G-code File Research Articles

From CAD to G-code: Strategies to minimizing errors in 3D printing process

In this study, an analysis was conducted to quantify errors in the additive manufacturing process, with a focus on comparing data files. The primary objective was to minimise the reliance on physical testing of produced components by favouring verification within a virtual environment. The initial focus was on the conversion from the CAD (Computer-Aided Design) model to the STL (Standard Tessellation Language) file, where discrepancies between the two formats were identified. To achieve optimal meshing, it is crucial to configure conversion parameters effectively, avoiding both detail loss and the handling of excessively large files. Following this, a comparison between STL files and reconstructed G-code files was conducted, uncovering further approximations introduced by the most commonly used slicers. In conclusion, the analysis highlights that both the quality of the mesh and the slicing phase significantly impact the final component. Understanding these factors is essential for achieving an optimal print outcome.

3D-printed tool for creating standardized burn wounds in ex vivo skin tissues

IntroductionThe development of biomaterials and medical devices for burn wound treatment necessitates thorough investigation through in vitro/ex vivo models before transitioning to animal studies. Establishing a standardized and high-throughput burn wound model in ex vivo skin presents a considerable challenge. Our objective was to address this challenge by developing a practical and cost-effective 3D-printed burn wound tool capable of uniformly inducing burns in 12 skin samples simultaneously. Material and methodsUtilizing Autodesk Inventor software, we designed a 3D model comprising a plate-base component (PBC) and a rod-base component (RBC). The design was exported as a Standard Triangulation Language (STL) file, processed through "Slicer" software to generate a G-code file tailored for 3D printing. ResultsThe Rod-Base component underwent iterative design modifications to optimize weight, airflow, and material consumption, resulting in a final design featuring a unique star shape for enhanced airflow. Simultaneously, the Plate-Base component design evolved to enable easy and secure plate placement, demonstrating compatibility with 12-well plates. The average production time for the model was 14.5 h, with a production cost of approximately $20 (USD), covering printing material and steel rods. ConclusionIn conclusion, this study provides valuable insights into the required equipment and software, empowering researchers to efficiently produce their accurate and cost-effective 3D-printed tool for controlled and reproducible burn wound creation in ex vivo viable skin tissues.

A slicing and path generation method for 3D printing of periodic surface structure

Periodic surface (PS) model holds enormous potential in the field of lightweight, heat management, and biomedical implants. To achieve tunable mechanical strength and high surface area versus volume (SA/V) ratio, it is imperative to achieve solid representation of the PS models. However, because of the complex inner structure, converting the surface model to solid model with uniform thickness remains a major challenge. In the meantime, the most pervasive practice to achieve tunable wall thickness is by offsetting the contour with a constant value or setting a constant value difference between two implicit functions. However, these existing approaches cannot guarantee uniform wall thickness. In this paper, a novel method is proposed to define an adjacent implicit surface with a uniform offset distance to the original. By repeatedly generating implicit surfaces with uniform distance from each other, the solid representation of the PS model with uniform thickness can be achieved. Meanwhile, a new slicing method allowing for the slicing without stereolithography (STL) file is developed to slice the implicit surfaces and generate the printing path so that the accumulation of slicing errors introduced by meshing steps can be avoided. By slicing each implicit surface separately, the corresponding G-code file is generated. This developed method is demonstrated by fabricating typical PS with fused filament 3D printing.

Automated Composite Pipe Cutting Machine for ASTM Standard Testing Specimen Preparation

This thesis aims to design a pipe-cutting machine using costume-made metal fixtures, an Avid CNC Bentch Top machine, and Mach4 control software to cut strips off from pipes made of PVC, resin, and fibreglass materials automatically. The costume-made fixtures clamp down the pipe and rotate it to perform multiple cuts around it. Avid CNC Bentch Top Machine is used to perform the ramping cut with a 10mm diameter square shoulder milling cutter. A touch probe is mounted beside the cutter to measure the accurate pipe diameter. An HMI (Human Machine Interface) that allows the operator to input the dimension of the pipe and perform calibration before use is developed using the LUA language under Mach4 motion control software. Screen and button scripts are programmed to read the input from the operator and sensors to generate a Gcode file to drive the CNC machine. The machine prototype can cut 5 strips in 30 minutes with the dimensions and surface finish required by ASTM D790 and ASTM D638, significantly increasing the production rate and reducing the waste of human resources while focusing on the environmentally friendly and cost-friendly for small businesses.

