Introduction to Transport Material - Assignment Example

ORDER No: 508829 INTRODUCTION TO TRANSPORT MATERIAL INTRODUCTION For many years the majority of vehicle engine components were made from steelor aluminium, particularly where high mechanical strength, thermal stability and chemical resistance were concerned. This is still the case in oil pan modules [sumps] for diesel engines, where the function of the sump is not only to contain the hot oil, but also to maintain structural integrity in the event of damage (Leaversuch, 2004). Aluminium on its own is a relatively soft material but, when alloyed with copper, offers significant advantages over steel in the following respects: good resistance to oils and other chemicals at high temperatures, “high strength stiffness to weight ratio, good formability…recycling potential” (Miller et al., 2000). Of particular importance is the reduction in weight which contributes to fuel savings. Aluminium alloys for sumps are generally formed by pressure die casting, and significant reductions in cycle times [20-30%] have been achieved by Nissan and Ford leading to greater cost effectiveness (Kumar, 2007). THE CHANGE TO PLASTICS The so-called “engineering plastics” – phenol formaldehyde such as “bakelite”, the polyamides [nylon] (Clark, 2004) and polycarbonate possess sufficient mechanical strength [toughness and rigidity] as well as high resistance to moisture and chemicals, to be used as metal replacements in certain automotive applications. There are two main classes of polymers: thermosets [phenol formaldehyde for instance] – where, during the processing stage a chemical reaction takes place which “sets” the material irreversibly - and thermoplastics, which can be melted and remelted several time [the polyamides and polycarbonates]. Since these materials not only offered the properties already mentioned, but were also about half the weight of aluminium, they were considered for fabrication into oil pan modules. After a number of trials thermoplastics were considered superior to thermosets (Leaversuch, 2004). At that time there were essentially two major players in this field – BASF and DuPont; the former concentrating on the development of “nylon 6” and the latter “nylon 6,6”, whose structures are described by Clark (2004) – both using short glass fibres as reinforcement. Ultimately the semi-crystalline nylon 6,6 was found to have the necessary properties and the first plastics oil pan module was launched by BASF – and received the Society of Plastics Engineers [SPE] award in 2004 for innovation (BASF, 2004). Leaversuch (2004) describes the parameters governing this application. Firstly, in order to avoid design changes, it was necessary to work within the confines of the existing engine compartment and to accommodate the locations of the fixing geometry. Secondly, due to the material characteristics it was necessary to provide flow paths inside the injection tool to cater for undercuts and to control the orientation of the glass fibres so as to provide cross-sections with sufficient strength to remain stable for long periods under extreme conditions. The results were so successful that it was found possible to gain an extra sump volume of 30% and to “integrate the oil sensors and dipstick into the design” (Leaversuch, 2004). It was also found that the noise of the engine was less than that experienced when using thermosets. However, things do not stand still, and the use of more powerful engines, still within the same confined space, has led to higher operating temperatures which, in turn, required further enhancement of material properties. NEW AND BETTER POLYAMIDES These requirements led to the search for polymers with further enhanced properties, and one of the research programmes initiated by DuPont is described by Glasscock and co- workers (2008). Essentially the performance of both amorphous and semi-crystalline polymers fall within the confines of a triangle, with the higher levels of performance towards the apex. While the two conventional nylon types polyamide 6 [PA 6] and 6,6 [PA 66] have aliphatic chain structures (Clark, 2004; Glasscock et al., 2008), “ the addition of an aromatic ring structure to a polyamide provides many advantages…higher Tg, higher melting point, and reduced absorption of