Browsing by Author "Treurnicht, N. F."
Now showing 1 - 9 of 9
Results Per Page
- ItemEconomic requirements analysis for table grape check weighing(Industrial Engineering, Stellenbosch University, 2011-09) Smit, R.; Treurnicht, N. F.; Blanckenberg, M. M.South Africa’s table grape industry exports most of its production to the developed world where customer satisfaction is very important and strictly regulated. Severe penalties are levied for underweight packaged products and contracts could even be lost. This study aims to determine the feasibility of automated check weighing of final product prior to shipping. The frequency of occurrence of underweight packages is investigated by means of structured interviews conducted within the industry. The probable financial impact of underweight packing is estimated and the paper concludes with a presentation of the capital amount producers can spend to eliminate underweight packaging profitably.
- ItemEvaluation of work piece temperature measurement techniques for milling of Ti6Al4V(Stellenbosch : Stellenbosch University, Department of Industrial Engineering, 2011-09) Conradie, P. J. T.; Oosthuizen, G. A.; Treurnicht, N. F.; Al Shaalane, A.Ti6Al4V is one of the most widely used titanium alloys in aerospace applications, but its machining remains a challenge. This is partly due to the lack of understanding of the thermal- and mechanical constraints during milling. Extensive research has been done in the past investigating catastrophic tool failure of various tool materials. However, not much research has been done to investigate the cause of work piece failure. The catastrophic effect of overheating the work piece and the resulting alpha case formation in titanium is well known. Current techniques of temperature measurement of the machined surface can be divided into two categories: contact- and optical methods. In this study these temperature measurement techniques were studied and evaluated. The response time of contact methods are found to be to relatively slow. The optical methods have the advantage of immediate response, allowing capture of intermittent heat generation as required in milling. The infrared camera temperature measurement experiments were conducted with a special setup in order to have a good visual of the temperature flow. The results of these experiments were found to correspond with literature.
- ItemExploring critical failure modes in the rail environment and the consequential costs of unplanned maintenance(CIE & SAIIE, 2012) Conradie, P. D. F.; Treurnicht, N. F.This study explores in-service failure modes for rolling stock in the rail environment, identifies the most critical failures and explores the consequential cost of these failure modes. Rolling stock is maintained according to maintenance plans with a major goal being the prevention of in-service failures, but due to the nature of the equipment not all failures can be prevented. In-service failures normally result in train delays or the cancellations of trains not only disrupting commuter services but also causing financial losses. The typical failures of rolling stock are analysed using data from the facility maintenance management system. The critical failure modes are identified and classified according to cause, severity, consequence and frequency parameters. A decision model is employed to classify the criticality of the failure modes. The most prominent critical failure modes are analysed to determine root causes, to conclude the investigation. Areas are identified where the focus of future investigation and planned maintenance will have the most significant impact.
- ItemHigh speed cutting and electric discharge machining as complementary processes in the die and mould industry(Stellenbosch : Stellenbosch University, 2003-04) Treurnicht, N. F.; Fourie, C. J.; Stellenbosch University. Faculty of Engineering. Dept. of Industrial Engineering.ENGLISH ABSTRACT: High Speed Cutting (HSC), specifically milling is a significant contemporary development in machining. The Die and Mould industry is experiencing a difficult business climate. There is competitive pressure for shorter lead times and lower prices. Companies worldwide, are under financial pressure, to meet the challenges of a globalised business environment. The conventional position of milling and Electric Discharge Machining (EDM / Erosion) is discussed with the proposal to use HSC and EDM as complementary processes. Among new developments the progress in computer infrastructure is prominent. There is also a paradigm shift that should be made from experience based process planning to modern, up to date knowledge based process planning. High Speed Cutting is now a mature process capable of acceptable process security. The examples detailed include crankshaft-forging tooling, injection moulding tooling and powder sintering tooling. A process chain is proposed for the complementary HSC / EDM process with estimated illustrative time saving over the conventional EDM dominated process. HSC will be the first process removing the bulk of the material, finishing as far as possible and with EDM finally machining the features that will be difficult or impossible with HSC. To facilitate the use of the complementary processes a decision model to determine the crossover point between HSC and EDM is proposed. The decision model is firstly presented as a flow diagram to determine whether the task is a candidate for HSC only, EDM only, or the complementary HSC / EDM process. The key parameters e.g tool H d ratio are variables. This is in order that the flow diagram may be adapted to a specific machine tool infrastructure and expertise level in a company. The second part is a HSC machining time estimation model. The time is estimated per segment roughed, semi-finished, or finish machined. The model is in an empirical form with constants that can be adapted to the practices of a specific company. It is intended that the constants also be periodically revised to reflect the development in HSC expertise that will occur during the use HSC in the company. The model is practically evaluated with a case study, including the detail steps, not included in the model. Conceptual guidelines are given for software implementation. It is concluded that HSC and EDM are suitable complementary processes. It is a necessary prerequisite to use pallets to avoid multiple set-ups. Complementary HSC and EDM is especially appropriate for the gradual deployment and skill development for HSC. HSC and complementary HSC / EDM is considered the opportunity for companies to make a major breakthrough in lead time and operating expense if the necessary pallet/fixturing equipment, CAx infrastructure and human capability is available.
