Cylindricity Error Research Articles

Experimental investigation and optimization during the fabrication of arrayed structures using reverse EDM

ABSTRACTIn recent years, reverse electric discharge machining (R-EDM) has been evolved as a method for the fabrication of arrayed structures for surface texturing which find applications in fabrication of fins and component assembly. In this study, the feasibility of R-EDM process in the fabrication of arrayed features of ∅3 mm and height 2 mm on mild steel has been investigated utilizing response surface methodology (RSM)-based experimentation. Influence of control variables such as peak current (Ip), pulse-on time (Ton), and flushing pressure (Fp) on some of the vital geometric characteristics like taper and cylindricity error along with material removal rate (MRR), surface roughness (SR), microhardness, and surface morphology of pillared structure has been investigated. Analysis of variance (ANOVA) results show that Ip has a significant influence followed by Ton on MRR. Ip has a significant contribution toward SR, taper, and cylindricity error. High microhardness was found in heat-affected zone (HAZ). The optimal combination of parameter obtained using principal component analysis (PCA)-based grey relational analysis (GRA) is determined to be Ip = 10 A, Ton = 100 μs, and Fp = 0.3 kg/cm2, which was further ascertained using confirmatory test.

Machinability analysis of dry drilling of carbon/epoxy composites: cases of exit delamination and cylindricity error

The aim of this work is to define the cutting conditions that allow the dry drilling of carbon fiber reinforced epoxy (CFRE) composite materials taking into consideration the quality of the drilled holes (the exit delamination factor and the cylindricity error) and the optimum combination of drilling parameters. A further aim is to use grey relational analysis to improve the quality of the drilled holes. The machining parameters were measured according to 33 full factorial parameter designs (27 experiments with independent process variables). The experiments were carried out under various cutting parameters with different spindle speeds and feed rates. Drilling tests were done using WC carbide, high-speed steel (HSS), and TiN-coated carbide drills. The experiment design was accomplished by application of the statistical analysis of variance (ANOVA). Results show that the thrust force is mainly influenced by the tool materials and the feed rate, which has a strong influence on the exit delamination factor. On the other hand, the spindle speed particularly affects the cylindricity error of the holes. Correlations were established between spindle speed/feed rate and the various machining parameters so as to optimize cutting conditions. These correlations were found by quadratic regression using response surface methodology (RSM). Finally, tests were carried out to check the concordance of experimental results.

Possibility to Increase the Life Time of Surfaces on Parts by the Use of Diamond Burnishing Process

New trends appeared in product design and technological planning, which contributed in the development of new finish machining procedures like diamond burnishing. With the influence of diamond burnishing process, the surface roughness, the hardness of machined surface, and the dimensional accuracy can be improved. In this paper the effect of burnishing technological parameters on the cylindricity error of the burnished cylindrical surface and furthermore on changing of hardness of the burnished surfaces were examined, too. Burnishing parameters, which were taken into consideration during the examinations, are burnishing speed, burnishing feed, and burnishing force. Formulas suitable for determination of the improvement ratios of cylindrical shape error and improvement of hardness were determined by the Taguchi type Factorial Experimental Design.

Experimental investigation, prediction and optimization of cylindricity and perpendicularity during drilling of WCB material using grey relational analysis

Manufacturing is always the heart of majority of industries. Drilling is an extremely important and an essential machining process which requires a lot of attention as in most of the cases it is required for assembly purposes. Majority of the holes produced during drilling are made with the help of Vertical Machining Centre (VMC) meant for pin- hole assembly. Though the tolerance is within limit, assembly problems arise due to the improper geometry of these holes. Various geometrical tolerances like cylindricity, circularity, perpendicularity and position errors are responsible for such assembly problems. This investigation is focussed on cylindricity and perpendicularity in the drilling of Wrought Cast Steel Grade B (WCB) material using SOMX 050204 DT insert. In this work, effect of machining variables like cutting speed, feed rate and depth of cut (canned cycle) are investigated and optimized using grey relational analysis (GRA). Reliable experiments are conducted based on a 33 full factorial, replicated twice. Second order regression models are developed for predicting cylindricity and perpendicularity. The models’ adequacy has been checked by calculating correlation coefficient. It shows that the developed models are well fitted for the prediction of responses within the specific range of input variables.

