G-code File Research Articles

FIBR3DEmul—an open-access simulation solution for 3D printing processes of FDM machines with 3+ actuated axes

This paper introduces a virtual emulator software for additive manufacturing (AM) processes based on filament deposition, the FIBR3DEmul. The presented software is capable of reading and parsing a G-Code file (ISO/DIN 66025), and realistically emulating a custom-designed 5-axis printer or a standard 3-axis Cartesian printer. The FIBR3DEmul was designed and implemented in two separate applications for reusability and scalability. First, the G-Code Interpreter is responsible for parsing the g-code script, controlling the flow of its execution, and notifying the user about detected printer-printer or printer-workpiece collisions. The second application involves the robotics simulator tool V-Rep. A custom plugin was implemented to mediate the communication with the Interpreter application, to generate the tool trajectories, to emulate the extrusion process, and to handle motion execution and collision detection. The process of designing and implementing a custom-printer control and motion execution in these two software is described. The performance of the virtual 5-axis printer was compared with the real machine in terms of position and velocity profiles. Results show a tight match between virtual and real printer-generated plots. The presented solution can also be extrapolated to CNC machines or WHASPs. The FIBR3DEmul source code is publicly available.

A dimension-driven adaptive programming for tool-path planning and post-processing in 5-axis form milling of hyperboloidal-type normal circular-arc gears

Hyperboloidal-type normal circular-arc gears (HNCGs) are a latest application of circular-arc tooth profile in the gearing with perpendicular non-intersection axes, and the existing software programs provided by the original equipment manufacturers (OEMs) for specific machine tools cannot yet directly support the manufacture of HNCGs. In this paper, a dimension-driven adaptive programming methodology is proposed to automatically carry out the tool-path planning and generate the G-code file for the form milling of HNCGs on general 5-axis CNC machine tools. Based on the mathematical model of tooth surface, the basic strategy for 5-axis form milling of tooth is presented, an interference-free tool path considering both roughing and finishing operations is planned, and furthermore, the tool-path data is transformed to achieve the machine tool coordinates. To quickly respond to the changes of design and machining parameters, a dimension-driven adaptive programming software package is developed to automatically compute the tool path, conduct the post-processing, and generate the G-codes for 5-axis form milling of HNCGs with different specifications, and example verification is carried out to demonstrate the validity of the proposed method.

Analysis of cross axis wind turbine blades designed and manufactured by FDM based additive manufacturing

Additive manufacturing is emerging as a preferred approach to manufacture complex three dimensional components easily within a short span of time. In this study, cross axis wind turbine blades and its components are produced using fusion deposition modeling using Acrylonitrile Butadiene Styrene (ABS) material. The 3D CAD models are converted into .STL file which are processed further in “Slicer” freeware software. This convert the model into series of thin layers and creates G-code file which acts as an input to automated 3D printing machine to lay layers of loaded thermoplastic material successively to build the model from series of cross sections. The components produced by additive manufacturing is assembled and the obtained cross axis wind turbine (CAWT) is investigated using an open jet wind tunnel for wind velocities varying from 4 m/s to 10 m/s. The dimensionless performance parameters i.e., coefficient of power (Cp) and tip speed ratio (λ) are plotted. In general, the Cp value of CAWT increases gradually and reaches the maximum value around λ = 1.20. A maximum Cp value of 0.02385 is observed for wind velocity Vα = 10 m/s. Thus, the 3D printed components by additive manufacturing can be used to produce small wind turbines.

STEP-NC-based machining architecture applied to industrial robots

This paper presents a method for applying the ISO 10303-238 (AP-238) standard in robotic machining operations by using two industrial robots. The method encompasses programming, simulation and machining by industrial robots. Application and validation of robotized machining is performed using two industrial robots, and the following tools are used: (a) a commercial CAD/CAM software with a plug-in to generate STEP-NC files (AP-238); (b) simulation with a STEP-NC-compliant software using two virtual robot models, as well as the generation of G-code files through postprocessors; and (c) two industrial robots (ASEA IRB6-S2 and LOLA 50) using the LinuxCNC controller adapted to STEP-NC. Initially, a 3D part is designed using any CAD system, and it is sent through the Internet to a CAM specialist who uses a commercial software to generate a process plan to manufacture the part. Operators of the robots download the part and its process plan information in the STEP-NC format, simulate its machining through the working steps and then perform machining using the robots.