Tool path planning for hole-flanging process using single point incremental forming

Hole-flanging is a process used to create flanges around holes in sheet metal parts. It traditionally relies on dies and punches, posing cost and time challenges for small quantities or prototypes. While Incremental forming does not require dedicated sets of tools and dies, and it provides more flexibility and adaptability with enhanced formability, and emerged as a better alternative to conventional press forming. However, precise and efficient tool path planning is essential to achieve high-quality hole-flanged components. Precise toolpath planning is one of the crucial and important part in designing of hole flanging process for both through numerical simulations and experiments. The objective of the present work is to generate tool paths as well as associated G-codes using MATLAB code for different geometries of incremental hole flanging process using SPIF. Six different geometries of hole flanges were considered to generate tool path using MATLAB code. The proposed methodology was successfully applied for different shapes of hole flanges. Since the proposed methodology provides unified programming technique in the current MATLAB environment, which performs dual duties, creating toolpath coordinates against time data and outputting a G-code file and it saves computational time and programming efforts. Hence, proposed methodology is found to be better for incremental hole flanging in contrast to previously existed methodology for development of toolpath for incremental forming cases. Thus, it was concluded that this proposed methodology can be effective for capturing any intricate shapes for incremental hole flanging. You should leave 8 mm of space above the abstract and 10 mm after the abstract. The heading Abstract should be typed in bold 9-point Arial. The body of the abstract should be typed in normal 9-point Times in a single paragraph, immediately following the heading. The text should be set to 1 line spacing. The abstract should be centred across the page, indented 17 mm from the left and right page margins and justified. It should not normally exceed 200 words.

Enhanced Dynamic Impact Resistance of 3D-Printed Continuous Optical Fiber-Reinforced Helicoidal Polylactic Acid Composites.

Characterized by light weight and high strength, composites are widely used as protective materials in dynamic impact loading under extreme conditions, such as high strain rates. Therefore, based on the excellent tensile properties of continuous fiber and the good flexibility and toughness of the bionic spiral structure, this study uses a multi-material 3D printer to incorporate continuous fiber, and then modifies the G-CODE file to control the printing path to achieve the production of a continuous fiber-reinforced Polylactic Acid composite helicoidal (spiral angle 60°) structure (COF-HP). Dynamic behavior under high-strain-rate impact experiments have been conducted using the Split Hopkinson Pressure Bar (SHPB). Stress-strain curves, impact energy curves and high-speed camera photographs with different strain rates at 680 s-1 and 890 s-1 have been analyzed to explore the dynamic process and illustrate the damage evolution. In addition, some detailed simulation models considering the incorporation of continuous optical fiber (COF) and different strain rates have been established and verified for deeper investigations. The results show that the COF does enhance the impact resistance of the laminates. When the porosity is reduced, the maximum stress of the continuous fiber-reinforced composite material is 4~7% higher than that of the pure PLA material. Our findings here expand the application of COF and provide a new method for designing protective materials, which have broad application prospects in the aerospace and automotive industries.

Bending behaviour of a topologically optimised ABS mesostructures 3D printed by the FDM process: numerical and experimental study

This paper is intended to investigate numerically and experimentally the influence of raster angle on the structural performance of an optimised printed structure.The topology optimisation (TO) problem for compliance minimisation using Solid Isotropic Material with Penalization (SIMP) method has been solved with a Messerschmitt-Bolkow-Blohm (MBB) beam under three-point bending, then the resulting optimal design was additively manufactured using Fused Filament Fabrication (FFF) with varying raster angle. The mechanical behaviour of these geometries was investigated and compared. A numerical approach has been developed through a script in Python based on the G-code file and integrated into an ABAQUS to create a virtual sample identical to the physical specimen. The numerical results were coupled with an experimental investigation.The investigation presented in this work showed that the choice of raster significantly affects on the mechanical performance of the printed optimised structures. Indeed, the optimised structure printed with a 90 raster angle has the highest performance in contrast to 45 and 0, while the optimised structure printed at a 45 raster angle has an average performance. The experimental test validated the numerical data with an error of approximately 1.09%. Our numerical results are in good conformity with the experimental outcomes.In this research, we studied the impact of three raster angles (90, 45 and 0) on the mechanical behaviour of a FFF optimised part. The subsequent study will focus on the other print parameters, including the other raster angles.The analysis presented in this paper can be used for manufacturing a FFF optimised structure.This paper evaluates the effect of raster angle in printed optimised structures using a novel numerical approach. The presented results will establish a reference that many researchers can gear to develop the fabrication of TO structures by incorporating printing parameters.

