Proper Process Parameters Research Articles

A Classification-based Solution For Recommending Process Parameters of Production Processes Without Quality Measures

Abstract For production of sheet metal parts for car bodies, an adjustment of process parameters is required to maintain the desired part quality in presence of scattering blank properties. The digital transformation enables the application of data-driven methods for finding process parameters instead of a time-consuming experience-driven trial-and-error approach. However, due to cost and technical limitations, it is still hard to measure quality for every part. Removing data points of low-quality parts helps recommending proper process parameters. In this paper, we propose classification-based solution for recommending process parameters. In data preprocessing, the solution utilizes anomaly detection and knowledge-based methods to remove potential data points of low-quality parts without quality measures. On the processed data, a classification model is trained to predict process parameters according to blank properties. Our solution detects 30% low-quality parts and gives competitive performance (92.26% prediction accuracy) compared to a model trained on data comprising quality measures.

Application of Hot Press Bending for Shaping a Stack of HTS Tapes Operating as a Trapped Flux Magnet

Trapped-flux magnets made of stacks of superconducting tapes are an interesting and important alternative to the application of rare-earth permanent magnets and trapping flux in bulk superconductors. Many applications, such as electric motors, can require the complex shapes of magnetic elements to combat issues such as demagnetization during the operation. Therefore, a reliable production technique of high temperature superconductor (HTS) stacks with different geometries is required to meet the needs of industry. In this article, a method of shaping the epoxy-glued stacks of superconducting tapes is proposed and investigated. The application of hot press allows to easily change the shape of the stack. The influence of shaping the stack on the density of trapped magnetic flux as well as critical current are presented. Experimental and numerical analyses are performed and their results are matched to find the change in the superconducting properties of the tapes. They show that with the proper process parameters the stacks can be shaped with only minor decrease of performance. However, strong degradation is observed if the applied force is too high. The observed problems are discussed and the possible solutions are proposed.

Polymer self-heating during incremental forming

• Polymer sheets are formed by Incremental Forming with the aid of frictional heating. • The temperature is controlled as a function of tool rotation and traveling speed. • The influence of the temperature on significant process features is investigated. • A thermo-mechanical numerical model is developed with a commercial FEM code. • A phenomenological model of the heat exchange is described. The study investigates the suitability of friction heating, generated by the forming tool rotation, to form polymer sheets during single-point incremental forming, and the possibility to control the temperature of the sheet by the selection of proper processing parameters. Polycarbonate sheets were formed to produce a square pyramid frustum geometry, varying the tool rotation speed and the traveling speed and monitoring the temperature. Load measurements were performed during the process, as well as the evaluation of the surface roughness and the elastic springback, to determine the influence of these processing conditions. Moreover, a thermo-mechanical numerical model was developed to understand the main phenomena involved. The results confirmed that the processing temperature, which increases with the tool rotation speed and decreases with the traveling speed, influences the sheet forming process and can be controlled by the selection of the processing speeds. A phenomenological model of the heat exchange was introduced to better explain the temperature evolution during the process and how it is influenced by the processing speeds.

Controlling liquation behavior and solidification cracks by continuous laser melting process of AA-7075 aluminum alloy

Microstructure homogeneity, uniform elements distribution, and good mechanical properties are the main research challenges after the continuous laser melting (CLM) process. Adding modifiers to the AA7075 and selecting the proper process parameters are solvers for this challenge. Thus, this paper studies the effect of the CLM on the microstructure, elements distribution, and the microhardness of AA7075 with different modifier contents. The CLM process was carried out with a 300 V power and 0.1 m/s laser scanning speed. The microstructure and elements distribution of the standard and the modified alloys after the CLM were analyzed. The obtained structure was fine with a uniform distribution of elements in all alloys except modified alloy with Fe + Ni. Microhardness was enhanced after the CLM, and the modified alloys with Fe + Ni and Sc + Zr recorded the highest microhardness values in the laser melted zone (LMZ).

Effect of compaction pressure on mechanical properties of AA7075/B4C/graphite hybrid composite fabricated by powder metallurgy techniques

Composite materials are at top in material selection process due to its superior mechanical and tribological properties, properties of a composite can be modified by reinforcing different hard ceramic particles in a matrix material depend upon the requirement needed. Strength of the composite can be improved by creating good interface bond between matrix and reinforcements which can be achieved by selecting proper processing parameters i.e., compaction pressure, sintering temperature, sintering time. Present work focuses on fabrication of AA7075/B4C/Graphite hybrid composite by varying the compaction pressures while cold compaction process. In AA7075 matrix material 6 wt% Boron carbide (B4C) and 2 wt% graphite was added to optimize the ductility and brittleness of the composite material. Mechanical response of the hybrid composite was noted in compression and hardness tests, results reveal that increased compaction pressure has very positive impact on mechanical properties of the composite material, micro structural analysis reveals effect of increased compaction pressure clearly.

