Analysis Of Dimensional Accuracy Research Articles

Estimating the Uncertainty of Measurements for Various Methods and 3D Printed Parts

This paper presents the results of a study on the dimensional accuracy analysis of models produced by 3D printing technology—Fused Filament Fabrication (FFF). Geometric measurements were conducted using a dial caliper, a 3D scanner and a coordinate measuring machine. In addition, a statistical analysis of the test results was carried out, considering the division into different numbers of test samples (3, 5, 10, 20, 30). The analysis of the test results made it possible to assess the influence of the measuring tools used and the number of samples tested on the final measurement result, as well as to determine the consequences associated with it.

Study on the Optimization of Investment Casting Process of Exhaust Elbow for High-Power Engine

The high-power engine exhaust elbow has a complex construction, which makes it susceptible to casting flaws that could negatively impact its functionality. Therefore, the investment casting scheme was established and optimized in this study in order to cast structurally complete exhaust elbows for high-horsepower engines. ProCAST software was used to simulate and optimize the casting and solidification processes. The optimal process parameters were determined as follows: pouring temperature of 1650 °C, pouring speed of 1.5 kg/s, and shell preheating temperature of 1050 °C. The optimization of the primary parameters of the casting process, along with the results of dimensional accuracy analysis, shape and positional deviation, and defect detection, were validated through testing. The results indicated that the optimized castings had no casting defects and complied with the design specifications.

Rapid tooling of composite aluminium filled epoxy mould for injection moulding of polypropylene parts with small protruded features

Abstract Rapid tooling evolved from rapid prototyping is a novel method for developing prototype tooling rapidly using various additive manufacturing techniques. Traditional injection moulding is unsuitable for low-volume production because of the high initial cost. This study is focused on a rapid tooling approach for producing an injection mould insert for the low-volume production of plastic components. A plastic injection mould insert is designed, developed using composite aluminium filled epoxy with minute protruded features and tested on a vertical injection moulding machine as a rapid tool for low-volume production of plastic components. The composite aluminium filled epoxy (CAFE) mould insert is prepared using a wax master from silicon rubber mould prepared using a stereolithography master. Experiments are performed to determine the optimum mixing ratio of epoxy: aluminium powder for making the composite aluminium filled epoxy injection mould. The mould insert prepared was tested for the injection of polypropylene components on a vertical injection moulding machine and analyzed for dimensional accuracy. The analysis of dimensional accuracy and viability of minute features on the injected parts shows promising results for up to 30 injected parts. The injection of parts after 30 pieces resulted in increasing mould erosion and pitting, causing mould damage at the 36th injection shot. The experimental finding supports the feasibility of using the composite aluminium filled epoxy injection mould for low-volume production of the parts; however, the surface finish is inferior. The life of the mould is expected to give better results with a higher surface finish. It is also exposed that using mould release agents improves the life of the composite aluminium-filled epoxy injection mould.

Analysis of dimensional accuracy of RP pattern and RTV mould inserts using DOE technique

Analysis of dimensional accuracy of RP pattern and RTV mould inserts using DOE technique

Analysis of dimensional accuracy of RP pattern and RTV mould inserts using DOE technique

Analysis of dimensional accuracy of RP pattern and RTV mould inserts using DOE technique

Non-Contact Multiscale Analysis of a DPP 3D-Printed Injection Die for Investment Casting

The investment casting method supported with 3D-printing technology, allows the production of unit castings or prototypes with properties most similar to those of final products. Due to the complexity of the process, it is very important to control the dimensions in the initial stages of the process. This paper presents a comparison of non-contact measurement systems applied for testing of photopolymer 3D-printed injection die used in investment casting. Due to the required high quality of the surface parameters, the authors decided to use the DPP (Daylight Polymer Printing) 3D-printing technology to produce an analyzed injection die. The X-ray CT, Structured blue-light scanner and focus variation microscope measurement techniques were used to avoid any additional damages to the injection die that may arise during the measurement. The main objective of the research was to analyze the possibility of using non-contact measurement systems as a tool for analyzing the quality of the surface of a 3D-printed injection die. Dimensional accuracy analysis, form and position deviations, defect detection, and comparison with a CAD model were carried out.

