Aluminium International Today August 2016 Digital Edition by Quartz

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THE JOURNAL OF ALUMINIUM PRODUCTION AND PROCESSING

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Digital Edition - August 2016 Editorial Editor: Nadine Firth Tel: +44 (0) 1737 855115 nadinefirth@quartzltd.com

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Processing & Finishing Welcome to this special digital issue of Aluminium International Today, which focuses on the processing and finishing side of the aluminium industry. While the magazine tends to look at the manufacturing of aluminium and new technologies in this area, with the downstream sector experiencing more growth and the demand for aluminium increasing, we decided to take a closer look at innovations in the processing and finishing sector. Aluminium is a strong and durable metal with a natural ability to form a protective oxide layer when exposed to the atmosphere. The structural integrity is not impaired by atmospheric attack. Where the preservation of the metalâ&#x20AC;&#x2122;s surface appearance is desirable, or where a colour finish is required, aluminium can be treated with a variety of finishes including mechanical and chemical finishes, plating, anodising and organic coating. The most widely used processes are anodising and painting (organic coating). This issue features a host of different articles around this subject, with a look at trends and technology solutions (page 4), anodised aluminium (page 12), value-added aluminium products (page 14), and there are also two separate articles, which highlight the future of aluminium powder coatings (pages 20 & 23). I hope you enjoy this issue and if youâ&#x20AC;&#x2122;d like to contribute a processing or finishing article to a future issue of Aluminium International Today, I would love to hear from you. Nadine Firth Editor, Aluminium International Today

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Trends and technology solutions for aluminium processing By Mirco Pavoni, Morgan Advanced Materials

As the second largest metals market in the world, the aluminium sector currently has a total value of around £45 billion. Demand for aluminium continues to grow, not least in the automotive sector, wherever stricter regulation on emissions is behind a continued drive to reduce weight. Meanwhile, the rising prices of potential alternatives such as zinc and copper continue to make aluminium an attractive option for specifiers across a broad spectrum of sectors. Aluminium prices currently remain low due to oversupply and stockpiling, although modest output cuts have seen prices start to rise slightly in recent times. Global demand estimates are for roughly 40 million tons of aluminium production by 2025 – meaning 230 million additional tons of bauxite must be Digital Edition - August 2016

extracted and processed. Analysts predict that the increased demand will mainly be fuelled by emerging economies such as India and China. Production by the end of 2016 is expected to be 59 million tonnes with consumption slightly higher, making modest inroads into stockpiles. However, prices are likely to remain depressed, perhaps even as low as US$1,400, though they may rise towards the end of the year. Global aluminium production in the first seven months of 2015 averaged just over 158,000 tonnes per day (tpd) compared with 143,300 tpd during the same period in 2014, according to the International Aluminium Institute (IAI). However, Chinese production fell to 87,871 tpd from 91,867 tpd in June. A long-term drop in Chinese output would be the key to creating the type of supply

deficit which would have a real impact on the stock burden. Demand is likely to remain robust as it is still one of the metals with the most rapidly growing demand profiles. Market summary by region Currently accounting for 8% of global aluminium production, the use of aluminium in India is dominated by the country’s automotive sector, with recycling also growing very rapidly. What the rapid growth in the automotive sector has created is an increased focus on quality, particularly in the area of castings, alongside a need to minimise costs by reducing total cost of ownership. The world’s largest single market, China produces 43% of global aluminium yet remains a net importer, consuming 44% of all aluminium used worldwide despite Aluminium International Today

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not being a market-driven economy. Rapid growth in the Chinese economy led to considerable overcapacity and the construction of many new smelting facilities, some of which have now been agglomerated. This has been accompanied by a drive by the Chinese government to do away with the less economical and higher-polluting facilities. China’s automotive market has grown rapidly but this growth has slowed somewhat in recent years. Prices have suffered to a degree, partly due to overcapacity and excess domestic stock levels, but recovery is under way, bringing some smelters back on-line. An increasingly important area of the Chinese market is the production of high-purity aluminium for the electronics industry. While growth in this area has slowed slightly, demand is strong for products and technologies able to contribute to optimised purity. Energy is also an increasingly important driver, and demand is growing for consumable products able to contribute to reduced usage. China’s exports of unwrought aluminium and products have fallen, partly due to lower premiums and outright prices. If Chinese exports do not rise, the world outside China may find itself in a deficit, which will help reduce stockpiles. But if prices rally because of lower exports from China, its exports are likely to pick up again. Europe, the Middle East and Africa (EMEA) probably represents the most stable of all of the current main aluminium markets. One of the main developments here is the growing co-location of facilities for primary and secondary processing, to reduce transport and storage costs while benefiting from economies of scale. Perhaps more than anywhere else, quality is the key driver, in both purity of the casting in terms of its metal content and also in ensuring that unwanted gas is removed from the process. The drive for quality applies not just to the secondary aluminium sector but to primary processes too, where processors are exploring the benefits of achieving greater quality at first melt stage. The desire to reduce energy usage is not quite so pronounced in the Americas as in other regions due to the more prevalent use of gas-powered heating with gas generated from fracking. The market is strengthening rapidly, not least in the secondary aluminium sector, where the desire for quality and longer-lasting consumables to optimise productivity is behind many of the innovations being brought to the market by the major players. Aluminium International Today

Across the world, as is the case across the majority of industry sectors, the goal is to reduce total cost of ownership of production consumables. And while the focus on end product quality has usually been the preserve of the secondary aluminium processors, primary aluminium processors are also increasingly seeking to gain competitive advantage through optimised production quality. Suppliers of consumables are realising that their products must be approved by OEMs, generating increased co-operation with machinery manufacturers at the component design stage. Price always remains a key driver, with falling prices having made some smelters uncompetitive. A further effect of the continued cost pressures is on the receptiveness to change within the sector. Traditionally, very conservative and loyal to tried and tested techniques, products and processes, there is now a far greater openness to the use of alternatives in the areas of consumables, especially if these

products can last longer – increasing maintenance intervals and lowering total cost of ownership – and reduce energy usage. This last point is key in the light of rapidly rising energy costs and more stringent emissions regulation across almost the entire globe, with the possible exception of North America. In the automotive sector, the goal of reducing vehicle weight remains at the heart of component development and design, with aluminium still representing an attractive option in terms of total cost of ownership compared with most other lightweight alternatives. Ultimately current consumable innovation and supply is driven by the need to transfer energy better and to optimise finished product quality.

Belly bands

Furnace insulation

Optimising furnace insulation Given the high energy usage of aluminium furnaces and the need to maintain consistent temperatures to optimise

Ramp

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quality, any action which can be taken to reduce energy loss during the melting process is to be welcomed. Alongside this sits the requirement to meet increasingly stringent local and global safety regulation in the area of insulation materials. For many years, refractory ceramic fibreboard was the industry standard but concerns about its carcinogenic properties – meaning it is being outlawed completely in some regions – led to the development of the first low biopersistent fibre-based alternatives. These were originally launched to the market in the late 1990s, and recent innovations have delivered higher melting points and improved insulation to meet ever more demanding process requirements. Well-suited to the aluminium industry because of their ability to withstand temperatures of up to 1,200°C (2192ºF), these products are available in both blanket and board forms, making them suitable for applications in anode bake ovens, casthouses and potlines, and boast key properties such as low shrinkage – less than 1% at 700°C (1292°F) - and compression. A suitable solution can be developed based on individual application requirements such as operating

