Surface Quality Of Parts Research Articles

Multiobjective Optimization of Laser Polishing of Additively Manufactured Ti-6Al-4V Parts for Minimum Surface Roughness and Heat-Affected Zone.

Metal parts produced by additive manufacturing often require postprocessing to meet the specifications of the final product, which can make the process chain long and complex. Laser post-processes can be a valuable addition to conventional finishing methods. Laser polishing, specifically, is proving to be a great asset in improving the surface quality of parts in a relatively short time. For process development, experimental analysis can be extensive and expensive regarding the time requirement and laboratory facilities, while computational simulations demand the development of numerical models that, once validated, provide valuable tools for parameter optimization. In this work, experiments and simulations are performed based on the design of experiments to assess the effects of the parametric inputs on the resulting surface roughness and heat-affected zone depths. The data obtained are used to create both linear regression and artificial neural network models for each variable. The models with the best performance are then used in a multiobjective genetic algorithm optimization to establish combinations of parameters. The proposed approach successfully identifies an acceptable range of values for the given input parameters (laser power, focal offset, axial feed rate, number of repetitions, and scanning speed) to produce satisfactory values of Ra and HAZ simultaneously.

Research on Rapid Measurement Technology of Roughness Based on Light Scattering

The roughness is an important parameter to evaluate the parts surface quality, so it is very important to measure the surface roughness of high-precision parts. In order to meet the needs of rapid and non-contact measurement of surface roughness, a new method based on optical scattering distribution is proposed in this paper. By analyzing the modulation effect of surface roughness on incident light, the relationship between surface roughness and scattering distribution is established. Based on the analysis of the characteristics of light source, detector and their relative position, the scattered light distribution measurement system is constructed. In the measurement system, the surface roughness is measured by real-time acquisition of scattering distribution. The roughness of different samples is measured by this method and white light interferometer, and the measurement standard deviation is less than 0.15nm. The measurement results show that this method is feasible and effective.

Study the effect factors on chromium plating on the frictional and wear properties of machine parts

This paper studies the influence of current density and solution temperature when chromium plating on the surface quality of machine parts through friction and wear characteristics. By the experimental results using modern equipment the authors find out the best suitable range of current density and solution temperature to improve the surface quality of machine parts. It is shown that the optimal current density used for chromium plating should be the range of 20 ÷ 30 A/dm2 and the optimal solution temperature range should be 50 ÷ 60oC. Plating at these ranges will create the shiny coating with the best wear resistance while still ensure the thickness of the plating. Experimental results are the additional scientific basis for theoretical research in order to evaluate the surface quality of machine parts.

ON THE SURFACE ROUGHNESS OF 3D PRINTED PARTS WITH FDM BY A LOW-BUDGET COMMERCIAL PRINTER

As additive manufacturing machines price is decreasing, while, at the same time, the expertise in the relevant field is rising, it is essential to test and evaluate the low-budget machines that are available for commercial use. Whilst low-budget machines are widely utilized for rapid prototyping and experimentation, they are not capable of producing parts with high surface quality and achieve high levels of repeatability due to low quality hardware and not optimized software. Having said that, the main aim of the current study is to experiment with a low budget Fused Deposition Modeling (FDM) 3D-Printer, and evaluate the surface roughness of the printed parts in respect to the angle from the print plate. Polylactic Acid (PLA) was chosen as filament material, while the printed parts surface roughness was measured according to the ISO ASTM 52902-2021 standard. The surface roughness was estimated in terms of the Ra and Rz values, while a statistical analysis was implemented in order some interesting conclusions to be deduced regarding the correlation between part orientation and surface quality.

Effect of Hot Machining on the Surface Quality of Cylindrical Parts

The article describes studies of the quality of the surface layer of the deposited metal of a cylindrical part when combining the processes of surfacing and milling, as well as subsequent grinding of the deposited metal in hot and cold states. Photos of the surface of the deposited and processed parts are presented, showing the effect of the processing method on the metal structure and data on the distribution of residual stresses in the surface layer of the metal.