Establishment of a 3D printing system for bone tissue engineering scaffold fabrication and the evaluation of its controllability over macro and micro structure precision

To establish a 3D printing system for bone tissue engineering scaffold fabrication based on the principle of fused deposition modeling, and to evaluate the controllability over macro and micro structure precision of polylactide (PLA) and polycaprolactone (PCL) scaffolds. The system was composed of the elements mixture-I bioprinter and its supporting slicing software which generated printing control code in the G code file format. With a diameter of 0.3 mm, the nozzle of the bioprinter was controlled by a triaxial stepper motor and extruded melting material. In this study, a 10 mm×10 mm×2 mm cuboid CAD model was designed in the image ware software and saved as STL file. The file was imported into the slicing software and the internal structure was designed in a pattern of cuboid pore uniform distribution, with a layer thickness of 0.2 mm. Then the data were exported as Gcode file and ready for printing. Both polylactic acid (PLA) and polycaprolactone (PCL) filaments were used to print the cuboid parts and each material was printed 10 times repeatedly. After natural cooling, the PLA and PCL scaffolds were removed from the platform and the macro dimensions of each one were measured using a vernier caliper. Three scaffolds of each material were randomly selected and scanned by a 3D measurement laser microscope. Measurements of thediameter of struts and the size of pores both in the interlayer overlapping area and non-interlayer overlapping area were taken. The pores in the printed PLA and PCL scaffolds were regular and interconnected. The printed PLA scaffolds were 9.950 (0.020) mm long, 9.950 (0.003) mm wide and 1.970 (0.023) mm high, while the PCL scaffolds were 9.845 (0.025) mm long, 9.845 (0.045) mm wide and 1.950 (0.043) mm high. The struts of both the PLA and PCL parts became wider inthe interlayer overlapping area, and the former was more obvious. The difference between the designed size and the printed size was greatest in the pore size of the PLA scaffolds in interlayer overlapping area [(274.09 ± 8.35) μm)], which was 26.91 μm. However, it satisfied the requirements for research application. The self-established 3D printing system for bone tissue engineering scaffold can be used to print PLA and PCL porous scaffolds. The controllability of this system over macro and micro structure can meet the precision requirements for research application.

Simulator of an additive and subtractive type of hybrid manufacturing system

Additive Manufacturing (AM) facilitates the production of intricate objects despite its weakness in attainable part quality and fabrication speed compared to the conventional manufacturing methods. To alleviate the problems arising as a natural outcome of AM methods, hybrid technologies become viable options by employing concurrent manufacturing procedures, e.g. synergetic additive and subtractive manufacturing (SM) actions. Hybrid workstations have recently opened up new dimensions to 3D-printing industry, but related research topics remain underexplored in the literature. In this study, a hybrid manufacturing simulator that imitates AM and SM operations is presented. The hybrid simulator reported aims to provide users with a comprehensive interpretation of the G-codes, thereby previews the AM/SM tool paths and the eventual shape of the fabricated object. Consequently, the simulator lets users realize the final form of the artifacts besides enabling them to notice possible problems on the manufacturing trajectories. In addition, a post-processor customized for multi-axis hybrid platforms is built for the generation of G-code files. As a significant feature of the proposed manufacturing simulator, the capability to handle variable bead-width on the additive infill path has also been addressed in the study.

