Die-casting Molds Research Articles

Control and optimization of defects in die casting of complicated right crankcase cover

The die-casting process of ADC12 aluminum alloy right crankcase cover was simulated based on AnyCasting software, and the influence of pouring temperature, initial mold temperature and injection speed on the filling and solidification process of ADC12 right crankcase cover casting was explored by orthogonal experiment method. The optimal process parameters were obtained through optimization, and the die-casting mold was designed. The program was verified in production. The results show that the porosity and shrinkage of the right crankcase cover are mainly concentrated in the thick wall part. The sequence of process parameters that affect the residual melt modulus is pouring temperature, initial mold temperature, and injection speed; The best combination of process parameters: pouring temperature is ∼680 °C, initial mold temperature is ∼200 °C, injection speed is ∼5 m/s. By analyzing the filling process and temperature field simulation results, the casting structure, mold structure and cooling system were optimized, and the process plan was improved. The production verification was carried out according to the optimized process plan. The casting quality is good and has no obvious defects, which meets the actual production needs.

Microstructure characterization and high-temperature wear mechanism of high-entropy alloy matrix composite coating fabricated by laser cladding

The development of diecasting technology requires hot die steels with high-temperature resistance. In this study, a high-entropy alloy (HEA) was combined with ceramic particles to generate a CoCrFeNiMo0.2Nb0.2/WC composite coating via laser cladding. The coating consisted of a face-centered cubic (FCC) matrix with unmelted WC particles, eutectics and nanoscale (Mo)NbC phases. With the strong lattice distortion caused by the sequestration of W atoms, a nanoscale amorphous layer existed between the Laves and HEA matrix phases. A transition layer with the same structure as the Laves phase was facilitated between the WC particles and the HEA matrix. Due to the hard phases in the HEA matrix and their interfaces, the composite coating with a high proportion of WC exhibited excellent wear resistance under high-temperature dry friction conditions. When the WC was 60 wt%, a minimum wear rate reached to 0.74 × 10−5 mm3/(N·m) at 600 ℃ and 1.46 × 10−5 mm3/(N·m) at 800 ℃. The destruction pattern of the composite coating at 600 ∼ 800 °C was due to the interaction of the adhesive, oxidative and abrasive wear. The composite coatings fabricated in this study provide a route to enhance the high-temperature wear resistance of die-casting molds.

Development and Process Integration of an Alternative Demoulding System for High-Pressure Die Casting Using a Contoured Vacuum Mask

This study presents the development and process integration of an alternative demoulding system for high-pressure die casting. The system is aimed at the removal of large structural castings, which are becoming increasingly popular in the industry under the terms mega- and gigacasting. The development differs from conventional systems in the fact that it completely avoids ejectors and realises the demoulding via the principle of vacuum suction cups. Preliminary tests were carried out in which various established materials for vacuum cups were initially identified and the suitability of the selected cup concept was investigated by varying influencing variables from the high-pressure die casting. These tests showed that a suction pad material combination of an elastomer with a thermal barrier and an aramid felt on the surface provides the best results under the given process boundary conditions. Based on this, a multi-segmented vacuum mask with contour adaptation to the casting to be removed was developed. This vacuum mask is used to build up the holding force between the casting and the removal device. The necessary removal force is applied via pneumatic cylinders. The functional capability of the concept and the system integration was verified by experiments on a real die-casting mould for test specimens. The shrinkage and demoulding process can be successfully modelled in the simulation and the real measured demoulding force is only approx. 15% higher than in the simulation. During demoulding in the high-pressure die-casting process, vacuums of up to 88.7% were achieved at temperatures up to 395 °C.