Efficient toolpath planning for collaborative material extrusion machines

PurposeTiming constraints affect the manufacturing of traditional large-scale components through the material extrusion technique. Thus, researchers are exploring using many independent and collaborative heads that may work on the same part simultaneously while still producing an appealing final product. The purpose of this paper is to propose a simple and repeatable approach for toolpath planning for gantry-based n independent extrusion heads with effective collision avoidance management.Design/methodology/approachThis research presents an original toolpath planner based on existing slicing software and the traditional structure of G-code files. While the computationally demanding component subdivision task is assigned to computer-aided design and slicing software to build a standard G-code, the proposed algorithm scans the conventional toolpath data file, quickly isolates the instructions of a single extruder and inserts brief pauses between the instructions if the non-priority extruder conflicts with the priority one.FindingsThe methodology is validated on two real-life industrial large-scale components using architectures with two and four extruders. The case studies demonstrate the method's effectiveness, reducing printing time considerably without affecting the part quality. A static priority strategy is implemented, where one extruder gets priority over the other using a cascade process. The results of this paper demonstrate that different priority strategies reflect on the printing efficiency by a factor equal to the number of extrusion heads.Originality/valueTo the best of the authors’ knowledge, this is the first study to produce an original methodology to efficiently plan the extrusion heads' trajectories for a collaborative material extrusion architecture.

Image Processing Based Pattern Recognition and Computerized Embroidery Machine

In the last decades, embroidery getting much attention in industries and academics. Although the technique is very old, it is still very much adopted. The current era of machine learning and smart devices makes this method even more attractive, easy to adopt and high accuracy. The proposed research work aims to highlight the implementation of new smart devices in this field, and the work is based on microcontrollers. Adopting the proposed work will be very easy and feasible to transform from the old sewing machine to a new smart method. Using smart devices, it is very easy and precise to get the embroidery fulfilling the user's demands. It gives simple raster images, which are used to convert into digital images to portray any new product. The current work is a novel idea of generating simple images rather than complicated ones, which are difficult to draw. In our method, we introduce the digitization process to input any image file used for vectorizing raster images, where vector images can easily convert into a DST embroidery file, a commonly used embroidery format originally from Tajima. It also has a Gcode file. The machine runs on a Gcode file which can be easily generated and runs on a product.

Mechanical analysis and optimized performance of G-Code driven material extrusion components

In this work an end-to-end optimization procedure to maximize the mechanical performance of Additive Manufacturing (AM) components is presented. Material Extrusion (ME) is the selected demonstrative AM technology, but the approach is applicable to other AM processes where the manufacturing toolpaths of the geometry of the printed component are described in G-Code format. The proposed methodology is integrated into the AM workflow and drives a two-step optimization process in order to select the optimal printing orientation for a user defined case. The G-Code file containing the manufacturing toolpaths is used as input. This approach allows to operate as close as possible to the geometry of the actual component, avoiding the use of the STereoLithography (STL) geometry. A voxelized mesh is built from the G-Code by solving a modified 2.5D Shortest Path Problem (SPP) and high-fidelity Finite Element (FE) simulations are performed with the resulting mesh. A printing pattern-based material model that distinguishes three different zones of the printed component is used. Due to the orthotropic nature of the ME process, the Tsai–Wu failure criterion is applied to obtain the indicators of the mechanical performance of the component. These computed metrics are used to drive an optimization process where a robust criterion based on the Machine Learning (ML) algorithm Anomaly Detection (AD) is applied in order to select the optimal build direction from a prespecified span of orientations. Two test cases and one case study illustrate the performance of the proposed methodology. The results validate the approach against experiments, indicate that the selected optimization criterion is robust against factors alien to the actual physical problem and show that the accuracy of the voxelized method greatly improves the “traditional” STL-based simulations.