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Degassing rotor

temperature; duration of exposure; compression; environment; installation method; single or multiple use; amount of handling; and airborne fibre exposure. Recent tests carried out at the most common operating temperatures for furnace back-up board – between 600ºC (1112ºF) and 800ºC (1472ºF) – revealed that in the key area of thermal conductivity, the latest low biopersistent fibre-based board outperformed calcium

silicate alternatives by an average of 20% at 600ºC (1112ºF) and 15% at 800ºC (1472ºF). Block products are also available for use as insulation layers in aluminium reduction cells where they offer low thermal conductivity – no higher than 0.16W/m.K at a mean temperature of 900°C (1652°F), high dimensional stability and hot compressive strength, and high cryolite resistance. Thickness shrinkage reaches a maximum of 2.8% at 1,100°C after 24 hours’ soaking, with linear shrinkage under the same conditions no higher than 1.8%. The latest low biopersistent fibre systems also available in paper, felt, modules and custom shapes. Specialised materials are even available for caster tips while furnace cones, seals, gaskets, thermal covers and flexible launders are also on offer. Lining developments In the area of melt-hold furnace lining, continued investment in the optimisation of monolithic materials is delivering enhanced productivity and quality. These furnaces present a variety of challenges as each area of the furnace has varied requirements in terms of factors such as temperature, metal contact, flux contact and thermal shock, meaning suppliers must offer a variety of products with differing performance attributes. Products used on ramps, for example, must offer strong resistance to abrasion and thermal shock, as well as to aluminium and alkalis. Some of the latest products boast abrasion loss as low as 2.8cm³ at 815°C (1499°F), significantly lower than that of competing products. Their pickup of at 0.011% at 1,000°C (1832°F) over 100 hours is also more than 10 times lower than that of the nearest competing product. It is a similar story on belly bands, where the highly aggressive metal-to-air interface makes resistance to salts and alloys crucial, as well as resistance to abrasion, aluminium and thermal shock. The lower walls, superstructure, door, jambs and lintels, back-up lining and burner blocks all have their own requirements too – and the issue of testing is complicated by the fact that many industry standard test conditions, based on lower temperatures and operating times, do not truly reflect how operators use their furnaces. The only real way to ensure the product is appropriate is to test it under real operating conditions in the application in question. Modern products are improving all the time and the right combination is not just easily achievable but integral to optimising performance and productivity while reducing energy usage. Aluminium International Today

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Supporting the journey towards enhanced quality Quality in the secondary aluminium processing sector is inextricably linked to purity, especially in high-specification applications in sectors such as electronics. One of the key sources of impurity and physical imperfections – and therefore strength and performance issues - in cast aluminium components is the presence of gas, in particular dissolved hydrogen. This makes effective degassing technologies vital to production. However, their role in removing gas from the process area must be married to a long service life and an inertness to the presence of molten aluminium, as any reaction with the aluminium will itself cause impurities and potentially the loss of the cast product when it is machined. The latest degassing rotor technology has been developed in silicon carbide, delivering a high-performance and costeffective alternative to the graphite material traditionally used for this task. Graphite has previously been the most widely used material for degassing rotors but is subject to high replacement costs and frequent changeovers. Silicon carbide boasts superior wear resistance and anti-oxidation qualities when compared with graphite, meaning the new rotors can last several times as long as their graphite counterparts - one test revealed a usable life of more than 800 cycles in a heavy fluxing application, compared with an average of 300 for comparable graphite products - and are made from an isostatically pressed, singlepiece design. The rotor head has been optimised to reduce bubble size and deliver optimum gas dispersal through an innovative sixvane design. In testing, the new rotors have shown significantly lower oxidation levels compared with graphite products, whose degassing performance deteriorated as head geometry became distorted, while melt densities using the silicon carbide rotors were notably higher over time than with graphite products. Degassing technology is also widely adopted in the primary aluminium sector, with the use of compact in-line degassing rotors to process molten aluminium via rotating nozzles directly in the casting trough between the furnace and the casting pit. These products are contributing to improvements in overall metal quality, productivity, and safety, as well as reducing operation and maintenance costs by up to 60%. In particular, the need for high cost heating elements and thermocouples is removed, while there is no need to remelt aluminium or to maintain molten aluminium between casts in the degassing chamber. Aluminium International Today

Coating technology Another potential source of contamination in aluminium casting is the crucible in which the aluminium is melted. The high operating temperatures can cause fragments from crucibles, especially older products which have already seen lengthy service, to break off or melt into the molten aluminium, impacting significantly on purity and therefore on casting quality down the line – which may not be discovered until it is too late. The composition of the crucible itself can also be a cause of pollution. Where crucibles are ‘run to failure’ or changed at timed intervals rather than on the basis of actual wear, these effects can be significant and highly deleterious. To combat these issues, a variety of specialist coatings have been developed for all types of crucibles with different performance attributes depending on usage temperatures and desired performance. Coatings made from Al2O3, for example, play a key role in reducing dross adhesion and limiting metal contamination at temperatures of up to 1,600°C (2912°F). Other Al2O3 formulations deliver the same performance in very high purity applications. Where alloys using many fluxes are being processed, special glaze formulations can

be applied to reduce flux attack on the crucible material. These coating types are all wellestablished but are now being joined by a new technology which pushes performance boundaries even further. Boron nitride coatings can contribute towards superior dross adhesion reduction and limit contamination in very high purity applications (e.g. 5N and 6N Al) and can withstand temperatures of up to 1,000°C (1832°F). The global aluminium market is set to remain buoyant for the next few years at least due to its versatility, the variety of new applications, especially highpurity ones, and the high costs of many alternatives. Most regional markets are committed to growth and are seeking to work with consumable partners able to deliver solutions, which can help them marry productivity and quality with reduced energy usage and emissions. The harnessing of materials technology and design, and the expansion of existing technologies, will continue to create new opportunities for those suppliers also able to deliver agile and responsive service.  For further information visit: www.morganadvancedmaterials.com

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Cut-To-Length Line Southern Aluminium Finishing Co. (SAF) recently installed a Cut-To-Length (CTL) aluminium coil processing line in their SAF-West, Redding, CA plant. The heart of the line is a Herr-Voss 6 hi corrective leveler to enhance processing of nonferrous coil for surface critical sheet with the flatness important for architectural building applications. SAF’s new Cut-To-Length processing line can handle 0.024” - 0.125” thick aluminium coils up to 60” wide, ID 18” - 22” and 100 feet-per-minute. Newly renovated electronic controls for both

the leveler and the flying shear enable more precise and reliable production. An in-line slitting head and flying shear minimise processing time. The leveler’s rollers give SAF the capability to meet surface critical requirements for painted and anodised aluminium coil processing, not always available from other toll finishing providers specialising in carbon steel or other non-surface critical coils. The SAF-West CTL coil processing line supports both existing SAF manufacturing and third party

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toll-processing orders from other manufacturers in northern California. It also adds to SAF-West’s 60” Blanking Line production capabilities. SAF now offers Cut-To-Length aluminium coil processing from SAFWest and SAF-GA facilities. Combined with an expansive aluminium coil, sheet and extrusion inventory, this equipment enables SAF to reduce delivery times nation-wide for blanks and special lengths, while providing customers with improved aluminium sheet flatness and quality. 

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New perspectives for aluminium strip production Exact knowledge of the surface roughness and the oil layer provides pressing plants in the automotive industry with enormous potential in terms of reducing their waste and enhancing process reliability before continuing to process aluminium strip or plate material.

Surface roughness of aluminium strip material Aluminium body panels and sheet steel material obtain their fine surface structure during the last cold rolling stage by means of specific surface texturing with rollers that are textured accordingly. Aluminium sheet panels are commercially available today in three surface finishes, namely mill finish (MF), Electro Discharge Texturing (EDT) and dull finish (DF). EDT finely structured sheet materials are primarily used in Europe for frame and body construction (Hartfield-Wunsch & andere, 2011). EDT surfaces exhibit significantly better sliding properties compared to those surfaces that are produced using ground rollers. The depressions that are uniformly distributed over the surface assume the function of lubrication pockets. These then absorb the lubricant and apply it onto the metallic contact areas under pressure and simultaneous movement caused by the rollers. This enables a tribological state to be achieved between fluid and mixed friction, thereby significantly reducing the frictional coefficients. Formability is significantly improved as a result. In addition, frictional damage to the surface of the panels is also prevented during transport (Birkert, Haage, & Straub, 2013). Exact knowledge of the surface roughness over the entire length Aluminium International Today

