Tool Path Generation Research Articles

A Method for Generating Toolpaths in the Manufacturing of Orthosis Molds with a Five-Axis Computer Numerical Control Machine

This paper proposes a new algorithm for the automatic generation of toolpaths for machining complex geometric positions, such as molds used in orthosis production. The production of individualized orthoses often requires the use of multi-axis machining systems, such as five-axis machines or industrial robots. Typically, complex and expensive CAD/CAM systems are used to generate toolpaths for these machines, requiring the definition of a machining strategy for each surface. While this approach can achieve a reliable and high-quality machining process, it is very time-consuming and makes it challenging to meet the criteria for rapid production of orthopedic aids. Given that their production is a custom-made process using individual shapes as inputs, the toolpath generation process becomes even more demanding. To address these challenges, this paper proposes an algorithm suitable for the automatic generation of toolpaths for such complex positions. The proposed algorithm has been tested and has proven to be robust and applicable.

The generation of supplementary toolpaths for surface machining based on rapid prediction of scallop height distributions

The generation of supplementary toolpaths for surface machining based on rapid prediction of scallop height distributions

An automatic generation approach of process model based on feature knowledge and geometric modeling

Traditional process planning applies knowledge to convert design information within the part model into process information. This information is then displayed by manually drawing two-dimensional (2D) process cards from multiple views, illustrating the geometric design and the process details. However, this method has revealed several issues, including poor efficiency, information misinterpretation, and the potential for manual drawing errors. This traditional approach hampers the integration of manufacturing information across engineering software. It exacerbates the digital divide between computer-aided design (CAD), computer-aided process planning (CAPP), and computer-aided manufacturing (CAM). To address these issues, this study proposes an automated approach for creating three-dimensional (3D) process models based on feature knowledge and geometric modeling. The 3-axis milling features are recognized as the machining objects from the boundary representation (B-Rep) part model. Geometric and parameter knowledge for modeling is derived from the machining step. In the proposed approach, two geometric modeling methods are investigated to construct feature state volumes (FSVs). The first method utilizes FSV modeling to simulate the shape of unmachined features before rough machining, while the second method utilizes FSV modeling to construct the shape of machined features before finishing machining. The case studies illustrate that the proposed approach can construct FSVs for various machining states and autonomously generate process models. In digital manufacturing, this approach assists process planners in intuitively evaluating the reasonableness of process routes. Additionally, it provides the essential driving geometry required for the autonomous generation of tool paths.

Jerk limited continuous tool path generation for flexible systems in non-cartesian coordinate systems

Inspired by computer numerical control (CNC) technology and drastic changes in the world of electronics and microcontrollers, the idea of using non-cartesian coordinate system for CNC machines became a topic of interest. Non-cartesian coordinate systems provide freedom of movement in systems with large working spaces where high dimensional accuracy is not a prime concern. Applications of such systems can be found in murals, where a painting is applied to a large wall of any arbitrary build material. In the present paper, a new design was introduced to automate the process of drawing murals on large surfaces. The proposed mechanism utilized chain and sprocket to overcome the size limitations of traditionally available x-y tables. In addition to that, the developed mechanism does not utilize the common robust structures used in the conventional CNC systems and the tool motion is created using flexible arms that are not heavily constrained. The effect of systems unwanted vibration has been eliminated using continuous trajectory and kinematic profiles. Parametric curve interpolation algorithms for trajectory planning were implemented to increase the flexibility of drawing complex curves. Parametric curves such as B-spline and non-uniform rational B-spline (NURBS) were employed to generate a jerk limited trajectory for motion control and extraction of kinematic profiles. Such trajectory constrains the jerk of the system and guarantees a smooth motion free of feed-rate fluctuations. Compared to other methods available for extracting the kinematic profiles, jerk limited method decreases the travel time and trajectory error. Ultimately, motion commands were produced by using kinematic profiles and the second order Taylor interpolator. STM32746ZG card was used as the main processor and two stepper motors controlled by a Bit Pattern interpolation algorithm were utilized to drive the proposed mechanism. The input pulses of stepper motors were stored as binary bits and transmitted to drivers in real-time. The feedback was also evaluated by two rotary encoders, placed at the end of the motors’ shafts. Encoder data were acquired and transmitted using a TCP/IP protocol to guarantee zero data loss during the transmission.

