Investigation of effect of process variable on dimensional accuracy of FDM component using response surface methodology

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Nagendra Kumar Maurya ◽  
Manish Maurya ◽  
Shashi Prakash Dwivedi ◽  
Ashish Kumar Srivastava ◽  
Ambuj Saxena ◽  
...  
Keyword(s):  
Response Surface Methodology ◽  
Layer Thickness ◽  
Process Parameters ◽  
Dimensional Accuracy ◽  
Percentage Error ◽  
Content Type ◽  
Average Percentage ◽  
Raster Angle ◽  
Radial Dimension ◽  
Average Percentage Error

Purpose Nowadays, rapid prototyping is emerging as end use product in low volume. The accuracy of the fabricated components depends on various process parameters. Process parameters used in this investigation are layer thickness (150, 200 and 250 µm), infill pattern (linear, hexagonal and star fill), raster angle (0°, 45° and 90°) and infill density (40, 60 and 80%). Linear and radial dimension of knuckle joint are selected for the response factor. Design/methodology/approach The experiments are design by using response surface methodology (RSM). Four design variables at three levels are used to examine their influence on percentage error in linear dimension and radial dimension of the component. A prototype Knuckle joint is selected as component. Minitab-14 software is used for the design of experiments. Findings Experimental measure data is analyzed by using “smaller is better” quality characteristics. A regression model for the forecasting of percentage error in linear and radial dimension is developed. The developed model is within precision range. The optimum level of process for linear and radial dimensions are obtained: layer thickness of 150 µm, Infill pattern of linear, Raster angle of 90° and infill density of 40%. Research limitations/implications It proves that both the mathematical model is significant and can be able to approximate the desired output value close to the accurate dimensions. While comparing the calculated F-values for both linear and radial dimension with the standard table (F-table, 0.05), it is found that at the given set of degree of freedom the standard F-values (6.61) is lower for that regression, linear, square and interaction source of the predicted model, for which p-values have already less than 0.05. It is desirable for significant process parameters. Practical implications The dimensional accuracy with respect to average percentage error of FDM produced knuckle joint is successfully examined. The effect of process parameters, namely, layer thickness, infill pattern, raster angle and infill density on average percentage error was investigated by RSM and analysis of variance table. Social implications The novelty of this work lies in the fact that only few studies are available in archival literature related to influence of these process parameters on percentage error in linear and radial dimension for Polycarbonate (PC) material. Originality/value The novelty of this work lies in the fact only few studies are available in archival literature related to influence of these process parameters on percentage error in linear and radial dimension for Polycarbonate (PC) material.

Influence of processing parameters on creep and recovery behavior of FDM manufactured part using definitive screening design and ANN

2017 ◽  
Vol 23 (6) ◽  
pp. 998-1010 ◽  
Author(s):  
Omar Ahmed Mohamed ◽  
Syed Hasan Masood ◽  
Jahar Lal Bhowmik
Keyword(s):  
Layer Thickness ◽  
Process Parameters ◽  
Air Gap ◽  
Content Type ◽  
Screening Design ◽  
Definitive Screening ◽  
Raster Angle ◽  
Road Width ◽  
Recoverable Compliance ◽  
The Relationship

Purpose The purpose of this paper is to investigate the effect of process parameters of fused deposition modelling (FDM) 3D printing process on viscoelastic responses (creep compliance and recoverable compliance) of FDM built parts using a novel experimental design technique. Design/methodology/approach As part of the process characterization, a recently developed class of three-level design methodology – definitive screening design (DSD) – was used in this study to fit a second-order polynomial regression model. Artificial neural network (ANN) was also used to determine the optimal process parameters to improve creep compliance and recoverable compliance. The relationship between layer thickness, air gap, raster angle, build orientation, road width, number of contours and creep performance of FDM fabricated part was thereafter established empirically. Scanning electron microscope (SEM) is used to examine and characterize the morphology of the structures for some samples. Findings This study found that the creep resistance of FDM-manufactured part is significantly influenced by layer thickness, air gap, raster angle and number of contours and it can be improved by optimizing the settings of the selected parameters. The relationship between FDM process parameters and creep properties was determined, with the best creep performance observed by using 0.127 mm of layer thickness, zero air gap, zero raster angle, build orientation of 17.188°, road width of 0.4572 mm and 10 contours. Finally, the result is verified by confirmation experiments. The results prove that a DSD is a very effective design in characterizing the influence of process parameters on creep properties of FDM-built part at the lowest cost. Originality/value The originality of this paper lies in characterizing and optimizing the effect of process parameters on creep performance of FDM manufactured part that has not been studied in all previous studies. The paper highlights, for the first time, how the application of DSD can overcome most of the limitations encountered in the conventional techniques. This study can be used as a guide to the different additive manufacturing users of various industries and the results provide a good technical database on how FDM process parameters influence the creep performance of manufactured parts.