Cylindricity Error Measuring and Evaluating for Engine Cylinder Bore in Manufacturing Procedure

On-line measuring device of cylindricity error is designed based on two-point method error separation technique (EST), which can separate spindle rotation error from measuring error. According to the principle of measuring device, the mathematical model of the minimum zone method for cylindricity error evaluating is established. Optimized parameters of objective function decrease to four from six by assuming thatcis equal to zero andhis equal to one. Initial values of optimized parameters are obtained from least square method and final values are acquired by the genetic algorithm. The ideal axis of cylinder is fitted in MATLAB. Compared to the error results of the least square method, the minimum circumscribed cylinder method, and the maximum inscribed cylinder method, the error result of the minimum zone method conforms to the theory of error evaluation. The results indicate that the method can meet the requirement of engine cylinder bore cylindricity error measuring and evaluating.

Multi-response optimisation of surface texturing using artificial bee colony algorithm

Determination of the optimal combination of process parameters plays a pivotal role in reducing manufacturing costs while enhancing rate of productivity and standard of quality of the product. This paper deals with fabrication of arrayed structures consisting of cylindrical pillars using reverse electro discharge machining (R-EDM) process, followed by optimisation of the process using artificial bee colony (ABC) algorithm. The influence of various machining parameters such as peak current (Ip), pulse-on time (Ton) and flushing pressure (Fp) on multiple performance measures in R-EDM like material removal rate (MRR), surface roughness (SR), taper and cylindricity error (CE) has been investigated using response surface methodology (RSM) based approach. In the course of this paper, the optimal parameters have been found to be Ip = 10 A; Ton = 179.091 µs; Fp = 0.2 kg/cm2. The fast convergence and the high degree of closeness with the experimental data under optimal condition establishes the efficiency and robustness of the algorithm.

Image Processing Assisted Tools for Pre- and Post-processing Operations in Additive Manufacturing

Additive Manufacturing (AM) or 3D printing (3DP) process is a layer by layer manufacturing approach for manufacturing parts with complex geometries. The STL (Stereolithography) file format is the de-facto industry standard for manufacturing parts by AM/3DP. The STL file is a triangular mesh representation of CAD geometry in non-uniform rational B-spline (NURBS) surface format and thus is an approximation of actual part geometry. During the conversion of a complex CAD geometry to an STL file, geometric errors are introduced in the model. These drawbacks associated with the STL file may translate into a faulty or inaccurate final manufactured part. This paper presents a novel Image Processing (IP) based Direct CAD Slicer, IPSlicer, which can be used to manufacture components directly from CAD geometry (without converting to STL file). Using sectional image snapshots of a part, captured normal to the build direction and sectional 2D bounding box data, contour points for each section are identified by performing boundary tracing operation followed by application of Contour Mapping Algorithm (CMA). The method slices the actual NURBS geometry and thus parts manufactured by this method have reduced GD&T errors such as flatness, cylindricity, and profile error. In addition, a support removability analysis tool is developed by performing color-based segmentation on sectional image snapshots in conjunction with a pixel traversal approach. Using the segmented images and sectional bounding box, a sintering area and time calculation tool for each layer is also developed. The effectiveness of IPSlicer is verified by virtually manufacturing test components and calculating GD&T errors by the application of computational metrology algorithms on virtually manufactured data. The support removability analysis tool as well as sintering time and area calculator are validated using several test parts.

Research on Automobile Crankshaft Roundness and Cylindricity Errors Evaluation Mathematical Model Based on the Error Conversion

Research on Automobile Crankshaft Roundness and Cylindricity Errors Evaluation Mathematical Model Based on the Error Conversion

Study on Evaluation of Cylindricity Errors with a Hybrid Particle Swarm Optimization-Chaos Optimization Algorithm

Study on Evaluation of Cylindricity Errors with a Hybrid Particle Swarm Optimization-Chaos Optimization Algorithm

Cylindricity Error Evaluation Based on an Improved Biogeography-based Optimization Algorithm

Cylindricity Error Evaluation Based on an Improved Biogeography-based Optimization Algorithm

Using a high-stiffness burnishing tool for increased dimensional and geometrical accuracies of openings

The paper investigates ball burnishing of openings. A special high-stiffness tool was designed for the purpose of experimentation, allowing the burnishing of 40–120mm openings. Experiments were performed with aluminium alloy EN AW-6082 (AlMgSi1). The primary goal was to achieve dimensional and geometrical accuracy of the openings. Using a specially designed stiff tool, the openings were widened by 0.06mm on average, while the roundness and cylindricity errors were drastically reduced, especially at greater ball penetration depths. In addition, the surface roughness was improved by 35%. FEM analysis was conducted to determine the stress field distribution in the workpiece, as well as to approximate the residual stresses after the ball burnishing. Considering the experimental results, further investigation should be directed towards the achievement of high dimensional and geometrical accuracies, as well as increased process productivity.