Matheuristic and learning-oriented multi-objective artificial bee colony algorithm for energy-aware flexible assembly job shop scheduling problem

With the increase of mass customization, flexible job shop scheduling problem considering assembly stage has widely existed in many manufacturing industries, such as die-casting mould factories. This problem is to find a reasonable machine assignment and operation sequence both in fabrication and assembly stages and simultaneously maximize production efficiency. In reality, energy shortages and environmental pollution have given an impetus to the development of energy-aware production scheduling problems. In this study, we address an energy-aware flexible assembly job shop scheduling problem (EFAJSP) with the objectives of minimizing flow time and energy consumption and first develop a mixed-integer linear programming (MILP) model to solve EFAJSP problem. Then, the model-specific characteristics are extracted and applied to a matheuristic decoding method for exploring the Pareto optimal solution. Due to the complexity of EFAJSP problem, a matheuristic and learning-oriented multi-objective artificial bee colony algorithm (MLABC), which combines the advantages of mathematical programming, reinforcement learning and meta-heuristic algorithm, is proposed. In addition, an initialization, destruction/construction operator and population update operator are proposed and work together to improve the exploration and exploitation performance of the proposed MLABC. Finally, numerical experimental results demonstrate the effectiveness of the proposed MILP model and the superiority of the MLABC over other algorithms in the literature.

Die soldering and corrosion failure of high temperature tool steel for high-pressure die casting Al alloy

High-pressure die casting (HPDC) is regularly used to produce aluminum components. The die-casting molds are subjected to severe localized corrosion due to contact with the hot melted aluminum (700 °C) and accelerated by the intense thermal cycling generated by the cooling system. The correct understanding of each failure mode that occurs during the operation of these molds can increase tool life and reduce operational costs. Different components used in aluminum components production were evaluated after completing their useful tool life, and the failure modes were compared with two high-temperature laboratory tests, molten aluminum corrosion and die soldering tests. The primary crack mechanism observed in the HPDC die was heat checking, with a surface reaction of the tool steel with the molten aluminum. PVD coating increases the die's tool life, reducing the reactivity with the molten aluminum, which was observed in both laboratory tests. Die soldering tests represent the die mold behavior in HPDC production, showing a similar intermetallic phase and crack formation. Laboratory corrosion tests showed a more aggressive corrosion behavior than that observed in molds and dies used in HPDC industrial production.

DEVELOPMENT OF OPTIMAL TECHNOLOGICAL PARAMETERS FOR PLASMA COATING DEPOSITION

This paper considers using ion-plasma spraying of mold surfaces. This makes it possible to replace scarce and expensive tungsten-containing steels with other materials. 4Х5МФС and 5ХНМ steel grades were chosen as materials for copper alloy die-casting molds in this work. The choice of these steel grades is due to the fact that these steels do not contain tungsten due to its sharply increased scarcity and limited molybdenum content, and they also meet the requirements for the substrate material on which the titanium nitride coating is applied. Coatings were applied to samples for laboratory tests and die-casting mold parts by the condensation method with ion bombardment. Titanium nitride is applied at different partial nitrogen pressures – from 310-3 to 1 Pa to determine the required nitrogen pressure, which ensures that the working surfaces of mold parts receive coatings with the best performance haracteristics. The coatings obtained at different nitrogen pressures differ in the amount and size of the droplet phase. The largest amount of the droplet phase containing α-Ti is observed in coatings obtained at nitrogen pressures of 310-3, 310-2 Pa. An increase in nitrogen pressure (410-1, 1 Pa) significantly reduces the level of microdistortions of the crystal lattice in the coating, and its plasticity increases. In this regard, the coating's brittleness is reduced at a sufficiently high hardness. The titanium nitride coating obtained at a nitrogen pressure of 1 Pa is the most effective in protecting the working surfaces of mold parts from destruction. Laboratory tests have shown that the titanium nitride coating applied under optimal process parameters increases the corrosion resistance of mold parts to which it is applied by 3 times and the scale resistance by 2–4 times.

Modelling smart machining process towards intelligent manufacturing - a case study

According to the concept of Industry 4.0 (even Industry 5.0) managers strive to improve production by applying information technologies and next integrating them into operational technologies, that’s enabled to transform the traditional into Intelligent Manufacturing (IM). Introduction of these changes is particularly important to improve the machining process, which is complex and dynamic. In this article the smart machining process is modelled and demonstrated for a real-world case, namely manufacturing of the die casting mould in order to increase life of the die casting mould. Therefore, firstly, the data was acquired based on the applied within a company information system and additionally on the IoT sensors from the diecasting machines, the moulds themselves and the process parameters which are used during the manufacturing process of the diecasting parts from such mould. Next, a model for predicting the life of the die-casting mould using regression analysis, based on acquired data was applied. The results of mould design and mould manufacturing process are ultimately visible on the die casting machines. Such gathered data is used to model the prediction of the possibilities for increasing life of the die casting was elaborated.

