Mohamad Minhat

Machining Parameters Optimization for Trimming Operation in a Milling Machine Using Two Level Factorial Design

Trimming process using Solid Carbide, 4 flute endmill of 8mm diameter tool on stacks of multidirectional CFRP/Al-2024 in a CNC Milling machine was experimentally investigated. The machining parameters considered were spindle speed (N), feed rate (fr) and depth of cut (dc). The aims were to analyze the influence factors and the interaction of these parameters with respect to surface quality produced. A Two Level Factorial Design method was used to plan systematic experiments. The influence factors and the interaction between these parameters are analyzed and the optimum machining parameters for minimizing the surface roughness is determined. The analysis of variance (ANOVA) shows that dc and fr are the most significant parameters to the overall performance of surface quality. Surface roughness of CFRP is found to be 1.778 µm and Al2024 is found to be 0.983 µm at the setting of N = 1860 rpm, fr = 620 mm/min and dc = 0.12 mm respectively. The validation test shows deviation of predicted to actual value surface roughness is 7.87% for CFRP and 6.61 % for Al2024.

Development Tools of an Adaptive Controller

Manufacturing enterprise today crucially needs computer numerical control (CNC) to employ higher level input languages and reducing dependency on proprietary system. In traditional CNC system, most predefined numerical control (NC) commands programmed at early stage were often found to be unsuitable or sometimes unusable especially when the machining process was interrupted by unscheduled event. This will result in additional effort spent for advance process planning and NC code generation. Moreover, readjustment of the program consumes time and requires high skills. To address this issue, considerable efforts are being undertaken to improve CNC system by replacing traditional CNC to a next generation of intelligent CNC. This paper proposes a framework for adaptive controller of an open CNC system by merging established STEP-NC and IEC 61499 standards. This project applies STEP-NC as data input program; taking advantages offered by both standards. IEC 61499 is a layered architecture function that simplifies controller design and enhances the controller performance. As a result, both decision making and control activities are embedded inside the controller architecture whereby optimal machining parameters are issued automatically based on available online machine resources. Hence, a tool-path will be generated just-in-time by the CNC controller. The generated tool path can be directly used to drive the open architecture machine tool without any intermediate.

System Interface Design for CAD/CAM-Simulink Data Exchange System Using MATLAB®

Integration between advanced control system theory and automation tools and technology brings about advancement in machining technology in tandem with requirement for smart and flexible manufacturing system. The integration takes in the form of seamless and automatic data communication between a CAD/CAM system and the more advanced control systems technology. This paper presents an interface design of a novel CAD/CAM-Simulink Data Exchange System (CS-DES) which links part geometry design using CAD/CAM technology with position controller scheme and algorithm designed in Matlab/Simulink environment. The proposed CS-DES system enhances data automation through formation of the graphical user input reference interface of the machine tools control system using NC manufacturing codes data as the reference input signal. The framework and role of CS-DES are elaborated and described in detail including pseudocodes generation for the CAD drawing graphical data integrated with the controller scheme designed in Simulink. The CS-DES interface was designed using MATLAB graphical user interactive development platform. Functions related to the user interface design are discussed in this paper. Finally, the system interface design of the data exchange system is expected to further enhance versatility of existing control system performance of a machine tool via creation of flexible input reference forms hence improving system accuracy, efficiency and productivity.

Suppression on Effect of Cutting Forces Towards Tracking Performance in Milling Cutting Process Using State Observers

In milling cutting process, tracking performance of the CNC servo drive system is influenced by the characteristics of the cutting forces generated during the milling operation. The undesired frequency harmonics of the cutting force contributes negatively to the positioning accuracy; thus an effective compensation of these harmonics is desired. This paper presents results related to suppression of cutting forces in milling process for minimal impact on tracking performance using controller design approach. A cascade P/PI position controller was designed and numerically analysed in combination with an Inverse Model Based Disturbance Observer (IMBDO) plus Disturbance Force Observer (DFO). The effectiveness of this control approach was validated on the x-axis of the XY feed table of a ball-screw driven milling machine. Results showed that the combined approach of cascade P/PI controller with IMBDO plus DFO produced the best tracking control performance with reduction of 78.8% in magnitude component of the cutting forces using Fast Fourier Transform (FFT) analysis of the tracking errors; compared to individual dedicated approach using IMBDO (62.7%) and DFO (78.2%) respectively.

Development of Ergonomic Vehicle Model and Decision Support System for Driving Fatigue

Driving fatigue has been recognized as one of the significant contributory factors to the road accidents and fatalities in Malaysia. The aim of this study was to develop an ergonomic vehicle model (EVM) and decision support system (DSSfDF) model for improving the driving fatigue problem among the road users. The ergonomic vehicle model uses to capture the user information data and acts as the database storage to store all the input data and information. While the decision support system provides a systematic analysis and solution to minimize the risk and the number of accidents associated with driving fatigue. There are 6 main components as the pillars for the development of EVM and DSSfDF model; ergonomics evaluation tools, graphical user interface (GUI), ergonomics database, working memory, inference engine, and knowledge base. Both models are essential system and reliable advisory tool for providing analysis on risk factors that contribute significantly to driving fatigue and providing solutions and recommendation to the problem related to driving fatigue. Further analysis and validation are required in future to get the reliable system before being commercialized.

Analysis of Tool Performance during Ball-end Milling of Aluminium Alloy 6061-T6

This article presents the tool wear mechanism when machining Aluminium alloy 6061-T6 with PVD coated carbide under dry cutting condition. Cutting parameters selected were cutting speed, Vc = 115-145 m/min; feed rate fz = 0.15-0.2 mm/tooth and depth of cut, ap = 0.5-0.75 mm. The result showed the tool life of PVD TiAlN ranged from 11 to 97 min. Full factorial approach was employed to exhibit relationship between parameter input and output. From the analysis, cutting speed was found to be the most significant factor for tool performance followed by feed rate and depth of cut. It was also found that most of failure modes occurred were notch wear and flaking near those found near depth of cut line.

Future prospects of turning processes optimization using metaheuristics methods

In todays industries, optimization of turning processes is one of vital problems which aim to increase competitiveness and product quality. In fact, the decision of optimal machining parameters is arbitrary and complex. Traditionally, the selections is heavily relies on trial and error methods which is tedious and unreliable. To overcome these problems, metaheuristics methods has been proposed over the last decade. The results on several parameters such as cutting speed, depth of cut and feed rate indicate more effective and efficient way in comparison to traditional methods. This paper presents current development and future prospects due to metaheuristics techniques for optimizing the parameters of turning processes.