An assessment of the dimensional accuracy and geometry-resolution limit of desktop stereolithography using response surface methodology

2019 ◽  
Vol 25 (7) ◽  
pp. 1169-1186 ◽  
Author(s):  
Ivana Cotabarren ◽  
Camila Andrea Palla ◽  
Caroline Taylor McCue ◽  
Anastasios John Hart
Keyword(s):  
Response Surface Methodology ◽  
Response Surface ◽  
Layer Thickness ◽  
Orientation Angle ◽  
Dimensional Accuracy ◽  
Process Performance ◽  
Feature Location ◽  
Resolution Limit ◽  
Content Type ◽  
Dimensional Deviation

Purpose This paper aims to apply a robust methodology to establish relationships between user-configurable process parameters of commercial desktop stereolithography (SLA) printers and dimensional accuracy of a custom-designed test artifact. Design/methodology/approach A detailed response surface methodology study, Box–Behnken incomplete factorial design of four factors with three levels, was carried out to evaluate process performance of desktop SLA printers. The selected factors were as follows: printing orientation angle in x-direction, printing orientation angle in y-direction, position on build platform in spatial x-coordinate, position on build tray in spatial y-coordinate and layer thickness. The proposed artifact was designed to include 12 feature groups including thin walls, holes, bosses, bridges and overhangs. Two responses were associated with the features: the dimensional deviation according to the designed value and the minimum feature size. Findings Layer thickness was the most significant factor in 70% of the analyzed responses. For example, measurement deviation was reduced about 90% when cylindrical holes were printed with the lowest layer thickness. Further, in many cases, dimensional deviation was minimized for features at the center of the platform, where the beam cures the resin in a straight line. However, at distant positions, accuracy could be improved by compensating for beam deviation by changing the object orientation angle. Originality/value The findings of this study can serve, both generally and specifically, for SLA designers and engineers who wish to optimize printing process variables and feature location to achieve high-dimensional accuracy and further understand the many coupled considerations among part design, build configuration and process performance.

Experimental study of surface roughness, dimensional accuracy and time of fabrication of parts produced by fused deposition modelling

2020 ◽  
Vol 26 (9) ◽  
pp. 1535-1554
Author(s):  
Swapnil Vyavahare ◽  
Shailendra Kumar ◽  
Deepak Panghal
Keyword(s):  
Experimental Study ◽  
Surface Roughness ◽  
Layer Thickness ◽  
Process Parameters ◽  
Dimensional Accuracy ◽  
Fused Deposition Modelling ◽  
Content Type ◽  
Build Orientation ◽  
Fused Deposition ◽  
Significant Process

Purpose This paper aims to focus on an experimental study of surface roughness, dimensional accuracy and time of fabrication of parts produced by fused deposition modelling (FDM) technique of additive manufacturing. The fabricated parts of acrylonitrile butadiene styrene (ABS) material have pyramidal and conical features. Influence of five process parameters of FDM, namely, layer thickness, wall print speed, build orientation, wall thickness and extrusion temperature is studied on response characteristics. Furthermore, regression models for responses are developed and significant process parameters are optimized. Design/methodology/approach Comprehensive experimental study is performed using response surface methodology. Analysis of variance is used to investigate the influence of process parameters on surface roughness, dimensional accuracy and time of fabrication in both outer pyramidal and inner conical regions of part. Furthermore, a multi-response optimization using desirability function is performed to minimize surface roughness, improve dimensional accuracy and minimize time of fabrication of parts. Findings It is found that layer thickness and build orientation are significant process parameters for surface roughness of parts. Surface roughness increases with increase in layer thickness, while it decreases initially and then increases with increase in build orientation. Layer thickness, wall print speed and build orientation are significant process parameters for dimensional accuracy of FDM parts. For the time of fabrication, layer thickness and build orientation are found as significant process parameters. Based on the analysis, statistical non-linear quadratic models are developed to predict surface roughness, dimensional accuracy and time of fabrication. Optimization of process parameters is also performed using desirability function. Research limitations/implications The present study is restricted to the parts of ABS material with pyramidal and conical features only fabricated on FDM machine with delta configuration. Originality/value From the critical review of literature it is found that some researchers have made to study the influence of few process parameters on surface roughness, dimensional accuracy and time of fabrication of simple geometrical parts. Also, regression models and optimization of process parameters has been performed for simple parts. The present work is focussed on studying all these aspects in complicated geometrical parts with pyramidal and conical features.

