Khumbulani Mpofu

Conceptual Development of Modular Machine Tools for Reconfigurable Manufacturing Systems

Manufacturing industry is extremely broad and plays a key role in the global economy. However, there are rapid and continued technology changes due to rapid response required by the market challenges and customer demands, therefore the manufacturing industry needs to keep up with market demands at all the times. Reconfigurable manufacturing systems will enable manufacturers to produce a variety of goods within a short time and improve sales. Reconfigurable Machine tools (RMTs) together with Reconfigurable Manufacturing Systems (RMSs) are the new invention introduced in 1999 at the Engineering Research Center for Reconfigurable Manufacturing Systems (ERC/RMS). This paper presents the conceptual development of modular machine tools, by selecting and compiling a list of modules available commercially off the shelf. The machine tool is developed in such a way that it can be configured accumulatively in terms of degrees of freedom, to accommodate different reconfigurations of machine structures. As the modules can be assembled in different ways to create different types of tools capable of performing a variety of functions using the same hardware and software, depending on demand, one should be able to increase or decrease the number of degrees of freedom.

Adaption of Commercial off the Shelf Modules for Reconfigurable Machine Tool Design

A variety of methodologies have been utilised in the design of reconfigurable industrial machines. Authors consider some of the methods that have been used given the critical aspects of these methods, the commercial off the shelf (COTS) method of design of machine tools to achieve flexibility through reconfigurability is discussed. Highlights of the implication of this method and its repercussions to basic modules, alternate modules and additional modules are analysed. The role of the computer in the entire process is to be particularly highlighted.

A methodology for design and reconfiguration of reconfigurable bending press machines (RBPMs)

Customer requirements have become very dynamic and unprecedented. A manufacturing paradigm called reconfigurable manufacturing system was initiated to adjust the physical machine entities. The main enabler of a machine structure’s reconfigurability is a modular design approach. The paper explains a function-driven object-oriented methodology for the design and reconfiguration of RBPMs. The complete method aims to optimise initial design of RBPMs, followed by subsequent design of RPBM modules which are stored in a module library so as to enable full-automatic reconfiguration of the RBPMs. The methodology is implemented on a pilot project to design a 145 ton bending capacity RBPM, with a maximum reconfigured length of 5 m and total height of 3 m. In order to deduce the design for the reconfigurable bending press machine, the reconfigurability needs were identified first, followed by the construction of a function tree for the machine. The function tree identifies the primary function for the RBPM, which is to bend sheet metal. The primary function is further decomposed to lower level functions until terminal functions are arrived at. The terminal functions are then used to identify the modules for the machine. The modules implement specific brunches of the machine functions.

Towards achieving a fully intelligent robotic arc welding: a review

Purpose – The purpose of this paper is to review the progress made in arc welding automation using trajectory planning, seam tracking and control methodologies. Design/methodology/approach – This paper discusses key issues in trajectory planning towards achieving full automation of arc welding robots. The identified issues in trajectory planning are real-time control, optimization methods, seam tracking and control methodologies. Recent research is considered and brief conclusions are drawn. Findings – The major difficulty towards realizing a fully intelligent robotic arc welding system remains an optimal blend and good understanding of trajectory planning, seam tracking and advanced control methodologies. An intelligent trajectory tracking ability is strongly required in robotic arc welding, due to the positional errors caused by several disturbances that prevent the development of quality welds. An exciting prospect will be the creation of an effective hybrid optimization technique which is expected to ...

Re-balancing problem for assembly lines: new mathematical model and exact solution method

The purpose of this study is to develop a new mathematical model and an exact solution method for an assembly line rebalancing problem. When an existing assembly line has to be adapted to a new production context, the line balancing, resources allocation and component management solutions have to be revised. The objective is to minimize the number of modifications to be done in the initial line in order to reduce the time and investment needed to meet new production requirements. The proposed model is evaluated via a computational experiment. The obtained results the efficacy of the proposed method.

A morphology proposal in commercial-off-the-shelf reconfigurable machine tools

Global manufacturing is continuously facing changing demands, the unpredictable part family supply that a machine tool user has to deal with needs varying machine morphologies. The reconfigurable manufacturing system paradigm proposes the need for the right capacity, for the right demand with an economical ramp-up period. The machinist needs to have a systematic manner of configuring the machines, given a set of modules that will be configured and reconfigured for the various demands in the lifespan of a manufacturing system. In this article, the author proposes how the machinist can go about identifying the different morphologies in advance. The method is simple and user-friendly in consideration of the main users who may have basic skills being deficient in sophistication and complexity; it further assists in the determination of the capability the manufacturer has with the available modules.

Machine Morphology in Reconfigurable Machine Tools

Abstract Machine morphology within the reconfigurable machine tool environment is considered in this article in a bid to address the configurations and reconfigurations that will be needed to meet the uncertain and unpredictable demands in the market. This paper proposes a hierarchical classification mechanism for machine structures, these structures derive from module combinations where symbology is utilized to represent the machines and these symbols can be used in the configuration process. Authors envisage this method to be relevant in the combinatorial problem reconfigurable environments face.