and width of the strip is therefore a key factor for an optimum forming process. Oil layer for aluminium strip material The oil layer measurement has similar specific requirements. In general, the organic coating of aluminium sheet material makes it a very good lubricant carrier. This results in enhanced frictional and abrasion conditions during the forming process in comparison to thin sheet material that has only been galvanised. Direct contact between the metal surface and tool material (roller) is prevented by the organic matrix (zinc is prone to cold weld with the material). The formability of the sheet material can be fully exploited through additional oiling. When deep-drawing, the working area in which a pressed part can be deep-drawn flawlessly (i.e. without the emergence of folds or cracks), is significantly enhanced compared to zinc surfaces (Meuthen & Jandel, 2008). Surface oiling in a rolling mill The electrostatic application of oil in the rolling mill for automotive sheet material has constantly evolved over the past two decades. Whereas previous processes initially only involved the use of anticorrosive oils, which necessitated the application of additional lubricants in the pressing plant, significant progress

has been made with the introduction of prelubes. Prelubes are still anti-corrosive oils, but they also have additional additives that enable them to act as forming oils for the automotive pressing plant. The use of prelubes has enabled the oiling process to be relocated, to a large extent, from the pressing plant to the rolling mill (Zimmermann, 2001). Prelubes are equipped with a type of anti-flow system. However, in practice, extended storage or transport leads to a redistribution of the oil from the strip centre to the strip edge due to physical conditions. The degree of crowning over the strip width, which is caused during the production process, causes the pressure at the centre of the strip to be higher than that near the strip edge. Crowning of the strip cannot be fully prevented during the rolling process, otherwise a clean guidance of the strip would no longer be possible. The previously described redistribution of oil is noticeable as a result of a lack of lubrication in certain areas, originating from the strip centre, which can lead to manufacturing problems for critical components constructed from high strength material. This has been corrected in pressing plants initially through the use of wash oils (on the surface) and forming oils, as applying additional doses of lubrication (so-called spot lubricants). This, of course, has resulted in increased Digital Edition - August 2016

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production costs. A solution to this problem was to simply increase the melting range of the prelube to better control the redistribution of oil in the coil. At the request of the automotive industry, the oil producers therefore developed a so-called hot melt, which is suitable for both steel and aluminium. With a melting range of approximately 40Â°C, a drylube/hot melt can no longer be redistributed. Despite the pressure conditions occurring in the coil, the oil that is applied in the rolling mill is also maintained during storage and transport. Since the 2000s, hot melts have ultimately become established as the standard for most OEMs in the aluminium sector, while the use of prelubes remains the norm in the steel industry. The trend today is towards higher strength material with thinner oil layers, which, overall, means enhanced requirements for the pressing process in terms of accuracy. Due to the close relationship between the oil layer and material roughness described above, as well as the significant influence they have on the forming process, e.g. for the automobile manufacturer, accurate monitoring and control of both factors during production of the strip will provide the aluminium manufacturer with an important competitive advantage. The standard methods that are used for measuring surface roughness and the oil layer during the production of aluminium strip material are currently

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based on the use of handheld devices. Due to the low statistical significance of the individual measurement (point measurement) and the human factor, the accuracy of this approach is extremely limited and prone to errors. In addition, direct intervention in the production process (e.g. adjustment of the skin pass level) by employing manual methods or downstream laboratory measurements is not possible. As the relationship between strip roughness and the amount of oil applied, particularly with regard to prelubes, is crucial for the redistribution properties of the strip, the online measurement can also be used here for controlled intervention. If the surface roughness cannot maintain the applied quantity of oil, this will inevitably result in migration towards the strip edge. These problems and limitations can be overcome with the introduction of the EMG SORM 3plus and EMG SOLIDÂŽ online measuring systems, which are also suitable for the aluminium production process.

Roughness measurement with EMG SORM 3plus EMG SORM 3plus is a laser-based online roughness measuring system, which delivers online roughness values in a quasicontinuous manner at production speeds of up to 2400m/min (e.g. skin pass mills). The SORM 3plus system initially measures the micro profile of the surface using an optical scanning method (infrared laser

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scattered light measurement) over a length of up to 300 mm per measuring point. This surface profile can be compared to the profile, which is detected by a tactile stylus instrument. The measured profile is then used as a base to calculate the corresponding roughness parameters (Ra, RPc, Rz, etc.) according to the applicable standards (DIN / ISO / SEP). The measuring range for Ra lies between 0.1...3.0 μm. Peak values of up to 120 can be measured easily. The measuring head used by the system (see figure a) is mounted on a traversing device and is usually moved in a zigzag motion at a maximum distance of 50mm above the strip. As the measuring distance must remain virtually constant (± 0.1mm) when recording a measured value, this is typically installed on a deflection or idler roller. Roughness measurements are produced in this arrangement over the entire strip length, e.g. in three tracks (driving side, centre, operating side), thereby resulting in a "roughness map" of the strip that has just been produced. Based on this, the operator is able to instantly recognise any deviations from the required roughness values. Even long-term trends, such as the slow decrease of roughness values due to roller wear, are thereby visible in the rolling process. The surface roughness values determined during the incoming inspection can be used in the pressing plant to optimally adapt the deep-drawing process to any special conditions of the semi-finished material. Oil layer measurement with EMG SOLID® The EMG SOLID® system, which is based on infrared spectroscopy and used for continuous online measurement of the oil layer, is suitable for use on uncoated and pre-treated aluminium strip material and can be used for a wide variety of lubricants (mineral oils, thixotropic mineral oils, prelubes, dry-film lubricants/dry lubes/hot melts, etc.). The actual measuring principle implemented by EMG SOLID® is based on the Lambert-Beer law. According to this law, the attenuation of the radiation's intensity as it passes through a medium with an absorbent substance (in this case the applied oil layer) depends on the concentration of the substance and its layer thickness. In the arrangement employed by the EMG SOLID® system, two halogen lamps (see figure: b; measuring head) emit infrared radiation onto the surface of the material. A portion of the light is reflected from the illuminated and oiled strip surface and then registered via an infrared spectrometer, which is arranged Aluminium International Today

perpendicular to the strip level between the two halogen lamps (measuring distance: 120mm). The light beams penetrate the oil layer twice on their way. The intensities of specific wavelengths of the light spectrum are attenuated by the oil layer in this setup. The thickness of the oil layer is then ascertained from the spectroscopic analysis of the backscattered light. The traversing measuring head uses a measuring frequency of 60 Hz to determine the surface weight of the oil layer in g/m2 within a measuring range of 0.1 - 6 g/m² (measurements are also possible from 0.05 g/m² with special calibration). The system can be used for all metallic and non-metallic surfaces (with the exception of reflective surfaces); this includes, for example, steel/cold-rolled strip (hot-dip galvanised, electrogalvanised, phosphated, aluminised, ZnMg surfaces, galvannealed, etc.), as well as aluminium strip material (uncoated, pre-treated). a) and b) glimpse into the SORM 3plus measuring heads and SOLID®, c) distribution of the oil layer over the width/ length of the strip Application in a rolling mill and pressing plant In addition to providing online measurement data and enabling the operator to intervene immediately in the process to prevent variations in quality and complaints, both systems also provide valuable historical data that can be used for trend analysis, statistical process optimization and the verification of process models. The systems are electromechanically optimised for use in a rolling mill and pressing plant as far as possible, thereby ensuring they can even be installed in confined spaces. Thanks to the intelligently structured storage and visualisation of measured data, the user is provided with an overview of the strip or the metal sheet from a single source. In addition, the combined use of the systems enables an immediate decision to be made in the pressing plant regarding subsequent processing steps (e.g. automatic ejection. It is possible to respond specifically to material, surface and oiling fluctuations. In addition, for example, by labelling the respective metal sheet via marking systems and assigning various measured values to the markings, the pressing parameters can be modified, an additional application of oil could be initiated or the additional use of wash oil can be triggered. Furthermore, long-term trends exhibited by the measured values and manufacturerspecific characteristics of the material and oiling properties can be followed closely in

order to optimise the forming process and enhance process reliability. By combining the systems, the aluminium manufacturer is also able to generate data consistently throughout the process chain - at least with regard to surface roughness - thereby enabling the production of individual plate material to be replicated exactly in the downstream processes. In terms of the oil layer, the aluminium manufacturer is able to demonstrate that their product was oiled with the necessary level of quality when delivered - an important supporting argument when disputing any complaints. The data cannot only be used for subsequent error analysis, but it can also be used in the future for targeted control of presses and post oiling systems in the pressing plant. This is, at the very least, potential that can be derived from the industry-wide activities conducted in the context of the Industry 4.0 paradigm. As a rule today, however, an exact assignment of quality values, with the available solutions for monitoring material over several processing stages and at various presuppliers, makes little sense economically. At present, it's only the combination of online systems for roughness measurement and oil layer determination in an aluminium rolling mill and pressing plant that promises the desired level of reliability in production, as well as scrap minimisation (Irle, Aha, & Zimmermann, 2016). 