Manufacturing of Closed Impeller for Mechanically Pump Fluid Loop Systems Using Selective Laser Melting Additive Manufacturing Technology.

In the space industry, the market demand for high-pressure mechanically pumped fluid loop (MPFL) systems has increased the interest for integrating advanced technologies in the manufacturing process of critical components with complex geometries. The conventional manufacturing process of a closed impeller encounters different technical challenges, but using additive manufacturing (AM) technology, the small component is printed, fulfilling the quality requirements. This paper presents the Laser Powder Bed Fusion (LPBF) process of a closed impeller designed for a centrifugal pump integrated in an MPFL system with the objective of defining a complete manufacturing process. A set of three closed impellers was manufactured, and each closed impeller was subjected to dimensional accuracy analysis, before and after applying an iterative finishing process for the internal surface area. One of the impellers was validated through non-destructive testing (NDT) activities, and finally, a preliminary balancing was performed for the G2.5 class. The process setup (building orientation and support structure) defined in the current study for a pre-existing geometry of the closed impeller takes full advantages of LPBF technology and represents an important step in the development of complex structural components, increasing the technological readiness level of the AM process for space applications.

Analysis of dimensional accuracy for micro-milled areal material measures with kinematic simulation

The calibration of areal surface topography measuring instruments is of high relevance to estimate the measurement uncertainty and to guarantee the traceability of the measurement results. Calibration structures for optical measuring instruments must be sufficiently small to determine the limits of the instruments.Besides other methods, micro-milling is a suitable process for manufacturing areal material measures. For the manufacturing by micro-milling with ball end mills, the tool radius (effective cutter radius) is the corresponding limiting factor: if the tool radius is too large to penetrate the concave profile details without removing the surrounding material, deviations from the target geometry will occur. These deviations can be detected and excluded before experimental manufacturing with the aid of a kinematic simulation.In this study, a kinematic simulation model for the prediction of the dimensional accuracy of micro-milled areal material measures is developed and validated. Subsequently, a radius study is conducted to determine how the tool radius r of the tool influences the dimensional accuracy of an areal crossed sinusoidal (ACS) geometry according to ISO 25178-70 [1] with a defined amplitude d and period length p. The resulting theoretical surface texture parameters are evaluated and compared to the target values. It was shown that the surface texture parameters deviate from the nominal values depending on the effective cutter radius used. Based on the results of the study, it can be determined with which effective tool radius the measurands Sa and Sq of the material measures are best met. The ideal effective radius for the application considered is between 50 and 75 μm.

Dimensional Accuracy Analysis of Samples Printed in Delta and Cartesian Kinematic Three Dimensional Printers

The motion mechanisms of manufacturing and robotic systems are developed in different structures, mainly in cartesian and delta structures having series or parallel movement abilities according to the capacity and construction structure of the system. Different systems are used according to the criteria such as bearing load capacity, sensitivity or cost of the system. In this study, the performances of machines installed in the delta and cartesian kinematic structures, which are mostly used in the kinematic systems of three - dimensional printers, were analyzed. In this context, in two different machines with these two construction structures, the same boundary conditions and 4 pieces of calibration parts especially in manufacturing features were printed. 23 different elements that constituted the calibration part were measured, tabulated, statistically analyzed, and the acceptable measuremental tolerance ranges of the elements were determined and the accuracy values of the machines were compared. As a result of this study, according to T test results, 15 of the 23 measurements on the Cartesian system based three-dimensional printers were obtained as acceptable in terms of tolerance range as well as 9 of the 23 different measurements were obtained as acceptable on Delta system. Consequently, operation accuracy of the Cartesian system based three-dimensional printers were higher than the Delta system under the same working conditions and manufacturing parameters.

