Traditional Computer Numerical Control Research Articles

Designing and implementation of a novel online adaptive control with optimization technique in hard turning

Determination of optimum cutting parameters is one of the most essential tasks in process planning of metal parts. However, to achieve the optimal machining performance, the cutting parameters have to be regulated in real time. Therefore, utilizing an intelligent-based control system, which can adjust the machining parameters in accordance with optimal criteria, is inevitable. This article presents an intelligent adaptive control with optimization methodology to optimize material removal rate and machining cost subjected to surface quality constraint in finish turning of hardened AISI D2 considering the real condition of the cutting tool. Wavelet packet transform of cutting tool vibration signals is applied to estimate tool wear. Artificial intelligence techniques (artificial neural networks, genetic programming and particle swarm optimization) are used for modeling of surface roughness and tool wear and optimization of machining process during hard turning. Confirmatory experiments indicated that the efficiency of the proposed adaptive control with optimization methodology is 25.6% higher compared to the traditional computer numerical control turning systems.

Analysis of the Construction of Comprehensive CNC Training Course for Application-oriented Undergraduate in New Situation

Computer Numerical Control (CNC) comprehensive training courses are the core courses of application-oriented undergraduate mechanical majors. Traditional CNC training has been unable to adapt to the development of society. In order to fit the current teaching system and train qualified application-oriented CNC technical personnel, the teaching content, teaching implementation and quality evaluation of the NC comprehensive training course were reconstructed, and a suitable environment for the current intelligent manufacturing was created under the practical teaching system.

Research on Deterministic Figuring of Ultra-Precision Shaft Parts Based on Analysis and Control of Figuring Ability.

The application of ultra-precision shaft parts is widely used, such as the spindle core of the air bearing spindle in ultra-precision machine tools. The precision of the spindle core is extremely high, and it is very difficult to obtain directly by traditional Computer Numerical Control (CNC) machine tools but is mostly obtained by manual grinding, whose machining efficiency is greatly limited. Based on the deterministic figuring theory, this paper focuses on the ultra-precision roundness, optimizing the filtering parameters of the measurement error data and studying the generation mechanism of the removal function morphology; the shape of the removal function is adjusted by combining the analysis of the figuring ability and positioning error. Finally, the optimized removal function is used on an experimental steel shaft, the average roundness convergence ratio is 72% higher than that of the original removal function, and the roundness reaches a 0.1 μm level. The result shows that a reasonable filtering of measured data and the removal function adjusted for the surface feature can improve the efficiency and precision of deterministic figuring on shaft parts.

Design and implementation of evanescent mode waveguide filters using dielectrics and additive manufacturing techniques

In this contribution, we describe the design of bandpass filters using evanescent mode waveguides and dielectric resonators implemented with additive manufacturing techniques. Two C-band Chebyshev evanescent mode waveguide filters of order five have been designed using a low cost commercial dielectric material (ABSplus), widely used by Fused Deposition Modeling (FDM) 3D printers. The housings of the filters have been manufactured using traditional computer numerical control (CNC) machining techniques. Practical manufacturing considerations are also discussed, including the integration of dielectric and metallic parts. We first discuss two breadboards using two different resonator geometries. We then demonstrate how different transfer functions can be easily implemented by changing the 3D printed parts in the same metallic housing. Breadboards show fractional bandwidths between 3% and 4.6% with return losses better than RL=18 dB, and spurious free ranges of SFR=1 GHz. Insertion losses are better than IL=4.3 dB. Even though dielectric losses from the plastic material are shown to be high, the measured results are quite satisfactory, thereby clearly showing that this strategy maybe useful for the fast production of low cost microwave filters implementing complex geometries.

A K-Band 3-D Printed Focal-Shifted Two-Dimensional Beam-Scanning Lens Antenna With Nonuniform Feed

A K-band (18-26.5 GHz) two-dimensional (2-D) beam scanning antenna is proposed. The hyperbolic lens is fed by an array of focal-shifted horns with nonuniform aperture. The feed at the focal point of the lens generates the boresight vertical beam, while the off-focal feeds are responsible for tilted beams. The nonuniform horn aperture helps to mitigate the gain decrement from the lens aperture tapering. It is fabricated taking full advantage of dielectric and metallic 3-D printing technologies. The lens is printed by stereolithography apparatus (SLA) in resin. The feed horn array is printed by selective laser melting (SLM). Process-wise, it features low cost, short turnaround time, and the capability to implement complex geometries versus traditional computer numerical control machining and mold casting. Simulation and measurement indicate that the antenna features desirable matching below -15 dB and mutual coupling between adjacent port below -25 dB. The gain is above 23 dBi across the K-band. Multiple beams at ±32°, ±12°, and 0° are observed on E- and H-planes. The proposed design can either function as multibeam antenna or a beam-scanning antenna together with switches. It is a capable candidate for applications such as multiple target tracking and wide region monitoring.

