An Intelligent Approach to High Quantity Automated Machining

Purpose: To investigate the possibility of application of knowledge-based expert systems to facilitate the task of techno-economical feasibility analysis of utilization of special purpose machines for high quantity production tasks. Also, to study the possibility of assisting special purpose machine designers in applying knowledge-based expert systems in the design task in order to reduce required machine design time, improve machine design efficiency, and eliminate possible human errors. Design/methodology/approach: Development of a knowledge-based expert system has been proposed to help decide where to utilize special purpose machines to accomplish the production task. The knowledge-based expert system consists of a rule-base which contains qualitative human knowledge and expertise in the form of if-then rules; and a database which contains qualitative information of machining operations, and characteristics of standardized special purpose machine components. Findings: A case study has been presented where an analysis has been made on the basis of techno-economical considerations for a typical part with three machining operations to be produced in large quantities. It has been concluded that for the given production task, special purpose machines would result in a significant 59% reduction of costs compared to CNC machines, and 95.5% compared to traditional machines. The proposed methodology also reduces the time and effort needed for decision making on utilization of special purpose machines and determination of machine layout. In addition, it minimizes the level of expertise required to perform these functions and eliminates possible human errors. Research limitations/implications: The current system focuses on drilling and drilling-related operations which cover about 60% of all machining operations. More work is needed to cover other machining operations including milling. Also the KBES developed currently works on a standalone basis. Work is in progress to integrate it with a 3D CAD modelling system. Upon completion the information could be directly extracted from the CAD system, eliminating the need for manual data input by the user. Originality/value: In spite of a large number of publications on machine tool design in the literature, publications on special purpose machines are very limited. The method of techno-economical analysis presented here for utilization of special purpose machines in comparison with other production alternatives is of great value to manufacturing engineers and specialists. Also the methodology presented for machine design and implementation is highly valued by machine tool designers and manufacturers

Intelligent Analysis of Utilization of Special Purpose Machines for Drilling Operations

Drilling and drilling-related operations constitute more than 60% of all machining processes in manufacturing industries. Consequently, it is important to know how to perform these operations properly. With availability of many machining processes capable of performing drilling operations sometimes it is difficult to decide which process would result in a higher profit or a lower unit cost for a given task. Due to increasing global competition, manufacturing industries are now more concerned with their productivity and are more sensitive than ever to their investments with respect to flexibility and efficiency of production equipment (Boothroyd and Knight, 2005, Wecka and Staimer, 2002). Researchers (Ko et al., 2005) believe that increasing the quality of production and reducing cost and time of production are very important factors in achieving higher productivity. Achieving this goal requires reconsidering current production methods that could lead to introduction of new production techniques and more advanced technologies

The heat treatment analysis of E110 case hardening steel

This paper investigates mechanical and microstructural behaviour of E110 case hardening steel when subjected to different heat treatment processes includingquenching, normalizing and tempering. After heat treatment samples were subjected to mechanical and metallographic analysisand the properties obtained from applying different processes were analysed. The heat treatment process had certain effects on the resultant properties andmicrostructures obtained for E110 steel which are described in details. Quenching produced a martensitic microstructure characterized by significant increase in material’s hardness and a significant decreased in its impact energy. Annealed specimens produced a coarse pearlitic microstructure with minimal variation in hardness and impact energy. For normalized samples, fine pearlitic microstructure was identified with a moderate increase in hardness and significant reduction in impact energy. Tempering had a significant effect on quenched specimens, with a substantial rise in material ductility and reduction of hardness with increasing tempering temperature. Furthermore, Results provide additional substantiation of temper embrittlement theory for low.carbon alloys, and indicate potential occurrence of temper embrittlement for fine pearlitic microstructures

