Comprehensive servo control strategies for flexible and high-efficient wire electric discharge machining. A systematic review

Almeida, Sergio; Mo, John P.T.; Bil, Cees; Ding, Sheng; Wang, Xiangzhi

doi:10.1016/j.precisioneng.2021.02.007

Cited by 17 publications

(3 citation statements)

References 83 publications

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“…Since the ultimate objective of the proposed wire control is to provide a stable and controlled HS-WEDM cutting process, the widely accepted EDM key process indicator of gap voltage is adopted. The principle behind the gap voltage metric is its capability to depict the distance between the wire and the workpiece based on the existing capacitance between the charged wire electrode and the workpiece [35]. To analyse if the process is under statistical control, we adopt the robust six sigma approach to The potential process capability analysis deals with forecasting the short-term process's capability to meet the gap voltage specifications through two metrics.…”

Section: Statistical Analysis Of the Hybrid Open And Closed-loop Cont...mentioning

confidence: 99%

Control design of a reciprocating high-speed wire feed system for 7-axis robotic electric discharge machining

Almeida

Ding

et al. 2022

Int J Adv Manuf Technol

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For decades, researchers have struggled to solve 6-axis robotic vibration while machining hard-to-cut materials. On the other hand, wire electric discharge machining (WEDM) stands out as a non-conventional machining process able to cut large and complex profiles of any conductive hard-to-cut material with minor non-contact forces. Thus, WEDM is a promising process to be combined into a robot to overcome vibration and low accuracy. However, the robot characteristics of a high degree of freedom combined with payload limitation oblige to separate the heavy wire winding system from the robot end-effector, demanding an equally high degree of freedom and unconventional solutions to feed and control the wire electrode. This study designs and reports experimental findings of the first robotic WEDM apparatus based on a high-speed winding system with 600 m of wire length, capable of controlling the wire speed from 1 to 10 m/s and wire tension from 0.1 to 10 N. The system adopts flexible outer cases to travel and reciprocate the wire into a 7-axis robotic system composed of a 6-axis robot and an external rotating axis. The proposed design is a highly dynamic process whose wire tension and speed are achieved by a hybrid controller to cope with the non-linear relation of speed and tension provided by the magnetic clutch. It combines a regression open-loop control for optimality and wire breakage avoidance with a closed-loop control to guarantee admissibility while coping with wire friction disturbances. The findings review a novel wire winding system capable of controlling usual wire disturbance and stepped surface of reciprocating high-speed WEDM as well as additional friction and elastic behaviour of the flexible case, delivering wire tension of ± 12% along with stable EDM process and uniform surface roughness between wire reciprocation areas with a Ra of 2.94 μm. Potential adoption of the method can finally make 6-axis robots a feasible and advantageous technique compared to computer numeric control (CNC) while shaping monolithic and complex workpieces of conductive and hard-to-cut materials.

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Section: Statistical Analysis Of the Hybrid Open And Closed-loop Cont...mentioning

confidence: 99%

Control design of a reciprocating high-speed wire feed system for 7-axis robotic electric discharge machining

Almeida

Ding

et al. 2022

Int J Adv Manuf Technol

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“…Fortunately, fuzzy controllers can capture knowledge and make reasoning to simulate human intellect for controlling stochastic processes such as EDM . However, the current range of industrial robots needs from 0.3 to 0.5 s to implement a speed change command [42]. Such delay is considered significant for the EDM.…”

Section: Adaptive Fuzzy Edm Controllermentioning

confidence: 99%

Accurate vibration-free robotic milling electric discharge machining

Almeida

Bil

et al. 2022

Int J Adv Manuf Technol

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Traditional computer numeric control (CNC) machines have high accuracy but are limited by workpiece size and axes. Therefore, many researchers attempted to equip six-axis industrial robots (IRs) with milling end-effectors to explore the robot’s large and flexible working envelope. However, IRs lack stiffness and have limited force, resulting in low accuracy, poor surface roughness (SR), and low material removal rate (MRR). On the contrary, electric discharge machining (EDM) is a non-conventional process capable of shaping complex profiles in any conductive material. Since the EDM process has no physical contact between the electrode and the workpiece, it can machine diverse hard-to-cut materials accurately and free of vibration. However, to this day, EDM is found in limited conditions of CNC machines only. Thus, this research investigates a synergistic combination of IR and milling EDM. Adopting advanced CAM tools and offline programming, it examines pre-designed electrodes working analogue to conventional milling to perform the desired machining by intricate cutting paths. The results deliver a robotic machining technique able to cut hard materials using small industrial robots yet free of vibration and not pose dependent.

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“…The wire EDM process has emerged as a pivotal technology in the manufacturing industry, facilitating the precise shaping of materials that are often challenging to machine using conventional methods [1]. In particular, AISI 431 martensitic stainless steel has greater attention in the field of engineering and manufacturing due to its exceptional combination of hardness, corrosion resistance, and mechanical properties [2].…”

Section: Introductionmentioning

confidence: 99%

Wire EDM Process of AISI 431 Martensitic Stainless Steel: A Machinability Investigation

Chandrasekaran,

Sampath,

Anbalagan

et al. 2024

The International Conference on Processing and Performance of Materials (ICPPM 2023)

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Comprehensive servo control strategies for flexible and high-efficient wire electric discharge machining. A systematic review

Cited by 17 publications

References 83 publications

Control design of a reciprocating high-speed wire feed system for 7-axis robotic electric discharge machining

Control design of a reciprocating high-speed wire feed system for 7-axis robotic electric discharge machining

Accurate vibration-free robotic milling electric discharge machining

Wire EDM Process of AISI 431 Martensitic Stainless Steel: A Machinability Investigation

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