Optimization of build orientation in FFF using response surface methodology and posterior-based method

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mohammad Javad Hooshmand ◽  
Saeed Mansour ◽  
Amin Dehghanian
Keyword(s):  
Layer Thickness ◽  
Process Parameters ◽  
Empirical Models ◽  
High Quality ◽  
Content Type ◽  
Build Orientation ◽  
Build Time ◽  
Raster Angle ◽  
Quality Surface ◽  
Response Variables

Purpose The advancement of additive manufacturing technologies has resulted in producing parts of high quality and reduced manufacturing time. This paper aims to achieve a simultaneous optimal solution for build time and surface roughness as the output data and also to find the best values for the input data consisting of build orientation, extrusion width, layer thickness, infill percentage and raster angle. Design/methodology/approach For this purpose, the effects of process parameters on the response variables were investigated by the design of experiments approach to develop empirical models using response surface methodology. The experimental parts of this research were conducted using an inexpensive and locally assembled fused filament fabrication (FFF) machine. A total of 50 runs for 4 different geometries, namely, cylinder, prism, 3DBenchy and twist gear vase, were performed using the rotatable central composite design, and each process parameters were investigated in two levels to develop empirical models. Also, a novel optimization method, namely, the posterior-based method, was accomplished to find the best values for the response variables. Findings The results demonstrated that not only the build orientation and layer thickness have notable effects on both response variables but also build time is dependent on extrusion width and infill percentage. Low infill percentage and high extrusion width resulted in increasing build time. By reducing layer thickness and infill percentage while increasing extrusion width, parts of high-quality surface finish and reduced built time were produced. Optimum process parameters were found to be of build direction of 0°, extrusion width of 0.61 mm, layer thickness of 0.22 mm, infill percentage of 20% and raster angle of 0°. Originality/value Through the developed empirical models and by minimizing build orientation and layer thickness, and also considerations for process parameters, parts of high-quality surface finish and reduced built time could be produced on FFF machines. To compensate for increased build time because of reduction in layer thickness, extrusion width and infill percentage must have their maximum and minimum value, respectively.

Open hole tensile testing of 3D printed parts using in-house fabricated PLA filament

2020 ◽  
Vol 26 (1) ◽  
pp. 21-31 ◽  
Author(s):  
Harshit K. Dave ◽  
Ashish R. Prajapati ◽  
Shilpesh R. Rajpurohit ◽  
Naushil H. Patadiya ◽  
Harit K. Raval
Keyword(s):  
Tensile Strength ◽  
Layer Thickness ◽  
Process Parameters ◽  
Geometrical Shape ◽  
Content Type ◽  
Fused Deposition ◽  
Open Hole ◽  
Raster Angle ◽  
3D Printed ◽  
The Impact

Purpose Fused deposition modeling (FDM) is being increasingly used in automotive and aerospace industries because of its ability to produce specimens having difficult geometrical shape. However, owing to lack of critical information regarding the reliability and mechanical properties of FDM-printed parts at various designs, the use of 3D printed parts in these industries is limited. Therefore, the purpose of this paper is to investigate the impact of process parameters of FDM on the tensile strength of open-hole specimen printed using in-house-fabricated polylactic acid (PLA). Design/methodology/approach In the present study, three process parameters, namely, raster angle, layer thickness and raster width, are selected for investigation of tensile strength. To produce the tensile specimens in the FDM machine, the PLA filament is used which is fabricated from PLA granules using a single-screw extruder. Further, the experimental values are measured and critically analysed. Failure modes under tests are studied using scanning electron microscopy (SEM). Findings Results indicate that the raster angle has a significant effect on the tensile strength of open-hole tensile specimen. Specimens built with 0° raster angle, 200-µm layer thickness and 500-µm raster width obtained maximum tensile strength. Originality/value In this work, a new concept of testing a plate that has a rectangular shape and a circular hole at the centre is tested. Open-hole tensile test standard ASTM D5766 has been implemented for the first time for the FDM process.