Establishment of the best maintenance practices for optimal reconfigurable vibrating screen management using decision techniques

Purpose Reconfigurable vibrating screen (RVS) is an innovative beneficiation machine designed at Tshwane University of Technology, Republic of South Africa (RSA); with adjustable screen structure to ensure sorting, sizing and screening of varying mineral particles (sizes and quantities) demanded by the customers in a cost-effective manner through the screen structure geometric transformation. In order to ensure that this machine is optimally maintained and managed when utilized in surface and underground mining industries, there is a need to establish or ascertain the best maintenance practices that would be used in optimally managing the RVS machine using decision making techniques. In view of this, the purpose of this paper is to ascertain the best maintenance practices that would be used to optimally maintain and manage the RVS machine when used in surface and underground mines. Design/methodology/approach Decision making techniques such as weighted decision matrix (WDM) and analytical hierarchy process (AHP) were used in this research work to establish the best maintenance practice for optimally maintaining and managing the RVS machine using relevant literature survey on maintenance management systems as well as the different maintenance criteria decision indices obtained from different conventional vibrating screen machine manufacturers and maintenance experts. Findings Based on the results obtained from the WDM analysis, it was anticipated that e-maintenance (e-M) system embedded with diagnosing and prognosing algorithms; with a cumulative weight score of 2.37 is the best maintenance practice for managing the RVS machine when used in surface mines, while AHP with deeper decision making analysis anticipated that the robotic-driven maintenance (RM) system with an important decision criteria; safety, and a cumulative hierarchy score of 28.6 percent, supported by e-M management system with a cumulative hierarchy score of 17.6 percent are the best maintenance mix that could be used in optimally maintaining and managing the RVS machine, when used in a craggy and hazardous underground mining environment. Practical implications To this effect, it could be anticipated that e-M management system (endowed with the ability to detect fault on the machine, diagnose and prognose the different subsystems of the RVS machine and ascertain the reconfiguration time and process of the RVS machine in recovering production loss during the maintenance of the machine as well as meeting customers demand, etc.) is the best maintenance practice for optimally maintaining the RVS machine when utilized in surface mines while both e-M management system and RM management system (endowed with the ability to carry out automated maintenance tasks achievement under little or no maintenance manager intervention) are also anticipated as the best customized maintenance practices mix that could be used in optimally maintaining the RVS machine, when used in dangerous and hazardous underground mining environment. Originality/value This maintenance management system evaluation and selection for optimal RVS machine functionality will serve as a useful information to different mining machines (and other related machines) maintenance managers, in selecting the best maintenance management system for ensuring optimal functionality, reliability and maintainability of machines used in their industries.

Mining business optimisation through a reconfigurable vibrating screen design

Fluctuation in mineral concentrates demand, unstable mineral market conditions and high machine downtime and its associated costs have been the most recent challenges that have affected the mining industry. This sector has not fully understood these factors. In order to provide solutions for the aforementioned bottlenecks faced by mining industries, the Innovative Manufacturing Design Solution (IMDS) Group in the department of Industrial Engineering at Tshwane University of Technology (TUT) has designed a new beneficiation machine called a reconfigurable vibrating screen (RVS) machine using reconfigurable manufacturing system principles. The RVS machine achieves mineral beneficiation optimisation through geometric transformation of the screen surface structure and productivity adjustments. Geometric transformation of the screen surface structure involves horizontal (screen surface length and breadth) reconfiguration which is automatically achieved using a hybrid control system that is open and modular, while productivity and adjustment are enabled using a plug and produce device. Geometric transformation mechanism feasibility on the RVS machine allows the mineral beneficiation experts and mining engineers in mining industries to adjust the machine screen length and breadth to the required configuration dimensions, thus improving the capability; beneficiation capacity and productivity of the machine. It is envisaged that this innovation will increase profitability in small to medium mining enterprises (SMMEs) with medium to moderate capital in the mining business through production of scalable and customised RVS machines (at a reduced cost) which SMMEs can afford. A full-scale RVS machine computer-aided design (CAD) model of this machine was designed to a specification of approximately 4.7 m length by 2.5 m breadth with a total estimated screen weight capacity of 16 121 tons for beneficiating and screening mineral particles between size ranges of 50 mm to 3 mm. Furthermore, a hand simulation-based optimisation was carried out to showcase how the RVS machine can be used to manage the aforementioned difficulties faced by the mining industries.

Educating tomorrows engineers: Reinforcing engineering concepts through Virtual Reality (VR) teaching aid

The research focuses on the practicality of applying Virtual Reality (VR) as tool for conveying engineering concepts to first year engineering students. It does this by presenting a VR platform aimed at achieving a simplified methodology for depicting and analyzing facility layout and production process. Current reality shows that Higher Education Institutions (HEIs) are towing the electronic teaching path and more practical concepts are delivered to learners, using digital e-learning simulation tools. Equally, HEIs are adopting dynamic models for virtual interaction with students, globally, via e-classrooms and VR platforms. The article presents the developed teaching tool and validation method for conveying factory layout optimization concepts and production process model, through a partially-immersive VR design platform developed using a 3D design tool and complementary high-level applications. The developed teaching aid has an interactive user interface through which the building framework, sections and prototype schema of the industrial process may be visually analyzed.