From computer-aided to intelligent machining: Recent advances in computer numerical control machining research

The aim of this paper is to provide an introduction and overview of recent advances in the key technologies and the supporting computerized systems, and to indicate the trend of research and development in the area of computational numerical control machining. Three main themes of recent research in CNC machining are simulation, optimization and automation, which form the key aspects of intelligent manufacturing in the digital and knowledge based manufacturing era. As the information and knowledge carrier, feature is the efficacious way to achieve intelligent manufacturing. From the regular shaped feature to freeform surface feature, the feature technology has been used in manufacturing of complex parts, such as aircraft structural parts. The authors’ latest research in intelligent machining is presented through a new concept of multi-perspective dynamic feature (MpDF), for future discussion and communication with readers of this special issue. The MpDF concept has been implemented and tested in real examples from the aerospace industry, and has the potential to make promising impact on the future research in the new paradigm of intelligent machining. The authors of this paper are the guest editors of this special issue on computational numerical control machining. The guest editors have extensive and complementary experiences in both academia and industry, gained in China, USA and UK

An accuracy evolution method applied to five-axis machining of curved surfaces

Currently, some high-value-added applications involve the manufacturing of curved surfaces, where it is challenging to achieve surface accuracy, repeatability, and productivity simultaneously. Among free-form surfaces, curved surfaces are commonly used in blades and airfoils (with a teardrop-shaped cross-section) and optical systems (with axial symmetry). In both cases, multi-axis milling accuracy directly affects the subsequent process step. Therefore, reducing even insignificant errors during machining can improve the accuracy in the final production stages. This study proposes an “evolution” method to improve the machining accuracy of curved surfaces. The key is to include compensation for the machining error after the first part through profile error measurement. Thus, correction can be applied directly after the manufacturing programming is fully developed, achieving the product with the minimum number of iterations. Accordingly, this method measures the machining error and changes only one key parameter after the process. This study considered two cases. First, an airfoil in which the clamping force was corrected; the results were quite good with only one modification in the blade machining case. Second is an aspherical surface where tool path correction in the Z-axis was applied; the error was effectively compensated along the normal vector of the workpiece surface. The experimental results showed that the surface accuracy increased from 44.4 to 4.5 μm, and the error was reduced by 89.9%, confirming that the accuracy of the machine tool and process had achieved “evolution.” This technical study is expected to help improve the quality and productivity of manufacturing highly accurate curved surfaces.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. This work was supported by: Natural Science Foundation of Shaanxi Province (Grant number: 2021JM010) Natural Science Foundation of Suzhou City (Grant number: SYG202018) Spanish Ministry of science and innovation (Grant number: RTC2019-007,194–4) funded by MCIN/AEI/ 10.13039/501100011033 Basque government group IT 1573-22 Fundamental Research Funds for the Central Universities (Grant No. xzy012019007) Project ITENEO Grant PID2019-109340RB-I00 funded by MCIN/AEI/ 10.13039/501100011033 Project HCTM Grant PDC2021-121792-100 funded by 702 MCIN/AEI/ 10.13039/501100011033 and by the “European Union NextGenerationEU/PRTR The Basque Government Department of Education for the pre-doctoral grant PRE_2021_1_014

Close-to-process compensation of geometric deviations on implants based on optical measurement data

The production of implants is challenging due to their complex shapes, the filigree structures and the great regulatory effort. Therefore, a manufacturing cell with an integrated optical measurement was realized. The measurement system is used to determine the geometric deviations and to fulfill the documentation obligation. The measurement data are used to create a matrix containing the nominal coordinates and the error vector for compensation points at the relevant shapes. Based on this, the corresponding tool-path segments are isolated in the G-Code and compensated in order to reduce the geometric deviations. With this method, the deviation could be reduced by 85 %. However, it is pointed out, that the result of the compensation strongly depends on the quality of the optical measurement data

Selected Papers from IEEE ICASI 2019

The 5th IEEE International Conference on Applied System Innovation 2019 (IEEE ICASI 2019, https://2019.icasi-conf.net/), which was held in Fukuoka, Japan, on 11–15 April, 2019, provided a unified communication platform for a wide range of topics. This Special Issue entitled “Selected Papers from IEEE ICASI 2019” collected nine excellent papers presented on the applied sciences topic during the conference. Mechanical engineering and design innovations are academic and practical engineering fields that involve systematic technological materialization through scientific principles and engineering designs. Technological innovation by mechanical engineering includes information technology (IT)-based intelligent mechanical systems, mechanics and design innovations, and applied materials in nanoscience and nanotechnology. These new technologies that implant intelligence in machine systems represent an interdisciplinary area that combines conventional mechanical technology and new IT. The main goal of this Special Issue is to provide new scientific knowledge relevant to IT-based intelligent mechanical systems, mechanics and design innovations, and applied materials in nanoscience and nanotechnology

