Methodology of Taguchi optimization for multi-objective drilling problem to minimize burr size

Formation of exit burr on part edges during drilling has several undesirable features with regard to product quality and functionality. Hence it is essential to select optimum drilling process parameters to minimize burr size at the production stage. This paper presents the application of the Taguchi optimization method for simultaneous minimization of burr height and burr thickness influenced by cutting conditions and drill geometry. The Taguchi design approach to the multi-objective optimization problem is based on the introduction of a new concept of fitness function for each trial of orthogonal array. The fitness function is derived through mapping the objective functions of the drill optimization problem. In the present work, optimal values of cutting speed, feed, point angle and lip clearance angle are determined for selected drill diameter values to minimize burr height and burr thickness during drilling of AISI 316L stainless steel workpieces. The details of experimentation, analysis of means and analysis of variance are presented in the paper.     

Design of the aerostatic linear guideway with a passive disk-spring compensator for PCB drilling machine

Problems with the conventional linear aerostatic guideway for a PCB drilling machine include deviation from straightness or parallelism tolerance between the granite guideways, and thermal expansion caused by the heat generated from ball screw and the driving system. These factors will result in vibration and affect the positioning accuracy during machine drilling.This paper describes the development of the resistance network method (RNM) for analyzing the static behaviors of aerostatic grooved thrust bearing designed with a disk-spring compensator to hold the table in a suitable position. Comparison is demonstrated between the RNM results and experimental data. Finally, a realizable application of these types of bearing to the linear guideway system for a PCB drilling machine is presented.     

印制板数控钻床的研究与开发

介绍用系统机作上层控制系统 ,单片机作下层控制系统 ,多下层控制系统并行处理的印制板数控钻床的研制与开发。该印制板数控钻床采用了相互独立的细分驱动单元分别控制各轴的步进电机 ,从而提高了机床数控系统的运算速度和控制精度。软件采用模块化设计 ,具有与CAD软件的接口 ,可减少加工工序 ,缩短加工周期     

Cryogenic drilling of aluminum-based printed circuit boards: a review and analysis

Abstract

An aluminum-based printed circuit board (Al-PCB) is a composite material comprising a copper layer, an insulating layer, and an aluminum base layer. In the drilling of Al-PCBs, exit burrs are formed because of the plastic deformation of the remnant aluminum under high drilling temperatures. In this work, a new method using cryogenic media is suggested to prevent exit burrs in Al-PCB drilling. The effects of cryogenic media, such as cold air, supercritical carbon dioxide solvent (scCO₂), and liquid nitrogen (LN₂), on the drilling temperature, chip removal, tool wear and exit burr formation were observed and analyzed. The Al-PCB drilling temperature could be effectively reduced when drilling with cold air, scCO₂ or LN₂. The chip removal and tool wear could be improved when drilling with cold air or LN₂. The exit burr formation when drilling with scCO₂ or LN₂ was greater than that when drilling under cooling and cold air conditions. A cold air matching composite wood backup board (MW-0.5) could effectively control the exit burr formation within 20?μm. This is the first study on the effects of three different cryogenic media on PCB drilling and is expected to provide a good reference for the cryogenic drilling of PCBs.     

Optimization of cutting parameters on drill bit temperature in drilling by Taguchi method

In this study, the optimization of the cutting parameters on drill bit temperature in drilling was performed. Al 7075 work piece and the uncoated and Firex® coated carbide drills in the experimental were used. The optimization of the cutting parameters was evaluated by Taguchi method. The control factors were considered as the cutting speed, feed rate and cutting tool. Taguchi method was used to determining the settings of cutting parameters. The L₁₈ orthogonal array was used in experimental planning. The most significant control factors affected on drill bit temperature measurements was obtained by using analysis of variance (ANOVA). Taguchi design method exhibit a good performance in the optimization of cutting parameters on drill bit temperature measurements. In addition, the empirical equations of drill bit temperatures were derived by using regression analysis. The obtained equations results compared with the drill bit temperature measurement results. The empirical equations results indicated a good agreement with experimental results.     

PCB钻孔自动影像测量的SPC开发

随着电子行业的发展,电子产品的质量要求越来越高。使用传统的接触式方法检测PCB孔存在困难,且板上孔的数量庞大,效率不高,孔的质量得不到保证。利用自动影像测量仪可以进行非接触测量,在此基础上运用统计学原理,开发出SPC功能,对孔的测量数据进行统计分析,可及时评测和调整孔的质量,保证了PCB钻孔生产过程中的品质。     

PCB钻铣机CAD/CAM集成数控系统的设计与开发

介绍PCB钻铣机CAD/CAM集成数控系统的设计与开发的若干关键技术及其实现的方法。该系统主要解决印刷线路板加工中的图形设计、前/后置处理、路径优化和钻铣机数控系统等实用问题,目前已成功应用于多家印刷线路板生产厂和钻铣机生产厂。     

Determination of optimum parameters for multi-performance characteristics in drilling by using grey relational analysis

The theory of grey systems is a new technique for performing prediction, relational analysis and decision making in many areas. In this paper, the use of grey relational analysis for optimising the drilling process parameters for the work piece surface roughness and the burr height is introduced. Various drilling parameters, such as feed rate, cutting speed, drill and point angles of drill were considered. An orthogonal array was used for the experimental design. Optimal machining parameters were determined by the grey relational grade obtained from the grey relational analysis for multi-performance characteristics (the surface roughness and the burr height). Experimental results have shown that the surface roughness and the burr height in the drilling process can be improved effectively through the new approach .     

