Search Results for die

In the world, automobile rim production is carried out in a repeatable quality with low pressure die casting process. Traditional die coatings used to separate molds on casting mold surfaces cause significant losses in production due to their weak strength. The applicability of an alternative mold coating application with thermal sprayings has been examined in this study. MgO-ZrO 2 based ceramic thermal barrier coatings are deposited on the mold surfaces by flexicord spray method.

In metal die casting as well as plastic injection molding, controlling the heat balance during the injection and solidification process can lead to fewer defects and a better component quality. An appropriate cooling channel design for the mold can help to control the solidification to a certain extent. But the heat control achievable by cooling channels is limited due to the high effective thermal mass, and therefore near-cavity energy input is of interest. In this paper, a simulation study is performed demonstrating the use of plasma sprayed ceramic coating as a heating coating at the cavity of the mold. The goal is to apply heat faster and locally focused during the solidification process in metal die casting as well as before the injection phase in plastic injection molding. The heat generation of these ceramic coatings is modelled using experimentally measured values and the effects of this approach on defects such as distortion and hot tearing is discussed.

The demand for energy reduction increases every year. In general, reducing the weight of mechanical components is a direct and efficient way to reduce the energy consumption. Therefore, the automotive industry has been growing its use of low-density alloys, as the cases of aluminum and magnesium. High production rate and dimensional precision are need, which narrows the manufacturing techniques suitable. Among the manufacturing processes, high pressure die casting (HPDC) has shown a viable solution. Nonetheless, every process has gaps for improvement. In the case of HPDC tooling is one of the major costs, being responsible for a significant ratio of the final product price. Whereas many articles are focused on the improvement by the development of new materials and thin coatings for HPDC, there is a lack of thermal spray coatings as solution for the wear problems over HPDC. This paper has the focus on showing the use of Cr 3 C 2 25 NiCr as a coating for the components used for HPDC, mainly the ones submitted to direct contact to the metal in fluid state. The idea is to compare the coating with the substrate regarding to thermal fatigue and verify whether it is a viable solution or not.

This study assesses the potential of kinetic-spray coatings for dealing with the effects of soldering and erosion on aluminum casting dies. In the experiments, molybdenum-boride cermet and cobalt-based alloy powders are cold sprayed onto SKD61 substrates. Coating microstructure is assessed via SEM and XRD analysis and several mechanical properties are measured. In order to evaluate soldering resistance, the coatings are immersed in a molten aluminum bath. Although cold-sprayed CoCrNiWC exhibited high coating density and low porosity, its soldering resistance was significantly lower than that of MoB-NiCr. The boride cermet coating not only exhibited superior soldering resistance, but also higher hardness, bond strength, and wear resistance. However, its deposition efficiency needs further improvement.

Superplastic forming (SPF) is an advanced sheet manufacturing process typically used for low- volume, high-value products. SPF dies made from refractory castables have a lower production cost than metal dies, but their brittle nature is a limiting factor. This work investigates surface degradation mechanisms in ceramic dies and how they are affected by the application of thermal spray coatings. Among the more notable accomplishments of the study is the development of a test rig that simulates die-part interface conditions during superplastic forming and monitors die wear, making it possible to predict ceramic die lifetime for different coatings.

The processing of frozen foods places high demands on the strength and edge retention of knives, which are typically made of chromium steels due to their corrosion resistance. In meat processing, in addition to cutting, the knives also assume a transport function, where enormous bending forces can occur. A trade-off between strength and ductility is thus required when choosing a material and heat treatment. This paper describes the implementation of a path-controlled build-up welding system for complicated flat contours and the special properties of a newly developed corrosion-resistant powder optimized for knife edges. Field tests indicate that, with the plasma transferred arc welding process and new powders, service life can be extended by a factor of five. Paper text in German.

Future above-average success factors do not depend solely on a good product and on qualified marketing. The source of success lies in a new type of service to success. Strategic thinking with regard to sprayed surface technology with GTS as a partner. Paper text in German.

This paper assesses the potential of thermal spraying in the context of rapid production tooling. The tooling described, which is intended for sheet metal forming, overcomes the limitations of rapid tooling techniques by leveraging the benefits of rapid prototyping and thermal spray technologies. Paper text in German.

This paper provides a sampling of current and emerging applications for thermal spraying both in manufacturing and in equipment repair. As the examples show, thermal spraying is making an impact in many areas of industry, including automotive, aviation, biomedical, energy, printing, pulp and paper, and textiles, as well as in military and defense. Paper text in German.