The selection of laser beam diameter in directed energy deposition of austenitic stainless steel: A comprehensive assessment

One focus of laser directed energy deposition (L-DED) is to increase productivity, and this can be achieved by using a larger beam diameter and higher laser power. However, it is difficult to build complex metallic components with fine structures using a laser beam of large diameter. Under the trade-off between formability and productivity, the choice of beam diameter needs to be thoroughly evaluated. Herein, three beam diameters (0.75 mm, 1.5 mm, and 3 mm) in building austenitic stainless steel parts have been investigated and compared in four aspects: microstructure, mechanical properties, powder utilization, and as-built part surface quality. Specifically, cooling rate and powder splashing in the building process, and phase composition, grain size and dislocation density of as-built parts are revealed by means of numerical simulation, high-speed camera, electron backscattered diffraction, and X-ray diffractometry. Results show that for a small beam diameter, the microstructure formed has finer grains and less amount of ferrite due to higher cooling rate of the molten pool, and grain refinement and high density of dislocations lead to superior mechanical properties of the as-built part; conversely, for a larger beam diameter, more stable molten pool and less amount of powder splashing brings higher material utilization rate and better surface quality. A brief evaluation of beam diameter selection is accordingly proposed, and a novel hybrid beam diameters building strategy is presented for building complex metallic components with high quality and efficiency.

Impact of machine factors on the surface quality of parts fabricated by selective laser melting

In the growing additive manufacturing (AM) industry, there are growing demands for better as-built surface quality of parts fabricated by selective laser melting (SLM) process, especially for the aerospace, medical and tooling industrial sectors. The surface of SLM parts is relatively bad due to the inherent layer-by-layer processing method. Currently, the surface roughness of SLM components, depending upon the material used, ranging from Ra values of 5 to 50 μm. To enhance the as-build surface quality, various approaches, such as modifying printing process parameters, optimizing support designs and upgrading laser hardware have been explored by a variety of groups. In this study, we investigated the machine factors on the as-build surface quality of parts in the SLM process. Results showed the surface quality of as-build 1.2709 tool steel parts, with a layer thickness of 30 μm, is largely affected by its distance to the laser centre and with little impact from the gas flow direction and recoating direction. The present study demonstrated the possibility of enhancing the as-build surface quality of SLM parts through better planning of machine settings without changing key processing parameters.

Study of machining strategies for CNC milling of cavities on Ultra High Molecular Weight Polyethylene

Cavity milling is one of the most used machining operations by the industry in different types of materials; among them, thermoplastics. Several cutting strategies are available that influence different parameters of the manufacturing process and the surface quality of the final part. In this research, the spiral, zigzag, and one-way performance cutting strategies for CNC cavity milling on Ultra High Molecular Weight Polyethylene (UHMW) were compared using a methodology and measuring machining time, power, energy, and surface roughness. The results allowed a performance strategy ranking according to the measured parameters. The developed methodology can be applied to other materials, geometries, and cutting strategies.

Based on the Influence of Standard parts Installation and Surface Quality on Aircraft Assembly

In the process of aircraft assembly, various parts have an important impact on the aircraft assembly, among which the fasteners play an important role in the aircraft assembly, affecting the stability of the aircraft assembly and the service life of the aircraft. Standardized fastener installation and surface quality affect the aircraft assembly quality. Proper fastener installation and guaranteed quality are conducive to reducing the risk of aircraft assembly. However, the characteristics of standard fasteners in aircraft assembly need to be studied urgently. This paper analyzes the assembly characteristics of aircraft standard parts, the information and constraints of standard parts, discusses the assembly information of standard parts, and explores the types and installation requirements of fasteners, hoping to improve the assembly effect of standard parts in aircraft assembly.