Process parameters selection in manufacturing of sharp conical parts based on Taguchi design of experiments

Among the sheet metal forming processes, hydrodynamics deep drawing and hydromechanical deep drawing process are two main types of the deep drawing process that can fabricate complicated parts. In the hydroforming process, the blank is formed to the desired shape by applying a considerably high hydraulic pressure. In this article, the selection of the process parameters will be investigated during the manufacturing of a pure copper sharp conical part by finite element analysis and experimental tests. Two finite element models are developed for hydrodynamics deep drawing and hydromechanical deep drawing processes. After verification of the FE model by experimental results, the effect of process parameters includes the applied pressure, friction coefficient, die radius and blank holder force on thinning of the blank are investigated. The thinning ratio of blank is calculated in different zones of the conical part under different working conditions determined according to the Taguchi design of experiment methods. Signal to noise ratio analysis has been carried out and the influence of process parameters on the thinning ratio is determined at different zones of the conical part. The results show that the friction coefficient has an important role in the thinning of the conical nose while at the lateral surface of the cone, the die radius is the most effective parameter on the thinning ratio. The results show that by implementing statistical tools (Taguchi method and signal to noise ratio analysis), it is possible to select the proper process parameters conditions and fabricate defect-free parts. In addition, a non-linear regression equation is developed for prediction of thinning ratio in the hydrodynamics deep drawing and hydromechanical deep drawing processes.

Synthesis of graphene flakes using a non-thermal plasma based on magnetically stabilized gliding arc discharge

The use of non-thermal plasma at atmospheric pressure has emerged as a technique for the substrate-free, gas-phase synthesis of graphene nanoflakes (GNFs). In this paper, a non-thermal plasma based on magnetically stabilized gliding arc discharge (MSGAD) was employed to prepare GNFs. The effects of the carbon-containing precursor, plasma gas, and arc current on the GNFs synthesis were investigated. The technique produced GNFs with sizes of 50–200 nm and 1–20 layers, spherical carbon nanoparticles with 10–40 nm diameters, and graphitic particles. The results showed that the formation of GNFs depended on the selection of proper process parameters, such as precursors with a high H/C ratio, an Ar-N2 plasma gas, a low arc current, a low precursor flow rate, and a suitable plasma gas flow rate. Correlations between the process parameters and the product morphology indicated that abundant H atoms and fewer polycyclic aromatic hydrocarbons were favorable for the formation of GNFs.

Optimisation of edge quality on stainless steel 316L using low power fibre laser beam machining

ABSTRACT In the manufacturing industry critical importance lies upon the dimensional accuracy of a machining part especially for precision assembly operation in sheet metal cutting. But the converging diverging shape of the laser beam profile causes the existence of kerf taper in laser cut specimen. Use of low power fibre laser beam machining in the order of 50 watt makes it extremely difficult to perform good quality cut on stainless steel sheet metal. Cutting wedge angle, a relatively uncommon process variable performs a critical role for the determination of unevenness in kerf characteristic. Cutting result of kerf taper with a 50-watt fibre laser is presented in this investigation. The purpose of the investigation is to reveal the ability of the low power fibre laser to cut stainless steel AISI 316 L with 1 mm thickness. The effect of the cutting wedge angle and other process variables like power, duty cycle, pulse frequency and scanning speed has been analysed through an application of Response Surface Methodology (RSM) with CCD technique. Validation of experiments on the proposed model reveals that adjustment of proper process parameters can optimise the required edge quality.