Effects of design parameters on dimensional accuracy of parts made on a mini 3-axis CNC router

Computer numerical control (CNC) is a very broad term that encompasses a variety of types of machines used in industrial automation — all with different sizes, shapes, and functions. But the easiest way to think about CNC is to simply understand that it is all about using a computer as a means to control a machine that carves useful objects from solid blocks of material. Traditional CNC machines are expensive, complicated, and typically only found in large manufacturing companies that can afford them. Small hobbyist CNC machines can run anywhere from $7,000 and higher; professional machines can cost millions of dollars! Now, for a fraction of the cost — under $800 one can own a Mini 3-axis CNC machine and cut, drill, mill, and carve objects of one's imagination. In this paper, a Mini 3-axis CNC router was assembled and tested for machining different materials such as plastic and wood. Simple shapes of circles (diameter, d = 1") and squares (side, a = 1") were cut using the CNC router. G-Code programs were developed to cut the required circles and squares. A digital caliper was used to measure the diameter of the circles and the side of the squares. Data were collected for a 2k factorial design experiments considering 2-levels for parameters: spindle speed, feed rate, cut depth, object shape, and material. Statistical analyses were performed to determine the effects of chosen parameters on the dimensional accuracy of the parts made. The results indicated that the parameters material, object shape, and cut depth have significant effects on the dimensional accuracy of the parts made.

A Substrate-Less Microwave Power-Combining Module Utilizing Ridge Gap Waveguide

This letter presents the development of a microwave module that does not require a transition substrate to interface with the ridge gap waveguide (RGW). The RGW-to-chip transition is implemented on an all-metal structure using traditional computer numerical control machining and electrodischarge machining. The fabricated module is self-packaged, and the chip carrier assembly allows for quick monolithic microwave integrated circuit substation/exchange in the event of device failure. The designed module operates between 11 and 14.5 GHz, and the simulation and measured results are compared.

A Rechargeable, Aqueous Iron Air Battery with Nanostructured Electrodes Capable of High Energy Density Operation

In order to decrease the global dependence on fossil fuels, high energy density, rechargeable batteries with high charge capacity are required for mobile applications and efficient utilization of intermittent sources of renewable energy. Metal-air batteries are promising due to their high theoretical energy density. In particular, the iron-air battery, with a maximum specific energy output of 764 W h kg−1Fe, represents a low cost possibility. This paper considers an iron-air battery with nanocomposite electrodes, which achieves an energy density of 453 W h kg−1Fe and a maximum charge capacity of 814 mA h g−1Fe when cycled at a current density of 10 mA cm−2, with a cell voltage of 0.76 V. The cell was manufactured by 3D printing, allowing rapid modifications and improvements to be implemented before an optimized prototype can be manufactured using traditional computer numerical control machining.

A Phase Center-Stabilized K/Ka/V-Band Linearly Polarized Horn for Luneburg Lenses

Phase center stabilization and fabrication methods for a K/Ka/V-band dual-ridged horn antenna are discussed. The antenna operates from 18 to 45 GHz and has good impedance match and compact aperture suitable for assembling into feed manifolds for Luneburg lenses. The phase center is stabilized by using sin2 ridge profile. Geometrically identical horns are fabricated by means of additive direct metal laser sintering (DMLS) three-dimensional metal printing and traditional computer numerical control split block machining. No significant difference in performance is found in spite of apparent surface roughness on the DMLS antenna.

Concentric hole drilling in multiple planes for experimental investigation of five-axis reconfigurable precision hybrid machine

A five-axis machining center integrates two mechanical models: a three-degree-of-freedom parallel platform and traditional computer numerical control X–Y table. There is a trend for machining centers to be reconfigurable precision hybrid machine tools (RHMTs) for the fabrication of complex and precision products. Most industrial robots have open kinematic chains and serially connected links. A parallel manipulator is a closed-chain mechanism with two platforms (a base and moving platform) connected together by at least two independent kinematic chains. A parallel machine tool has the advantages of high rigidity, high precision, low inertia, and a simple mechanism. It is not easy to correct the errors in a five-axis machine tool. This paper focuses on the initial calibration of the static state errors, which consist of the errors from the component part machining, work-piece orientation, and mechanism combination. In an RHMT mechanism, a three-axis motion platform primarily controls the Z, α, and β freedoms. A laser displacement meter is fixed on the Z axis and measures the error in relation to the central position of the moving and fixed platforms when the x-y table is moved. The inverse kinematics of this mechanism will be revised, and an improvement will be made in the attitude precision of the moving platform. Finally, this paper discusses an experiment involving the drilling of concentric holes in multiple planes using an RHMT, and examines the cutting results from a coordinate measuring machine.

