Papers by Keyword: Tool Coating

Abstract: To increase product quality injection molding tools are equipped with innovative tempering technologies. The customers strive for the technology with the lowest energy consumption. Ceramic materials like yttria-stabilized zirconia (YSZ) are able to thermally insulate tool surfaces providing a more precise temperature regulation with intent to shorten cycle times as well as to decrease energy demands during the molding process. High quality ceramic thin films could be applied by metalorganic chemical vapor deposition (MOCVD). Laser machining technologies have been developed for machining the ceramic materials. In this work we demonstrate the fabrication of zirconia based thin films on steel tools via MOCVD using solid metalorganic precursors. Shorter coating times and a solvent free process are some of the advantages of our new developed coating process. The ultrashort pulse laser processing (USPLP) was used to structure the developed MOCVD coating. Using this technology the ceramic material undergoes no thermal stress cracks, because USPLP is characterized by the preference of cold material removal. The laser processing procedure was developed by working out machining parameters for the different materials. The difference between steel and ceramic in the removal behavior was determined immediately so that a machining strategy for the ceramic CVD coating could be designed successfully. The implementation of defined roughness and a carbon fiber like structure in the coating were realized. Coated and laser-structured injection molding tools were tested regarding their desired properties under production conditions.

Abstract: Steel tools, which are used in industrial high-throughput processes like injection molding, are susceptible for wear and corrosion due to rapid cyclic temperature and pressure fluctuation as well as the use of abrasive polymers. For the protection of tool surfaces high quality ceramic thin films can be applied by metal-organic chemical vapor deposition (MOCVD). In addition to protective properties ceramic materials like yttria-stabilized zirconia (YSZ) are able to thermally insulate tool surfaces providing a more precise temperature regulation with intent to avoid the formation of surface flaws, e.g. weld lines, in the later plastic parts. At the same time it enables the shortening of cycle times as well as the decrease of energy demands during the molding process. In this work we demonstrate the fabrication of zirconia based thin films and multilayer systems on steel tools with complex 3D surfaces via MOCVD using metal acetylacetonates as precursor materials. Coating development was carried out by measuring the film thicknesses at different parameter settings. The usage of autonomous liquid flow controllers enables the formation of multilayer systems as well as the control of crystallinity by addition of different dopants to the material. For process development substrates were engineered according to tool geometry containing typical cavities and defined cracks with aspect ratios up to 1:60. That application enables the proof of conformity and the verification of homogeneous film thickness distribution. Exploitation of these results offers the coating of tools, which are tested regarding their desired properties by industrial project partners under production conditions.

Abstract: This paper is to evaluate the cutting force and surface roughness in turning of Glass fiber reinforced plastics (E-glass fiber) using coated carbide insert. The comparison of the results with uncoated carbide inserts. The carbide insert is coated by multilayer chemical vapour deposition process, the coating elements are TiN/Al2O3/TiCN. The experiment is carried out in the conventional lathe machine under dry condition by varying the three cutting parameter such as speed, feed and depth of cut. The cutting force is measured using a lathe tool dynamometer and surface roughness are measured by using surf tester.The result of the experiment shows the effect of machining parameter on cutting force and surface roughness. The results have confirmed that the coated carbide insert has better results than uncoated and tool life is increased.

Abstract: Hot sheet metal forming is gaining in importance in many fields, because of its capability to produce more complex components than possible with cold forming. Hot forming is also used to influence the final material properties with the hot forming of manganese-boron steels being a good example. One of the major challenges in hot forming is the tribological conditions between the tool and sheet material at the required high temperatures. This article will discuss the influence of different tool material coatings, ranging from PVD to mechanically bonded ceramic coatings, on the tribological conditions during forming. It will also shed light on how these coatings influence the heat transfer between the component ́s material and the tool material.