Sources: Birkert, A., Haage, S., & Straub, M. (2013). Umformtechnische Herstellung komplexer Karosserieteile: Auslegung von Ziehanlagen. Springer. Hartfield-Wunsch, S., & andere. (2011). The Effect of Surface Finish on Aluminum Sheet Friction Behavior. SAE Int. J. Mater. Manuf. 4(1):818-825, 2011, doi:10.4271/2011-010534. Irle, M., Aha, B., & Zimmermann, R. (2016). EMG - Online-Qualitätssicherung für den Abpressprozess:Festigkeit, Rauheit und Ölauflage in Kombination. EFB Kolloquium 2016. Meuthen, B., & Jandel, A.-S. (2008). Coil Coating: Bandbeschichtung: Verfahren, Produkte und Märkte. Springer Verlag. Zimmermann, R. (2001). Gesamtkonzept „schmierstoffarme Blechumformung“ Teil 3. ZG-News. Digital Edition - August 2016

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Anodised aluminium as a catalyst support By Eoghan McAlpine, Innoval Technology

As a technical consultancy itâ&#x20AC;&#x2122;s really important that we keep up to date with the latest developments in light metals. One of the ways we do this is by leading and participating in pre-competitive R&D projects. Most of the projects we have been involved with over the last 10 years have had either an automotive focus, or have been to do with the exploitation of the unique properties of anodised aluminium films. This article describes some of the work we did as part of the Integration of Nanoreactor and multisite CAtalysis for a Sustainable chemical production (INCAS) project. The INCAS project involved the exploration and development of anodised aluminium substrates as a potential catalyst support in downstream industrial applications.

Free-standing membranes Initially, the project focussed on the development of a freestanding anodised aluminium membrane film. This is a 60Âľm thick alumina-based material produced by electrolytic processing. It has a high density of flow-through channels (Fig 1). While we successfully produced these materials, our project partners deposited or coupled Palladium-based nanoparticle catalysts within the pores of the membrane (Fig 2). They then tested their catalytic performance characteristics. In a number of cases the anodised aluminium substrate had distinct performance advantages. However, in some instances, chemical and mechanical instability issues relating to the membrane material had to be addressed. Consequently there were a number of anodic material modifications,

Fig 1. Top surface SEM view of anodic membrane with flow-through channels

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system reconfigurations and alternative developments. In the case of material modifications, thermal processing significantly enhanced the chemical stability of the anodic membrane material. This resulted in the formation of more chemically resistant phases. Furthermore, system reconfigurations enhanced the mechanical stability by producing tubular anodic membranes (Fig 3a) and incorporating them within protective steel mesh tubes (Fig 3b). However, despite these approaches, underlying concerns over the freestanding membrane stability continued to exist. This led to two completely alternative developments from that originally envisaged. These were the anodising of aluminium foam material (Fig 4), and the polymer templating of an anodic film structure to

Fig 2. TEM of a slice through one pore of Pd-treated membrane, with Pd seen as fine black (~2nm) nano-particles

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produce a sheet-like polymer substrate with a high surface area.

Fig 3(a). (below) Tubular anodic membrane

Anodised aluminium foams A European Roadmap study on heterogeneous catalysis for process intensification identified the approach of using metal foams. Consequently, we developed suitable anodic film structures on mechanically stable aluminium foam. The project partners successfully impregnated the anodic films with catalyst nano-particles and assessed their performance. They found that, from a technical point of view, such a solution to mechanical and chemical stability concerns had clear merits. Unfortunately, wider economic considerations by downstream partners resulted in the postponement of future development work in, for example, industrial catalysis. However, several niche applications are being considered which were beyond the scope and time frame of the project. Polymer replication Polymer replication involves ‘flooding’ the pores of the anodic membrane with a polymer. As a result, the topography of the membrane is perfectly replicated in the polymer. Our project partners considered this to be a completely novel and alternative approach. They found the idea of continuously producing large scale coils of replicated polymer films with controlled microstructures for catalyst deposition (or incorporation) especially promising. In addition, this polymer replication approach from anodised substrates, has the added potential of being mechanically flexible. As such, it could be reconfigured in several ways e.g. spiral wound modules which could be retrofitted into existing plant systems. Although promising in principle, this latter approach requires more extensive development and this was beyond the scope of the project. Project conclusions The project determined that the use of the free-standing anodic film membranes as originally envisaged was not considered fit for the specific project application. However, with the developments undertaken and alternatives explored by Innoval, niche applications and alternative approaches employing anodising technology clearly had technical merit and longer-term development potential. Also, it should be noted that the scientific and technical literature for much broader and functional applications of anodised anodic films continues to be Aluminium International Today

Fig 3(b). (right) Protective steel mesh tube

Fig 4. Aluminium metal foam

highly active, and has been for over a decade. Finally, I would like to express thanks to the EU for project funding and to my European project partners for their collaboration: CSIC-ITQ (Spain); Sasol (UK); TU/e (Netherlands); Hybrid Catalysis (Netherlands); TUM (Germany); Bayer Technical Services (Germany); Shell (Netherlands); INSTM (Italy); Repsol (Spain); and ERIC (Italy).

Conventional anodising As well as specialised development work such as this, we can support conventional anodising operations. For example, we can carry out process audits and training courses.  Please get in touch if you’d like to know more: www.innovaltec.com/contact Digital Edition - August 2016

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Adding value

The new machining building

Sapa is challenging customers in France to bring their ideas to the table.

A decade of new investments in valueadding services in France is part of Sapa’s plan to make life easier and business better for aluminium solutions customers located all over the country. It implies greater involvement from Sapa in the A to Z of new projects. Local and regional authorities cut the ribbon at Sapa’s new 2,400 square-meter machining workshop in Le Garric, north of Albi, formally opening the facility on May 20. It was a big day in several ways, the most important being that the investment in value-adding services extended the company’s ability to meet the growing needs of French customers. The new workshop is providing additional production capacity for Sapa’s Albi extrusion plant in terms of increased machining capabilities. It gives the plant a better opportunity to develop and manufacture more complex aluminium Digital Edition - August 2016

parts and solutions for current and future customers. “Our key skills lie in providing aluminium solutions and state-of-the-art machining,” says Gilles Le Bouquin, managing director of the company’s general extrusion company in France, Sapa Extrusion France. “The investment helps us meet the growing needs in the marketplace.” Sapa spent EUR 2 million on the industrial facility, including new equipment, and created an additional 27 jobs to the company’s workforce in France, which numbers some 1,000 employees.

The Le Garric site offers the following services:  Aluminium extrusion  Surface treatment (lacquering)  Machining  Logistics  Quality control laboratory  Technical center Project support was provided by Albibased Themelia, a company managing real estate projects for communities, associations and private corporations for over 30 years. Aluminium International Today

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Gilles Le Bouquin, Manager Sapa Extrusion France

Xavier Delevacque, Sapa industrial director showing Thierry Carcenac Senator, president of the Tarn departement and president of Themelia, our know-how and expertise.

String of improvements The opening of the Le Garric workshop – part of the Albi plant structure – was also important because it was the last in a string of improvements that Sapa has made in recent years in its extrusion system in France, which includes four aluminium extrusion and fabrication plants. The opening in Le Garric completed the process of change. Advances in technology and customer requirements demand that manufacturers continuously reassess their capabilities, and because Sapa aims to be best-in-class Aluminium International Today

in all its markets, the upgrades in France were essential. Sapa as a brand does not have a long tradition in France, but its plants certainly do. The company has four general extrusion plants in France – Albi, Châteauroux, Lucé, Puget sur Argens – in different parts of the country. These are plants that have been operating in their communities for many years and which are well-established locally. In fact, one of the sites, the Lucé plant, has been supplying aluminium solutions to French customers for nearly a century.