Process improvement in laser hot wire cladding for martensitic stainless steel based on the Taguchi method

Laser hot wire cladding, with the prominent features of low heat input, high energy efficiency, and high precision, is widely used for remanufacturing metal parts. The cladding process, however, needs to be improved by using a quantitative method. In this work, volumetric defect ratio was proposed as the criterion to describe the integrity of forming quality for cladding layers. Laser deposition experiments with FV520B, one of martensitic stainless steels, were designed by using the Taguchi method. Four process variables, namely, laser power (P), scanning speed (V _s), wire feed rate (V _f), and wire current (I), were optimized based on the analysis of signal-to-noise (S/N) ratio. Metallurgic observation of cladding layer was conducted to compare the forming quality and to validate the analysis method. A stable and continuous process with the optimum parameter combination produced uniform microstructure with minimal defects and cracks, which resulted in a good metallurgical bonding interface.     

Measurement and analysis of thrust force in drilling of particle board (PB) composite panels

Particleboard is a wood based composite extensively used in wood working. Drilling is the most commonly used machining process in furniture industries. The surface characteristics and the damage free drilling are significantly influenced by the machining parameters. The thrust force developed during drilling play a major role in gaining the surface quality and minimizing the delamination tendency. The objective of this study is to measure and analyze the cutting conditions which influences the thrust force in drilling of particle board panels. The parameters considered are spindle speed, feed rate and point angle. The drilling experiments are performed based on Taguchi’s design of experiments and a response surface methodology (RSM) based mathematical model is developed to predict the influence of cutting parameters on thrust force. The results showed that high spindle speed with low feed rate combination minimizes the thrust force in drilling of pre-laminated particle board (PB) panels.     

基于毛刺的切削参数优化试验研究

金属切削中的毛刺是切削加工中产生的常见现象,它严重地影响产品的精度和使用性,有必要对毛刺的预测进行深入的研究。本文针对铣槽时产生的出口毛刺高度进行试验与检测,并通过田口直交表进行统计分析,对检测到的试验数据运用相关公式进一步进行计算优化,然后根据传统的经验值与优化计算的数据进行比较,获取了以毛刺高度为控制对象的切削用量优化值,以此为依据提出在加工过程中夹具、机床等相关的数据优化,为进一步对毛刺控制的非线性数学模型的建立提供试验数据。     

Investigating the recast layer formed during the laser trepan drilling of Inconel 718 using the Taguchi method

This paper presents an investigation into the recast layer formed during the laser trepan drilling of Inconel 718 by a Nd:YAG laser. Laser drilling has evolved into the method of choice for the drilling of cooling holes in aerospace components. However, holes drilled with this particular technique are liable to display a variety of defects, including spattering, tapering, microcracks, and a recast layer. In order to meet the standards specified by the original engine manufacturer, this paper investigates the effects of the various laser drilling parameters on the recast layer thickness in the trepan drilling mode. A total of eight laser drilling parameters are considered in a series of experiments arranged using a Taguchi L18 orthogonal array. Taguchi analytical techniques are employed to establish the optimum set of parameters which yields a minimum recast layer thickness. The results indicate that the assist gas pressure, the peak power, and the focal position exert the greatest influence on the recast layer thickness. Having performed a confirmation experiment based on the initial Taguchi design experiments, the recast layer thickness is reduced further by adjusting the values of the assist gas pressure and the trepanning speed.     

The evaluation of the effects of control factors on surface roughness in the drilling of Waspaloy superalloy

In this study, the effects of cutting tool type (Ct), cutting speed (Vc), feed rate (f) and drill bit angle (A) on the average surface roughness (Ra) were investigated in the drilling of Waspaloy superalloy with coated and uncoated solid carbide drills. Experimental studies were performed in the orthogonal array of L18 (2¹ × 3³) by using Taguchi method. A second order predictive equation was developed with Linear Regression Analysis and coefficient of correlation for Ra calculated as R² = 96.9%. The most effective parameters on Ra were determined as A, f, Vc and Ct with 49.44%, 15.0%, 14.45% and 13.47% contribution ratios, respectively. Ra surface roughness values increased with the increasing tool wear. In this study, the chip formation and tool wear were also evaluated. Three types chip formation such as spiral chip, string chip and short chip were observed in the drilling of Waspaloy with solid carbide drills.     