Single print optimisation of fused filament fabrication parameters

Single print optimisation (SPO) of process parameters, for the improvement of dimensional accuracy of an additively manufactured (AM) printed part with fused filament fabrication (FFF), is presented. A test object is sliced with different slicer parameters, as determined by a design of experiments (DOE) run table. The resulting files are merged into a single G-code file, which is used to perform a single print run. This prints the objects sequentially in super layers, where a super layer consists of several normal layers of sequentially printed parts limited by the printer Z-axis clearance. The test object is designed to be measured with accessible, affordable and easy-to-use dimensional measurement instruments. The goal of the optimisation is to improve the deposition of a single track, since all FFF objects are built up from several extrusions called tracks in the printer XY plane. The track height and width are key quantifiable measurands. Retraction effectiveness is also considered, with a qualitative response variable called stringing length. Ordinary least squares (OLS) regression is used to fit linear models to the three response variables. The bed level, as a function of X and Y coordinates, is used to improve part height accuracy. Track width is modelled with liquefier temperature and feed speed, whilst stringing length is modelled as a function of temperature. The models are verified by selecting an operation point which maximises print speed and minimises a cost function for the track width.

Design and Implementation of CNC Milling Bot for Milled Circuit Board Fabrication

This research paper presents an alternative way to fabricate a Milled Circuit Board (MCB) with the help of a Computer Numerical Controlled (CNC) milling robot. Printed Circuit Boards (PCB) are one of the most widely used control modules in electrical and electronic industries. In this research paper we propose a computer controlled milling machine which can be used for quick fabrication of double layered PCBs called MCB where a user wants to test the circuit without the need to wait for the conventional PCB fabrication. The end effector of the CNC milling machine has the provision to move in 3 axes-x, y and z in accordance with the input received from the controller. DipTrace, an EDA/CAD software is used for creating the schematic diagram for the milled circuit boards. The design to be engraved on the copper clad board is uploaded to a software called CopperCam, where it can be converted to G-code files after making the necessary modifications. These G-code files are then uploaded to the CNC machine using the software Universal G-code Sender, thus enabling the microcontroller to direct the rotation of motors and coordinate the movements of the end effector so as to engrave the board design on to a copper clad.

Abstract 5018: Bioprinted (3D) co-cultured spheroids with NSCLC PDX cells and cancer associated fibroblasts (CAFs) using alginate/gelatin hydrogel

Abstract 3D bioprinting which is a significant improvement over 2D models offers layer by layer positioning of various cells which can provide superior cell-matrix interactions in the tumor microenvironment in vitro. The objective of the present study was to develop a co-culture model using Non-small cell lung cancer (NSCLC) patient derived xenograft (PDX) cells and lung cancer associated fibroblasts (CAFs) in sodium alginate/ gelatin hydrogel using a 3D bioprinter. Various concentrations of sodium alginate/gelatin hydrogels (w/w) were prepared and rheological properties were evaluated. PDX cells (EGFR T790M, obtained from Dr. Rishi's Laboratory, Wayne State University) and CAFs (AA0022, obtained from Dr. Noyes Laboratory, Moffit Cancer Center) were mixed with the hydrogel and printed usingINKREDIBLE bioprinter (Cellink, Sweden). A two layered cube was designed in Slic3r software, converted to g-code file and printed through a 22G needle. Printed scaffolds were cross linked by Crosslinking Agent (Cellink, Sweden) for 5 minutes, washed with HBSS and maintained with media at 37°C and 5% CO2. Spheroid formation was observed using an inverted microscope (Olympus IX70). Live/Dead and NucBlue/ActinGreen staining was performed to determine cell viability and spheroid formation. Immuno-fluorescence staining was performed for E-cadherin, α-SMA and vimentin to study cellular crosstalk within the spheroid. Printable hydrogels were prepared by adding 3.25% sodium alginate to 4% gelatin which was found to be the most optimal mixture. Decrease in storage modulus (G') from 995.29± 30.69 Pa to 12.16± 8.83 Pa and loss modulus (G”) from 314.10± 17.54 Pa to 22.22± 12.69 Pa was observed from 18°C to 37°C when using a temperature sweep test. At lowest shear rate (1s-1), the viscosity of the hydrogel was 2.75± 0.37 Pa.s and at 100s-1 the viscosity was 0.50± 0.12 Pa.s. Decrease in hydrogel viscosity with increasing shear rate confirmed shear thinning. The height, width and length of the printed scaffolds were found as 1.45± 0.06 mm, 9.56± 0.15 mm and10.67± 0.13 mm respectively. Formation of spheroids was observed after 4 days and after 15 days, 59.88± 14.81% small (0-400µm2), 15.43± 4.86% medium (401-1000 µm2) and 24.67± 10.14% large size spheroids (1001 µm2-above) were observed which indicated proliferation of individual cells within the scaffolds. LIVE/ DEAD assay showed approximately 82% cells were viable in the printed scaffold. Up-regulation of vimentin and α-SMA and concomitant loss of E-cadherin was observed in the printed co-cultures indicating cross talk between the two cells. This study demonstrates the preparation and characterization of NSCLC lung PDX and CAF co-culture spheroids in 3D bio-printed sodium alginate/ gelatin scaffold. This model can be further used for high throughput drug screening platform. Citation Format: Arindam Mondal, Aragaw Gebeyehu, Ramakrishnan Subramanian, Arun Rishi, Mandip Singh. Bioprinted (3D) co-cultured spheroids with NSCLC PDX cells and cancer associated fibroblasts (CAFs) using alginate/gelatin hydrogel [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5018.