Prediction and Analysis of Energy Consumption in Fused Deposition Processing Based on G-code

In order to solve the problem of energy consumption prediction in the fused deposition process, an energy consumption prediction method is proposed by associating G-code files with fused deposition hardware. This method systematically studies the energy consumption in the process of fused deposition 3D printing by analyzing the relationship between G code files and fused deposition 3D printers. Starting from the energy consumption mechanism, a prediction model of fused deposition energy consumption for G code files is proposed. By obtaining the specific parameters of the fused deposition processing equipment and the selected experimental model, the experimental process parameter level is designed, and the orthogonal experiment is carried out to predict the energy consumption of the fusion processing in detail. The verification shows that the method can not only predict an accuracy rate of more than 90%, but also effectively predict the optimal process parameter value, which fully proves that the prediction method has high prediction accuracy and good practicability, and can be used for model processing. Provide tool support for energy consumption prediction before processing, saving production costs.

A Customizable Controller for 3 Axis Modular CNC Machine

Numerical control is a useful technology to control a machine that utilize numeric values and codes. The machine comes with various sizes and built-in with its own controller. However, most of the commercial CNCs controllers are expensive and work only on the dedicated machine. With recent advancement of automation, a custom conrtoller for CN machine operation is possibly to be build. In this project, the three axis motion is controlled by Arduino Uno board with Atmega 328p microcontroller. In this case, the Arduino serves as an open source burner that burns the microcontroller using the provided programmes. Stepper motor drivers and the CNC shield accept signals from the Arduino board and transmit power to the stepper motors. Using Inkspace software, the user must first convert any image or text file into G-code before feeding it to the machine. The G-code file is then browsed in Universal G-code Sender software connected to a GRBL shield v0.9i and Arduino board through a laptop serial interface. The Universal G-code Sender programme has a G-code visualizer feature that allows to see the manufacturing processes alongside the simulation.

Advanced software development of 2D and 3D model visualization for TwinPrint, a dual-arm 3D bioprinting system for multi-material printing

This research highlights the development of a two-dimensional (2D) and three-dimensional (3D) preview software for additive manufacturing (AM). The presented software can produce a virtual representation of an actuator’s path movements by reading and parsing the orders of the desired geometric code (G-code) file. It then simulates the coded sections into separate 2D layers and colored 3D objects in a graphical model. This allows users to validate the shapes before the 3D printing process. G-code is an operation language which is based on command lines of code written in an alphanumeric format. Each line of these commands controls one machining operation; this instructs the machine’s motion to move in an arc, a circle, or a straight line to perform a specific shape after compiling all code lines. AM technology is widely used in most manufacturing fields (e.g., medical, chemical, and research laboratories) as a prototyping technology due to its ability to produce rapid prototyping models. 3D printing creates physical 3D models by extruding material layer by layer as 2D layers. At present, the most critical challenges in AM technology are drastically reducing prototyping materials’ consumption and time spent. To address these challenges, the proposed software allows for visualization of G-code files and predicting the overall layers’ shapes, allowing both structure prediction and subsequent printing error reduction.

Needle in a Haystack: Detecting Subtle Malicious Edits to Additive Manufacturing G-Code Files

Increasing usage of digital manufacturing (DM) in safety-critical domains is increasing attention on the cybersecurity of the manufacturing process, as malicious third parties might aim to introduce defects in digital designs. In general, the DM process involves creating a digital object (as CAD files) before using a slicer program to convert the models into printing instructions (e.g., g-code) suitable for the target printer. As the g-code is an intermediate machine format, malicious edits may be difficult to detect, especially when the golden (original) models are not available to the manufacturer. In this work, we aim to quantify this hypothesis through a red team/blue team case study, whereby the red team aims to introduce subtle defects that would impact the properties (strengths) of the 3-D printed parts, and the blue team aims to detect these modifications in the absence of the golden models. The case study had two sets of models, the first with 180 designs (with two compromised using two methods) and the second with 4320 designs (with 60 compromised using six methods). Using statistical modeling and machine learning (ML), the blue team was able to detect all the compromises in the first set of data, and 50 of the compromises in the second.