The Dimensional Accuracy of Thin-Walled Parts Manufactured by Laser-Powder Bed Fusion Process

Laser-Powder Bed Fusion brings new possibilities for the design of parts, e.g., cutter shafts with integrated cooling channels close to the contour. However, there are new challenges to dimensional accuracy in the production of thin-walled components, e.g., heat exchangers. High degrees of dimensional accuracy are necessary for the production of functional components. The aim is to already achieve these during the process, to reduce post-processing costs and time. In this work, thin-walled ring specimens of H13 tool steel are produced and used for the analysis of dimensional accuracy and residual stresses. Two different scanning strategies were evaluated. One is a stripe scan strategy, which was automatically generated and provided by the machine manufacturer, and a (manually designed) sectional scan strategy. The ring segment strategy is designed by manually segmenting the geometry, which results in a longer preparation time. The samples were printed in different diameters and analyzed with respect to the degree of accuracy and residual stresses. The dimensional accuracy of ring specimens could be improved by up to 81% with the introduced sectional strategy compared to the standard approach.

Ti6Al4V Parts Produced by Electron Beam Melting: Analysis of Dimensional Accuracy and Surface Roughness

Additive manufacturing (AM), applied to metal industry, is a family of processes that allows complex shape components to be realized from raw materials in the form of powders. Electron beam melting (EBM) is a relatively new additive manufacturing (AM) technology. Similar to electron-beam welding, EBM utilizes a high-energy electron beam as a moving heat source to melt metal powder, and 3D parts are produced in a layer-building fashion by rapid self-cooling. By EBM, it is possible to realize metallic complex shape components, e.g. fine network structures, internal cavities and channels, which are difficult to make by conventional manufacturing means. This feature is of particular interest in titanium industry in which numerous efforts are done to develop near net shape processes. In the field of mechanical engineering and, in particular, in the aerospace industry, it is crucial for quality certification purpose that components are produced through qualified and robust manufacturing processes ensuring high product repeatability. The contribution of the present work is to experimentally identify the EBM job parameters (sample orientation, location of the sample in the layer and height in the build chamber) that influence the dimensional accuracy and the surface roughness of the manufactured parts in Ti6Al4V. The repeatability of EBM is investigated too.

A Perspective on Using Machine Learning in 3D Bioprinting.

Recently, three-dimensional (3D) printing technologies have been widely applied in industry and our daily lives. The term 3D bioprinting has been coined to describe 3D printing at the biomedical level. Machine learning is currently becoming increasingly active and has been used to improve 3D printing processes, such as process optimization, dimensional accuracy analysis, manufacturing defect detection, and material property prediction. However, few studies have been found to use machine learning in 3D bioprinting processes. In this paper, related machine learning methods used in 3D printing are briefly reviewed and a perspective on how machine learning can also benefit 3D bioprinting is discussed. We believe that machine learning can significantly affect the future development of 3D bioprinting and hope this paper can inspire some ideas on how machine learning can be used to improve 3D bioprinting.

Analysis of Dimensional Accuracy (Over Cut) and Surface Quality (Roughness) in Electrical Discharge Machining of Inconel-718 Alloy

Inconel-718 is a nickel based super alloy (difficult-to-cut material) used in aerospace industry. Analysis of machining performances viz. Over Cut (OC) & Surface Roughness (SR) for Inconel-718 through rotary Cu-pin tool electrode have been carried out. Peak current (Ip), pulse-on time (Ton), tool rotation (Nt) & hole depth (h) were used as input factors in Electrical Discharge Drilling (EDD) of Inconel-718 work-piece. Effect of input parameters on performance characteristics like OC & SR were found by Taguchi’s L9 (34) orthogonal array. It is reveals that Ip & h are most affecting factors that affects OC & SR. The Scanning Electron Microscope image was used to measure diameter of hole on work-piece after machining.