Integrated Interface Development Environment using STEP Universal Data Structure

Nowadays modern manufacturing demands advanced computer controller, having higher input language and less proprietary vendor dependencies. STEP stands for Standard for the Exchange of Product model data is the next generation of data model between CAD/CAM and CNC system. STEP is still under research and development all around the world. This paper describes the design, development and testing of an integrated Interface development environment for STEP file using Universal Data Structure, which aims to provide support for machining operation. The system also aims to provide function of reading and extracting the relevant information associated with the machining data and to write the G-Code file. The sample of machined block is designed from 3D CAD modeler which consisted of features need to be machined from a blank workpiece and saved in the STEP file format. The validation process will be done using the simulation in the Mach3 software.

Identifying 3D printer residual data via open-source documentation

Additive manufacturing, also known as 3D printing, is a rapidly growing technology that enables the production of customized complex objects. Its proliferation into both industrial and consumer markets, combined with the potential for misuse, raises questions about how to investigate an incident involving 3D printers. A survey of product documentation acquired from Open Source Intelligence (OSINT) sources reveals patterns in the processes used to print objects with consumer 3D printer models used by 3D object printing services. Both the ability to operate without an attached controlling computer and the methods by which G-code instructions move to the device are identified as features relevant to the potential presence of residual data. The implications of this residual data are discussed within the contexts of digital forensics, intellectual property protection, and privacy. It is concluded that classes of 3D printers are predisposed to containing residual data based on the functionality offered to the user. Additionally, investigations of 3D printers should involve not only the printer itself, but also any devices used in the production or transport of the object design and G-code files in order to develop a comprehensive picture of the events leading to the production of an object.

G-code Visualization and Editing Program for Inexpensive Metal 3D Printing

This work focuses on improving an existing system for 3D printing of metal objects using a sinterable clay or paste. The existing software and firmware used by the current 3D Mini Metal Maker (MMM) printer produce a high rate of poor quality products that result from either under-extrusion or over-extrusion conditions. In practice, to successfully print an object, different extrusion rates and printing speeds are needed for different sections of the part, such as the outline, the infill, and the lettering. For an MMM printer, the extrusion rate is manually controlled by a knob, which is ineffective and inaccurate given the noticeable lag response of the extruder motor. In this paper, a 3D visualization MATLAB™ program is developed to read the G-code file, separate the G-code into color-coded sections and produce a 3D graphical model, and change the values according to user specifications. It allows users to easily and visually recognize and select a separate chunk of G-code, such as layer by layer or individual graphical elements in each layer, then to edit the printing speed and extrusion rate accordingly. It also allows users to optimize these printing parameters in a batch mode if such desired printing speeds and extrusion rates for a different section of the printing part are already known. Experiments conducted with an MMM printer and bronze-paste materials show improvements in both printing time and quality.