A parameterized g-code compiler for scaffolds 3D bioprinting

Parameterization of geometries for g-code compiling arises as an attractive option to control 3D printers. Based on the geometry of the object to be fabricated, and the construction platform, or the container where de material will be deposited, tool-paths can be obtained and compiled in the g-code format. This last includes the tool-path coordinates and all the process parameters. Thus, without the need for CAD(Computer-Aided Design) software or slicers, it is possible to obtain g-code files quickly. This article reports the development of a g-code compiler software called BioScaffolds PG V2.0.; it is compatible with open-source desktop 3D printers and is oriented to be used in the 3D bioprinting field by material extrusion processes. The software was programmed using the VB.NET language and enables the scaffolds fabrication in the construction platform, inside Petri dishes, or in cell culture plates. The deposition process was also parameterized; it is calculated as a function of the tool-path and considers the mass conservation according to the printing head geometry. The graphical user interface allows easily set the process and geometrical parameters to generate a g-code file. As validated through CAM (Computer-Aided Manufacturing) simulations and hydrogel samples fabrication, the parameterized g-codes were successfully compiled. First, the hydrogel-based ink was formulated and rheologically characterized. Then, it was used to test the software in a desktop 3D printer. Once validated, the ink was used to formulate a bioink to perform a 3D bioprinting validation. The in vitro qualitative and quantitative assays were performed using Incucyte live-cell analysis up to 4 days of culture. The results showed cellular proliferation in the printed samples, which is a promising in vitro result. Then, considering that open-source 3D printers are widely used for bioprinting, this free software could help to expand and automate applications in this field.

A multi-criteria h-adaptive finite-element framework for industrial part-scale thermal analysis in additive manufacturing processes

This work presents an h-adaptive finite-element (FE) strategy to address the numerical simulation of additive manufacturing (AM) of large-scale parts. The wire-arc additive manufacturing is chosen as the demonstrative technology for its manufacturing capabilities suitable for industrial purposes. The scanning path and processing parameters of the simulation are provided via a RS-274 (GCode) file, being the same as the one delivered to the AM machine. The approach is suitable for industrial applications and can be applied to other AM processes. To identify the location in the FE mesh of the heat affected zone (HAZ), a collision detection algorithm based on the separating axis theorem is used. The mesh is continuously adapted to guarantee the necessary mesh resolution to capture the phenomena inside and outside the HAZ. To do so, a multi-criteria adaptive mesh refinement and coarsening (AMR) strategy is used. The AMR includes a geometrical criterion to guarantee the FE size within the HAZ, and a Zienkiewicz–Zhu-based a-posteriori error estimator to guarantee the solution accuracy elsewhere. Thus, the number of active FEs is controlled and mesh manipulation by the end-user is avoided. Numerical simulations comparing the h-adaptive strategy with the (reference) fixed fine meshes are performed to prove the computational cost efficiency and the solution accuracy.

Topology optimization of a 3D part virtually printed by FDM

This research work aims to exhibit the possibility to topologically optimize a mesostructured part printed virtually by FDM taking into account the manufacturing parameters. The topology optimization of a 3D part printed by FDM was carried out using the software ABAQUS. On the other hand, a numerical approach using a script based on G-code file has been achieved to create a virtual model. Then, it was optimized according to the Solid Isotropic Material with Penalization (SIMP) method, which minimizing the strain energy was the objective function and the volume fraction of 30% was the constraint. The final topological optimization design of the virtual model is approximately similar to the homogeneous part. Furthermore, the strain energy of the virtual model is less than the homogeneous part. However, the virtually 3D optimized part volume is higher than the homogeneous one. In this study, we have limited our study on one layer owing to reduce the simulation time. Moreover, the time required to optimize the virtual model is inordinate. The ensuing study, we will optimize a multiple layer of the mesostructure. Our study provides a powerful method to optimize with accurately a mesostructure taken into consideration the manufacturing setting. In this paper, we have studied through an original approach the potential of topology optimization of a 3D part virtually printed by FDM. By means of our approach, we were able to optimize topologically the 3D parts printed by FDM taking into account the manufacturing parameters.