Studying the new modes of deposition of plasma coatings

Problem. This paper considers using ion-plasma spraying of mold surfaces. This makes it possible to replace scarce and expensive tungsten-containing steels with other materials. Purpose. The purpose is to study the possibility of using the KIB method to increase the stability of die-casting molds, to establish the possibility of replacing scarce, expensive tungsten-containing steels with other materials. Materials and methods. 4Х5МФС and 5ХНМ steel grades were chosen as materials for copper alloy die-casting molds in this work. The choice of these steel grades is due to the fact that these steels do not contain tungsten due to its sharply increased scarcity and limited molybdenum content, and they also meet the requirements for the substrate material on which the titanium nitride coating is applied. Coatings were applied to samples for laboratory tests and die-casting mold parts by the condensation method with ion bombardment. Titanium nitride is applied at different partial nitrogen pressures – from 3×10-3 to 1 Pa to determine the required nitrogen pressure, which ensures that the working surfaces of mold parts receive coatings with the best performance characteristics. The coatings obtained at different nitrogen pressures differ in the amount and size of the droplet phase. Results of experiments. The largest amount of the droplet phase containing α-Ti is observed in coatings obtained at nitrogen pressures of 3×10-3 Pa, 3×10-2 Pa. An increase in nitrogen pressure (4×10-1 Pa, 1 Pa) significantly reduces the level of microdistortions of the crystal lattice in the coating, and its plasticity increases. In this regard, the coating's brittleness is reduced at a sufficiently high hardness. Results. The titanium nitride coating obtained at a nitrogen pressure of 1 Pa is the most effective in protecting the working surfaces of mold parts from destruction. Laboratory tests have shown that the titanium nitride coating applied under optimal process parameters increases the corrosion resistance of mold parts to which it is applied by 3 times and the scale resistance by 2-4 times.

Enhanced Anti-Corrosion Performance of Co-Cr-Mo Alloy in Molten Al by Prior Oxidation Treatment

Co-based alloys are promising alternatives to replace the currently used tool steels in aluminum die-casting molds for producing sophisticated products. Although the reaction is significantly less severe compared to that of tool steels, bare Co-29Cr-6Mo (CCM) alloy is still gradually corroded under molten Al, leading to the local failure of the alloy due to the formation of intermetallic compounds between the matrix and molten Al. This study indicated that prior oxidation treatment at 750 °C on CCM alloy is beneficial in enhancing the corrosion resistance of the alloy to molten Al. The is more pronounced in the alloy after a longer oxidation treatment. However, after oxidation for longer than 24 h, the protectiveness of the film cannot be enhanced anymore. In addition, even after the full failure of the oxide film, the thickness loss rate of a sample with prior oxidation treatment is much lower than that of a bare sample. This can be attributed to the fact that network-aligned oxide particles of the cone structure boundary inhibit both the outwards movements of alloying elements and the dissolution of the intermetallic layer.

Development Trend in Composition Optimization, Microstructure Manipulation, and Strengthening Methods of Die Steels under Lightweight and Integrated Die Casting.

In the general environment of lightweight automobiles, the integrated die-casting technology proposed by Tesla has become the general mode to better achieve weight reduction in automobiles. The die-casting mold required by integrated die-casting technology has the characteristics of large scale and complexity. Hence, higher requirements are put forward for the comprehensive performance of the die steel. Despite the stagnation in the progress of conventional strengthening methods, enhancing the performance of die steel has become increasingly challenging. Indeed, it necessitates exploring novel die steel and optimizing heat treatment and reinforcement technologies. This article summarizes and analyzes the development status of die steel and corresponding heat treatment and microstructure manipulation as well as strengthening methods and elaborates on an excellent nano-strengthening technology. Furthermore, this review will aid researchers in establishing a comprehensive understanding of the development status of die steel and the processes utilized for its strengthening. It will also assist them in developing die steel with improved comprehensive performance to meet the high demand for mold steel in the integrated die-casting technology of the new era.