Comparing environmental impacts of additive manufacturing vs traditional machining via life-cycle assessment

Purpose – The purpose of this study is to compare the environmental impacts of two additive manufacturing machines to a traditional computer numerical control (CNC) milling machine to determine which method is the most sustainable. Design/methodology/approach – A life-cycle assessment (LCA) was performed, comparing a Haas VF0 CNC mill to two methods of additive manufacturing: a Dimension 1200BST FDM and an Objet Connex 350 “inkjet”/“polyjet”. The LCA’s functional unit was the manufacturing of two specific parts in acrylonitrile butadiene styrene (ABS) plastic or similar polymer, as required by the machines. The scope was cradle to grave, including embodied impacts, transportation, energy used during manufacturing, energy used while idling and in standby, material used in final parts, waste material generated, cutting fluid for CNC, and disposal. Several scenarios were considered, all scored using the ReCiPe Endpoint H and IMPACT 2002+ methodologies. Findings – Results showed that the sustainability of additive manufacturing vs CNC machining depends primarily on the per cent utilization of each machine. Higher utilization both reduces idling energy use and amortizes the embodied impacts of each machine. For both three-dimensional (3D) printers, electricity use is always the dominant impact, but for CNC at maximum utilization, material waste became dominant, and cutting fluid was roughly on par with electricity use. At both high and low utilization, the fused deposition modeling (FDM) machine had the lowest ecological impacts per part. The inkjet machine sometimes performed better and sometimes worse than CNC, depending on idle time/energy and on process parameters. Research limitations/implications – The study only compared additive manufacturing in plastic, and did not include other additive manufacturing technologies, such as selective laser sintering or stereolithography. It also does not include post-processing that might bring the surface finish of FDM parts up to the quality of inkjet or CNC parts. Practical implications – Designers and engineers seeking to minimize the environmental impacts of their prototypes should share high-utilization machines, and are advised to use FDM machines over CNC mills or polyjet machines if they provide sufficient quality of surface finish. Originality/value – This is the first paper quantitatively comparing the environmental impacts of additive manufacturing with traditional machining. It also provides a more comprehensive measurement of environmental impacts than most studies of either milling or additive manufacturing alone – it includes not merely CO2 emissions or waste but also acidification, eutrophication, human toxicity, ecotoxicity and other impact categories. Designers, engineers and job shop managers may use the results to guide sourcing or purchasing decisions related to rapid prototyping.

Rapid Prototyping of Aerodynamics Research Models

Rapid prototyping techniques are ideally suited to the manufacture of aerodynamics research models as these items usually consist of highly complex 3 Dimensional (3D) forms. The fabrication of complex curvatures on traditional Computer Numerical Control (CNC) machines often requires the production of additional tooling supports to allow for full machining of all surfaces. Such a necessity often results in extra cost and fabrication time, as well as a potential loss in accuracy due to any repositioning required to allow machining of internal and external features. It is often necessary to divide the model into additional sections to allow for the machining of internal features which can cause issues with mismatching of adjacent surfaces. The inclusion of small or complex internal features and hollow sections may be problematic if not impossible. In contrast, many rapid prototyping techniques eliminate most of these manufacturing issues due to the additive nature of modern 3D printing processes. Popular techniques for the rapid prototyping of polymers include Selective Laser Sintering (SLS), Fused Deposition Modeling (FDM) and stereolithography. The basic technique reduces a 3D object into a series of thin 2D slices. The 2D slices are then “printed” vertically in succession to produce the final 3D item The “slicing” technique is readily compatible with the formation of complex 3D curvatures as well as internal and hollow features. In addition, any required tooling supports are produced simultaneously with the desired item, which greatly reduces processing time and loss of accuracy due to part repositioning. The necessity to produce a model from multiple sections to allow access for machining of internal features can in many cases be reduced significantly. The characteristics intrinsic to many modern 3D printing techniques are greatly beneficial for the production of complex wind tunnel models made from polymer. The current work describes the design process and features of a wind tunnel model used for research into a novel aerodynamic flow control technique. An additive manufacturing technique was chosen as the most suitable for the rapid, accurate and simplest fabrication process for the model.