Experimental investigation and analysis of dimensional accuracy of laser-based powder bed fusion made specimen by application of response surface methodology

This study reports the dimensional accuracy of laser based powder bed fusion made parts with the effect of various input parameters while processing CL50WS material as the workpiece material. CL50WS material is mainly used in die and mould manufacturing industry for making die, tool insert, mould or casting die. In today’s competitive era, the quality of the final product is driven by the mechanical properties of the die or mould, for die and mould manufacturing industry. This study focuses on studying the effects of process parameters, such as laser power, scanning speed, layer thickness and hatch spacing, on fabricated specimens. Analysis of variance was used to test the adequacy of the established models and also to find the significance of the parameters on response. The R2 was found to be 0.9265 which depicted that the developed models are suitable and effectively predict the dimensional accuracy within the range of chosen process parameters. The results suggest that layer thickness is the most significant parameters for dimensional accuracy.

Dimensional accuracy analysis of Direct Metal Printing machine focusing on roller positioning errors

Despite of the great deployment of Direct Metal Printing (DMP) technology for additive manufacturing, there is still an issue in the dimensional evaluation of built parts. To establish (or define) a reachable dimensional accuracy value in this kind of technologies is an arduous work due to the wide variety of factors involved. The high flexibility allowed by this technology (regarding geometry, materials, strategies, form and size of the powder particles, post-processing method, etc.) causes a high grade of uncertainty on the final part quality. This uncertainty not only affects the surface roughness or the mechanical properties, but also has a high impact on the dimensional accuracy, and this without considering ulterior post-processes. This paper analyses the geometrical and dimensional accuracy of DMP machines focusing on the positioning error of the leveling roller. Another objective of this survey involves the design and validation of a prismatic test part dedicated to characterize the positioning accuracy of a given DMP printer. The analysis is carried out by determining the positioning errors of the printed geometries according to several printing orientations, both in the directions of the roller (metal dust-feeder) displacement, within the roller itself, as well as in the height direction. The high number of prismatic features manufactured onto the built-up plate, and the uniform spatial distribution of these features, allow for obtaining values of the manufacturing repeatability within the machine working volume, providing the deviations with regard to the nominal model as the variability achievable in the different printing directions.

Selective laser melting of titanium parts: Influence of laser process parameters on macro- and microstructures and tensile property

The laser process parameters play an important role in the macro- and microstructures and tensile property of titanium samples fabricated by selective laser melting (SLM). In this study, the effect of laser process parameters on the density, surface morphology, dimensional accuracy, microstructure and tensile property of SLMed Ti6Al4V parts was investigated. With the increase of laser power and decrease of scan speed, the densification increased and the relative density showed reduced sensitivity to laser power under higher laser power (>175 W). The morphology of scan tracks on the top surface changed from clear and uniform mode to disordered mode with the increase of scan speed. The marks of melt flow, molten pool overlap and adhered powder could be observed obviously on the side surface. In the analysis of dimensional accuracy, the size shrinkage effect in the building direction (z-axis) was discussed and the “periphery spreading effect” in horizontal direction (x-axis and y-axis) was presented. Martensite α’ was the main constituent phase in SLMed Ti6Al4V samples. With the increase of scan speed, the width of prior β grains decreased gradually and the formed α’ phase changed into a relatively refined acicular shape. Conclusively, the relationship between microstructure and tensile property was discussed and a relative high tensile property was obtained.

Statistical analysis of dimensional accuracy in additive manufacturing considering STL model properties

Additive manufacturing (AM) is a technology that produces a part layer by layer based on the computer-aided designed (CAD) model. Each AM process is defined by a set of parameters and materials. The laser power, scan spacing and speed, preheating and bed temperatures, hatch length, pulse frequency, and part placement (coordinates of a part placed in the build) are among the most studied process parameters reported in the literature. Recent attention to improving part quality is caused by the possibility of using AM for manufacturing, but the inconsistency of results’ repeatability is the main challenge that is not solved yet. This work attempts to improve the dimensional accuracy by predicting dimensional features of the part, namely length, width, and thickness. Data is collected from two identical runs done on EOS P395 polymer laser sintering system. By identical runs is meant that build layout, material and process parameters were kept constant in both runs. Pearson correlation test is used to identify whether the new parameters (the number of mesh triangles, surface, and volume of CAD model) are significantly correlated to dimensional features. Based on the correlation results, linear regression models are developed to predict dimensional features (compensate shrinkage effect). The obtained results are the following: models for thickness (in XZY orientation), length (in ZYX orientation), and length and thickness (in Angle orientation) can already be used to predict dimensional features (to minimize shrinkage effect by proposing scaling ratio for each specimen in the build separately).