Preparation and Thermal Conductivity of Copper Plated Carbon Fiber Dispersed Steel Matrix Composites

Since the die-casting mold repeats rapid heating and cooling during operation, the defects such as heat checks generate. Therefore, the quality and the life of the mold are degraded. To improve these demerits, the improvement of the thermal conductivity of the mold material is effective. In this study, carbon fibers were added to SKD61(40CrMoV5) tool steel to fabricate the composites with high thermal conductivity. Since carbon fiber has a chemical reaction with steel, electroless copper plating was applied to carbon fiber to suppress the reaction. The composites were fabricated by the unidirectional arrangement of carbon fibers and spark plasma sintering. The results obtained are as follows. 1) Carbon fiber/SKD61(40CrMoV5) composites with a high relative density were obtained. It is considered that the copper plated on the carbon fiber acted as a sintering accelerator. Furthermore. the plated copper remained around the carbon fibers in the composite, and it seems copper prevented the direct reaction between carbon and steel. 2) The composites had higher thermal conductivity than the monolithic SKD61(40CrMoV5) block. As increasing the carbon fiber content, the thermal conductivity increases. 5vol.% copper-plated carbon fiber/SKD61(40CrMoV5) composites have a thermal conductivity of 42 W /mK.

Electrochemical milling of deep-narrow slots with a pulsating electrolyte flow field

Deep-narrow slots (DNSs) (width<4 mm and depth/width>2 mm) are inherent features in die-casting molds as heat-dissipating slots and turbomachinery components for seal slots. Electrochemical milling (EC-milling) is a flexible method to machine variety of structures by controlling the tool path. The process employs a tubular tool with a flat end face through which the electrolyte is supplied coaxially. However, owing to the small inter-electrode gap (IEG), the quantity and velocity of electrolyte flowing into the IEG are weakened during machining of DNSs. This reduces the machining quality and efficiency. Therefore, this paper proposes a method of EC-milling of DNSs with a pulsating flow field. A tubular tool with a wedge-shaped end face (WS-tube) is designed, and both the quantity and velocity of electrolyte flowing into the IEG will be changed with the rotation of WS-tube. Thus, a pulsating flow field is generated which can enhance the mass transport in the IEG. Consequently, both the machining efficiency and quality are improved. Flow-field simulation results indicate that as compared with the traditional flat end face tube (F-tube), WS-tube can generate a periodic pulsating flow field in both front and side IEG, and the peak electrolyte flowing velocity is also increased. The experiment results reveal that compared to that of 0.24 mm/min with F-tube, the maximum feeding speed reaches to 0.42 mm/min with WS-tube, and both the surface quality and taper are improved at the same time. Increasing the rotation speed of tube tool and pulse frequency further enhances the transport of electrolytic by-products, and the machining quality is improved. With the optimized parameters, a 5 mm deep DNS with width of 1.48 mm ± 0.02 mm, taper of 1.44° ± 0.27° and the surface roughness (Ra) of 0.7 µm has been successfully fabricated. • Pulsating flow field was proposed for electrochemical milling of deep-narrow slot. • A tube tool with wedge-shaped end face was designed to generate pulsating flow field. • With the rotation of wedge-shaped tube tool, pulsating flow field was generated in both front and side inter-electrode gap. • Both the machining quality and feeding speed of DNS were improved with pulsating flow field.