DEVELOPMENT OF A3-AXIS CNC MILLING MACHINE WITH AN OPEN SOURCE CONTROLLER

This report presents one of the application performed by Arduino Uno when sandwiched with Grbl shield which is a high performance open source CNC controller written in optimized C-language. Here in this paper a file with extension .jpeg or .png, or .pdf is imported in an open source Aspire software which converts it into .txt or .prt file. Vectors of the imported file is traced accordingly, followed by modelling and manufacturing procedures. Once the simulation of the manufacturing file is visualized in Aspire software then G-code file is generated using post processing operation, this G-code file is saved with .txt extension. The G-code file is then browsed in Universal G-code sender software coupled to Grbl shield v0.9j and Arduino board through a laptop serial port, G-code visualizer option is available on Universal G-code sender software to visualize the manufacturing steps along with the simulation. In this way proprietory control of a controller is eliminated, and CNC machine is made user friendly.

An error compensation scheme for multi-axis machine tool using machining method template

In this paper, a software-based geometric error compensation method using the machining method template is proposed to modify the long and complicated G-code file with multiple machining features. Firstly, an error model is established to evaluate the error distribution. Then, a new segmentation method is proposed to split the long multi-axis line into several parts with the same length to eliminate the nonlinear effect. Furthermore, a compensation scheme according to the machining method is presented to determine which segments and axes should be compensated when facing with a long and complicated G-code file. In addition, a framework is developed to process the G-code file with high efficiency. The G-code file is firstly separated into the motion and non-motion command files, which are then merged together to form a new G-code file after the motion commands are modified by an error compensation module. Finally, a machining experiment with a test workpiece containing multiple features is conducted on a five-axis machining center to validate the effectiveness and correctness of the proposed method.

Streamlined, Inexpensive 3D Printing of the Brain and Skull.

Neuroimaging technologies such as Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) collect three-dimensional data (3D) that is typically viewed on two-dimensional (2D) screens. Actual 3D models, however, allow interaction with real objects such as implantable electrode grids, potentially improving patient specific neurosurgical planning and personalized clinical education. Desktop 3D printers can now produce relatively inexpensive, good quality prints. We describe our process for reliably generating life-sized 3D brain prints from MRIs and 3D skull prints from CTs. We have integrated a standardized, primarily open-source process for 3D printing brains and skulls. We describe how to convert clinical neuroimaging Digital Imaging and Communications in Medicine (DICOM) images to stereolithography (STL) files, a common 3D object file format that can be sent to 3D printing services. We additionally share how to convert these STL files to machine instruction gcode files, for reliable in-house printing on desktop, open-source 3D printers. We have successfully printed over 19 patient brain hemispheres from 7 patients on two different open-source desktop 3D printers. Each brain hemisphere costs approximately $3–4 in consumable plastic filament as described, and the total process takes 14–17 hours, almost all of which is unsupervised (preprocessing = 4–6 hr; printing = 9–11 hr, post-processing = <30 min). Printing a matching portion of a skull costs $1–5 in consumable plastic filament and takes less than 14 hr, in total. We have developed a streamlined, cost-effective process for 3D printing brain and skull models. We surveyed healthcare providers and patients who confirmed that rapid-prototype patient specific 3D models may help interdisciplinary surgical planning and patient education. The methods we describe can be applied for other clinical, research, and educational purposes.

DEVELOPMENT OF A STEREOLITHOGRAPHY (STL) INPUT AND COMPUTER NUMERICAL CONTROL (CNC) OUTPUT ALGORITHM FOR AN ENTRY-LEVEL 3-D PRINTER