High-pressure die casting (HPDC) is a well-established manufacturing process used in the automotive sector to make high-precision components. The necessity to reduce fuel consumption increases the use of low-density components in the automotive industry. Corrosion induced by molten metal is one of many failure modes for dies, changing the die's geometry and surface roughness. All combined wear changes the dimensional precision of the manufactured parts but also the surface quality of the components. Many additive deposition methods are applied to decrease wear and recover the surface. Thermally sprayed coatings can improve the surface properties and recover the geometry of the die caused by the aluminum attack. The main objective of this work is to observe the behavior of the H13, Cr3C2-25NiCr, and WC10Co4Cr coatings deposited by HVOF and HVAF, tested against Aluminum corrosion and Die-soldering tests. After dissolution, the chromium carbide reacts with the aluminum, creating a tough intermetallic interface, and raising the extraction tensile stress. After Aluminum corrosion tests, it was observed that the WC 10Co 4Cr HVAF coating presented low adhesion to the aluminum with no observed coating failure due to the formation of intermetallic. Die soldering tests indicated that the WC 10Co 4Cr protects the substrate, resulting in lower extraction tensile stress than H13 base material and other HVOF coatings. It was possible to observe that WC 10Co 4Cr HVAF coating showed results comparable to AlCrN PVD coating.

High-entropy alloys are of great interest due to their unique phase structure. They are constructed with five or more principal alloying elements in equimolar or near-equimolar ratios and thus derive their performance from multiple elements rather than one. In this work, solid-state cold spraying is used for the first time to produce a FeCoNiCrMn high-entropy alloy coating. As a low-temperature process, cold spraying completely retained the high-entropy phase structure in the coating without any phase transformation. Examination shows that the grains underwent significant refinement due to dynamic recrystallization and that the coatings are much harder than the feedstock powder because of increased dislocation density and grain boundaries.

Advanced spraying technologies as High Pressure-HVOF Spraying or Cold Gas Spraying as well as new concepts for the next generation of plasma sprayed TBC's demanding spray powders with strongly decreased powder grain sizes (< 15µm or even less). Although, with decreasing powder grain size the flowability of the powder is also decreased, causing finally problems in the transport of powder. Within this paper a new powder feeder design will be presented, that makes the precise feeding of ultrafine powders possible, even through feeding lines several meters in length. All known powder feeders for thermal spraying use the pneumatic convey for powder transport through the feeding line. In opposite, the new developed powder feeder is using the dense phase convey of powders. The powder transport can be compared with the transport of a liquid in an hydraulic system. The new powder feeder shows no restrictions in the flowability of a powder. The feeding of normal spray powders (carbides, oxides, metals) as well as submicron powders were successfully tested. Feeding rates from several grams per hour to hundred kilogram and more per hour can be realised, depending on the design of the system. The transport through feeding lines longer than 10 meters also causes no difficulties. The system is self-cleaning and there are no mechanical parts in contact with the powder.

The main purposes of applying the coatings on the surface of different components include the improvement of their functional and decorative properties. The functional properties of coating are strongly dependent on its microstructure. The main goal of the paper is to show the differences of two microstructures that can be obtained using suspension plasma spraying technology: (i) columnar one; and, (ii) lamellar, two-zone microstructure. Initially, the optimization of spray parameters was made and then the microstructural studies were performed. The work was focused on zirconia stabilized by yttria (YSZ) and both by yttria and ceria (YCSZ) which are most frequently used as thermal barrier coatings (TBC). Moreover, two types of microstructure were achieved using two different plasma torches, namely SG-100 of Praxair and Triplex of Sulzer Metco. After optimizing the spray parameters the microstructure of prepared coatings was analyzed using electron microscopy (SEM). The conventional SEM microscopy with secondary electrons detector (SE) and back scattered electrons one (BSE) were used. The energy dispersive spectroscopy (EDS) was performed to analyze the chemical composition. Finally, by electron backscatter diffraction (EBSD) grain shape, size and texture were determined for discussion of the coatings growth mechanism.

For the application as a thermal barrier coating (TBC) the partially stabilized zirconia approaches some limits of performance, which hardly can be overcome in the near future. To further enhance the efficiency of gas turbines, higher temperature and a longer lifetime of the coating are needed for the next generation of TBC´s. This paper presents the development of new materials and concepts for application as TBC. Materials such as compositions with pyrochlore structure or doped zirconias are compared with new concepts like nanolayer between top- and bondcoat, metal-glass composites and double layer structures. One concept is to use new compositions in a combination with zirconia, as a double, multi or graded layer coating. In this case the benefits of zirconia will be combined with the promising properties of the new top-coating. For the concept of metal glass composites the influences of different plasma spraying processes on the microstructure are described. The quality of these coating systems are evaluated by a burner rig test.