Abstract: For more than three decades, the machining industry has been employing coated tools to enhance productivity via improving tool life. Nonetheless, the problems associated with machining titanium alloys have been still prevalent. Advanced alloy materials such as diamond-like carbon (DLC) coatings are developed to combat these issues. In this study, the performance of a DLC coated tool is assessed and its tool wear mechanisms investigated. For the cutting conditions used during these trials, it has been identified that the DLC coated tool exhibited severe tool wear due to delamination and diffusion in comparison with the uncoated carbide tools. In conclusion, it is suggested that the performance of the DLC coated tools can be enhanced by applying alternate strategies to remove heat from the cutting region.

Abstract: Titanium is a hard-to-machine material. An improvement in tool life via advanced tool coating materials can lead to higher productivity of titanium. In this study, a Grade 5 Ti workpiece was milled using a diamond-like carbon coated (ta-C) cutting tool and its performance compared with the standard TiAlN coated endmill. It was found that a ta-C coated tool experienced higher cutting forces than the TiAlN coated tool; however, it showed slower rate of tool wear indicating better tool life and the possibility of achieving higher metal removal rates. Hence, it was concluded that the ta-C coated cutting tool performed better than the standard TiAlN coated tool.

Abstract: In this paper, based on finite element simulation software AdvantEdge, the effects of different coating materials and thickness on the wear of cutting tools during the machining process have been studied. For the tools with coating materials of TiAlN, Al₂O₃, TiN, TiC, we can calculate the wear rate according to the Usui mathematical model of tool wear, and then consider thickness factor of TiC coating. Because of the lowest thermal conductivity, the workpiece cut by TiC coated tool will soften first and more over cutting time, it result in the lowest wear rate. And with the increase of coating thickness, the effect of "thermal barrier" is more obvious for the relatively thicker coating tool, but the relative sliding velocity between the chip and tool is increasing meanwhile, so a suitable coating thickness is necessary.

Abstract: The large hydrogenated cylindrical shell is an important part of petrochemical pressure vessels. From the macroscopic aspects, the influence that the surface defects of the large hydrogenated cylindrical shells forging blank has on the high efficiency machining was analyzed in the paper firstly. Then, through the chemical point of view, the new chemical components of the shells material were known, and the shells material physical properties were also dissected. The phenomenon of compatibility between the Co element which is in tools material and the siderophile element of the 2.25Cr-1Mo-0.25V steel which is the material of the large hydrogenated cylindrical shell was found. Therefore, the technical performance requirements of the heavy-duty turning tool which is to achieve the goal of high efficiency cutting were put forward. Through researching the chemical and the physical properties of the shell, the new high-efficiency turning tool was designed from the aspects of the tools material and the tools geometric structure. Finally, the comparative test between the new heavy-duty turning tool which was named XF8 and the YT5 tool which was being used in factory was made, and by way of comparing both the service life and the chip-breaking performance of XF8 with YT5s, the test results showed that the XF8 met the requirements of high-efficiency heavy-duty turning, and the feasibility of the tools design scheme was further verified.

Abstract: Nickel-based alloy Inconel718 is a difficult-to-cut material due to lower thermal conductivity, affinity to react with tool material, the cutting tools wear very rapidly due to the high cutting temperature and high cutting force. It is important to choose tool material reasonably. In this paper, cutting performance of the multi-layer CVD-coated (TiN/Al2O3/TiC) tool and PVD-coated (TiAlN) tool were evaluated by cutting temperature, cutting force, tool wear and tool life. The results showed that PVD-coated (TiAlN) tool was suitable for cutting Inconel718.

Abstract: One characteristic of hot stamping of ultra high strength steels is the high wear rate of the used tools which leads to shorter tool life. Coatings improving wear resistance can increase the lifetime of the used tools but process relevant data such as the heat transfer capability of coated tool steels are missing. Within this paper the heat transfer capabilities of coated tool steels for the hot stamping processes are determined. Therefore different coating systems based on AlCrN are applied on the tool steels and the pressure dependent heat transfer coefficient is determined using process relevant conditions. As semi-finished blank the hot stamping steel 22MnB5 with an aluminum-silicon pre-coating is used. With respect to a finite element analysis of the forming operation of the hot stamping process the heat transfer coefficient represents an important input data for the process layout.