Design of modular fixtures using a 3D-modelling approach

The need for improved productivity and reduced time to market has been increased significantly in manufacturing processes in recent decades. There are many factors that play a role in providing manufacturing processes with more productivity. One is the use of modular fixtures (MFs). MFs have brought many benefits to manufacturing industries including reduced costs and times of production. An MF can be defined as a complete system that consist different elements for effectively and securely holding the workpiece in place for performing various machining operations. Generally an MF is made by assembling a number of fixture elements in a feasible sequence that is properly determined. Traditionally, the most common method of determination of fixture elements and assembly sequences are making use of 2D drawings and physical models. Obviously these are not efficient methods in the world of advanced manufacturing technologies and there is a vital need for developing more efficient methods. A solution to this is developing a CAD-based 3D-modelling and simulation system to determine the types and of feature elements and the sequence of assembly. Such a system can help fixture designers find the proper MF designs by defining the relationships between fixture elements and workpieces. Designing MFs and fixture elements is a very complex and time-consuming task even by making use of CAD software. A methodology has been developed to simplify this task by determining fixture elements and assembly sequences in a 3D-modelling environment. A fixture elements database is established and the fixture elements are divided into different categories depending on geometries and functions. Currently, MF systems can be constructed from standard MF elements. These elements are pre-manufactured components that include base-plates, clamps, and locators; and they can be re-used after disassembly. These can later be used for other workpieces within a specified range of sizes and shapes. In order to use these elements effectively, the CAD environment is exploited with developing a database which contains 3D models of standard MF elements. For most workpieces standard MF elements can be extracted directly from the developed database. However, for some workpieces with non-conventional geometries or shapes customised fixture elements should be designed in a 3D CAD environment. A modelling approach is used to find the appropriate MF design that suits the machining processes in need. To do so many parameters are taken into consideration including the number of workpieces to be machined; type of machining operation; locating method; clamping mechanism; and so on. The methodology developed for MF design has been implemented in a 3D modelling environment by making use of a powerful 3D modelling software, SolidWorks. It makes use of a database which contains 3D models for standard fixture elements. This database is divided into three main categories and each category is divided into different sub-categories depending on the type and function of the MF elements. SolidWorks software provides an excellent 3D environment that can be utilised to model fixture elements and determine assembly processes. This is accomplished by applying mating relationships after considering workpiece setup and fixture elements to achieve the optimum MF assembly design. This paper explains the methodology developed for semi-automated MF design. A case study has been presented to show the validity of the methodology proposed

Simulation of a mobile robot navigation system

Mobile robots are used in various application areas including manufacturing, mining, military operations, search and rescue missions and so on. As such there is a need to model robot mobility that tracks robot system modules such as navigation system and visi on based object recognition. For the navigation system it is important to locate the position of the robot in surr ounding environment. Then it has to plan a path towards desired destination. The navigation system of a robot has to identify all potential obstacles in order to find a suitable path. The objective of this research is to develop a simulation system to identify difficulties facing mobile robot navigation in industrial environments, and then tackle these problems effectively. The simulation makes use of information provided by various sensors including vision, range, and force sensors. With the help of battery operated mobile robots it is possible to move objects around in any industry/manufacturing plant and thus minimize environmental impact due to carbon emissions and pollution. The use of such robots in industry also makes it safe to deal with hazardous materials. In industry, a mobile robot deals with many tools and equipment and therefore it has to detect and recognize these objects and then track them. In this paper, the object detection and recognition is based on vision sensors and then image processing techniques. Techniques cove red include Speeded Up Ro bust Features (SURF), template matching, and colour segmentation. If the robot detects the target in its view, it will track the target and then grasp it. However, if the object is not in the current view, the robot continues its search to find it. To make the mobile robot move in its environment, a number of basic path planning strategies have been used. In the navigation system, the robot navigates to the nearest wall (or similar obstacle) and then moves along that obstacle. If an obstacle is detected by the robot using the built-in ultrasonic range sensor, the robot will navigate around that obstacle and then continue moving along it. While the robot is self-navigating in its environment, it continues to look for the target. The robot used in this work robot is scalable for industrial applications in mining, search and rescue missions, and so on. This robot is environmentally friendly and does not produce carbon emissions. In this paper the simulation of path planning algorithm for an autonomous robot is presented. Results of modelling the robot in a real-world industrial environment for testing the robot’s navigation are also discussed

An integrated model to use drilling modular machine tools

Modular machine tools provide a platform for drilling-related operations within automotive companies. The use of these machine tools is widespread; however, manufacturers wishing to use this technology frequently face the challenge of selecting the most appropriate manufacturing system. Accordingly, a comprehensive feasibility analysis procedure is required to assist decision-makers before any investment is made on the preparation of detailed machine design or purchase one. This paper presents a model, which collects the previous works of the authors. To do this, an integrated framework for decision-making of using machine tools is developed. The aim of this model is to enable users to make a logical decision by assessing the strengths and limitations of machine tools. To do this, the parameters which have a key influence on the decision-making process and relevant procedures are identified and integrated into a model. A case study is presented to illustrate the application of proposed model, and results are discussed. The results show that the proposed model is useful in assisting manufacturers in evaluating the performance of a modular machine tool in comparison with other alternatives

