Effect of Fluorine Incorporation on DLC Films Deposited by Pulsed Cathodic Arc Deposition on Nitrile Butadiene Rubber and Polyurethane Rubber Substrates

Diamond-like carbon (DLC) and fluorinated diamond-like carbon (F-DLC) films were deposited via pulsed cathodic arc deposition on pretreated nitrile butadiene rubber (NBR) and polyurethane (PU) rubber substrates. Both DLC and F-DLC films showed a more than 50% decrease in coefficients of friction compared to uncoated NBR and PU rubber substrates. The incorporation of fluorine was found to have little influence on the film coefficient of friction. However, a decrease in film wettability was overserved in the F-DLC films compared to the DLC films.

Film Coefficient Optimization for Al2O3 (50%) – CuO (50%)/ Water Hybrid Nanofluid using Taguchi Technique

To have the maximum benefits of nanofluid for high film coefficient, like hybrid composite materials in the material’s revolution, the hybrid nanofluid was prepared and its performance was realized by experimentation. In this investigation, the prepared Al2O3 (50%) – CuO (50 %)/water hybrid nanofluid was used as a coolant for making pen barrel in injection moulding machine. For experimentation, the three process parameters viz., Volume Fraction (VF), Volume Flow Rate (VFR) and Temperature (Temp) were controlled and optimized by using Taguchi’s L9 orthogonal array to yield the maximum film coefficient. To optimize it, total nine different experiments were conducted by controlling these factors. All these three parameters were considered in three levels. Regression equation was established to predict film coefficient by incorporating independently controllable process parameters. Based on the optimization result, it was found that the high film coefficient was achieved at 0.2 %, 6 LPM and 35 °C of VF, VFR and Temp of hybrid nanofluid respectively.

Influence of 3% slip stabilizing paste added to flexographic inks on coefficient of friction of OPP cast film

For a number of years, flexographic printing has been used in the process for the production of flexible packaging as well as other applications where high quality is required. Today, this printing technology is highly automated in all phases of the process. Production time is shorter and product quality is constantly improved. Flexographic inks consist of three main ingredients: pigment, binder and solvent., Each of these components has different functions, however, one depends on the others. Additives used for ink can be of various types. They can be added during ink production or during the printing process to improve printing properties. The film coefficient of friction is one of very important parameters in the flexographic printing process. The determination of static and dynamic coefficient of friction is particularly useful for film substrates that are further processed in packaging and printing machines. The value of the COF is a guide for further processing and refers to the surface structure, which in turn is important for printing. Influencing COF gives packaging manufactures the opportunity to optimize performance and avoid problems during the printing and packaging process, transport, and storage of packaging. In order to examine the effect of the addition of slip stabilizing paste on COF of OPP cast film and on the printing process, a test was carried out in a printing house using the 8-colour UTECO machine with a central cylinder. The amount of 3% additive was added to flexographic ink.

Identification of temperature-dependent boundary conditions using MOR

Purpose A mathematical description of temperature-dependent boundary conditions is crucial in manifold model-based control or prototyping applications, where accurate thermal simulation results are required. Estimation of boundary condition coefficients for complex geometries in complicated or unknown environments is a challenging task and often does not fulfill given accuracy limits without multiple manual adaptions and experiments. This paper aims to describe an efficient method to identify thermal boundary conditions from measurement data using model order reduction. Design/methodology/approach An optimization problem is formulated to minimize temperature deviation over time between simulation data and available temperature sensors. Convection and radiation effects are expressed as a combined heat flux per surface, resulting in multiple temperature-dependent film coefficient functions. These functions are approximated by a polynomial function or splines, to generate identifiable parameters. A formulated reduced order system description preserves these parameters to perform an identification. Experiments are conducted with a test-bench to verify identification results with radiation, natural and forced convection. Findings The generated model can approximate a nonlinear transient finite element analysis (FEA) simulation with a maximum deviation of 0.3 K. For the simulation of a 500 min cyclic cooling and heating process, FEA takes a computation time of up to 13 h whereas the reduced model takes only 7-11 s, using time steps of 2 s. These low computation times allow for an identification, which is verified with an error below 3 K. When film coefficient estimation from literature is difficult due to complex geometries or turbulent air flows, identification is a promising approach to still achieve accurate results. Originality/value A well parametrized model can be further used for model-based control approaches or in observer structures. To the knowledge of the authors, no other methodology enables model-based identification of thermal parameters by physically preserving them through model order reduction and therefore derive it from a FEA description. This method can be applied to much more complex geometries and has been used in an industrial environment to increase product quality, due to accurate monitoring of cooling processes.

Residual Stress Assessment for Pressure Vessel Subject to Thermal Shock

API 579-1/ASME FFS-1 Part 9 provides assessment procedures for evaluating crack-like flaws in components to determine if it is fit for continued service. Although residual stress distribution is required as an input to perform a fatigue life assessment, no procedure or guideline is available for evaluating this crack driving force resulting from thermal shocks. Through a systematic analysis, a conservative residual stress distribution can be obtained for pressure vessels subject to thermal shocks. For the two thick-walled vessels considered, the maximum residual stress occurs when the vessel is half filled with water. The conservative residual stress provides the needed input when using API 579-1/ASME FFS-1 for evaluating crack-like flaws in components. Dependence of the residual stress on film coefficient, temperature difference between water and metal surface, and water level inside the vessel is also presented so that refinement can be made on life assessment when additional field data becomes available.

Robustness of the Tailored Hot Stamping Process

The final mechanical properties of hot stamped components are affected by many process and material parameters due to the multidisciplinary nature of this thermal-mechanical-metallurgical process. The phase transformation, which depends on the temperature field and history, determines the final microstructure and consequently the final mechanical properties. Tailored hot stamping parts – where the cooling rates are locally chosen to achieve structures with graded properties – has been increasingly adopted in the automotive industry. Robustness of the final part properties is more critical than in the conventional hot stamping. In this paper, the robustness of a tailored hot stamping set-up is investigated. The results show that tailored hot stamping is very sensitive to tooling temperature, followed by latent heat radiation emissivity, and convection film coefficient. Traditional hot stamping has higher robustness compared to tailored hot stamping, with respect to the stamped component’s final material properties (i.e. phase fraction, hardness).