Non-planar 5-axis directional additive manufacturing of plastics: Machine, process, and tool path

Additive manufacturing (AM) of plastics is a rising research and application area for light weighting. The conventional way of AM is conducted layer-by-layer, whereas recently non-planar AM is proposed with several advantages such as better use of the material through decreased weight-to-strength ratio, reuse of support material and increased conformity for AM of complex shapes. As for all the tool path-based manufacturing processes, generation of the tool path, selection of process parameters and the machine tool configuration significantly affects the product quality. In this study, non-planar AM of plastics is handled in a holistic manner covering tool path, process, and machine perspectives. Tool path generation for non-planar and directional AM is discussed in accordance with the CAD-CAM software, where the tool path is generated using a novel approach which works with the bead directions obtained from FEM based mechanical analysis. The effects of critical process parameters on the geometrical conformity for non-planar AM are discussed through visual inspection. The proposed cluster-based tool path planning is successfully shown demonstrated from the geometrical perspective.

Spiral tool path generation method for complex pocket machining based on electrostatic field theory

Spiral tool path generation method for complex pocket machining based on electrostatic field theory

A Toolpath Generator Based on Signed Distance Fields and Clustering Algorithms for Optimized Additive Manufacturing

Additive manufacturing (AM) methods have been gaining momentum because they provide vast design and fabrication possibilities, increasing the accessibility of state-of-the-art hardware through recent developments in user-friendly computer-aided drawing/engineering/manufacturing (CAD/CAE/CAM) tools. However, in comparison to the conventional manufacturing methods, AM processes have some disadvantages, including the machining precision and fabrication process times. The first issue has been mostly resolved through the recent advances in manufacturing hardware, sensors, and controller systems. However, the latter has been widely investigated by researchers with different toolpath planning perspectives. As a contribution to these investigations, the present study proposes a toolpath planning method for AM, which aims to provide highly continuous yet distance-optimized solutions. The approach is based on the utilization of the signed distance field (SDF), clustering, and minimization of toolpath distances among cluster centroids. The method was tested on various geometries with simple closed curves to complex geometries with holes, which provides effective toolpaths, e.g., with relative distance reduction percentages up to 16.5% in comparison to conventional rectilinear infill patterns.

Tool Path Strategies for Efficient Milling of Thin-Wall Features

The milling of thin-wall geometries has been a challenge due to inherent chatter vibrations and workpiece deflections. Moreover, tool path generation strategies in CAD-CAM systems are not able to fully address all such concerns. The objective of this study is to demonstrate potential 5-axis milling tool path strategies, which do not exist in the conventional tool path generation. The demonstration is performed for increased efficiency in milling of thin-wall features considering the main limitation of chatter. The effects of varying workpiece dynamics on milling stability are shown in case studies through simulations and cutting experiments. Based on the simulation results, tool path strategies are developed. The effect of tool path generation and the relation to parameter selection are highlighted. Most of the discussion relies on previously reported experimental results. The results showed that by tailoring the tool path considering the concerns and limitations associated with thin-wall part structure and geometry, it is possible to increase productivity by at least two folds.

Generation of cubic Hermite spline-based trochoidal milling toolpath by introducing a coefficient factor in machining curved slots

Trochoidal milling has become popular in high-speed milling due to its ability to reduce cutting force, enhance thermal dissipation, and prolong tool life. Among other toolpath patterns, the cubic Hermite spline offers significant advantages in generating trochoidal milling toolpath in machining complex and curved slots. However, determining those two different relation coefficients in the polynomial function of cubic Hermite spline remains complicated and empirical. This paper introduces a coefficient factor to simplify the determination process, which only requires the position and tangent vector parameters of each endpoint pair. The coefficient factor combines an instantaneous in-process slot width (IISW)-related width factor and a tangent vector direction-related direction factor. Two complex-curved slots are used to validate the performance of the proposed method. The results show that this method is straightforward and effective in generating trochoidal milling toolpaths for machining complex-curved slots while matching the slot geometry. Additionally, compared with a direct 5-axis trochoidal milling (one-step slotting strategy) in trochoidal milling of 3D slots on both serial and hybrid machining tools, a two-step slotting strategy (3-axis trochoidal milling and a successive 5-axis perpetual milling) is preferable in improving machining efficiency.