Integrating Box-Behnken design with genetic algorithm to determine the optimal parametric combination for minimizing burr size in drilling of AISI 316L stainless steel

This paper illustrates the methodology of genetic algorithm (GA) based multi-objective drilling process optimization. The optimal values of cutting speed, feed, point angle and lip clearance angle for a specified drill diameter were determined using GA, which simultaneously minimize burr height and burr thickness at the exit of holes during drilling of AISI 316L stainless steel. The burr size models required for GA optimization were developed using response surface methodology (RSM) with drilling experiments planned as per Box-Behnken design. The GA optimization results reveal that point angle has a significant role in controlling the burr size.     

Research on the arc type aerostatic bearing for a PCB drilling station

This paper describes the development of the resistance network method (RNM) for analyzing the static behavior of arc type aerostatic grooved bearing. In this study the nonsymmetrical complexity geometry of gas film clearance and its influence on the bearing behaviors are taken into account when the misalignment takes place between shaft and arc type bearing due to the external nonsymmetrical load.     

面向生物医学应用的微操作机器人技术发展态势

近年来,生物医学得到了迅猛发展,研究领域多涉及到微纳米操作.手动操作存在工作效率低,成功率低等缺陷.因此,由生物医学与微操作机器人结合而产生的生物微操作机器人已成为全世界范围内的研究热点.基于此,通过对当前国内外生物微操作机器人的研究现状、实际应用等方面进行分析,总结出生物微操作机器人在视觉伺服控制、驱动器、执行机构、微操作控制策略、几何标定、传感器融合等方面存在的不足,并提出改进意见,以期对该领域未来的创新设计以及发展研究提供一定的参考及指导作用.     

Development of an innovative plate dynamometer for advanced milling and drilling applications

Tool geometry optimization, workpiece material characterization, process monitoring and optimization are based on the measurement of cutting forces by using machining dynamometers. Commercial dynamometers cover a wide range of machining applications, nevertheless there is a lack of measuring devices suitable for investigating milling and drilling applications with relatively small cutters and high spindle speeds. In this work, the development and testing of an innovative plate dynamometer designed for this purpose is discussed. The new measuring system was based on three high-sensitive triaxial piezoelectric force sensors arranged in a novel triangular configuration. Component design was optimized by using FE numerical approaches, according to the general guidelines derived from mathematical modeling of sensor dynamics. The prototype of the proposed device was manufactured and experimentally tested against two high-end commercial plate dynamometers by performing static calibration, modal analysis and cutting tests. Experimental results proved the excellent characteristics of the new device and its effectiveness for investigating advanced machining applications.     

Development of a drilling and coring test-bed for lunar subsurface exploration and preliminary experiments

Drill sampling has been widely employed as an effective way to acquire deep samples in extraterrestrial exploration. A novel sampling method, namely, flexible-tube coring, was adopted for the Chang＇e mission to acquire drilling cores without damaging stratification information. Since the extraterrestrial environment is uncertain and different from the terrestrial environment, automated drill sampling missions are at risk of failure. The principles of drilling and coring for the lunar subsurface should be fully tested and verified on earth before launch. This paper proposes a test-bed for conducting the aforementioned experiments on earth. The test-bed comprises a rotary-percussive drilling mechanism, penetrating mechanism, drilling medium container, and signal acquisition and control system. For granular soil, coring experiments indicate that the sampling method has a high coring rate greater than 80%. For hard rock, drilling experiments indicate that the percussive frequency greatly affects the drilling efficiency. A multi-layered simulant composed of granular soil and hard rock is built to test the adaptability of drilling and coring. To tackle complex drilling media, an intelligent drilling strategy based on online recognition is proposed to improve the adaptability of the sampling drill. The primary features of this research are the proposal of a scheme for drilling and coring a test-bed for validation on earth and the execution of drilling experiments in complex media.     

新型钻井岩屑清洗机的研究与设计

在分析研究钻井岩屑清洗技术的基础上,根据现场要求设计了新型钻井岩屑清洗机.压力水流以喷射冲洗的方式对岩屑进行淘洗,提高了岩屑清洗的质量和效率.还对微滤膜技术在污水处理方面的应用以及超声波技术在工业领域的应用进行了深入研究,提出综合采用超声波和微滤膜两项技术处理废水的工作原理,并基于此原理设计出一套超声波微滤膜净化处理装置(轴向过滤),实现了清洗用水的循环利用.研制的钻井岩屑清洗机采用的清洗方法和超声波微滤膜水处理装置经现场实际应用证明,具有一定的实用价值.     

Simultaneous Optimisation of Multiple Quality Characteristics in Manufacturing Processes Using Taguchi's Quality Loss Function

Taguchi methods have proved to be successful over the last fifteen years or so for the improvement of product quality and process performance. Most Taguchi experiments are concerned with the optimisation of a single quality characteristic. Optimisation of multiple quality characteristics in manufacturing processes is not common and has received very little attention among the Taguchi practitioners. Many engineers using Taguchi methods have employed pure engineering judgement when dealing with multiple quality characteristics in manufacturing process optimisation. This approach is very subjective and therefore always brings an element of uncertainty to the decision-making process. This paper presents an alternative approach for tackling such optimisation problems using Taguchi’s quality loss function analysis. The paper also presents a case study to illustrate the potential of the proposed methodology.