Design and testing of a digital twin for monitoring and quality assessment of material extrusion process

In this paper are illustrated conception, realization and validation of an original solution for the digital twin of a material extrusion 3D printer, the most popular additive manufacturing machine. The system is composed by three main modules: a core containing the simulation engine, a data interface managing incoming data and a graphical interface enabling user remote control. It receives as input the process data collected by several sensors and the same part program (G-Code file) used by the real machine; thus, the system provides various real time functions for process monitoring, condition monitoring and geometrical accuracy control. Alongside detecting load on critical components and checking wear and tear, it can also systematically sort data collected or calculated during operation to help in optimizing printing parameters. Through interaction with the print host software, the twin is able to intervene directly in the current process to pause printing in case of anomalies and to assist users along a recovery procedure. An index of quality of the printed piece is obtained by comparing the CAD model of the printed part and a 3D model of the deposited material powered by the data coming from the machine. The system has been tested on a custom-made Cartesian printer: a number of prints were made with different speeds and accelerations to assess the impact of these settings on the average quality, and a more in-depth study was carried out on the digital models of the prints to investigate the origin of the defects detected. The programs and devices used do not rely on commercial solutions, so that the system is easily replicable.

Finite Element Analysis and Computational Fluid Dynamics Verification of Molten Pool Characteristics During Selective Laser Melting of Ti-6Al-4V Plates.

The finite element (FE) method is used to characterize the thermal gradient, solidification rate, and molten pool sizes of Ti-6Al-4V plates in the process of selective laser melting (SLM). The results are verified by using the computational fluid dynamics (CFD) simulation. The proposed FE model contains a series of toolpath information that is directly converted from a G-code file, including hatch spacing, laser power, layer thickness, dwell time, and scanning speed generated by using Slic3r software from a CAD file. A proposed multi-layer, multi-track FE model is used to investigate the influence of the laser power, scanning speed, and scanning path on the microstructure in the Ti-6Al-4V plate built via SLM. The processing window is also determined based on the proposed FE model. The FE results indicate that, with a decrease in the laser power and an increase in the scanning speed, the morphology of the crystal grains, showing fully columnar crystals, gradually deviates from the fully equiaxed region. The formed grains are dependent on the laser power, scanning speed, and deposition position, but they are not sensitive to the scanning path, and with the deposition from the bottom layer to the top layer, the size of the formed grains is gradually increasing, which shows a good agreement with the experimental results.

Effect of infill and density pattern on the mechanical behaviour of ABS parts manufactured by FDM using Taguchi and ANOVA approach

Purpose: The present work aims to investigate the effect of many infill patterns (rectilinear, line, grid, triangles, cubic, concentric, honeycomb, 3D honeycomb) and the infill density on the mechanical tensile strength of an Acrylonitrile Butadiene Styrene (ABS) test specimen manufactured numerically by FDM. Design/methodology/approach: Computer-Aided Design (CAD) software has been used to model the geometry and the mesostructure of the test specimens in a fully automatic manner from a G-code file by using a script. Then, a Numerical Design of Experiments (NDoE) has been carried out by using Taguchi method and the Analysis of Variance (ANOVA). The tensile behaviour of these numerical test specimens has been studied by the Finite Element Analysis (FEA). Findings: The FEA results showed that a maximal Ultimate Tensile Strength (UTS) was reached by using the ‘concentric’ infill pattern combined with an infill density of 30%. The results also show that the infill pattern and the infill density are significant factors. Research limitations/implications: The low infill densities of 20% and 30% that have already been used in many previous studies, we have also applied it in order to reduce the time of the simulations. Indeed, with high infill density, the simulations take a very excessive time. In an ongoing study, we predicted higher percentages. Practical implications: This study provided an important modelling tool for the design and manufacture of functional parts and helps the FDM practitioners and engineers to manufacture strong and lightweight FDM parts by choosing the optimal process parameters. Originality/value: This study elucidated the effect of various infill patterns on the tensile properties of the test specimens and applied for the first time a NDoE using numerical test specimens created by the mesostructured approach, which considerably minimized the cost of the experiments while obtaining an error of 6.8% between the numerical and the experimental values of the UTS.