It was established in 1926 as Aluminium Meridional. “Investing in the value-adding activities that our customers want today and which we believe will need in the future, at each of our four locations, this is part of our national strategy,” says Le Bouquin. “Customers want suppliers who can deliver everything from the extrusion to surface treatment, fabricating, assembling, logistics. Our goal is to provide every service to our customers from any of our sites.” The investments have lifted the capabilities of each of the sites, which are now able to deliver much more in the way of value-adding products and services. Each is capable of supplying the complex solutions that more customers are requiring. This also means a greater shift away from the simpler and more commodity-type work that was previously Digital Edition - August 2016

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Top: Plant Puget sur Argens offices Right: Machining operations 1/2 deburring 3/ drilling / cutting

the bread and butter of the general extrusion industry. “The biggest change is the knowledge aspect: Customers now know a lot more about aluminium and aluminium extrusions, especially the middle-sized companies. The bigger companies have always had more know-how, but the midlevel companies are catching up,” says Le Bouquin. “This is changing the way we need to run our business, because they are bringing to the table ideas that are more challenging than before. And they need support with them.” Sapa has long worked toward lifting the level of customer competence through its Sapa Profile Academy, which is the main training program in the field of aluminium extrusions. The goal with the two-day workshops is to provide customers with a deeper understanding of aluminium principles, tooling design, fabrication, current applications and new technologies. The company normally hosts around 100 Academies and workshops around the world every year, drawing more than 1,600 participants, mainly in Europe and the United States, but also in Asia and South America. In total, some 10,000 people have attended since the first workshop in 1996. Digital Edition - August 2016

“Our aim with the Academies is to increase knowledge levels and inspire because we have the technicians who can get the job done. The global competence we have in Sapa, we also bring here to France,” says marketing manager Morgane Leroy. “And when customers know more, they see more, more opportunity.” Largest global team Aluminium, the 13th element on the periodic table, is sometimes referred to as the miracle metal. It is light, highly resistant to corrosion, easily formed, nontoxic, durable and recyclable. Sapa is the largest global supplier of extruded aluminium solutions, and also has the largest team of engineers in the field. The company’s 1,000 engineers, located all around the world, work together on aluminium alloys and process development, heat transfer, transportation, and building and construction. The company’s aim is to bring its research and application development everywhere it does business. As such, even the smallest customers can benefit from this engineering team, not only the largest carmakers in the world, for example. Its main research hubs are located in Sweden and in the United States, but the company also has pockets of R&D

activity in a handful of other countries, including France. Sapa also works with a number of independent institutions around the world, including the University of Oxford and the Massachusetts Institute of Technology. Some of the company’s projects include:  New crash management alloys. As leading European car manufacturers saw the urgent need for down-weighting passenger cars, Sapa and its corporate research center developed a high-strength crash alloy in record time.  Aluminium in HVAC&R. By transferring its experience and knowledge from the automotive industry, Sapa’s tech center is providing test and technical argumentation proving that aluminium is the preferred metal – replacing copper – for stationary heating, ventilation, air conditioning and refrigeration applications.  Developing a bridge to the future. As a partner in a research project to find more environmentally friendly and costefficient solutions for deep and long-span fjord crossings, Sapa is applying offshore technology to create a floating bridge with a submerged floating tunnel at midspan.  Lighter, exhaust-free vehicles. Tesla is a front-runner in the light-weighting and electrification of cars. Together with Tesla, Aluminium International Today

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Clockwise from top: New machining website, Plant Puget sur Argens - extrusion, CN sawing, long lengths machining capabilities

Sapa has developed many of the extruded aluminium solutions for the Model S and X , from toe boards and side sills to side impact rails and enclosure structures.  A powerhouse in the far north. With its partners, Sapa has renovated an Oslo office building that will generate more renewable energy over its lifetime than it takes to produce the building materials, construct, operate and dispose the building. Sapa’s window and façade solutions contributed to fulfilling the energy balance requirements. Bringing this competence in a timely manner into the local markets and spreading the relevant knowledge across the world is a differentiator for Sapa.

receiving support from corporate R&D when needed. On average, Sapa starts a new development project every working day of the year. “We are being asked to solve challenges that are more complex than they used to be,” says Le Bouquin. “Again, this is partly due to the rising level of knowledge in the market about aluminium and extruded solutions. “Customers want suppliers with a high

Leveraging R&D Traditionally, the general extrusion business has meant local business, and aside from occasional exceptions, this is still the case today. It also reflects the way Sapa carries out its research and application development. Most of its work starts in the market, typically with a customer request. Can this be done? How can it be done better? Can it be done more cost-effectively? If local application engineers can answer the questions by identifying value for the customer, then they will start a project and go to work on the solution, also

 Sapa Extrusion France operates four aluminium extrusion plants in the country: Albi, Châteauroux, Lucé and Puget sur Argens.

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ABOUT SAPA EXTRUSION FRANCE

 The company has seven extrusion presses in all and has fabricating and surface treatment capabilities at each location.  Sapa Extrusion France employs about 1,000 people.

level of engineering competence, and who can manufacture either simple or complex solutions locally. This is why we have been upgrading our sites in France. We have had the technical competence, but not the one-stop shop capabilities. Now we feel that if we cannot meet the needs of the customer, then nobody can.” Many markets Most of the customers working with Sapa in France are companies in the building and construction and the industrial markets. But because extruded aluminium can be used favorably in so many ways, the company also delivers to customers working in other fields, such as:  Transportation  General engineering  Electrical engineering  Solar  Furniture and lighting  Ladders and access systems  Distribution and trading “Although we extrude some standard profiles, we are spending more time on projects working from A to Z by supporting the conception and suggesting solutions or alternate ideas for improving the profile, for example with fabricating or surface treatment or even assembly,” says Le Bouquin.  Digital Edition - August 2016

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The Second Severn Crossing Bridge celebrated its 20th birthday this year and while it remains a stunning example of the use of aluminium in construction, it also serves as a valid and enduring demonstration of the durability of its paint finish. The applicators of that finish were Tomburn Ltd (LBL Finishers), a business, which was also launched in that same year and has, like the bridge, prevailed and thrived through demanding climates. Thirty years earlier, in 1966, the original Severn Bridge had opened with just two traffic lanes, a cycle path and a narrow footpath. By the mid 80s the unexpectedly large volume of traffic using the bridge, particularly the high number of HGVs, resulted in a pattern of extensive maintenance and frequent lane closures. As a result, plans were put in place to build a much wider, second bridge further downstream, and in 1990 the concession to build the bridge was awarded to Severn River Crossing plc, led by John Laing plc and GTM-Enterpose. In order to reduce the effect on the traffic of lateral windloads coming from the Severn Estuary, baffle plates needed to be fitted onto the deck of the bridge. Whilst steel was ruled to be too heavy for these three metre baffle plates the engineers had reservations about switching to aluminium. They were convinced that the demanding marine climate would cause it to corrode, and it was against this backdrop that Baco Contracts and Tomburn Ltd (LBL Finishers) began their initial discussions. They were asked by Baco Contracts to devise a finish that would be suitable to withstand a period of 20 years without the need for repair on an aluminium substrate. Understandably, the location of the new bridge made this task extremely challenging. The River Severn has the second highest tidal range in the world with winds up to 129km per hour and waves up to 2.5m high and such a harsh marine climate would be a severe test for any coating treatment. Tomburn very quickly identified Syntha Pulvin as the company they wished to support them in this exciting and very difficult challenge. Whilst Tomburn and Syntha Pulvin continued to work with Baco Contracts on the coating process, the bridge started to take shape. Because of the river’s high winds and waves, prefabrication was done onshore. A large tracked vehicle, similar to the ones used to move the Apollo space shuttle at Cape Kennedy, then carried the sub-assemblies onto a barge and this was Digital Edition - August 2016