Actuation and dynamic mechanical characteristics of a core free flat dielectric electro-active polymer soft actuator

2020 ◽  
Vol 14 (4) ◽  
pp. 7396-7404
Author(s):  
Abdul Malek Abdul Wahab ◽  
Emiliano Rustighi ◽  
Zainudin A.
Keyword(s):  
Theoretical Model ◽  
Resonance Frequency ◽  
Dynamic Testing ◽  
Experimental Results ◽  
Percentage Error ◽  
Initial Tension ◽  
Average Percentage ◽  
Soft Actuator ◽  
Average Percentage Error ◽  
Mechanical Dynamics

Various complex shapes of dielectric electro-active polymer (DEAP) actuator have been promoted for several types of applications. In this study, the actuation and mechanical dynamics characteristics of a new core free flat DEAP soft actuator were investigated. This actuator was developed by Danfoss PolyPower. DC voltage of up to 2000 V was supplied for identifying the actuation characteristics of the actuator and compare with the existing formula. The operational frequency of the actuator was determined by dynamic testing. Then, the soft actuator has been modelled as a uniform bar rigidly fixed at one end and attached to mass at another end. Results from the theoretical model were compared with the experimental results. It was found that the deformation of the current actuator was quadratic proportional to the voltage supplied. It was found that experimental results and theory were not in good agreement for low and high voltage with average percentage error are 104% and 20.7%, respectively. The resonance frequency of the actuator was near 14 Hz. Mass of load added, inhomogeneity and initial tension significantly affected the resonance frequency of the soft actuator. The experimental results were consistent with the theoretical model at zero load. However, due to inhomogeneity, the frequency response function’s plot underlines a poor prediction where the theoretical calculation was far from experimental results as values of load increasing with the average percentage error 15.7%. Hence, it shows the proposed analytical procedure not suitable to provide accurate natural frequency for the DEAP soft actuator.

PP15 Predicting variations of calls to an ambulance service in the UK caused by circulating infections using-deep learning methods

2019 ◽  
Vol 36 (10) ◽  
pp. e7.2-e7
Author(s):  
Thilo Reich ◽  
Marcin Budka
Keyword(s):  
Deep Learning ◽  
Short Term Memory ◽  
Prehospital Care ◽  
Machine Learning Algorithms ◽  
Ambulance Service ◽  
Percentage Error ◽  
Learning Methods ◽  
Average Percentage ◽  
Average Percentage Error ◽  
The Uk

BackgroundDigital patient records in the ambulance service have opened up new opportunities for prehospital care. Previously it was demonstrated that prehospital pyrexia numbers are linked to an increase in overall calls to the ambulance service. This study aims to predict the future number of calls using deep-learning methods.MethodsTemperature readings for 280,447 patients were generously provided by the South Western Ambulance Service Trust. The data covered the time between 05/01/2016 and 30/04/2017 with overall 44,472 patients being pyretic. A rolling window of 10 days was applied to daily sums for both pyretic and apyretic patients. These windows were used as input features to train machine-learning algorithms predicting the number of calls 10 days ahead. Algorithms tested include Linear Regression (LR), basic Recurrent Neural Networks (RNN), Long Short Term Memory (LSTM) and Gated Recurrent Unit (GRU) architectures. A genetic approach was used to optimise the architecture, in which parameters were randomly modified and over several generations the best performing algorithm will be selected to be further manipulated. To assess performance the Mean Average Percentage Error (MAPE) was used.ResultsThe initial analysis showed that the total patient number and pyretic patient numbers are correlated. The best performing algorithms with varying numbers of hidden units had the following MAPE in comparison to simple LR: LR=19.4%, LSTM (104 units) = 6.1%, RNN (79 units)=6.01%, GRU (80 units)=5.97%.ConclusionsThese preliminary results suggest that deep-learning methods allow to predict the variations in total number of calls caused by circulating infections. Further investigations will aim to confirm these findings. Once fully verified these algorithms could play a major role in operational planning of any ambulance service by predicting increases in demand.