This paper presents a prototype Stereolithography (STL) file format slicing and tool-path generation algorithm, which serves as a data front-end for a Rapid Prototyping (RP) entry- level three-dimensional (3-D) printer. Used mainly in Additive Manufacturing (AM), 3-D printers are devices that apply plastic, ceramic, and metal, layer by layer, in all three dimensions on a flat surface (X, Y, and Z axis). 3-D printers, unfortunately, cannot print an object without a special algorithm that is required to create the Computer Numerical Control (CNC) instructions for printing. An STL algorithm therefore forms a critical component for Layered Manufacturing (LM), also referred to as RP. The purpose of this study was to develop an algorithm that is capable of processing and slicing an STL file or multiple files, resulting in a tool-path, and finally compiling a CNC file for an entry-level 3- D printer. The prototype algorithm was implemented for an entry-level 3-D printer that utilises the Fused Deposition Modelling (FDM) process or Solid Freeform Fabrication (SFF) process; an AM technology. Following an experimental method, the full data flow path for the prototype algorithm was developed, starting with STL data files, and then processing the STL data file into a G-code file format by slicing the model and creating a tool-path. This layering method is used by most 3-D printers to turn a 2-D object into a 3-D object. The STL algorithm developed in this study presents innovative opportunities for LM, since it allows engineers and architects to transform their ideas easily into a solid model in a fast, simple, and cheap way. This is accomplished by allowing STL models to be sliced rapidly, effectively, and without error, and finally to be processed and prepared into a G-code print file.

Design and Control System of Parallel Kinematic Manipulator

This paper presents parallel kinematic manipulator design. A manipulator with three axis and parallelogram mechanism was made using aluminium profile rods. This mechanism was controlled by PC with the use of stepper motors. Kinematics analysis was conducted and its findings were used to make a special software to generate G-code control file. X and y mouse cursor indications with given z value were used as data showing the position of the effector to establish the movement of the arms of the presented manipulator. Step2CNC software was used to control the manipulator. Tests have confirmed the correctness of the study.

Tool Path Definition for Numerical Simulation of Single Point Incremental Forming

Incremental sheet forming is a promising process for sheet metal prototyping and for bio-medical implants. The entire process cycle is computer integrated and part is manufactured on computer numerical control (CNC) milling machine. This process uses a spherical ended tool to press the sheet into required shape. The path of the tool is controlled by a part program generated using computer aided manufacturing (CAM) softwares. For the numerical simulation of the process tool has to follow the same path as in experimental work. But numerical simulation softwares normally do not accept the G-code file generated using CAM packages directly. In the present paper a methodology has been proposed to input the tool path trajectories generated using CAM packages in to numerical simulation softwares such as ABAQUS and Ls-Dyna. For certain sample symmetric and asymmetric shapes, this proposed methodology has been implemented in Matlab and Ls-Dyna. The results were found to be satisfactory.

Postprocessor of 5-Axis Non-Orthogonal Machining Center

The 5-aix machining postprocessor of non-orthogonal machine tool is difficult to develop. On the analysis of characteristics of non-orthogonal machining center with dual worktables and 5-axis milling programming, a postprocessing algorithm of 5-axis milling is presented. Based on the algorithm, a postprocessor is developed by Visual C++ to convert tool path file to G-code file. For tentative validation of the postprocessor, a simulation model of the machine is established by Ver-icut to simulate G-code files created by the program. Finally a test workpiece is machined, which confirms the validity of the postprocessor.

Identification of acceleration deceleration profile of feed drive systems in CNC machines

In process planning, trajectory planning has generally disregarded the limitations of the feed drive systems in terms of acceleration, jerk, and motion blending. It results in poor prediction of the feed rate mainly in the transient phases and affects, consequently, the machining integrity and safety. Therefore, identifying and integrating the feed drive system limitations with the trajectory planning of the tool path are crucial in order to achieve the desired feed rate at the appropriate tool position. In this paper, a methodology based on time series modeling is proposed to identify the acceleration/deceleration (Acc/Dec) profile of a feed drive system. This profile provides the relationship between the actual feed rate, assumed proportional to the tachometer signal, and the commanded feed rate specified in the G-Code file. A particular shape of the input has been addressed to allow the application of the time series modeling. The different characteristics of this input are carefully considered to avoid both nonlinear response due to saturation and excitation of the high frequency components of the feed drive. The resulting model is transformed into a Finite Impulse Response (FIR) filter and applied as an (Acc/Dec) processor to determine the actual feed rate from the commanded feed rate. The good agreement between the model output and the experimental results demonstrates the effectiveness of the proposed identification method. It is demonstrated that integrating these limitations with the trajectory planing results in a feasible trajectory.