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then floated into position on the high tide. By now a powder coating solution had been agreed upon by Tomburn and Syntha Pulvin and this had been presented to Baco Aluminium. Their choice was a new, original colour to be specially manufactured by Syntha Pulvin - RAL 6019, a mint green finish for the whole of the 10 linear kilometres of aluminium. As well as Tomburn’s ongoing quality controls, numerous visits were made during the painting process by Doctor Michael Clark, a respected specialist in the field of paint, who was independently employed to ensure that all aspects of the coating process met with the required standard. A lot of time and attention was spent checking the powder coating curing process prior to the work commencing. Because of the different thicknesses of aluminium used on the bridge, it was imperative that the curing process was strictly adhered to. The bridge’s marine location meant that it was vital that any repair or remedial work was avoided, at least for the 20-year warranty. The system that Tomburn and Baco Contracts decided on was to clean and chemically pre-treat the aluminium sections with a chromate conversion coating. The uprights were then coated using a Syntha Pulvin Super Durable powder coating and then, once cured, the base of the upright was then treated using a bitumen-based paint. The windplanks were coated using the same system but these did not require any bitumen treatment to the cured product. Each windplank was almost three metres in length and there were three planks fitted between each two upright posts. Because of the volumes involved it was imperative that the process operated to the exact timetable agreed with Baco Contracts. David Hepburn, the present Chairman of Tomburn Ltd, remembers the logistical problems they faced: “The Tomburn factory could only accommodate a certain number of piece parts at a time. These were delivered on a heavy goods vehicle on a Friday – the painting process completed and wrapped for collection on the following Friday when the next load would be delivered. I’m glad to say that this operation ran like clockwork. The combined efforts of Baco Contracts, Syntha Pulvin and Tomburn all meeting their obligations enabled the whole process to complete in the originally agreed lead times”. “When the last planks had been installed

Standing the

it was the job of our then quality manager, Adrian Singleton, and a representative from Baco Contracts to fully inspect the coating on site prior to its opening. Adrian told me he thinks he checked seven miles of planking and uprights – no mean feat”. The £330m Second Severn Bridge, completed on time and on budget, was duly opened by HRH Prince Charles on 5th June 1996. At the time it was the UK’s longest river crossing and deservedly won that year’s British Construction Industry Award. The 5.128km long structure carries over 60,000 vehicles every day. Tomburn’s Chairman is proud of his company’s participation in the project: Aluminium International Today

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test of time

“The decision to place faith in the Syntha Pulvin finish was an important one which has certainly paid off. It has retained its original finish with no remedial work needed.” “It’s only now, on looking back, that I think we have fully understood the enormity of the project. Normally when paintwork leaves your factory you have little or no opportunity to see what you have helped manufacture and finish. But whenever I travel over the bridge it always fills me with pride that the work we did all those years ago still stands the test of time”. 

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As a specialist architectural powder coater, Powdertech (Corby) Ltd enjoys the privilege of working on projects where the exceptional properties of aluminium allow fabricators, architects and designers to improve and innovate, enhancing the function, form and aesthetics of public and private sector buildings for commercial, residential and mixed use. Over the past thirty years we have witnessed the growing prominence of aluminium as a building material, and the exciting developments in construction to which this metal is so well suited. Of course, aluminium has long been the metal of choice for the automotive, aerospace and rail industry and our partners at Powdertech Surface Science (Bicester) deliver expert pre-treatments and powder coatings for these sectors. It is little wonder that aluminium has become the 21st century’s building material of choice. In addition to its abundance and high level of recyclability, aluminium is extracted, processed and fabricated with high degrees of efficiency, consistency and quality. As metal finishers, our task is the very last in the aluminium supply chain, the success of our service depending upon the integrity of the supply chain that has brought the aluminium to our factory door. Professional metal finishing is a robust and well-regulated industry with internationally recognised standards and specifications. There are a number of specific standards for metal coating, the most important for aluminium being ISO12206 Coating of aluminium and aluminium alloys for architectural purposes. Other standards include ISO 1519 and ISO 1520 which, respectively, specify empirical test procedures for assessing the resistance of a coating of powder coating to cracking and/ or detachment from aluminium when subjected to bending around a conical mandrel or gradual deformation by indentation. ISO 2409 specifies a “cross cut” test method for assessing the resistance of paint/powder coatings to separation from substrates when a right-angle lattice pattern is cut into the coating, penetrating through to the substrate. Powder applicators and manufacturers of powders and pre-treatment chemicals are represented within Qualicoat, the quality label organisation formed in 1986. Qualicoat is committed to maintaining the quality of powder coating on aluminium for architectural applications. Companies from all five continents are members of this global organisation, ensuring a wide exchange of ideas between coating applicators, their suppliers and their customers. Digital Edition - August 2016

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Eurostar refurbished e300 train on the right, new e320 on left.

Powder coating the versatility

Richard Besant, Sales Director for Powdertech (Corby) Ltd, discusses the benefits of working with aluminium. Powdertech specialises in metal finishing for architectural and transport markets and was established in 1988. Richard’s Co-Director Giles Ashmead is Vice President of ALFED (Aluminium Federation, UK) and Powdertech is a member of CAB (Council for Aluminium in Building). Coating of aluminium involves a rigorous process of cleaning and pre-treatment before the powder can be applied. These systems are also well regulated. Recent legislation has meant that pre-treatment processes will be changing radically over the next 12 months. REACH legislation has given our industry the opportunity to develop chrome-free pre-treatment systems that maintain the integrity of the paint system whilst improving the environmental and re-cycling credentials of the process. There are also approval networks for the application of the powders. Many manufacturers of high performance powders ensure that metal finishers applying their products are

qualified and approved to do so. At Powdertech we are proud to be approved applicators of powders from Valspar (Syntha Pulvin), Axalta, IGP and Plascoat amongst others. Aluminium is unparalleled in the versatility of its appearance, achieved through the finishing processes - anodising and powder coating. Powder coating protects the metal from the environment and prevents corrosion. It does not detract from the ‘green’ credentials of the metal as the coatings are free of solvents and VOCS and there is no hazardous waste. Powder coating can be removed from aluminium with no detrimental effect so recyclability is not affected. Aluminium International Today

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celebrates of aluminium

Felda House, London. pre-coated ACM and powder coated folded sheet

Queen Elizabeth Park car park facade

At Powdertech (Corby) Ltd we offer a range of finishes for aluminium that add design value in differentiating the surface and suiting it to purpose, as well as offering protection to the underlying metal. These include architectural polyester powders from companies such as Akzo Nobel, Tiger, Valspar (Syntha Aluminium International Today

Pulvin & Inver), Axalta (Dupont) and IGP. We also offer PWF (Powdertech Wood Finish), Plascoat thermoplastic coating and Anomatch (a range of finishes that closely resemble architectural anodising.) Every finish has its own particular features and benefits. Thermoplastic powders have a built-in advantage in the level of

Rainscreen cladding powder coated in 7 shades, Hull

grip the surface offers, and the ‘warm to touch’ feel. There are powders with ‘antigraffiti properties’ through incorporation of hard polymers making the resulting surface especially resistant to paint, pen and markers and ‘self-cleaning’ powders with a hydrophobic surface that sheds rain water, taking dirt and grime with it. Digital Edition - August 2016

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Powder coated perforated aluminium with image revelealed

More than 2000 colours are available as standard with most colours available in matt, satin and gloss finishes. Textured, metallic, hammer and patina finishes are increasingly being used in architectural design and most manufacturers have special house colours and finishes, which can be made on request. From a metal finisher’s point of view, aluminium has some unequalled advantages amongst substrates:  Manufacturing flexibility - it is ductile and can therefore be formed into complex shapes and profiles whether extruded, folded, rolled, cast or machined. The products can be flat, curved, perforated, expanded or sandwiched with other materials.  It is lightweight, approximately one third the weight of copper or steel and therefore easier to transport and to work with.  It has an exceptional strength to weight ratio of 2.7g/cm², this is 66% lighter than steel.  It has excellent corrosion resistance and it does not become brittle at low temperatures, in fact it increases in tensile strength.  Its recyclability is not affected by powder coating.