This paper presents the results of an emission study on plasma spraying equipment and processes. Various measurements and samples were taken outside the spraying booth, at the operator level, and in the suction ducts upstream and downstream of the filtration equipment, creating a detailed profile of the aerosol emitted by the injection of NiAl powder in the plasma jet. The results show the existence of two families of particles, one ranging in size from 0.5 to 20 µm, the other of nanometric proportions. Concentrations of the larger particles were in the range of 600 cm-3 in the booth. As for submicron particles, concentrations of up to 107 cm-3 were observed but decreased significantly at the outlet of the filter system. The aerosol samples examined were dominated by a nanometric background of aggregates made up of oxidized nickel particles. Aggregates up to 100 nm in size, consisting of finer particles in the 5-20 nm size range, were found in high concentrations upstream of the filtration system. Great vigilance is thus required to protect equipment operators, an important part of which is placing dust collectors as close as possible to spraying booths connected by short, straight pipe runs.

This paper addresses a need for information on nanoparticle emissions and related issues such as worker exposure, filtration efficiency, and dustiness. A survey has been conducted on the working conditions and safety measures used in thermal spray companies and the results compared to scientific literature and previous surveys. Responses to questions on matters of health and safety reveal a lack of information and awareness of the risks posed by the emissions of ultrafine particles generated by thermal spraying processes.

The application of ceramic die coatings on tool steel dies in the casting industry has been common practice for many decades. The main function of these coatings is to provide a thermal barrier to prevent premature solidification during die filling, and protect the tool steel die from the effects of molten metal during casting with aluminium alloys. Although these coatings provide good insulation they are fragile and require on-going in-situ maintenance by machine operators. These inherent poor qualities makes the die casting process difficult to control and to maintain cast product quality because the solidification pattern and porosity changes and leads to increased cast product rejects. To overcome the limitations a novel die coat has been developed for the light metal casting industry utilising thermal spraying of co-deposited MgZrO 2 and polymer particles. The coating is then thermally treated to reveal a fine network of porosity that has been found by heat transfer coefficient testing to enhance the thermal properties and overall coating durability during casting. This paper describes the porosity control system which was used to tailor the heat transfer coefficient of co-deposited MgZrO 2 and polymer coatings and compare them with the heat transfer coefficient of commercially available die coats. The inherent porosity and the overall coating thickness were found to have a large effect on the heat transfer coefficient. Results of industrial trials are also presented and show that co-deposited MgZrO 2 and polymer coatings provide considerable improvements to productivity and enhanced coating life in Gravity and Low Pressure Die casting of aluminium alloys.

Diamond films have been deposited on WC - 6% Co hard metal tools by the DC plasma jet CVD synthesis. The parameters of the process (gas composition, temperature of the gas phase and the substrate, process pressure) as well as of the substrate surface (material, pretreatment) are related to the diamond film growth. For machining abrasive materials the hard and wear resistant diamond coatings must adhere good to the substrate. The wear behaviour of thin diamond films on hard metals under cavitation treatment has been examined. Thus the conditions of diamond synthesis have been varied especially concerning the coating duration and the process pressure and engineering. The cavitation test reacts more sensitive to coating defects of pm size than the conventional testing methods (scratch test, indenter method) and considers the microstructure of the material. Paper text in German.

In order to improve the properties profile of thermally sprayed coats (in particular, the corrosion resistance), the coats are, amongst other items, posttreated with organic and/or inorganic posttreatment media. The coat combinations used are Al 2 O 3 /TiO 2 (87/12), APS-sprayed, and WC-Co (88/12), HVOF-sprayed. Commercially available sealants and two products from other areas of application were used for sealing purposes. The main contribution of the sealing agents to the anti-corrosion protection lies in the fact that they seal open, (inter)connected pores and/or cracks and thus prevent corrosive media from penetrating into the sprayed coat and from reaching the substrate. In this respect, the best results are achieved with sealing agents which form a dense film extending into the pores of the coat. The component underneath can be protected optimally by the combination of the sprayed coat and the sealing agents. Paper text in German.

In this paper, metal matrix composite layers are produced by thermal spraying using cored aluminum wire. Two types of wire were produced, one containing mechanically alloyed Al and Cr 2 O 3 powders, the other, Al and AI 2 O 3 . The powders undergo self-propagating high temperature synthesis during the spraying process, which has a positive effect on coating properties such as bonding, cohesion, and wear resistance. Different spraying methods were used in the experiments, but satisfactory results were only achieved via atmospheric plasma spraying. Paper text in German.