정밀금형용 SKD61 강의 복합표면처리에 의한 표면신뢰성 향상

Purpose: The lifespan of a die-casting steel mold depends on its surface hardness and wear resistance. Gas nitriding treatments for forming surface hardening layers have been widely applied to fabricate reliable die-casting molds. In the present study, we propose a complex surface treatment consisting of a micro-shot peening process and a sulfo-nitriding treatment to improve the surface hardness of SKD61 mold steel.BRMethods: The cross-sectional microstructure of the complex surface-treated SKD61 mold steel was observed using an optical microscope and a scanning electron microscope. The phase of the surface hardening layer was analyzed using an X-ray diffractometer. The micro-hardness and residual stress of the complex surface-treated SKD61 mold steel were evaluated as well.BRResults: The surface hardening layer consisted of the top-most compound layer and a diffusion layer. The micro-shot peening pretreatment increased the thickness of the compound layer. The general nitriding (GN) treatment led to the formation of the FexN compound layer, while the sulfo-nitriding (SN) treatment led to the formation of the FexN and FeS composite compound layer, which was thicker than the compound layer of the GN specimen. The hardness of GN and SN hardening layers improved by 125% and 135%, respectively, relative to that of the as-received SKD61 mold steel with a hardness of 450 HV.BRConclusion: The SN treatment formed a reliable hardening layer with superior hardness than the GN treatment. Furthermore, the thicker sulfo-nitride compound layer produced by the SN treatment can further improve the lifespan of SKD61 steel molds.

Improving the quality of AISI H13 tool steel produced by selective laser melting

AISI H13 tool steel is intended for making various tools and die-casting molds, which generally are of complex shapes. The application of selective laser melting (SLM) can significantly speed up their production, but it is accompanied by the appearance of various defects, such as high surface roughness, cracking, and reduced density. In particular, there is a fairly limited amount of data on the influence of SLM process parameters on the surface roughness of tool steels. The aim of this work is to study the possibility of improving the quality of AISI H13 steel by varying laser power and scanning speed during SLM. Optical profilometry and microscopy are used as methods of investigation, with statistical data analysis being carried out. It has been discovered that both surface roughness and porosity can be effectively influenced by varying the laser power and scanning speed during SLM. A direct relationship between surface roughness and porosity has been established, and this makes it possible to control effectively the quality of AISI H13 tool steel produced by selective laser melting. Steel of the highest quality with the lowest surface roughness and porosity has been obtained at a laser power of 250 W and a scanning speed of 350 mm/s. It has also been found that varying laser power and scanning speed does not prevent crack formation, and other technological solutions should be sought to eliminate cracking.

A Development of Computer Aided Program for Aluminium Die-Casting Mold Design

A Development of Computer Aided Program for Aluminium Die-Casting Mold Design

Structural Design of Die-Casting Die for Industrial Cabinet Lock Handle Based on Pro/E

This paper uses Pro/E and CAD software to carry out the design of die-casting mold structure for industrial cabinet lock handle.Firstly, the three-dimensional modeling, process analysis and calculation of the handle parts are carried out, and then the solid model is established.The die-casting machine is selected according to the clamping force. Finally, the opening and closing die is simulated, and the general assembly drawing of the die-casting die is drawn to ensure the cooperation with other parts without interference, which is of certain guidance to the actual production.

MQL assisted face milling of EN-31: Tool wear optimization and its correlation with cutting temperature

EN-31 is one of the difficult-to-cut steels that has applications in the manufacturing of die-casting moulds, high-strength bearing, and several heavy automobile parts. Generation of heat while cutting such material is the principal cause of tool wear and diminishing surface qualities of a machined part. The application of lubricant lowers the temperature of machining but the excess use of lubricant is responsible for increasing the overall cost of machining. Also, due to health and environmental concerns related to lubricant exposure, the application of the Minimum Quantity Lubrication (MQL) technique as an alternative to flood cooling is increased in recent times. In this work, an attempt is made to increase the effectiveness of the MQL technique by optimizing the parameters associated with it. The face milling experimentation on EN-31 steel is accomplished by arranging MQL parameters using Taguchi’s method-based L18 orthogonal array. CRITIC approach is exploited to determine the correlation between the tool flank wear and cutting temperature. The optimum parameter setting for tool flank wear is discovered as 150 ml/h lubricant flow rate, 40 mm spraying distance, 60 % lubricant concentration, and 45° nozzle elevation angle. A reduction of 2.10 % in the value of the flank wear is achieved at the optimal MQL parametric settings.