A Review on End-effectors of Robotic Grinding

Background: As a kind of device applied to grinding, the robot grinding end-effector, combining force control structure, adaptive structure, and other structures, has been widely used in machine grinding. Grinding end-effectors can greatly help industrial robot technology used in operations that require continuous contact, such as polishing, grinding, deburring, chamfering, and assembly. Therefore, the structure design of the end-effector will become an inevitable trend in the research on robot grinding in the future. Objective: The existing grinding end-effectors for robot grinding are summarized, and their classification, characteristics, and development are introduced. Method: Various products and designs related to grinding end-effectors are summarized. The structural features, differences, and applications of typical grinding end-effectors are introduced. Results: Three typical end-effectors are analyzed. The structural features and functions are summarized, and the development trend has been prospected. The current situation and future research direction of grinding end-effector products and patents are discussed. Conclusion: Grinding end-effectors are classified into the force-controlled grinding end-effector, the adaptive grinding end-effector, and the special structure grinding end-effector. The grinding end-effector plays an important role in promoting the development of the robot grinding industry, improving the surface quality of parts and the finishing process. The grinding end-effector needs further improvement in image processing, humanization, force control, and so on. More in-depth research should be carried out in this direction.

Rotary dressing model for grinding wheel active surface prediction

A kinematic model of rotary dressing of corundum grinding wheels is presented. Based on wheel and dresser specifications and process kinematics, effects of rotary dressing parametres on wheel topography are predicted. For model validation, wheel surface is characterized by areal roughness parametres, obtaining a deviation less than 15%. Besides, influence of wheel topography on ground part surface quality is investigated. Results highlight the significance of modelling the dressing process and show the model translates into a useful tool for selection of most suitable dressing parametres for achieving specific surface qualities. Moreover, it eases the way to predicting dressing originated defects.

Analysis and characterization of additive manufacturing processes

Recently, additive manufacturing (AM) processes have expanded rapidly in various fields of the industry because they offer design freedom, involve layer-by-layer construction from a computerized 3D model (minimizing material consumption), and allow the manufacture of parts with complex geometry (thus offering the possibility of producing custom parts). Also, they provide the advantage of a short time to make the final parts, do not involve the need for auxiliary resources (cutting tools, lighting fixtures or coolants) and have a low impact on the environment. However, the aspects that make these technologies not yet widely used in industry are poor surface quality of parts, uncertainty about the mechanical properties of products and low productivity. Research on the physical phenomena associated with additive manufacturing processes is necessary for proper control of the phenomena of melting, solidification, vaporization and heat transfer. This paper addresses the relevant additive manufacturing processes and their applications and analyzes the advantages and disadvantages of AM processes compared to conventional production processes. For the aerospace industry, these technologies offer possibilities for manufacturing lighter structures to reduce weight, but improvements in precision must be sought to eliminate the need for finishing processes.

Surface finishing method based on laser re-melting using a cone annular beam for additive manufacturing

In this paper, a novel surface finishing method of cone annular beam laser re-melting (CALR) is proposed which aims at optimizing the side surface quality of AlSi10Mg parts produced by directed energy deposition. Meanwhile, a feature-based characterization method was conducted to realize the multiscale analysis of the topographic features. The results show that the developed CALR is a powerful tool which can greatly reduce the surface roughness: the final optimal aluminum alloy thin-walled parts with a roughness of 7.1 µm was obtained, which was 68.3% less than the original roughness of 22.4 µm without the implementation of CALR. The optimization mechanism reveals the roughness reduction was mainly attributed to the elimination of the stair-step effect, while the role of powder particle features was much less significant on roughness reduction of the overall surface. The CALR method together with the feature-based surface characterization provides an innovative solution for side surface quality optimization for laser additive manufacturing.