Development of working procedures of a 5 Axis CNC milling machine

Dissertação de mestrado em Mechanical EngineeringThe work developed and presented on this dissertation tends to the installation and configurations of a 5-axis CNC machine with the creation of working procedures intended to build a stable workflow that can be employed by any individual expected to use the machine. Being a large field within mechanical engineering as well as being involved in a large selection of different industrial sectors, the concept of 5-axis machining will be explored to develop knowledge in terms of CAM programming and manipulation/optimization of toolpaths. The importance/functioning of the transmission of information both from post-processor to the controller and from the controller to the actual machine is also a critical point in this work as they are directly related to the quality of the parts produced. To accomplish this, the theoretical knowledge foundations regarding CNC machining work were researched, studied, and explained. Furthermore, the machine model in question (HY-6040 5-axis CNC Router) was meticulously analysed regarding to the machines structure, post-processor, and controller. Upon assembling all this information, and through the production of some test parts, a permanent manufacture workflow for different machining approaches was established and described.O trabalho desenvolvido e apresentado nesta dissertação tende à instalação e configuração de uma máquina CNC de 5-eixos, com a criação de procedimentos de trabalho destinados a criar um fluxo de trabalho estável que possa ser empregue por qualquer individuo que pretenda utilizar a máquina. Sendo um grande campo dentro da engenharia mecânica e estando também envolvido numa grande seleção de diferentes setores industriais, o conceito de maquinagem em 5-eixos será explorado com a finalidade de desenvolver conhecimentos a nível de programação CAM e manipulação/otimização de trajetórias de corte. A importância/funcionamento da transmissão de informação quer do pôs-processador para o controlador, quer do controlador para a máquina constituem também um ponto critico neste trabalho já que estão diretamente relacionados com a qualidade das peças produzidas. Para a realização de tal, foram pesquisados, estudados e explicados os fundamentos do conhecimento teórico relativamente ao trabalho de maquinagem CNC. Para além disso, o modelo da máquina em questão (HY-6040 5-axis CNC Router) foi meticulosamente analisado quanto à estrutura da máquina, pós-processador e controlador. Após reunir toda esta informação, e través da produção de peças teste, foi estabelecido um fluxo de trabalho de manufatura (CAD/CAM/Maquinagem) para diferentes abordagens de maquinagem

Shoe last machining using virtual digitising

Shoe lasts are the moulds used in the footwear industries in order to mount the shoe. Most of the machines used in the sector to make lasts are simply mechanical copiers. CAD/CAM systems have just arrived to the shoe last market but its accuracy and efficiency is not better than traditional machines, for this reason new systems have difficulty to implant. Presented in the paper there is a tool path generation algorithm that takes the advantages of traditional copier systems that do not fulfil the CNC standards. The tool path is computed from a “virtually digitised” model of the last surface. The algorithm is then analysed in terms of computing cost and accuracy and refined by applying a series of optimisations. Some computer architectures are proposed in order to reduce the computation time. The proposed algorithm has been successfully implemented in a commercial CAD/CAM system specialised in shoe last making. Finally, some illustrative examples are shown

Development of an integrated robotic polishing system

This thesis presents research carried out as part of a project undertaken in fulfilment of the requirements of Loughborough University for the award of Philosophical Doctorate. The main focus of this research is to investigate and develop an appropriate level of automation to the existing manual finishing operations of small metallic components to achieve required surface quality and to remove superficial defects. In the manufacturing industries, polishing processes play a vital role in the development of high precision products, to give a desired surface finish, remove defects, break sharp edges, extend the working life cycle, and meet mechanical specification. The polishing operation is generally done at the final stage of the manufacturing process and can represent up to a third of the production time. Despite the growth automated technology in industry, polishing processes are still mainly carried out manually, due to the complexity and constraints of the process. Manual polishing involves a highly qualified worker polishing the workpiece by hand. These processes are very labour intensive, highly skill dependent, costly, error-prone, environmentally hazardous due to abrasive dust, and - in some cases - inefficient with long process times. In addition, the quality of the finishing is dependent on the training, experience, fatigue, physical ability, and expertise of the operator. Therefore, industries are seeking alternative solutions to be implemented within their current processes. These solutions are mainly aimed at replacing the human operator to improve the health and safety of their workforce and improve their competitiveness. Some automated solutions have already been proposed to assist or replace manual polishing processes. These solutions provide limited capabilities for specific processes or components, and a lack of flexibility and dexterity. One of the reasons for their lack of success is identified as neglecting the study and implementing the manual operations. This research initially hypothesised that for an effective development, an automated polishing system should be designed based on the manual polishing operations. Therefore, a successful implementation of an automated polishing system requires a thorough understanding of the polishing process and their operational parameters. This study began by collaborating with an industrial polishing company. The research was focused on polishing complex small components, similar to the parts typically used in the aerospace industry. The high level business processes of the polishing company were capture through several visits to the site. The low level operational parameters and the understanding of the manual operations were also captured through development of a devices that was used by the expert operators. A number of sensors were embedded to the device to facilitate recording the manual operations. For instance, the device captured the force applied by the operator (avg. 10 N) and the cycle time (e.g. 1 pass every 5 sec.). The capture data was then interpreted to manual techniques and polishing approaches that were used in developing a proof-of-concept Integrated Robotic Polishing System (IRPS). The IRPS was tested successfully through several laboratory based experiments by expert operators. The experiment results proved the capability of the proposed system in polishing a variety of part profiles, without pre-existing geometrical information about the parts. One of the main contributions made by this research is to propose a novel approach for automated polishing operations. The development of an integrated robotic polishing system, based on the research findings, uses a set of smart sensors and a force-position-by-increment control algorithm, and transpose the way that skilled workers carry out polishing processes

Compensation of machining errors of Bspline and Cspline

The evolution of the interpolation methods towards a very high technicality requires a good choice of used type in the operation of high-speed milling (HSM). The “Bspline” and “Cspline” interpolations present good solutions to guarantee the tool’s continuous movement during machining. However, in a previous article, we have shown by a simulation tool that they generate significant dimensional errors that decrease the precision of the machined part. In this article, a method of compensating for these errors based on the insertion of the nodes, while respecting the predefined tolerance, has been developed. To do this, we have modeled and simulated machining errors before and after compensation for each type of interpolation. To validate our results,we have machined a test piece with the compensated and uncompensated Bspline and Cspline interpolations on theHuron KX10 machine and we have measured the corresponding machining errors. The results have shown that the method of compensation by the insertion of the nodes causes a significant reduction of the machining errors