moisture and solvents” (Glasscock et al., 2008). The aromatic component is generally tere-[TPA] or iso-[IPA] phthalic acid and the compounds are known as polyphthalamides [PPA]. The flex modulus of the polymer is dependent on Tg and, as the amorphous regions become more mobile with rising temperature the flex modulus decreases. The role of the glass reinforcement is therefore to bridge the gaps between the crystalline segments and, in order to generate the desired characteristics, modifications can be made to the glass fibre type and content and as well as the chemistry of the two parts of the polyamide. In this respect PPA(6T/DT), in which the two parts of the copolymer are TPA and a proportion of the amine segment is replaced by 2-methylpentamethylenediamine [MPMD] to improve melt flow while processing, has high flex modulus and tensile modulus, low creep, good high temperature performance in adverse conditions (Glasscock, 2008). One of the benefits from this research programme has been the ability of ElringKlinger – the German automotive supplier – to produce an oil pan as a one shot moulding which incorporates a number of integral parts [suction pipeline, fastening flanges for pressure pipelines, as well as a number of separately moulded parts from the same material] (DuPont, 2009). Future benefits could come from segment substitution by different chemical structures and attention to the structure of the glass fibre reinforcement so as to ensure enhanced flow characteristics for moulding complex shapes while maintaining the desired mechanical, thermal and chemical properties. A second programme of work, following on from Glasscock and co-workers’ study (2008) was undertaken by Gavenonis & McIlvaine (2009) which further established the suitability of nylons for automotive applications in a hostile environment. As a result it was found possible to use thermoplastics for oil pan modules in “the new 4 cylinder diesel engines from Daimler…in a serial-production car” (DuPont, 2011). The component comprises two different materials, an aluminium upper shell combined with a moulded plastic sump tray which is “sandwiched” to a second moulded part so as to maintain mechanical stability due to the constraints of the engine compartment design. The high flow characteristics of the plastic have made possible the incorporation of not only additional structural features, but the inclusion of an oil deflector and baffles to “calm the circulating oil “churned up by the crankshaft” (DuPont, 2011). The success of this design, used in the Mercedes-Benz C Class cars was recognised by the award of the SPE 2008 “Most Innovative use of Plastics” (DuPont, 2008). In this particular context it is difficult to predict likely developments over the next 20 years for the following reasons: polymer manufacturers are nowadays reluctant to produce specific ideas, but prefer to offer solutions in co-operation with processors and users. Also in this relatively narrow specialisation it is not easy to speculate on future automotive power units and their requirements. However, it is profitable to speculate on the likely prospects for the development of ultra high performance polymers as a group. FUTURE PROSPECTS As a staring point it is sensible to look again at the upper end of the performance triangle, and the candidates include polyphenylene sulphide [PPS], which has high mechanical strength, good thermal stability chemical resistance (Rosato, 2009) and is finding application in the aerospace industry (Burke, 2009). Polyimides [PI] and Polyaryletherketone [PEEK] polymers, both near the apex, are – by appropriate chemical modifications – showing promise in harsh automotive applications, as is the new family of acetals (Grande & Sherman, 2004; Quadrant, 2010; Victrex, 2011). DuPont (2007) have also developed a novel series of plastic/metal hybrids [MetaFuse™] using nanotechnology to produce lightweight materials with exceptional properties. Finally, the Martin Research Group (n.d.) have collaborated with the University of Michigan and others to study molecular engineering techniques to enhance the performance of polymer fibres. These include the incorporation of multifunctionalised monomers which increase cross-link density after processing and, in certain cases, call up new characteristics when circumstances require them. Although some 10 years old this programme highlights some exciting lines of work. Finally, although these new lines of research and emerging polymer structures can only give a snapshot of the probable outcomes of what is currently being undertake, it points the way to an exciting array of new “tailor-made” materials for use in demanding conditions. REFERENCES BASF, 2001. Family of High Modulus (HMG) Nylon Based Plastics Increases Mileage and Reduce Weight. In: The Automotive & Transportation Technology Congress & Exhibition. 