scholarly journals Validity of Consumer Activity Monitors and an Algorithm Using Smartphone Data for Measuring Steps during Different Activity Types

2020 ◽  
Vol 17 (24) ◽  
pp. 9314
Author(s):  
Verena Hartung ◽  
Mustafa Sarshar ◽  
Viktoria Karle ◽  
Layal Shammas ◽  
Asarnusch Rashid ◽  
...  
Keyword(s):  
Physical Activity ◽  
Arm Movements ◽  
Percentage Error ◽  
Activity Measurement ◽  
Overground Walking ◽  
Activity Monitors ◽  
Average Percentage ◽  
Study Results ◽  
Promotion Of Physical Activity ◽  
Average Percentage Error

Background: Consumer activity monitors and smartphones have gained relevance for the assessment and promotion of physical activity. The aim of this study was to determine the concurrent validity of various consumer activity monitor models and smartphone models for measuring steps. Methods: Participants completed three activity protocols: (1) overground walking with three different speeds (comfortable, slow, fast), (2) activities of daily living (ADLs) focusing on arm movements, and (3) intermittent walking. Participants wore 11 activity monitors (wrist: 8; hip: 2; ankle: 1) and four smartphones (hip: 3; calf: 1). Observed steps served as the criterion measure. The mean average percentage error (MAPE) was calculated for each device and protocol. Results: Eighteen healthy adults participated in the study (age: 28.8 ± 4.9 years). MAPEs ranged from 0.3–38.2% during overground walking, 48.2–861.2% during ADLs, and 11.2–47.3% during intermittent walking. Wrist-worn activity monitors tended to misclassify arm movements as steps. Smartphone data collected at the hip, analyzed with a separate algorithm, performed either equally or even superiorly to the research-grade ActiGraph. Conclusion: This study highlights the potential of smartphones for physical activity measurement. Measurement inaccuracies during intermittent walking and arm movements should be considered when interpreting study results and choosing activity monitors for evaluation purposes.

scholarly journals Comparison of Otolith Readability and Reproducibility of Counts of Translucent Zones Using Different Otolith Preparation Methods for Four Endemic Labeobarbus Species in Lake Tana, Ethiopia

Water ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1336 ◽  
Author(s):  
Gebremedhin ◽  
Bekaert ◽  
Getahun ◽  
Bruneel ◽  
Anteneh ◽  
...  
Keyword(s):  
Management Strategies ◽  
Tropical Fish ◽  
Percentage Error ◽  
Systematic Bias ◽  
Preparation Technique ◽  
Lake Tana ◽  
Preparation Methods ◽  
Average Percentage ◽  
Average Percentage Error ◽  
Preparation Techniques

The analysis of fish age data is vital for the successful conservation of fish. Attempts to develop optimal management strategies for effective conservation of the endemic Labeobarbus species are strongly affected by the lack of accurate age estimates. Although methodological studies are key to acquiring a good insight into the age of fishes, up to now, there have not been any studies comparing different methods for these species. Thus, this study aimed at determining the best method for the endemic Labeobarbus species. Samples were collected from May 2016 to April 2017. Asteriscus otoliths from 150 specimens each of L. intermedius, L. tsanensis, L. platydorsus, and L. megastoma were examined. Six methods were evaluated; however, only three methods resulted in readable images. The procedure in which whole otoliths were first submerged in water, and subsequently placed in glycerol to take the image (MO1), was generally best. Except for L. megastoma, this method produced the clearest image as both the coefficient of variation and average percentage error between readers were lowest. Furthermore, except for L. megastoma, MO1 had high otolith readability and no systematic bias. Therefore, we suggest that MO1 should be used as the standard otolith preparation technique for the first three species, while for L. megastoma, other preparation techniques should be evaluated. This study provides a reference for researchers from Africa, particularly Ethiopia, to develop a suitable otolith preparation method for the different tropical fish species.

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