System for off-line feedrate optimization and neural force control in end milling

SUMMARY Based on hybrid process modeling, off-line optimization and neural control scheme (NCS), the combined system for off-line optimization and adaptive adjustment of cutting parameters is built. This is an adaptive control system controlling the cutting force by digital adaptation of cutting parameters. In this way, it compensates all disturbances during the cutting process, prevents excessive tool wear, and maintains a high chip removal rate. It is the combination of these methods that yields accurate force control. The basic control principle is based on the NCS consisting of two neural identifiers of the process dynamics and feedback controller. An overall procedure of hybrid modeling of cutting process, used for working out the computer numerical control (CNC) milling simulator has been prepared. CNC simulator is used to evaluate the controller design before conducting experimental tests. Numerous simulations and experiments have been conducted to confirm the efficiency of this control architecture. The experimental results show that not only does the end-milling system with the design controller have high robustness and global stability, but also the machining efficiency of the end milling system with the proposed controller is 27% higher than for traditional CNC milling system. Copyright © 2011 John Wiley & Sons, Ltd.

Numerical analysis and design of pinion with inner helical gear by FEM

In the design of the cold forging process one of the most important tasks is the determination of the required number of processes. Preforming in incremental steps is aimed at achieving high accuracy of the forged part, high quality of the surfaces and also decreasing the die damage during the forging process. Cold forging of pinion gear with shape of outer spur gear and inner helical gear have been investigated in this study. A numerical analysis for preform design substituting a cutting process in the gear forging was developed by means of upsetting process. By using the finite element (FE) program DEFORM-3D, the analysis is carried out. Using this simulation, the preform of the pinion and helical gear forging process was designed. The suggested valuable information regarding the forging process shows a successful attempt. The suggested process is verified by experiment. Compared to the traditional computer numerical control (CNC) processing, the upsetting process can form a preform without cutting, which leads to shorter forming time and reduced material usage.

Real‐time trajectory resolution for a two‐manipulator machining system

AbstractRecent research has considered robotic machining as an alternative to traditional computer numerical control machining, particularly for prototyping applications. However, unlike traditional machine tools, robots are subject to relatively larger dynamic disturbances and operate closer to their torque limits. Combined with inaccurate models of the manipulators and the machining process, joint actuators can often saturate during operation. Once a joint is saturated, tool‐path tracking may not be possible and the blank and/or tool may be damaged. This paper presents a real‐time trajectory planner designed to mitigate the effect of unmodeled disturbances, thus avoiding controller saturation and potential tool/blank damage. The forces acting on the end effectors are monitored to identify the onset of a disturbance so that the system can be slowed down before saturation actually occurs. In response to disturbances, a time‐scaling method reduces the tool speed, thereby reducing the demand on the joint torques and allowing the precomputed process plan to continue. When there is sufficient torque available, the tool speed is returned to its planned magnitude. The effectiveness of the proposed time‐scaling algorithm has been demonstrated with simulations. © 2006 Wiley Periodicals, Inc.

Acceleration and torque redistribution for a dual-manipulator system

Recent research has considered robotic machining as an alternative to traditional computer numerical control machining, particularly for prototyping applications. However, unlike traditional machine tools, robots are subject to relatively larger dynamic disturbances and operate closer to their torque limits. These factors, combined with inaccurate manipulator and machining process models, can cause joint actuator saturation during operation. This paper presents a trajectory planner that will reduce torques that are near saturation by generating trajectories with a weighted pseudoinverse. Using a relative Jacobian, the tool path is resolved into joint trajectories at the acceleration level. This paper presents a new method for selecting the weighting matrix based on the proximity of the joint torques to saturation limits. This weighting reduces the joint accelerations contributing the most to the torques near saturation, thereby reducing the joint torques. The accelerations of other joints increase to satisfy the increased demand. The effectiveness of the acceleration and torque redistribution algorithm has been demonstrated via extensive simulations.

A new type of machine control system to replace traditional CNC

This paper discusses the rationale behind a new form of machine tool control system which has been developed at the Key Centre for Computer Integrated Manufacture (CIM Centre) in Melbourne Australia. The new control system is based upon standard computer hardware and is intended as a replacement for computer numerical control (CNC), which has severe limitations in the CIM environment. The paper also outlines the new CIM possibilities which are now available as a result of this development.