The Use of Feature Technology in Selecting Cutting Tools and Generating Tool Paths

The Use of Feature Technology in Selecting Cutting Tools and Generating Tool Paths

Energy-efficient tool path generation and expansion optimisation for five-axis flank milling with meta-reinforcement learning

Energy-efficient tool path generation and expansion optimisation for five-axis flank milling with meta-reinforcement learning

Accuracy Assessment and Reinforcement Training of Deep Neural Networks in the Context of Accelerating a Simulation-Based Toolpath Generation Method

Accuracy Assessment and Reinforcement Training of Deep Neural Networks in the Context of Accelerating a Simulation-Based Toolpath Generation Method

Toolpath generation for automated wind turbine blade finishing operations

AbstractIncorporating automation into wind turbine blade manufacturing is important for reducing costs to meet current offshore wind energy production goals in the United States. This work proposes a process for automating three operations in wind blade manufacturing: trimming to remove flashing left over after bonding two blade skins together, grinding to produce a desired leading‐edge shape, and sanding to prepare the blade for bonding overlamination or adding paint to the surface. The majority of this work focuses on the toolpath generation. The algorithms were tested on a 5‐m blade section, and the results were analyzed in terms of operation speed and accuracy. Finally, future work is discussed to improve the performance of the system.

Fabrication of the freeform Fresnel lens by swinging-rotating diamond ruling

Freeform optics are widely applied across various industries, encompassing both imaging and non-imagining optical systems. To compact the freeform surface, the freeform Fresnel lens has been devised by optical designers. However, conventional slow slide servo techniques cannot effectively fabricate the intricate lens, due to its asymmetry and discontinuity. In this paper, a novel swinging-rotating diamond ruling method is proposed to fabricate a biconical freeform Fresnel lens, with the synchronized motions of X-, Z-, C- and A-axes. The morphed Archimedean driving spiral based on contour lines is constructed to avoid the tool-microstructure interference. The tool path generation algorithm is proposed to generate smooth and accurate tool path, encompassing an adaptive projection principle, a transition tool path interpolation method and a postprocessing method. Finally, the feasibility and superiority of the proposed method is validated through two case studies. It is demonstrated that the precise and efficient fabrication of the freeform Fresnel lens can be realized by swinging-rotating diamond ruling method.

NURBS-based path planning for aerosol jet printing of conformal electronics

Conformal printing offers a promising capability to integrate complex electronic functionality with intricate objects consisting of curved surfaces. However, motion planning to support these printing configurations presents a challenge, in part due to conventional reliance on tessellated surface representations that limit the accuracy and scalability of the printing process. In this paper, we introduce a direct approach to conformal aerosol jet printing on topographically complex surfaces, represented using non-uniform rational B-splines (NURBS). Using the NURBS surface definition directly offers a scalable and continuous approach for toolpath generation, which is well-aligned with standard computer-aided design practices. We select a patch that directly corresponds to the area of interest on the NURBS surface and extract the associated surface points. These surface points are then appropriately connected to generate the machine code (G-code) for a 3-axis printing system. We demonstrate this capability by printing a strain gauge on a curved model of a wind turbine blade. Our approach offers a promising avenue for manufacturing printed electronics with diverse applications that require conformal printing. This approach is particularly valuable for incorporating printed circuits on intricate underlying structures, including structural health monitoring for aerospace and civil infrastructure applications.

Adaptation of Symbolic Discrete Control Synthesis for Energy-Efficient Multi-Pocket Milling

In engineering, cost minimization, especially in Computer Numerical Control (CNC) machining like pocket milling, is crucial. Existing tool path definition software often lacks optimization, particularly at critical starting and ending points. This study optimizes CNC machine tool paths for energy-efficient multi-pocket milling, utilizing the Symbolic Discrete Control Synthesis (SDCS) method for formal correctness. In our work, the tool path generation is formulated as a traveling salesman problem. We introduce a modeling framework to adapt SDCS to multi-pocket-milling processes, aiming to enhance precision and efficiency for potential cost savings, including energy and time, in engineering applications. This study reports experimental and comparative results, where comparative evaluations were made using metaheuristic algorithms. Our proposed approach improves CNC machining processes for multi-pocket milling. We experimentally evaluate our control algorithms and demonstrate and validate our approach through case studies.