Computer-Aided Modeling of a Screw Firmware of the Workpiece and Adequacy Evaluation of Solution Results

In the work were set and solved the task of the FEM simulation process, the screw firmware blank on the double roller mill with mushroom-shaped rolls. The decision of the task allowed us to calculate the parameters of the contact surface of the workpiece to roll as well as the analysis of dimensional accuracy of the casings. The adequacy of the models is proved by comparison of calculated and experimental values of the parameters of the contact surface and the sizes of the casings. Implementation of the developed technical solutions for adaptation of a piercing mill in the shop No1 PJSC "STZ" has allowed to provide high stability of the rolling of thin-walled shells with size 328×433 of 20.55 mm x 26,9 mm.

Dimensional accuracy analysis of coupled fused deposition modeling and vapour smoothing operations for biomedical applications

Abstract Fused Deposition Modeling (FDM) is one of the most extensively used Additive Manufacturing technique which has substantially shortened the product development time and cost. The application has been extended to fabricate biomedical implants through investment casting process. But the FDM replicas exhibit poor surface quality which requires further post finishing. Thus, it is very difficult to achieve adequate dimensional accuracy as surface finishing techniques resulted in material removal and erosion of upper surface. The vapour smoothing is an advanced finishing technique which eliminates tool-workpiece contact and yield ultra smooth finish but dimensional accuracy of FDM replicas is yet to be ascertained. In present research, the efforts are made to explore the influence of FDM and VS process parameters in dimensional features of complex designs. The influence of six parameters on radial (head diameter) and linear dimensions (neck and stem thickness) is studied using Taguchi orthogonal array. The CMM measurements showed shrinkage in head diameter while positive deviation has been observed in linear dimensions before vapour smoothing with maximum impact of orientation angle. The vapour smoothing process caused shrinkage in both linear and radial dimensions with maximum effect of smoothing time. The process parameters and their levels are optimized and confirmatory experiments indicated reduced deviations in dimensional features with consistency in IT grades.

Comparative Analysis of Dimensional Accuracy of Two Types of Silicone Impression Materials: Optosil and Elite-HD

Statement of the Problem: Understanding about impression materials, their properties, uses and manipulation can guide operators towards having more successful restorations. Purpose: The aim of this in vitro study was to compare the accuracy of a condensation silicone impression material, Optosil, and an addition poly siloxane impression material, Elite-HD. Materials and Method: A laboratory model with two metallic dies was used to make impression. A horizontal notch on one of the two dies simulated an undercut. Ten impressions were made by each impression material by the putty-wash technique. After pouring impressions with velmix die stone, a total of 20 stone casts were made from both materials. Measurements of casts were compared with the master model. Statistical analyses were performed using t-test. Result: This results of this study showed that the height of die without undercut decreased in both groups. Also the height above the undercut decreased in both groups, which was more obvious in Elite-HD group than Optosil group. The distance between dies increased in both groups, with higher figures for Elite-HD. So, Optosil is a more accurate material for registering inter-abutment distance than Elite-HD. The diameter of die under the undercut decreased in Optosil group and was similar to the master model in Elite-HD. Statistical analysis showed significant differences between these two groups in the distance between abutments (p=0.001), the diameter of die under the undercut (p=0.014) and the height of die above undercut(p=0.057). Conclusion: Optosil is more accurate in registering inter-abutment distance than Elite-HD, so Optosil is preferred for fixed partial denture impressions. Since Elite-HD showed more accuracy in C measurements than Optosil, it is preferred for single crown impressions.