Analysis on Design and Manufacturing Technology and Precision Machining Technology of Woodworking Machinery

High speed machining (HSM) has become a development trend of modern manufacturing industry. It can not only significantly improve the production efficiency of products, but also greatly improve the machining accuracy and surface quality of production parts and reduce the production cost. Wood processing involves many processing processes such as sawing, milling and drilling. The compact four head motorized spindle can basically meet the milling and drilling requirements of wood processing. This paper studies the design, manufacturing technology and precision machining technology of woodworking machinery. This paper mainly adopts the finite element analysis method and applies the finite element analysis software ANSYS Workbench to simulate and model the woodworking four head high-speed motorized spindle, then analyzes and calculates its dynamic and static characteristics, and comprehensively considers the main influencing factors on the dynamic and static characteristics of motorized spindle. The test results show that the method proposed in this paper is of great significance to improve the actual working performance of motorized spindle.

Volumetric adaptive slicing of manifold mesh for rapid prototyping based on relative volume error

PurposeCompared with cusp height and area deviation ratio, volume error (VE) caused by the layer height could represent the stair-case effect more comprehensively. The proposed relative volume error (RVE)-based adaptive slicing method takes VE rather than cusp height as slicing criteria, which can improve part surface quality for functionalized additive manufacturing.Design/methodology/approachThis paper proposes a volumetric adaptive slicing method of manifold mesh for rapid prototyping based on RVE. The pre-height sequences of manifold mesh are first preset to reduce the SE by dividing the whole layer sequence into several parts. A breadth-first search-based algorithm has been developed to generate a solid voxelization to get VE. A new parameter RVE is proposed to evaluate the VE caused by the sequence of the layer positions. The RVE slicing is conducted by iteratively adjusting the layer height sequences under different constraint conditions.FindingsThree manifold models are used to verify the proposed method. Compared with uniform slicing with 0.2 mm layer height, cusp height-based method and area deviation-based method, the standard deviations of RVE of all three models are improved under the proposed method. The surface roughness measured by the confocal laser scanning microscope proves that the proposed RVE method can greatly improve part surface quality by minimizing RVE.Originality/valueThis paper proposes an RVE-based method to balance the surface quality and print time. RVE could be calculated by voxelized parts with required accuracy at a very fast speed by parallel.

The Influence of Heat Input on the Surface Quality of Wire and Arc Additive Manufacturing

Wire and arc additive manufacturing has unique process characteristics, which make it have great potential in many fields, but the large amount of heat input brought by this feature limits its practical application. The influence of heat input on the performance of parts has been extensively studied, but the quantitative description of the influence of heat input on the surface quality of parts by wire and arc additive manufacturing has not received enough attention. According to different heat input, select the appropriate process parameters for wire and arc additive manufacturing, reversely shape the profile model, select the appropriate function model to establish the ideal profile model according to the principle of minimum error, and compare the two models to analyze the effect of heat input on the surface quality of the parts manufactured by wire and arc additive manufacturing. The results show that, when the heat input is high or low, the standard deviation value and the root mean square value reach 1.908 and 1.963, respectively. The actual profile is larger than the ideal profile. When the heat input is moderate, the standard deviation value and the root mean square value are only 1.634 and 1.713, respectively, and the actual contour is in good agreement with the ideal contour. Combined with the analysis of the transverse and longitudinal sections, it is shown that the heat input has a high degree of influence on the surface quality of the specimen manufactured by wire and arc additive manufacturing, and higher or lower heat input is disadvantageous to it.