Evaluation of the effect of product demand uncertainty on manufacturing system selection

The use of advanced manufacturing systems is widespread; however, manufacturers frequently face difficult decisions when it comes to selecting the most appropriate system. Uncertainty regarding product demand makes this process more difficult, as many factors are influencing simultaneously. This paper focuses on analyzing the demand uncertainty on the performance of modular drilling manufacturing systems versus other alternatives and evaluating the uncertainty’s impacts on the final decision. To do so, a model is suggested and the effect of demand uncertainty on the output is investigated. Three automotive components of varying complexity are used to examine the approach for making reliable decision

Impact of 3D printing parameters on static and fatigue properties of polylactic acid (PLA) bone scaffolds

In the present study, polylactic acid (PLA) scaffolds with a 60 % porosity and gyroid pore structure were 3D printed using the extrusion-based method and employing various printing parameters. The specimens were loaded under quasit-static and cyclic conditions and their mechanical behaviour were evaluated. The Taguchi method was utilized to design experiments and investigate the impact of printing parameters on the compressive properties of the scaffolds. Moreover, thermography analysis was used to examine the influence of cyclic heating during fatigue experiments. The results indicated that extrusion width was the sole variable significantly affecting the quasi-static properties of scaffolds. The largest extrusion width (0.65 mm) resulted in the highest compressive properties (6–7 MPa), plateau stress (8–9 MPa), and compressive modulus (200–215 MPa). However, fatigue experiments revealed that nozzle temperature was the sole influencing factor on the fatigue performance of scaffolds, with specimens printed at low nozzle temperature (190 °C) demonstrating the highest fatigue resistance. Thermography analysis exhibited a negative correlation between scaffold temperature and stiffness. However, the impact of temperature on the structural integrity of the scaffolds was insignificant, given that the highest temperature recorded during fatigue cycles (i.e., 39 °C) was below the glass transition temperature of the scaffolds’ material

Drilling reconfigurable machine tool selection and process parameters optimization as a function of product demand

Special purpose machines (SPMs) are customized machine tools that perform specific machining operations in a variety of production contexts, including drilling-related operations. This research investigates the effect of optimal process parameters and SPM configuration on the machine tool selection problem versus product demand changes. A review of previous studies suggests that the application of optimization in the feasibility analysis stage of machine tool selection has received less attention by researchers. In this study, a simulated model using genetic algorithm is proposed to find the optimal process parameters and machine tool configuration. During the decision-making phase of machine tool selection, unit profit is targeted as high as possible and is given by the value of the following variables: SPM configuration selection, machining unit assignment to each operation group, and feed and cutting speed of all operations. The newly developed model generates any random chromosome characterized by feasible values for process parameters. Having shown how the problem is formulated, the research presents a case study which exemplifies the operation of the proposed model. The results show that the optimization results can provide critical information for making logical, accurate, and reliable decisions when selecting SPMs

Application of additive manufacturing in the development of polymeric bioresorbable cardiovascular stents: A review

Polymeric vascular bioresorbable stents (BRSs) have been widely used for the treatment of coronary artery diseases. While additive manufacturing (AM) is changing the landscape of the healthcare sector by enabling the realization of patient-specific stents with highly complex structures. There are, however, challenges associated with the use of polymeric BRS, particularly in-stent restenosis (ISR), related to its poor mechanical properties. Therefore, the aim of this review is to provide an overview of recent advancements in the development of polymeric BRSs designed to meet both mechanical and biological requirements. First, biopolymers as well as shape memory polymers (SMPs) that are suitable for BRSs are highlighted and briefly described. Second, different types of designing structures of vascular stents in addition to introducing effective mechanical metamaterials, e.g., negative Poisson ratio (NPR) structures are addressed. Subsequently, AM methods currently being used to fabricate polymeric BRSs, are discussed and compared with conventional fabrication methods. Lastly, future directions for research are proposed in relation to existing challenges to the realization of a new generation of AM BRSs. Overall, this paper serves as a benchmark for future cardiovascular applications, especially in order to obtain clinically viable polymeric vascular stents by selecting suitable polymers, designs, and AM technologies