Rapid Centrifugal Casting of Large Complex Thin-Walled Titanium Alloy Intermediate Casing Based on 3D Printed Pattern

Titanium alloy intermediate casing is a typical large casting, with many thin-walled and complex structures. It is a high cost and time-consuming process in the trial stage to manufacturing the wax pattern of the intermediate casing by metal mold. Rapid investment casting based on 3D printed patterns is the development direction of casting technology which integrates digitization and intelligence. In this study, selective laser sintering (SLS) technology was used to realize the rapid prototyping of polystyrene pattern in the precision casting of intermediate casing. A numerical simulation method was used to predict the filling process, solidification and casting defects of the intermediate casing. The simulation results show that the gating system for the casting of intermediate casting was reasonable, the number and size of gating risers met the open design requirements, and a sequential solidification of the casting could be realized. The titanium alloy intermediate casing with excellent metallurgical quality and size accuracy CT7 was successfully produced using centrifugal rapid casting technology.

Polymer Binders of Ceramic Nanoparticles for Precision Casting of Nickel-Based Superalloys

This study presents the general characteristics of binders used in precision casting of Nickel-based superalloys. Three groups of binders were described: resins, organic compounds, and materials containing nanoparticles in alcohol or aqueous systems. This study also includes literature reports on materials commonly used and those recently replaced by water-soluble binders, i.e., ethyl silicate (ES) and hydrolysed ethyl silicate (HES). The appearance of new and interesting solutions containing nano-alumina is described, as well as other solutions at the initial stage of scientific research, such as those containing biopolymers, biodegradable polycaprolactone (PCL), or modified starch. Special attention is paid to four binders containing nano-SiO2 intended for the first layers (Ludox AM, Ludox SK) and structural layers (EHT, Remasol) of shell moulds. Their morphology, viscosity, density, reactions, and electrokinetic potential were investigated. The binders were characterized by a high solid-phase content (>28%), viscosity, and density close to that of water (1–2 mPa·s) and good electrokinetic stability. The nanoparticles contained in the binders were approximately spherically shaped with an average particle size of 16–25 nm.

3D Printing of Ceramic Shell Molds for Precision Casting of Turbine Blades

Traditionally, the technology used in the production of gas turbine blade castings characterized by a large number of technological conversions, high labor costs with a large amount of manual labor and the need to produce various types of complex and expensive equipment at different stages of production. This work aims to reduce the time and money spent on the manufacturing of ceramic shell shapes — a form suitable for the standard methods of precision casting by traditional heat-resistant nickel alloys. The proposed approached involves obtaining a shell shape with an internal core as a single, non-assembled product, without lengthy and time-consuming design and manufacturing processes involved in forming equipment for the production of castings based on smelted models. The proposed method is based on the use of 3D printing with refractory ceramic pastes. Using both uncooled and cooled blades as examples, models of casting molds were designed, technological processes were developed, and ceramic shell molds were manufactured. Experimental casting into a manufactured ceramic shell mold for an uncooled blade with a bandage shelf was performed and showed satisfactory results.

Application of Stereolithography Based 3D Printing Technology in Investment Casting

Advanced methods for manufacturing high quality parts should be used to ensure the production of competitive products for the world market. Investment casting (IC) is a process where a wax pattern is used as a sacrificial pattern to manufacture high precision casting of solid metal parts. Rapid casting is in turn, a technique that eases the IC process by combining additive manufacturing (AM) technologies with IC. The use of AM technologies to create patterns for new industrial products is a unique opportunity to develop cost-effective methods for producing investment casting parts in a timely manner. Particularly, stereolithography (SLA) based AM is of interest due to its high dimensional accuracy and the smooth surface quality of the printed parts. From the first appearance of commercially available SLA printers in the market, it took a few decades until desktop SLA printers became available to consumers at a reasonable price. Therefore, the aim of this review paper is to analyze the state-of-the-art and applicability of SLA based 3D printing technology in IC manufacturing, as SLA based AM technologies have been gaining enormous popularity in recent times. Other AM techniques in IC are also reviewed for comparison. Moreover, the SLA process parameters, material properties, and current issues are discussed.

Fabrication of Ceramic Moulds Using Recycled Shell Powder and Sand with Geopolymer Technology in Investment Casting

Lost-wax casting, also called precision casting, is the process of casting a duplicate metal sculpture cast an original sculpture. The ceramic shell mould used in lost-wax casting usually consists of several layers formed with fine zircon and granular mullite particles using silica gel as a binder. However, it is a complicated and time-consuming process. Large amounts of waste moulds that need to be disposed and recycled become an environmental concern. In this study, waste shell sand from the recycled mould and calcium carbonate/metakaolin were used as raw materials to prepare geopolymer slurry and coating. The influence of mixing ratio and the SiO2/K2O modulus of the alkali solution on the setting time and green/fired strength were evaluated. Ceramic shells with one to four layers of geopolymer slurry and waste sand sprinkling were fabricated and tested for their permeability and green/fired strength. It was found that geopolymer shells had higher green/fired strength and better permeability than the original zircon/mullite shell. For foundry practice, metal casts were fabricated using recycled ceramic shell moulds with one to four layers of geopolymer coating. All cast results have their dimensions all within tolerance limitation and up to 13 h can be saved for the preparation of shell moulds.