Welding parameters prediction for arbitrary layer height in robotic wire and arc additive manufacturing

In wire and arc additive manufacturing, the weld bead geometry determined the slicing layer height, which was decided by the welding parameters. Generally, the determination of the welding parameters relied on empirical and experimental data through the trial-and-error methods that incur considerable time and cost. To obtain the proper welding process parameters according to the desired single bead geometry and layer height, a full factorial experimental design matrix was applied to collect the original data of welding parameters and bead geometrical variables. A forward artificial neural network (FANN) was built to predict the bead geometry form the welding parameters. Then, a closed-loop iteration method combined a genetic algorithm (GA) and the FANN model (FANN-GA) was developed to search for the most optimal welding process parameters in accordance with the selected bead geometrical variables. The results confirmed that the FANN-GA model has a good performance on the backward prediction of the welding process parameters compared with the direct backward artificial neural network (BANN). Several groups of single layer multi-bead and multi-layer multi-bead experiment were performed to testify the proposed method, and the relative error between the desired and actual layer height was small. The proposed method makes it possible to fabricate the component with an arbitrary desired layer height, and could be used in the adaptive slicing additive manufacturing or surface coating.

The effect of moulding process parameters on interlaminar properties of CF/PEEK composite laminates

Interlaminar properties are one of the most important indicators of thermoplastic composite quality. A series of laminates with different moulding process parameters were prepared by unidirectional carbon fibre-reinforced polyether ether ketone (CF/PEEK) prepreg to explore the influence of moulding process parameters on the interlaminar properties of CF/PEEK composite laminates. The influence of the three process parameters, moulding pressure, moulding temperature, and holding time on the interlaminar shear strength (ILSS) of [0/90]8 laminates was studied. The interlaminar shear failure modes of specimens under different moulding process parameters were compared, and the correlation between the ILSS and interlaminar shear failure modes was analysed. The results showed that the appropriate moulding pressure was 2 MPa, the proper moulding temperature range was 400–420°C and the holding time should not be less than 20 min. The main failure modes were tensile or compression when the laminates were moulded using proper process parameters; interlaminar shear failure might also appear in those moulded by non-optimised process parameters.

Uncovering Technological and Environmental Potentials of Aluminum Alloy Scraps Recycling Through Friction Stir Consolidation

Conventional metal chips recycling processes are energy-intensive with low efficiency and permanent material losses during re-melting. Solid state recycling allows direct recycling of metal scraps into semi-finished products. It is expected that this process category would lower the environmental performance of metals recycling. Friction Stir Consolidation is a new solid-state technique taking advantage of friction heat generation and severe plastic deformation to consolidate chips into billets. In this research, the feasibility of Friction Stir Consolidation as aluminum chips recycling process is analyzed. Specifically, an experimental campaign has been carried out with varying main process parameters. Three main aspects have been evaluated in order to highlight products quality and environmental impact of the process: (i) metallurgical and mechanical properties of the consolidated products; (ii) primary energy demand, as compared to conventional processes; (iii) forgeability of the consolidated products, as compared to parent material. Results revealed that a proper process parameters selection results in fully consolidated aluminum disk with satisfactory mechanical properties. Also, the new recycling strategy allows substantial energy savings with respect the conventional (remelting based) route.

Selective laser sintering and post-processing of sisal fiber/ poly-(ether sulfone) composite powder

Selective Laser Sintering (SLS) technology can be utilized to recycle residues from forestry and agriculture, thereby alleviating shortages of materials and reducing energy consumption by producing wood-plastic pieces for industrial application. The mechanical strength of wood-plastic SLS parts is low, which restricts the application of this technology. In this study, a novel type of sisal fiber/poly-(ether sulfone) (PES) composite was prepared using a polymer mixing method in order to improve the mechanical properties of SLS parts. Single-layer sintering method was adopted to determine the proper processing parameters. The mechanical properties of the parts with different ingredient ratios and different particle sizes of sisal fiber before and after post-processing were tested using a universal testing machine. The morphology was examined using scanning electron microscopy (SEM). Results showed that the mechanical properties of the printed parts were relatively enhanced; when the mixing ratio of composite powder was 10/90 wt/wt. In addition, the part fabricated by powder of particles size less than 0.105 mm (0.125 mm ≥ PS < 0.105mm) had the best mechanical strength. Moreover, the post-wax treatment significantly improved the strength of the parts, and the surfaces became smoother.

Experimental study on micro electrochemical slab milling using disc tool electrode

In this study, a method of micro-electrochemical slab milling with disc electrode is proposed for fabricating micro-groove structures on the surface of the workpiece. The disc electrode is in-situ prepared by micro-WEDM and subsequently used for micro-electrochemical slab milling process. The effects of the main electrochemical parameters, such as electrode feed rate of disc electrode and pulse width of power generator, on the width of the micro grooves and surface quality on 304 stainless steel were discussed. Finally, a micro-groove with a groove width of 254μm and good surface quality has successfully processed using the disc tool electrode with edge width of 170μm and proper process parameters. The proposed method broadens the machining flexibility and capability of micro electrochemical machining technology.