- ItemInvestigating of eco- and energy-efficient lubrication strategies for the drilling of light metal alloys(Southern African Institute for Industrial Engineerg, 2010) Treurnicht, N. F.; Joubert, H. J.; Oosthuizen, G. A.; Akdogan, G.ENGLISH ABSTRACT: Energy use will be one of the main drivers for the achievement of more eco-efficient drilling processes in the automotive industry. Industry awareness of the environmental impact of used cutting emulsions, and the negative effect on worker health, has increased sharply. This has led to innovative lubrication methods such as through-spindle minimal quantity lubrication (MQL) for drilling aluminium-silicon alloys. In this work the performance of MQL at different cutting speeds and feed rates has been investigated using infrared temperature measurements. The results indicate that MQL is a feasible eco-efficient alternative to conventional flood cooling when drilling aluminium-silicon alloys.
- ItemOverview of work piece temperature measurement techniques for machining of Ti6Al4V(Southern African Institute for Industrial Engineering, 2012-07) Conradie, P. J. T.; Oosthuizen, G. A.; Treurnicht, N. F.; Al Shaalane, A.ENGLISH ABSTRACT: Ti6Al4V is one of the most widely used titanium alloys in aerospace applications, but its machining remains a challenge. Comprehensive research has been done in the past, mainly investigating tool failure of various materials. Less research has been done to investigate the thermal effect of machining on work piece quality, including fatigue performance. Temperature measurement is considered to be a key enabling technology. This study presents an overview of current temperature measurement techniques for machined and tool surfaces. Two categories of methods were investigated: slower contact, and faster optical methods. Optical fibre two colour pyrometry experiments are reported that demonstrate the technique’s adequate response time. The infrared camera temperature measurement experiments synchronised temperature measurement with visual observation, aimed at mechanism analysis. The results corresponded with the literature.
- ItemA quantitative analysis of supply response in the Namibian mutton industry(Southern African Institute for Industrial Engineering, 2012-05) Van Wyk, D. N.; Treurnicht, N. F.ENGLISH ABSTRACT: Agricultural activities in Namibia contribute 5.5% of Namibia’s GDP, while 70% of the population relies on agriculture for employment and day-to-day living. The purpose of this study is to investigate the relationships between the various price and non-price factors contributing to the supply dynamics within the mutton industry in Namibia. The autoregressive distributed lag approach to co-integration was used to determine the longrun and short-run supply response elasticities between economic and climatology factors on time-series data. Supply shifters showed significant short-run and long-run elasticities with regard to the mutton produced. Results also revealed that the system takes nearly two months to recover to the long-run supply equilibrium, should any disturbances occur within the supply system.
- ItemTable grape punnet packaging : the influence of check-weighing(Southern African Institute of Industrial Engineering, 2012-11) Smit, R.; Treurnicht, N. F.; Blanckenberg, M. M.Most of South Africas table grapes are exported to the EU and the UK. In recent years, pre-packaged table grapes are now preferred in many European supermarkets. This increased demand has resulted in stringent quality standards, including the specification of punnet mass. Locally, table grapes are packed manually using seasonal labour, who often have limited formal education. Punnets must conform to upper and lower mass limits, but many deviations occur due to human and machine error. Check-weighing proved effective in reducing out-of-specification punnets, but human and machine errors were still problem factors.
- ItemUsing Poka-yoke methods to improve employment potential of intellectually disabled workers(Southern African Institute for Industrial Engineering, 2011-05) Treurnicht, N. F.; Blanckenberg, M. M.; Van Niekerk, H. G.ENGLISH ABSTRACT: In this project an electronic manufacturing process, namely ribbon cable assembly, was adapted for execution by intellectually disabled individuals. To make the work accessible to them, human error was controlled by a Poka-yoke approach. The design of the work process used industry standard tooling. Mistake-proofing design identified possible errors, and introduced mechanisms and tests that enabled the worker to avoid them. Test results were analysed using learning theory. It is concluded that intellectually disabled individuals can be enabled to perform the task within normal variation compared with a minimum task time, by using the Poka-yoke approach. Selection, however, is desirable.