ИЗДАТЕЛЬСКИЙ ДОМ «ЛИТЕЙНОЕ ПРОИЗВОДСТВО»
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Contents



Rechkalov A. Balashikha Casting-Mechanical Plant - a Look into the Future
Marking its 75th anniversary in 2007, OAO Balashikha Casting-Mechanical Plant is continuously developing its scientific-and-technical, production and personnel potential formed over the years of operating in the aircraft branch. OAO operates along two basic lines: serial production of aircraft wheels, brakes and brake system control units for most types of the Russian aircraft; production of intricate castings from Ti, Mg and Al alloys. The works supplies castings for machine-building, aerospace, chemical, oil-refining and oil-producing industries.
OAO BLMZ's customers include both Russian and foreign businesses. High technical and quality characteristics of supplied products favor continuous extension of stock of orders. The works develops the supply of finish-machined castings. A quality management system in accordance with the requirements of GOST R ISO 9001-2001, GOST RV 15.002-2003, ISO 9001:2000, AS 9100-2003 is used at the works, modernization and re-equipment of production facilities are under way. A modern pattern tooling design system has been adopted. Complete reconstruction of the magnesium casting department is being finished, a new aluminum and magnesium casting department is being designed to automatically produce cold-hardening sand molds and cores. The most advanced technologies are used at the titanium casting department. The machining facilities are being equipped with CNC machines of the new generation.
The works' central laboratory has the most modern equipment and instruments including an ICP spectrometer, an all-purpose Inspekt dest 50 testing machine, an LPM-500 fluorescent penetrant line, an X-ray television system. OAO BLMZ plans to further develop its capability to produce Ti, Mg and Al alloy castings, including such with finish machining, and also keep its positions in the production of aircraft units.

Bibikov A.M., Khalturin I.P., Zarembo V.I. Controlling the Structure Formation and Properties of Cast Materials with Weak Acoustic ImpactProposed is a method of controlling the structure formation in crystallizing alloys with a weak acoustic impact by means of a short-circuited galvanic loop- antenna adjoining the crystallizing casting, to which loop-antenna weak electric current pulses are applied from a low-power generator. The pulsed electric current creates a transverse pulsing magnetic field and forms in the skin-layer of the antenna normal waves of longitudinal acoustic oscillations with a set of harmonics characteristic for the selected form of pulses, i. e. a process of electromagnetic-acoustic conversion takes place. The acoustic waves propagate in the influence medium freely and at a high speed, and, having a controlling impact on the permolecular structures of the pre-crystallization phase, accelerate the crystallization process.
The frequency of succession of electromagnetic pulses applied to the loop-antenna lies within the radio frequency band from unities to thousands of kilohertz and is determined experimentally by maximum efficiency.
When using this method, there is no intervention into the manufacturing process, no skilled supervision is required.
The method has been tested under production conditions at a number of foundries:

  • at OAO Motorostroitel (Samara) in investment casting of blades for gas-turbine engines using vacuum melting units under acoustic impact of 200 kHz a refinement of castings' macrograin from 2.0 … 4.0 to 0.5 … 1.0 mm was achieved. No columnar non-equiaxed grains, which cause casting rejects, formed at blade edges
  • at OOO AlphaLum (Samara) in casting a cylindrical billet for extrusion (posts) from АМц alloy by semi-continuous casting into a water-cooled crystallizer under an acoustic impact of 1000 kHz refinement and averaging of macrograin size through the casting's section was achieved. As a result, in the further processing of the billet (homogenizing annealing → extruding a tube blank → drawing a ∅ 8.0 x 0.4 mm tube) the total yield rose from 79.9 to 80.8%
  • at OAO Kirovsky zavod (St.-Petersburg) they made 300-kg Al alloy castings of complex configuration in cast-iron dies at a pouring temperature of 710°C. Pouring was done under an acoustic impact with a frequency of 250 kHz and without such impact. When crystallized under the impact, &sugma;B of specimens increases by 15%, δ increases by 90%, ψ increases by 130%. Moreover, the results of 20 parallel pourings showed that castings under acoustic impact had no L-gas (sulphur hexafluoride) porosity, while eight castings (40%) made by the conventional technology had such a defect.
Apart from casting processes, the proposed method of controlling the structure formation can be applied in a number of other spheres of industrial production - under the controlling acoustic impact the rate and density of galvanic coating increase, welding quality improves, the time of gaining strength of concrete in concrete products fabrication is reduced, etc.