Fabrication of a Large-Area, Fused Polymer Micromold Based on Electric-Field-Driven (EFD) μ-3D Printing.

An electric-field-driven (EFD), μ-3D printed, fused polymer technique has been developed for the fabrication of large-area microscale prototype molds using typical polymer materials, including microcrystalline wax (MC-wax), polycaprolactone (PCL), and polymathic methacrylate (PMMA). This work proposes an alternative for large area microscale modes and overcomes the limitation of high cost in the traditional mold manufacturing industry. The EFD principle enables printing of fused polymers materials more than one order of magnitude lower than the nozzle diameter, contributing to the necking effect of the Taylor cone jet, which is the key factor to achieve the microscale manufacturing. Numerical simulation of electric field distribution between the meniscus and substrate was carried out to elucidate the dependence of electric field distribution on the meniscus condition of three types of polymers under printable voltage, and the electrical field parameters for the EFD μ-3D printing were determined. A number of experiments were printed successfully using a large range of viscosity materials, ranging from tens of mPa·s to hundreds of thousands of mPa·s of PCL and PMMA. The differences in parameters of different materials, such as viscosity, tensile properties, and surface energy, were studied to assess their use in different fields. Using proper process parameters and a nozzle with an inner diameter of 200 μm, three different application cases were completed, including a Wax microarray and microchannel with a minimum dot diameter of 20 μm, a PCL mesh structure with a minimum line width of 5 μm, and a PMMA large-area mold with a maximum aspect ratio of 0.8. Results show that the EFD μ-3D printing has the outstanding advantages of high printing resolution and polymer material universality.

Experimental Study on Laser Welding of AISI 304 Steel with Design of Experiments Approach

Austenitic stainless steels find extensive applications in engineering and structural parts requiring inherent corrosion resistance. The main objective of this study is to achieve good quality butt joint in 2.5-mm thick 304 grade Stainless Steel. The joint quality is quantified in terms of weld-bead dimensions. The main issue that manufacturers face is controlling the input process parameters, to get a good quality joint, with required weld bead geometry under controlled thermal distortion. The objective of this work is to select proper input process parameters that would result in desirable weld-bead profiles with minimal heat input. The critical process parameters influencing laser-welding were found using response surface methodology technique. The results proved that the developed model could efficiently predict the responses. The criteria demonstrated a possible reduction in top width of weld bead with enhanced depth of penetration, which automatically envisaged an increase in aspect ratio. A two-factor five-level criteria design was used for predicting the optimized parameters by performing multi-response optimization. Among them, the third criterion has shown a significant decrease in heat input and it was chosen as the best-optimized parameter.

Modified constitutive model and workability of 7055 aluminium alloy in hot plastic compression

To obtain flow behavior and workability of 7055 aluminium alloy during hot deformation, hot compression tests at different temperatures and strain rates are conducted. True stress-strain curves of 7055 aluminium alloy under different conditions are obtained and the flow stress increases with ascending strain rate and descending temperature. For Arrhenius constitutive equation, each material parameter is set as a constant, which will bring forth large error for predicting flow behavior. In this work, material parameters are fitted as a function of temperature or strain rate based on experimental results and a modified constitutive equation is established for more accurate prediction of flow behavior of 7055 aluminium alloy. The effects of temperature and strain rate on power dissipation and instability are analyzed to establish a processing map of 7055 aluminium alloy. The dominant deformation mechanism for microstructure evolution at different deformation conditions can be determined and high efficiency of power dissipation may be achieved from power dissipation map. Meanwhile, proper processing parameters to avoid flow instability can be easily acquired in instability map. According to the processing map, optimized processing parameters of 7055 aluminium alloy are temperature of 673–723 K and strain rate of 0.01–0.4 s−1, during which its efficiency of power dissipation is over 30%. Finite element method (FEM) is used to obtain optimized parameter in hot rolling process on the basis of processing map.