A novel process of sheet metal inverse bulging pre-deformation for deep drawing forming using magnetorheological fluid as flexible media

At the Magnetic field condition, the surface quality of formed parts can be improved significantly. To investigate the technical advantages of Magnetorheological (MR) fluid as a soft media, eliminate the defects of the parts because of the complex deformation, such as wrinkling, cracking, and over thinning. A new method of sheet deep drawing forming with MR fluid through inverse bulging pre-forming was proposed, which has made the wall thickness distribution more uniform and changed the stress distribution of sheet by changing the rheological property of MR fluid. The theoretical pressure transfer model of MR fluid as media and the configuration model of inverse bulging pre-forming are established. It can be concluded that the relationship between bulge height and load time have been shown consistency compared with experimental results and agree well with the theoretical analysis. And the configuration model have shown good agreement from the experiments results and the numerical results espectively with theoretical results. The uniformity of the wall thickness and the surface quality of the deep-drawn parts are improved significantly with the increase of the inverse bulging height. When the inverse bulging height is about 9 mm, the pre-forming effect is optimal, which provides theoretical guidance and is of much potential to the forming of the and thin-walled complex parts in industry fields.

Evaluating performance metrics in non-homogeneous cutting processes using a random-grid based digital image correlation (DIC) method

The mechanics of chip formation is widely known to be a robust indicator of cutting performance. While chips have been studied and classified for several decades, a direct quantitative correlation between chip morphology and properties of the resulting machined surface is yet to be established. In this work, we develop and demonstrate a digital image correlation (DIC) technique that specifically addresses this issue. Our technique is a departure from standard DIC methods in that it uses an iterative technique on multiple independent random grids, allowing us to obtain accurate full-field deformation measurements during chip formation. The method works especially well at or near free surfaces (e.g., machined surface) and interfaces (e.g., tool-chip contact) and when deformation is temporally unsteady and spatially non-homogeneous. Given that these are central features of nearly all cutting processes, we show how our technique can quantify unsteady, non-uniform flow fields, residual surface and near-surface strains, as well as the amount of redundant deformation during chip formation. These results suggest the use of a simple heuristic test to evaluate critical process performance metrics, such as part surface quality, sub-surface damage and relative energy consumption during machining.

SLS Process Parameter Optimization to Improve Surface Quality and Accuracy of Polyamide Parts

The contribution of selective laser sintering (SLS) technique in the 4.0 manufacturing industry is undisputedly significant. SLS part quality exhibits high dependence on SLS process parameters and is a major challenge. Therefore, this research aims to investigate the effect of input parameters (i.e., part orientation, bed temperature, and layer thickness) on the surface roughness and accuracy of laser-sintered polyamide specimens. Response surface methodology (RSM) and ANOVA analysis aided the testing and evaluation. Optimal working conditions for minimum shrinkage were 0.17 mm layer thickness, 177.89°C part bed temperature, and part orientation at 88.91 degrees. The surface quality deteriorated with the increment in part bed temperature and layer thickness, and it shows an inverse trend (or improves) with the part orientation in the prescribed range. The optimal surface roughness was at a layer thickness of 0.11 mm, bed temperature at 174.55°C, and part orientation at 86.5 degrees.

Impact of print bed build location on the dimensional accuracy and surface quality of parts printed by multi jet fusion

Multi Jet Fusion (MJF) is one of the newly developed additive manufacturing techniques, based on the use of powder bed fusion technology. It provides the opportunity to build up 3D, complex polymer geometries, without the need for support structures. This study evaluates the effect of build location across a 380 × 284 mm2 build plate, on both the dimensional accuracy and surface quality of polyamide 12 (PA12) parts printed using the MJF technique. The cube test samples were printed at each of the four corners and the center of the build plate. Dimensional deviations were determined using optical metrology measurements, while surface deviations were measured using 2D tactile and 3D optical profilometers. The density and the degree of crystallinity of the samples were determined using the Archimedes method and Differential Scanning Calorimetry analysis, respectively. Moreover, the morphology of the internal polymer surfaces was evaluated using Scanning Electron Microscopy. It was concluded that while overall printed part dimensions and crystallinity homogeneity were relatively uniform across the build plate, some variations were observed. Parts printed in particular, closer to the front of the build plate exhibited higher porosity, higher surface roughness along with the highest level of geometry deviation, compared with the CAD drawing. This is likely to be associated with some non- uniformities in heating and cooling of the PA12 polymer parts across the build plate.