Geometric approaches to input file modification for part quality improvement in additive manufacturing

Additive manufacturing (AM) machines use the Stereolithography (STL) file as standard input file format to build parts. STL model is a triangular faceted approximation of a CAD model, which represents a part with less accuracy than the CAD model. Commercial softwares have the ability to convert a CAD file into an STL file based on a user defined threshold value to uniformly convert the entire part body into triangular facets. Increasing the geometric accuracy of STL models is typically accomplished by decreasing the user defined threshold value, which results in an increase in STL file size. In this research, a Surface-based Modification Algorithm (SMA) that adaptively and locally increases the facet density of an STL model is presented. The Surface-based Modification Algorithm is an error minimization approach to modify the STL facets locally based on chordal error, cusp height and cylindricity error for cylindrical features and is typically able to achieve a smaller file size compared to uniform export option. A novel bounding box based algorithm is developed to calculate cusp height error from the point cloud generated from the part by slicing the STL facets or from the CAD surface. Final results show a distinct improvement in the part error of the STL model using Surface-based Modification Algorithm (SMA) when compared to the original STL file.

Non-Contact Online Detection of Concentricity Error

This paper researches on the non-contact online detection of concentricity error, which mainly focus on the structural principle of the measurement system and the concentricity error evaluation methods. The paper using the method of projection, converting the three-dimensional model to a two-dimensional model and evaluating coaxially error. And it is validated by the simulation of MATLAB. In theory, the proposed measurement system can measure geometric tolerance, including coaxially error, cylindricity error, circularity error, etc.

Effect of Machining Parameters on Tool Wear and Hole Quality of AISI 316L Stainless Steel in Conventional Drilling

This paper focuses on the effect of drilling parameters on tool wear and hole quality in terms of diameter error, roundness, cylindricity, and surface roughness. In this work, the drilling was conducted using uncoated carbide tool with diameter of 4 ± 0.01mm with point angle of 135° and helix angle of 30°. The drilling was done at different levels of spindle speed (18 and 30 mmin-1) and feed rate (0.03, 0.045 and 0.06 mmrev-1). Austenitic stainless steel AISI 316L was the workpiece material. Comparatives analysis was done on hole diameter, roundness, cylindricity, and surface roughness of the drilled holes by experimentation. From the result, the hole quality characteristics are mostly influenced by cutting speed and feed rate. An exception was for circularity error where a two tail t-test for circularity error indicates that cutting speed and feed rate give no significant influence on circularity error. As the cutting speed increases, the surface roughness decreases (1.09μm). Contrary, when the feed rate increases, the surface roughness value increases as well. For cylindricity error, lower cutting speed and lower feed rate will give better result. In terms of diameter error, feed rate influences more than cutting speed. Minimum diameter error was achieved when low cutting speed and low feed rate were employed.

Increasing Part Accuracy in Additive Manufacturing Processes Using a k-d Tree Based Clustered Adaptive Layering

Additive manufacturing (AM) is widely used in aerospace, automobile, and medical industries for building highly accurate parts using a layer by layer approach. The stereolithography (STL) file is the standard file format used in AM machines and approximates the three-dimensional (3D) model of parts using planar triangles. However, as the STL file is an approximation of the actual computer aided design (CAD) surface, the geometric errors in the final manufactured parts are pronounced, particularly in those parts with highly curved surfaces. If the part is built with the minimum uniform layer thickness allowed by the AM machine, the manufactured part will typically have the best quality, but this will also result in a considerable increase in build time. Therefore, as a compromise, the part can be built with variable layer thicknesses, i.e., using an adaptive layering technique, which will reduce the part build time while still reducing the part errors and satisfying the geometric tolerance callouts on the part. This paper describes a new approach of determining the variable slices using a 3D k-d tree method. The paper validates the proposed k-d tree based adaptive layering approach for three test parts and documents the results by comparing the volumetric, cylindricity, sphericity, and profile errors obtained from this approach with those obtained using a uniform slicing method. Since current AM machines are incapable of handling adaptive slicing approach directly, a “pseudo” grouped adaptive layering approach is also proposed here. This “clustered slicing” technique will enable the fabrication of a part in bands of varying slice thicknesses with each band having clusters of uniform slice thicknesses. The proposed k-d tree based adaptive slicing approach along with clustered slicing has been validated with simulations of the test parts of different shapes.