2001. BASF, 2004). Oil pan made with BASF’s Ultramid nylon wins 2004 SPE award for innovation. [news release] 22 November 2004, Available at: http://www2.basf.us/corporate/112204_oilpan.htm [Accessed 4 March 2011] Burke. P., 2009. Polymers in Automotive Applications. In: Automotive and Aerospace Meeting. Napier University, Edinburgh, October 2009 Clark, J., 2004. Polyamides: [online] Available at: http://www.chemguide.co.uk/organicprops/amides/polyamides.html [Accessed 4 March 2011]. DuPont, 2007. Nanotechnology lets you ‘Design with new freedom’ [news release] 24 October 2007, Available at: http://www2.dupont.com/Plastics/en_US/News_Events/article20071024h.html [Accessed 10 March 2011]. DuPont, 2008. Two Automotive Components Using DuPont Engineering Polymers Capture Industry Innovation Honors. [online] Available at: http://www2.dupont.com/Plastics/en_US/News_Events/article20081121.html [Accessed 4 March 2011]. DuPont, 2009. ElringKlinger Increases Functionality of Oil Pan made of DuPont™Zytel® [press release] 22 May 2009, Available at: http://www.prweb.com/releases/2009/05/prweb2450184.htm [Accessed 7 March 2011]. DuPont, 2011. DuPont™Zytel® HTN high performance polyamide [press release] 2011, Available at: http://www2.dupont.com/Plastics/en_US/Products/Zytel_HTN/Zytel_HTN.html [Accessed 9 March 2011]. DuPont, 2011. First polymer oil pan module adopted for serial-production cars uses nylon resin. [online] New Materials International. Available at: http://www.newmaterials.com/Customisation?News/Plastics/Engineering_Plastics/Firs... [Accessed 7 March 2011].. Gavenonis, J. & McIlvaine, J. E., 2009. Zytel® HTN PPA and Zytel® Nylon 6,6 and Nylon 6 Resins in High Temperature and Automotive Chemical Exposure Environments. [online] DuPont Engineering Polymers. Available at: http://www2.dupont.com/Automotive/en_US/assets/downloads/HTN_Zytel _/whitepaper_07_2009.pdf [Accessed 9 March 2011]. Glasscock, D. et al., 2008. High Performance Polyamides Fulfil Demanding Requirements for Automotive Thermal Management Components. [online] DuPont Engineering Polymers. Available at: http://www2.dupont.com/Plastics/en_US/Products/Zytel_HTN/Zytel_HTN_whitepaper_R8.html [Accessed 4 March 2011]. Grande, J. A. & Sherman, L. M., 2004, K 2004 News Preview: Materials. Materials Technology, [online] Available at: http://www.ptonline.com/articles/k-2004-news-preview-materials [Accessed 9 March 2011]. Kumar, A., 2007. Aluminium Die Casting, Ezine Articles, [online] Available at: http://ezinearticles.com/?Aluminium-Die-Casting&id=632986 [Accessed 7 March 2011 Leaversuch, R.,2004. Nylon oil sump gets its start in trucks, Plastics Technology, [online]. Available at: http://www.thefreelibrary.com/_/print/PrintArticle.aspx?id=119782465 [Accessed 6 March 2011]. Martin Research Group, (n.d.). Molecular Engineering of High Performance Polymer Fibers, [online] University of Michigan. Available at: http://msewww.engin.umich.edu:81/people/milty/research_previous.php [Accessed 6 March 2011]. Miller, W. S. et al., 2000. Recent Development in Aluminium Alloys for the Automotive Industry. Materials Science and Engineering, A280, pp. 37-49. Quadrant, 2010. Quadrant Launches New Ultra-High Temperature PI and PEEK Materials for Machined Parts [press release] 14 July 2010, Available at: http://www.pressreleasefinder.com/item.asp?id=12810 [Accessed 10 March 2011]. Rosato, D., 2009. Ultra Performance Plastic Applications Heat Up, Special Chem – Omnexus, [online] Available at: http://wwwomnexus.com/resources/editorials.aspx?id=23737 [Accessed 10 March 2011]. Victrex, 2011. Polyaryletherketone PEEK™ Polymer For The Automotive Industry, [online]. Available at: http://www.hitechpolymersindia.com/peek%20auto.htm [Accessed 10 March 2011]. Read More