Design and analysis of sand casting process of mill roller

The quality characteristics of the mill roller in sand casting has been affected by casting defects caused by in proper process parameter usage and intern affects its proper function that lead to large number of shop floor trials, high rate of rejection, and low casting yield. The objective of this research is to design and analyze sand casting process of mill roller. In this research work, methods like critical observation, interview, discussion, numerical experimentation, and simulation have been done. Solid modeling of mill roller component with all incorporating gating system has been carried out by solidwork software and simulation process has been carried out by using ProCAST software for the mold filling and solidification analysis to reduce the level and intensities of shrinkage porosities in cast mill roller. Taguchi method of numerical experimentations has been carried out for parameter optimization and analysis of variance (ANOVA) using Minitab software. The confirmatory test with the optimal level of casting process parameters have been carried out. The casting process parameters of the mill roller have been identified by using cause and effect diagram. The parameters such as permeability, pouring temperature, and moisture content have been taken into consideration. Based on the numerical results, their interpretation and the optimal values of the parameters have been determined to eliminate the defects. The present research work has shown in the improvement of casting yield. It has been found that the casting defects are minimized by 2.98%. The results also reveal that sand sintering problem and porosity defects occurred in the mill roller castings were due to the weak sintering strength of fine mixed molding silica sand used in the process. Using simulation software, shrinkage porosity has been observed in both gating system and roller part.

OPTIMIZATION OF JOHNSON-COOK CONSTITUTIVE MODEL PARAMETERS

In modern machining industry, the concept of process optimization has gained widespread recognition. FEM simulations are commonly used for the optimization of machining operations, allowing for a proper choice of tool geometry and process parameters to obtain results that are in accordance with end user criteria. However, one has to be wary that a good agreement of experimental and simulation results is mandatory if the simulation is to be used as a basis for optimization of a real-life process. Therefore, a proper choice of constitutive model parameters is vital. Those parameter values are dependent on many variables. Constitutive model parameter values are determined experimentally – therefore, they are accurate only for the conditions (temperature, strain rate etc.) under which the experiment was performed. The alteration, or optimization of model parameters is necessary if cutting and experiment conditions differ, if one wishes to obtain applicable results. In this work, the authors aim to present a method of optimizing the Johnson-Cook constitutive model parameters to obtain a better fit with experimental data.

Nanocluster-ripple grating fabricated by high repetition femtosecond fiber laser

In this paper we studied the surface morphology of the grating fabricated on the soda-lime silicate glass using a 500 kHz, 1040 nm femtosecond laser. A nanocluster-ripple grating can be fabricated with proper processing parameters. Our results demonstrate that the scan line spacing plays an important role in the diffraction efficiency of the fabricated grating. Such gratings, used as a multi-beam splitter or a dispersion element, can be fabricated easily by changing the laser scan line spacing.

Study on laser sintering of pine/co-PES composites and the investment casting process

Purpose A pine/co-PES composite (PCPES composite) was proposed as the feedstock for powder bed fusion (laser sintering, LS). This paper aims to provide some necessary experimental data and the theoretical foundation for LS of pine/co-PES, especially for the application of using the laser-sintered pine/co-PES parts as complex structural patterns in investment casting. Design/methodology/approach The PCPES composites with different pine loadings were mixed mechanically. The composite’s preheating temperature and processing temperature during LS were determined experimentally based on the material’s thermal behavior. The effects of pine powder on the binding mechanism of PCPES composites were discussed through analyzing the microstructure of the laser-sintered parts’. Mechanical properties and dimensional precision of laser-sintered PCPES parts in different pine loadings were tested, and the parts’ mechanical properties were strengthened by wax-infiltration post-processing. The influence extents of process parameters on the mechanical properties of laser-sintered 20 Wt.% pine/co-PES parts were investigated using a 1/2 fractional factorials experiment. Findings 20 Wt.% pine/co-PES is considered to be a promising wood-plastic composite for laser sintering. The relationship between mechanical strength of its laser-sintered parts and process parameters was built up using mathematical formulas. Experimental results show density, tensile strength, flexural strength and surface roughness of laser-sintered 20 Wt.% pine/co-PES parts are improved by 72.7-75.0%, 21.9-111.3%, 26.8-86.2%, 27.0-29.1% after post-process infiltration with a wax. A promising application of the wax-infiltrated laser-sintered parts is for investment casting cores and patterns. Research limitations/implications The proper process parameters and forming properties of laser-sintered parts are limited to the results of laser sintering experiments carried on using AFS 360 rapid prototyping device. Originality/value This investigation not only provides a new feedstock for laser sintering with the advantages of low cost and fabricability but also uses an advanced technique to produce personalized wood-plastic parts efficiently. Mathematical models between mechanical properties of laser-sintered PCPES parts and LS process parameters will guide the further LS experiments using the 20 Wt.% pine/co-PES composite. Besides, the laser-sintered PCPES parts after wax-infiltration post-processing are promising as complex structural patterns for use in investment casting.