Surface slicing and toolpath planning for in-situ bioprinting of skin implants

Bioprinting has emerged as a successful method for fabricating engineered tissue implants, offering great potential for wound healing applications. This study focuses on an advanced surface-based slicing approach aimed at designing a skin implant specifically for in-situ bioprinting. The slicing step plays a crucial role in determining the layering arrangement of the tissue during printing. By utilizing surface slicing, a significant shift from planar fabrication methods is achieved. The developed methodology involves the utilization of a customized robotic printer to deliver biomaterials. A multilayer slicing and toolpath generation procedure is presented, enabling the fabrication of skin implants that incorporate the epidermal, dermal, and hypodermal layers. One notable advantage of using the approximate representation of the native wound site surface as the slicing surface is the avoidance of planar printing effects such as staircasing. This surface slicing method allows for the design of non-planar and ultra-thin skin implants, ensuring a higher degree of geometric match between the implant and the wound interface. Furthermore, the proposed methodology demonstrates superior surface quality of the in-situ bio-printed implant on a hand model, validating its ability to create toolpaths on implants with complex surfaces.

Data model-based toolpath generation techniques for CNC milling machines

Introduction: With the development of computer technology and data modeling, the use of point cloud models to generate tool paths is particularly important for improving productivity and accuracy.Methods: This study proposes a new method that first preprocesses the point cloud data using four-point denoising and octree methods to improve processing efficiency. Subsequently, roughing tool paths were analyzed using the layer slicing method and finishing paths using the residual height method.Results and Discussion: The experimental results show that the layer slicing method has a minimum error close to 10% on the roughing path generation and the computation time is reduced to 35 s, while the residual height method has an error rate of 10.17% on the finishing path and the computation time is only 11.82 s, which reflects a high trajectory smoothness and accuracy. The above results show that the study not only optimizes the tool path generation process and improves the machining efficiency and accuracy, but also demonstrates the potential application of point cloud models in the machining of complex parts.Conclusion: The novel tool roughing and finishing methods provide more reliable path planning for actual machining operations, and future research will be devoted to further improving the performance of the data processing algorithms and exploring more efficient path planning strategies to facilitate automated production.

Tool path generation with a uniform residual error distribution considering tool contour error for ultra-precision diamond turning

Tool path generation strategy plays a crucial role in improving the efficiency and surface quality of ultra-precision diamond turning mainly by influencing residual errors. However, current approaches in tool path generation have not achieved a uniform distribution of residual error due to the unexplored and significant impact of tool contour error on residual error. Therefore, this study introduces a novel tool path generation algorithm for ultra-precision diamond turning, aiming for a uniform residual error distribution with consideration of tool contour error. The tool contour is measured off-machine, fitted, and modeled to achieve its actual cutting-edge contour at a submicron scale. An estimation model is established to calculate residual error on the machined surface considering the tool contour error. A tool path generation approach is then proposed to achieve uniform residual error distribution by adaptively controlling stepovers. Then the proposed stepover is smoothed by cubic Hermite polynomial interpolation to avoid undesired tool path fluctuations. To further improve the machining accuracy, a spiral tool path is generated with proper discretization parameters to control chord error. Finally, a prototype software system is developed to optimize the tool path as well as predict the residual and machining error across the entire machined surface. Experiment results demonstrate a significant reduction of approximately 40 % in both residual error and machining error compared to unoptimized results.

Stress field-aware infill toolpath generation for additive manufacturing of continuous fiber reinforced polymer composites

The infill toolpath utilized in continuous fiber reinforced polymer composites via additive manufacturing (CFRPCs-AM) significantly influences the mechanical performance of printed structures. However, existing infill toolpath for CFRPCs-AM are primarily designed for 2D planar structures and do not account for 3D shell structures with complex shapes or load path dependent characteristics. To address these limitations, this paper proposes an explicit streamline tracing method to convert the stress field into adaptive infill toolpaths for CFRPCs-AM. The method leverages principal stress direction and value fields to control toolpath density and distribution while considering the minimum allowable bead width constraint. Additionally, the geodesic distance is employed to precisely represent the distance between adjacent infill toolpaths on shell structures. Experimental validation on 2D and 3D complex structures under varying conditions demonstrates the effectiveness of the proposed method, which significantly improves stiffness and strength by 200–300% compared to traditional uniform toolpaths for CFRPCs-AM.