with magnesium and is used for marine applications. By selecting the right alloy, designers can choose the most suitable characteristics for the job, such as high strength, low density, high thermal conductivity and good forming and joining properties. The creativity and innovation in the architectural aluminium fabrications we are asked to powder coat seems to increase year upon year. In the last 12 months we have worked on a diverse range of stunning projects. These have included: A perforated curved aluminium screen depicting the evolution of life for the Wellcome Genome Project Campus, Cambridge; the interior of the Eurostar

e300 fleet of refurbished intercity trains; horizontal aluminium pyramids as a car park façade at the regenerated Olympic Park (now Queen Elizabeth Park) in London and numerous other façade projects. For a metal finisher, the aluminium industry is an incredibly exciting one to be involved with. New treatments and powder coatings for aluminium are being developed continuously, expanding the versatility of this abundant, sustainable metal yet further within the building industry.  Visit: www.powdertechcorby.co.uk for more information

WPL Kia London. Expanded mesh

Within our work we come across aluminium alloys, incorporating other elements to give specific properties to the metal. Common to the construction industry is the 6000 series that alloys aluminium with magnesium and silicon making it suitable for extruding and machining. The 5000 series workhardened alloy combines aluminium Digital Edition - August 2016

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The future of powder coatings in outdoor applications:

Low solar absorption, high reflectivity By Tullio Rossini* & Russell Deane**

“Low-solar absorption”, “High Reflectivity”, “Cool coatings” are the new key words for the so-called “Architectural” segment, one of the main markets for thermosetting powder coatings, the

market which covers aluminium frames for windows and panels dedicated to facades and buildings. “Cool coatings” are able to reduce the heat generated through the solar absorption on the

coated metal parts. AkzoNobel has been developing and producing this type of powder coatings since 2009.

In traditional buildings most heat transfer was through the glass – from inside to outside on cold days, and outside to inside on hot days

Building Heat Loss

*Akzo Nobel Coatings SpA, Tavernola (CO), Italy, tullio.rossini@akzonobel.com ** Akzo Nobel Powder Coatings, Felling, UK, russell.deane@akzonobel.com Aluminium International Today

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4 methods of heat transfer

Sun

Reflectivity

Emission

Convectio Coating Transmission

Substrate

Fig 1: Diagram of the 4 factors influencing the heat of a surface

low solar absorption relates to roofs, as they are a large surface area and are at an angle that increases the strength of the sun. A white surface reflects more visible light than a black one, but it also reflects more heat – the infra-red part of the spectrum. For this reason, a white surface has the highest solar reflectance. People do not always want white roofs however, and so work has been on-going across several industries to increase solar reflectance in other colours. Measurement of solar reflectance can be expressed in % or in a value from 0-1. The state of Georgia in the USA is a pioneer in this area, instituting a “Georgia White Roof Amendment,” which requires the use of additional insulation for roofing systems whose surfaces do not have test values of 0.75 (i.e. 75%) or more for both solar reflectance and emittance. One early test of the technology was thus carried out in Georgia, on two identical school buildings (designed and built at the same time in 2002-3 by the same contractors). Both had metal roofs in the shade Hunter Green, but one was made using a cool roof coating, and the other with a standard green coating. Beneath each metal roof was vinyl-faced blanket insulation and then further insulation at the ceiling. The thermostats for each school were controlled from a district office, and were

The purpose of thermo-reflective powder coatings Most of the present norms and regulations, valid in many countries, require the preferential usage of solar panels and/or thermo-reflective systems and coatings. The building industry in general terms, and most particularly the producers and coaters of aluminium frames, windows and panels, are looking for the possibility to stabilize as much as possible the temperature levels inside the buildings. This means cost and energy efficiency and protection of the environment as the use of thermo-reflective powder coatings limits the heating and air conditioning costs, as well as the CO2 emissions. Window frames are actually the less efficient part, from the thermal point of view, of any modern building: The benefits of thermo-reflective powder coatings will increase the share in the building industry for aluminium-based panels and window frames, with respect to competitive materials and technologies.

3. Convection - heat transfer away from the surface by the action of air moving over the surface 4. Transmission – through the substrate to the other side.

Background The heat can be transmitted: a) From the glass of a window or door towards the internal part of the building b) From the window/door frame to the internal of the building c) From the window/door frame to the wall

Table 1. Improvement possible in solar reflectivity of different shades

There are four factors that affect the heat of a surface (Fig 1): 1. Solar reflectance - the percentage of the sun’s energy that is reflected by the surface 2. Thermal emittance - the ability to lose heat from the material once it has heated up. Digital Edition - August 2016

Solar reflectance RAL shade

Standard coating

Cool coating

Improvement

6008 5.9 43.8

642%

5013 7.2 34.9

385%

7011 10.8 36.3

236%

8000 20.2 49.2

144%

1014 61.9 67.6

Solar reflectance of cool black 100 90 80 70 60 %R

Also the greatest part of the heat dispersion in a traditional building happens through the windows, from inside to outside in winter period, and vice-versa during summer.

Since the thermal emittance is a function of the underlying substrate, a coating can only affect the solar reflectance. Metal has a poor thermal emittance and high transmission: a thermal break is still required on window extrusions, to ensure any heat in summer or cool in winter is not transferred indoors. This aspect affects the coating of metal, too. Much of the activity in the area of

50 40 30 20 10 0 280

500

RAL 9005 Std LSA Black

1000

2000

1500

2500

TSR of standard 9005: 4,6% TSR of LSA black: 29,4%

Fig 2. Improvement of a black coating solar reflectance by adding heat-reflective pigments.

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Effect in shade-dependend Imrpvement in solar reflectance using cool coating technology 700% 600%

% Solar reflecctance

500% 400% 300% 100% 100%

11 3 10 802

10 14 60 03 10 02 30 12

10 0 10 5 00 10 04

70 01 50 15 80 04

60 16 50 1 80 4 08 70 23

0% 1 1 6 4 3 8 4 600 500 6012 600 600 501 016 8028500 701 8

RAL shade

Fig 3. Improvement in solar reflectance using cool coating technology

28.6°C

25.3°C Standard products 21.9°C

18.6°C 15.2°C

TSR products

Panels heated with Infra Red radiation Traditional photo shows the panel colours. IR photo shows the heat of the panels

Fig 4. Some of the darker shades from AkzoNobel Collection Futura formulated with heat-reflective pigments and their correspondent infrared vision

set at the same temperature. After one year, the school with the cool metal roof had cost US$15,000 less in cooling costs. Progress has also been made on the glass used in windows. Typical glass transmits much of the visible light, but also the infra-red and ultra-violet portion. Tinted glass blocks out up to 55% of the visible spectrum, thus making rooms darker, but often still allows the infra red light through and so has no benefit in reducing the heating of the building. Modern methods use a coating on the glass to produce low-emissivity or “low-E” glass, which blocks infra-red whilst letting most visible light through. Clearly the trend for materials that keep buildings cool has now moved to other aspects of the building envelope, including the metal used on window frames and curtain walling and cladding on the external walls. Aluminium International Today

The technology to keep buildings cool The radiation of the sun that reaches the earth is divided into three parts:  Ultraviolet: UV accounts for only about 5% of the energy (however it is a major factor in the degradation of coatings)  Visible: 50% of the suns energy makes up the wavelengths that give us colour  Infrared: 45% of the sun’s energy is in the infrared region It is the infrared light that contributes to heat build-up. Coatings containing infrared-absorbing pigments will heat up faster and to a greater degree than coatings using infrared-reflecting pigments. Traditional coloured pigments tend to absorb infra-red.

A new generation of pigments are now available which significantly increase the spectral reflectance of coatings. These are already used widely in the coil coating field. It is important to note that while the use of cool coating technology can improve the spectral reflectance of coloured coatings compared to the standard versions of those colours, it does not raise them to the spectral reflectance level of white coatings. A typical white coating over a black substrate has a spectral reflectance around 70%; a black coating over a black substrate can have a reflectance as low as 4%. Using heat-reflecting pigments can improve the reflectance of a black coating by as much as seven times, as shown in Fig. 2 for tests carried out on powder coatings. The final result this depends on the initial colour (Table 1 and Fig. 3).