Layout Design and Die Casting Using CAE Simulation for Household Appliances

Due to the development and industrialization of science and technology, aluminum alloys have been developed in various fields. Recently, the government has been pursuing ways to decrease the weight and increase the recyclability of various components in order to conserve resources, energy, and the environmental. In keeping with this trend, cast iron products are being replaced by aluminum products in the foundry industry by using high-pressure die casting (HPDC). Casting layout design, relies on the experience and knowledge of mold designers in the casting industry, which proves insufficient to respond to the rapidly changing needs of the era and to increasing production costs. Designing and producing casting layouts using CAD/CAM/CAE technology has become a critical issue. Computer-Aided Engineering (CAE) technology is rapidly increasing with the development of computer software and hardware. CAE technology not only predicts defects in mass production but also performs filling or solidification analysis during the mold design stage before production, enabling optimal mold design methods. New technologies that combine the emerging casting processes of filling and solidification analysis using computer simulation with existing technology and practical experience in the field are rapidly increasing in the foundry industry. Based on empirical knowledge, the layout and design of casting products has traditionally progressed through trial and error. The solutions achieved through scientific calculation and analysis using CAE technology can save a great deal of money and time in the building of die-casting molds and in their design and fabrication. In this study, numerical analysis of household appliances (cooking grills) quickly and accurately predicts problems arising from the filling and solidification of the melted metal in the casting process, thereby ensuring the quality of the final cast product. These results can be used to quickly establish a sound casting layout with reduced production costs.

Corrosion behaviors of CoCrWAlx alloys by laser additive manufacturing in molten Al

The CoCrW alloy was widely used for aluminum alloy die-casting mold of auto industry owing to excellent high temperature strength and corrosion resistance. However, the corrosion mechanism of cobalt-based alloy in molten Al has not been researched clearly, which inhibited improvement in resisting corrosion and service performance further. The CoCrWAlx alloys were prepared by direct laser deposition and the wetting and corrosion mechanism in molten Al were investigated. The microstructures of CoCrWAlx alloys and solid-liquid interface reaction products were characterized comprehensively. The CoCrWAlx alloys contained cobalt solid solution and precipitates that increased with Al. The reaction interfacial structure was composed of five sub-layers: alloy substrate, two products sub-layers, diffusion layer and solidified Al, and reaction products were identified to Al9Co2, Al5Co2 and Al45Cr7 phases. The growth kinetics of product layer and sub-layers were investigated and corresponding theoretical growth models of single and double compound layers were established. The effects of Al addition on corrosion resistance of cobalt-based alloys were analyzed with experiment and phase boundary wetting theory. The 2Al alloy obtained the lowest rate of product layer growth and corrosion loss among all alloys due to increased precipitates and strengthening matrix reduced both reaction-diffusion of molten Al and dissolved alloy substrate. The intrinsic affecting mechanism of adding Al into alloy to resist molten Al was investigated and provided an effective way to improve the corrosion resistance.

Enhanced cooling channel efficiency of high-pressure die-casting molds with pure copper linings in cooling channels via explosive bonding

The cooling efficiency of aluminum die-casting molds is critical to prevent soldering, extend mold life and manufacture high quality castings. In this paper, we discuss a method of inserting a pure copper (Cu) lining using explosive expansion bonding process. A pure Cu bush was inserted into a cooling channel of die casting mold and bonded to the inner surface of the cooling channel through explosive bonding technology to form a copper lining in the cooling channel to improve the cooling performance of high pressure die casting (HPDC) mold fabricated from SKD61 material. Furthermore, the microstructure and mechanical properties of the bonding zone between the SKD61 tool steel and pure Cu lining were analyzed. By changing the thickness of the Cu bush, stand-off distance between the Cu bush and the predrilled cooling hole, and mold heat treatment sequence, the optimal explosive bonding process parameters were established for these cases. A high-frequency induction heating-cooling system was used to examine, the performance of the cooling channel sample bonded with pure copper lining, and it was confirmed that the cooling rate was improved by 12 %. After inserting the pure copper lining into the cooling channel for a practical die casting application, it was confirmed that the mold temperature was lowered, and soldering was prevented. The explosive bonding technology used in this study is an effective method to bond pure copper lining onto the inner surface of a cooling channel, thereby providing an alternative approach to increasing the cooling efficiency.