Ospennikova O.G., Rudnitsky S.V., Vdovets V.M., Nikishin V.A., Petrov Y.Y. Using a Cermet Riser and Heat Cycling in Casting Turbine Wheels
A new technology of casting turbine rotors and wheels is proposed. The technology comprises use of:

  • a cermet riser
  • a method of heat cycling the melt for refining the macrograin during casting and providing accelerating loads for the disk.
The effect of using a cermet riser is achieved through draining the melt into the internal cavity of the riser by heating it with the melt with the subsequent movement of the melt on the outside, which provides filling of the riser and heat removal from the ceramic wall. Thus, the ceramic partition that separates the internal riser from the external one provides heating-through the ceramic with the melt and decelerated cooling of the melt in the internal riser, which provides a high density of metal in the internal part of the riser.
The technology of heat cycling of the melt when casting parts of the wheel type allows obtaining a fine-grain structure, which considerably improves the fatigue strength of cast wheels.
A promising line of resolving the problem of heat-resistant alloys' ductility is to control the cast metal structure by inoculation. So, the volume inoculation made it possible to improve the ductility characteristics 1.5- to 2-fold, high-cycle fatigue strength 25…40%, and thermomechanical fatigue strength 2- to 3-fold.

Wies E. Filtration of Cast Iron for Massive Castings

Kablov Y.N., Mukhina I.Y., Korchagina V.A. Additive Materials for Molding Sands Used in Magnesium Alloy Casting
In the production of Mg castings, protection of Mg melt against oxidation in the sand mold in the pouring - casting crystallization temperature range is of great importance, when due to its high chemical activity magnesium reacts with the mold's moisture resulting in magnesium oxide formation and hydrogen evolution. The presence of hot metal, hydrogen and air oxygen favors intense burning of magnesium, which may be accompanied by an explosion. In that case, casting quality does not meet the existing requirements, since the oxidation processes in the mold cause surface defects: burns, gross blowholes, cavities, resulting in casting rejects. To prevent these phenomena, improve casting surface quality and casting yield, special protective additives are added to molding sands. However, the available additive materials do not fully meet the surface quality requirements for complex Mg castings for various applications. To resolve this problem, the mechanisms of protection, toxicity and hygroscopicity of additive components, their destruction at heating the molding sand with metal being poured were studied by the methods of metallurgical Mg castings investigation.
Use of new burn-on preventing additives with a lower hygroscopicity developed and produced by FGUP VIAM in the production of large-size shaped Mg alloy castings allows to ensure surface finish and quality of castings, enhance the reliability of structural parts and units.

FATA Aluminium - Forges Ahead in Gravity Die Casting

Glebov S.M., Pirainen V.Y. Molding by Freezing Binding Water Suspensions
The process of making ceramic refractory products, including foundry molds and cores, by freezing binding water suspensions (slips) is based on the known since 1889 phenomenon of SiO2 hydrosol coagulation when cooled down to temperatures below freezing point. The possibility of using the process in the metalcasting industry has been known since the 60s of the 20th century. However, up to the present the process has not been implemented in the industrial scale.
As a result of systematic investigations into the effect of freezing on the binding water suspensions that ended in the development of the low-temperature molding technology (LTM) the following tasks were accomplished:

  • the hardening mechanism of binding water suspensions by freezing has been investigated, and parameters ensuring its irreversibility have been determined;
  • impact of qualitative and quantitative composition of suspensions, freezing and heat treatment (HT) parameters on the physical-and-mechanical and process properties of molds and cores has been established;
  • the kinetics of solid skin formation at freezing of suspensions in contact with pattern tooling being cooled have been determined;
  • values of the main process variables, design features of equipment and tooling for making ceramic molds and cores have been determined;
  • quality of castings made by the new technology has been studied.
For serial production, a method of making two-sided shell molds and shell cores has been proposed. Molds are assembled to vertical or horizontal stacks.
Basic specimens of special equipment have been designed. To resolve one of the most important issues of industrial application of the technology - cooling of the mold-shaping tooling - an automatic low-temperature refrigerating machine has been created that provides for minimal heat loss and good control of the suspension freezing process. Mechanized equipment for making molds and cores using vertical and horizontal joint tooling has been designed. With minimum improvement, the equipment design allows switching the production to the automatic mode.
Regarding the application of the technology in the metalcasting industry, in the first place, serial production of castings of various casting alloys weighing 30…50 kg with higher dimensional accuracy and surface finish requirements should be mentioned.
Ceramic cores made by freezing binding water suspensions combine well with other known molding methods, providing them with certain advantages, for example, with investment casting, V-process.
Attractive is the possibility of using various refractory materials within the framework of a single process without changing process parameters and resetting the equipment. For example, thermal conductivity of quartz ceramics is about 20 times lower than that of corundum ceramics. By selecting cores and molds with different thermophysical parameters it is admissible, within certain limits, to control casting solidification.
In addition to foundry molds and cores, the method of freezing binding water suspensions may find application in the production of ceramic gating systems, heat-insulating riser inserts, filters, etc.
While the technological and economic indices of the process called LTM-process are still to be defined more precisely and evaluated, its environmental safety needs no comments.

Glotov Y.B., Kainov V.M., Matsnev V.N. Squeeze Casting of Thin-Walled Large-Size Aluminum Alloy Structures
For making thin-walled large-size aluminum alloy structures of integral type, OAO NIAT developed a fundamentally new squeeze casting method with plane-parallel half-mold joint.
A fundamental feature of the process consists in filling the mold with melt in solid-liquid state in a continuous one-dimensional flow when closing in, and pressing on the final stage of casting formation. Due to that, along with thin walls, high density and mechanical properties (as compared to other casting methods, including low-pressure die casting) are achieved.
A program for 3D simulation of the process and a microprocessor-based system for controlling the machine and process have been developed.
For forming the inner cavity of bodies, precise cores are used that are made from cold-hardening core sands, the alloy is prepared in a model ВРП-0,25Н vacuum furnace.
Model ЛПС8М squeeze casting machine of the last generation allows making castings with a diameter of 800 mm, a height of 1,700 mm and a thickness of as small as 2.5 mm.

Abramov A.A., Tikhomirov M.D. Technologies of Making Quality Castings from High-Strength Aluminum Alloys
The article discusses mechanical and service properties of high-strength (σB ≥ 300 MPa) corrosion-resistant weldable casting alloys of the Al-Si-Cu, Al-Mg, Al-Mg-Zn, Al-Mg-Li systems developed by FGUP (Federal State-owned Unitary Enterprise) Central Research Institute of Materials, in comparison with the high-strength aluminum-copper alloy ВАЛ10 and the most widely used wrought alloy Д16Т. Requirements on charge materials, melting equipment, casting tools, inoculation and refining processes that make it possible to obtain necessary mechanical properties of the alloys are discussed.
Because of low casting (technological) properties of high-strength aluminum alloys, casting technologies are recommended that allow making quality castings having no crystallization cracks. An example of making composite castings and an example of using computer simulation to work through the technology of casting marine engine cylinder blocks are given.

Melnikov A. P., Sadokha M. A., Kurakevich B. V. Saving Resources and Energy in the Manufacture of Critical Castings
The main ways of reducing the resource and energy intensity of casting have been shown, including:

  • Use of processes with minimal consumption of auxiliary materials;
  • Reduction of gating systems (GS) without changing casting design;
  • Creating combined castings (reinforced with metallic and nonmetallic inserts, etc.);
  • Improving casting accuracy and reducing machining allowances;
  • Ensuring production of near-net shape castings.
New casting production processes have been presented:
  • Metal mold casting by the self-filling method allowing to considerably reduce GS (about 2…3 times reduction as compared to conventional metal mold casting);
  • Production of piston castings for high-powered diesel engines, wherein the resource-saving effect is achieved by using processes with minimum consumption of auxiliary materials, reducing GS without changing the casting design, creating combined castings (reinforced with metallic and nonmetallic inserts, etc.).
Equipment by UP (Unitary Enterprise) INSTITUTE BELNIILIT making it possible to implement the above-mentioned casting production processes, including metal mold casting equipment for the self-filling method, equipment for piston production, metal mold casting equipment, core sand preparation equipment has been presented.





Русская версия

April 2007        June 2007

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