LSA Thermoreflect powder coatings AkzoNobel has applied the technology to minimise the solar absorption in powder coatings by introducing into the formulation a range of innovative pigments, which are able to slow-down the process of heating-up of the metalcoated surface. These pigments are able to reflect the most significant part of the radiation around Near Infra-Red (NIR), accounting to more than 50% of the total solar radiation. This implies that the final coating is able to reflect more than 45% of the total solar energy received by the piece. The formulation of many colours has been studied in such a way that the final coating, after its correct polymerisation, reflects the infra-red section of the solar spectrum, preventing both the heat transmission, and the convection. Use of heat reflecting powder coatings on coated aluminium extrusion will make a small but useful impact on the heat management of a building, contributing to the cost saving related to air conditioning and heating, and reducing CO2 emissions. AkzoNobel have formulated a number of products using this technology, both in “standard durability” and “super durability” qualities (under the name Collection Eternity, Fig. 4). They are all medium to dark shades, where the benefit is strongest, and several of them are metallic products. These products are already commercially available, and are receiving positive feedback from their target markets.  Digital Edition - August 2016

26 FINISHING

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Sapa Profiles UK helps Star Events create Football Heaven Sapa Profiles UK, part of Sapa Group - the world’s leading producer of aluminium solutions, has collaborated with Star Events to create the structure for the one-of-a-kind Hyundai FanDome, home to the innovative Football Heaven screening event for Euro 2016 at Kings Cross, London.

The FanDome screened every game of the football championship and gave fans the opportunity to enjoy the games via a world-first reactive, 360-degree, audio-visual experience. Action during the matches triggered a unique response, from goals to penalties and national anthems. It is predicted that the FanDome hosted 45,000 guests over 45 games during the championships. The covered aluminium structure stood at approximately 43 metres by 22 metres and was based on Star Events’ Orbit Flexidome® building system. Sapa Profiles extruded the aluminium for a major update using a bespoke die. Star Events utilised numerous Sapa Profiles fabrication services, including cutting, forming, slotting and drilling. Sapa Profiles has invested considerably in equipment and the latest control systems, including long length profile machining centres and double mitre saws, ensuring they offer customers a vast array of fabrication and finishing services to turn components into a finished product. Star Events approached Sapa Profiles for design advice on the new profile and to then supply it following a positive experience on Sapa’s Profile Academy and also benefitting from the company’s wealth of literature and educational material. Sapa Design Engineer, Ian Thompson worked closely with Star Events to ensure the project ran smoothly and Digital Edition - August 2016

was delivered on time to its location at Lewis Cubitt Square, Kings Cross, London. Star Events has designed and delivered stages, structures, seating and rigging for some of the world’s most high-profile events, as well as smaller community and commercial events. Using innovative designs, Star Events is able to create environments and experiences that are safe and versatile. Working with support from Sapa Profiles on this project, Star Events delivered another world-class experience. Project Manager at Star Events, Gavin Scott comments “Our experience of working with Sapa Profiles on this exciting project was great. The support and

knowledge from Sapa’s design team is outstanding and we are looking forward to working with them to continue to develop structures for other events in the future.” Myles Grennan, Marketing Manager at Sapa Profiles UK comments “Sapa Profiles prides itself on adding value for customers wherever possible. From design support to a wide range of complex fabrication services, we continue to invest our UK extrusion facilities re-enforcing our commitment to UK manufacturing.” Sapa Profiles is currently working alongside Star Events on a number of different projects.  Aluminium International Today

FINISHING 27

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How to efficiently grind your aluminium surfaces Grinding, cutting and finishing within the aluminium sector is going through constant change, with newly developed methods making the job much easier. Nigel Soulsby, director of metal finishing equipment and consumables supplier, Engineering Utilities, discusses the new techniques and products that companies could, and should, use when grinding aluminium products.

Grinding non-ferrous metals, particularly aluminium, has always been a very challenging process. However, this has recently changed with a number of new products being filtered through to the market, all of which are designed to assist manufacturers throughout the grinding, cutting and finishing procedure. When lubricating metal prior to grinding, engineers traditionally use natural and synthetic materials, such as the natural and synthetic bobbing grease, to help when conducting the process. While this technique does work, it has a number of disadvantages including the unethical nature of obtaining the product, which is essentially animal fat, and the product dispersing once the metal is ground, resulting in a difficult clean up procedure afterwards. However, with technology constantly evolving to ensure aluminium can be processed quickly, efficiently and, more importantly, safely, fewer companies are relying on animal fat as a lubricant in order to complete grinding processes. Many of these are replacing it with alternative highly advanced lubricants, which facilitate efficient grinding, cutting and finishing of aluminium and other soft metals, leaving behind minimal residues, and creating a smear and drag-free result. One of the most effective new products weâ&#x20AC;&#x2122;ve identified to assist with lubrication Aluminium International Today

during the grinding process is Kangru Alu-Fix Oil, which we distribute exclusively in the UK. Created by innovative grinding, polishing and cutting equipment manufacturer, Eisenblatter, Kangru AluFix Oil allows users to simply spray the product onto the work piece prior to grinding. When using the oil as an alternative to bobbing grease, one of the most important advantages of Kangru AluFix Oil is the prevention of smearing. Smearing occurs during grinding soft materials, such as aluminium, and causes a build-up of hot metal deposits, damaging the metalâ&#x20AC;&#x2122;s surface finish. This is a massive

issue within the industry, and one many companies are still trying to identify a solution for. To combat this, Kangru AluFix Oilâ&#x20AC;&#x2122;s innovative formulation lubricates the metal while cooling the surface, preventing smearing from taking place. In addition to smear-free finishes, the oil also increases the service life of the flap disc by up to 300%. This extended lifespan helps the user save on the amount of money spent on the product, as well as valuable man hours. The oil is perfectly complemented with Tiger Shark discs, which are also manufactured by Eisenblatter and distributed in the UK by our expert team. These flap discs are very flexible, with a Digital Edition - August 2016

28 FINISHING

high-quality special corundum compound and cooling effect for smooth and even grinding finishes, making them ideal for grinding aluminium. Furthermore, Kangru Alu-Fix Oil enables flap discs to remove material at a higher rate, while reducing the grinding temperature. This again allows businesses to save money, while ensuring a highly efficient aluminium grinding process with visibly better results. In addition to the Tiger Shark discs, we also supply customers with the ZAC grinding discs, which are another commonly used product within the aluminium grinding sector from world leading cutting disc manufacturer, Globe. Globe’s cutting discs are equipped with a patented heliciodal system, which causes less heat dissipation in the material. The disc’s low thickness also allows it to half the cutting rate when compared to standard wheels, and the advanced technology generates a spiral pattern on both sides of the disc, resulting in an alteration of low-and-pressure-relief surfaces. This heliciodal system ensures less heat is produced in the material

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and reduces low cutting friction, while improving cutting speed, rigidity and has a high cutting capacity, coupled to an extreme durability. As well as using the highest quality products, it’s also pivotal that the correct safety measures are undertaken when grinding aluminium to prevent potentially hazardous situations. It’s common knowledge within the industry that aluminium dust is highly explosive, and can very easily spontaneously combust. Because of this, we highly recommend companies use the best possible vacuum equipment to ensure the dust is sufficiently disposed of, fulfilling strict health and safety obligations. We’ve seen an increase in queries regarding dust extractor vacuums from aluminium manufacturers looking for ways to prevent the potentially dangerous repercussions when grinding aluminium. One product of particular interest in the sector is Dynabrade’s Raptor Vac – an electrical portable vacuum system which aggressively captures workplace dust and debris to provide a productive and safe working environment.

Adhering to the new and exacting standards of EU Working Dust Regulations, Raptor vacuums are certified for a number of EU standards, including M-class, ATEX, EX (explosive proof) Zone 21 and Zone 22. The product’s efficiency ensures production rates also greatly improve, as any dust particles caught between the tool and the work surface are sufficiently extracted, allowing the grit of the abrasive to cut into the work quickly and precisely. It’s important for companies to keep upto-date with the plethora of new products hitting the market. By keeping abreast of the new products available, businesses in the sector will not only become more time efficient, but will also save money in the long term, while meeting stringent health and safety regulations. From lubrication and grinding to cutting and dust extraction, Engineering Utilities provides companies with the complete aluminium preparation and finishing solution. 

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