Optimization of layered manufacturing process for reducing form errors with minimal support structures

Layered manufacturing (LM) has evolved from the rapid prototyping (RP) method to a mainstream process for manufacturing high precision parts for aerospace, automotive and medical industries. LM inherits from RP several advantages including the ability to produce complex shapes, low cost and elimination of special tooling, as well as disadvantages of poor surface finish, poor dimensional accuracy, high build time and high waste. As LM is increasingly being accepted as a traditional manufacturing process, it has to consistently manufacture parts with minimal errors while keeping the material utilization to a minimum. This paper analyzes the effect of part orientation on two types of form errors, namely, cylindricity and flatness errors. An algorithm to calculate the optimal orientation for minimizing flatness and cylindricity errors is developed and tested with the help of two test cases. However, an optimal orientation for minimum form errors may result in a greater utilization of support structures which increases the material consumption in LM processes and therefore should be avoided. A voxel-based approach for calculating support structures has been developed in this paper which is then applied to minimize the volume of support structures while minimizing the cylindricity and flatness errors of the part features. This combined optimization is applied on two test parts and the results are provided.

A Modified Particle Swarm Optimization for Form and Position Errors of Mechanical Parts

By studying the evaluation principles of mechanical parts’ form and position errors and many kinds of error algorithms, presented in recent patents and scientific articles, a project was proposed by using a modified particle swarm optimization (PSO) with linearly decreasing inertia weights to evaluate form and position errors. With its important parameters being analyzed based on the features of form and position errors’ evaluation, the modified PSO was proved to be of high accuracy and good robustness. The experiments were carried out for evaluating the form and position errors of a group of straight lines and planes produced by harmonic technologies, and the results indicated that the evaluation project was reliable. Finally, the modified algorithm was used to evaluate the roundness error and the cylindricity error of a transmission shaft and the evaluation results show the effectiveness of the modified PSO, compared with the results of a three coordinate measuring machine (CMM).

Study of Improvement of Measurement Precision for Roundness Measuring Instrument

Based on the requirement of small errors in measuring roundness (cylindricity) error, a leveling methodology which using a dual-point vertical layout has been put forward and analyzed. According to the direction cosine of the axis of workpiece, the amount of leveling has been defined and calculated, which overcomes the problem brought by manual adjustment technology and forms theoretical bases of fast, accurate leveling and high precise measurement. The assessment of roundness (cylindricity) error is to search for a center (cylinder axis) which satisfies the minimum condition. Due to the reliance of initial solutions and relative slowness in terms of convergence precision and convergence rate when using Nelder-Mead simplex method, a combinative method of Quasi-Newton and N-M simplex method has been proposed which achieves a fast, accurate search for global optimums. With the proof of the simulation of classical testing functions using Matlab and the measured data, the convergence rate and precision will be enhanced effectively has been certified with the combination of both methods mentioned above which ensuring and improving the measuring precision of workpiece.

圆度仪的调平和圆柱度误差评定

How to improve the measuring accuracy of a roundness measuring instrument was researched in consideration of the cylindricity error requirement and cylindricity error assessment searching algorithm.To reduce inclination error of a workpiece in measuring cylindricity error,a leveling method using a dual-point vertical layout was proposed and analyzed.According to the direction cosine of the axis of workpiece,the amount of leveling was defined and calculated to overcome the problem brought by manual adjustment technology and the accurate leveling and high precise measurement were completed.As the assessment of cylindricity error is to search for a cylinder axis that statisfies the minimum condition and the Nelder-Mead simplex method has lower convergence precision and convergence rate because it depends on initial solution,so that a combined algorithm with quasi-Newton method and simplex algorithm was proposed to achieve the fast and accurate search for global optimums.The Matlab simulation andexperimental testing on classical functions indicate that the combined algorithm improves the convergence rate and convergence precision effectively and the convergence rate has been increased over 50% and convergence precision increases over once as compared with that of Nelder-Mead simplex method,which ensures and improves the measuring precision of workpieces.

Experiment Investigation of Hole Accuracy and Surface Roughness in Femur Bone Drilling Using Different Parameters

Success indicators in bone drilling include clean, good accuracy drilled holes without damage at the surrounding tissue. This study investigates the influence of cutting parameters in bone drilling against hole accuracy (enlargement diameter, circularity error, and cylindricity error) and surface roughness (Ra). A series of bone drilling experiments was carried out using femur bovine bone and without irrigation. Variations of drill type (high speed steel and coated and uncoated carbide) and cutting speed (19 m/min and 94 m/min) were used as input variables, while the feed rate (0.025 mm/rev) was constant. It was found that coated carbide drill results minimum magnitude on all machining responses. Type of tool gives significant effect on diameter enlargement and surface roughness, yet not on circularity and cylindricity errors. The range of cutting speed evaluated does not give significant effect on any surface integrity measures.