Metallurgical Instruments Measuring beyond Expectation

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1 3rd Qtr Metallurgical Instruments Measuring beyond Expectation FERROLAB EXCEL TO FIND C, SI & CE METACUPS TEMP MASTER 530 To find Temperature Thermocouple mini tips Temp Master 430 Tempstick 529 Ajay Syscon (Pvt) Limited, Pune, India Telephone: / export@ajaysyscon.com Distributed & Marketted in Pakistan: MATERIALS SOURCING INTERNATIONAL, KARACHI Contact: Mr. Shamshad Ali on Cell Tele: Fax:

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3 President Message Pakistan Foundry Association is established with a vision to provide a platform for the growth of foundry industry in Pakistan promoting interest of its members through skills development and up gradation of technology. PFA is arranging trainings and expert advice, promoting establishment of training institutions for foundry technology, assisting in technology acquisition to facilitate members for export and import activities. PFA looks forward to expand manufacturing capacity of foundry industry and to promote trade, commerce and manufacture foundry products for the local and global markets particularly auto and agricultural tractor markets. We are competitively priced and know international standards of quality. CBI an Agency of Netherland has selected Pakistan Foundry Association as Business Support Organization (BSO) for a four year Export Coaching Program (ECP). The objective is to guide and motivate the foundry industry through BSO for export purpose to European countries. Pakistan Foundry Association has nominated Mr. Abdul Rashid Secretary PFA, CBI export coaching program Metalworking to participate in Hague, Netherlands. I hope his training will support PFA foundry members to develop their individual Export Marketing Plan (EMP) to enter in European and other international markets. It is expected that CBI project aims to achieve increased export turnover of 20 companies of total additional export turnover Euro 10 million by the end of 2017 (one year after the end of program), 15 companies supported by BSOs another Euro 10 million PFA individual target will be ascertained afterwards. PFA understands there are many obstacles for the development of export of foundry products. If these are removed by the CBI coaching program our foundry industry will be able to compete our neighbor countries to export in Europe etc. I advise all members to register with CBI export coaching program, considering the fact that our common objective is to develop Pakistan through export boost of engineering goods. It can be achieved only through mutual cooperation, support to each other and coordinated efforts. Mr. Sjaak Vink-Country Coordinator, PUM for Pakistan, Afghanistan, Russia visited PFA secretariat on September 16, He had a demonstration how to benefit from PUM senior experts in foundry trade and I advise PFA members to get utilized PUM services. Sikandar Mustafa Khan President PFA Technical Advisor 01

4 THE LOST FOAM TECHNOLOGY IN THE FOUNDRY INDUSTRY Environmentally Sound Production (Imtiaz A. Rastgar) Introduction: Foundry is the making of ready-for-use forms, or of relative simple forms, such as cylinders and blocks, which should be processed afterwards by heat treatment and/or machining. The most important environmental impacts during foundry are the large use of energy and all kinds of emissions, such as VOCs and dust. A new technology in the foundry industry is the lost foam technology. The main advantages of this technology are that there is much less waste, and much less machining, and thus less coolants and lubricants, necessary afterwards. The lost foam process can be used in the production of iron castings including crankshafts, camshafts, valve bodies, electric motor housings and engine blocks. This document first describes this new technology, after that the financial and environmental advantages are provided and the document concludes with some successful examples from industrialized and developing countries. of a precision moulded foam pattern made from lowdensity expandable materials such as expandable polystyrene (EPS). More recently, speciality materials were developed specifically for the lost foam process such as Dow Chemical's expandable Poly Methyl Methacrylate (PMMA), Foseco's Low Carbon Bead (LCB) and also BASF's Clearpour. The moulding process is a refined version of the technology used in the production of EPS packaging. It is generally performed in automated moulding machines using custom machined aluminiummoulding tooling. To achieve complex shapes, the patterns can be moulded in several sections and then assembled using a variety of adhesives. Usually the assembly takes place in a custom glue/assembly machine equipped with precision fixtures to support the individual mouldedcomponents. The most popular adhesives are EVA hotmelt offering minimum glue deposit and a fast cycle time. The assembled patterns are fixed to a runner or a sprue system, either moulded or fabricated from the same material as the patterns. Several patterns may be clustered to the runner system, depending on the size of the pattern and the moulding flask. The cluster Lost-foam investment casting is capable of complicated outer and inner shape, especially for big parts. Serving industries are mainly mining, general machinery, automobile/ truck/ train industry The production process The lost foam process begins with the production European high pressure die cast parts is dipped in a refractory type coating and dried. The refractory coating is designed to form a barrier between the pattern and the molten metal, and the sand during metal pouring. The cluster is then 02

5 positioned in a moulding flask and the flask filled with un-bonded sand, which is compacted through vibration around the clustered pattern. A pouring cup is then attached to the runner or thesprue system. During pouring, molten metal vaporises and displaces the clustered from patterns. After solidification the castings are extracted from the flask and separated from the runner system. The castings require a minimum amount of cleaning and fettling, as the patterns are free from the traditional lining and core flash. Environmental and financial advantages the lost foam process has some advantages for the production of castings which require complex cored passageways, uniform wall thickness and limited or no draft angles. As the casting is a virtual reproduction of the moulded foam pattern, dimensional control is improved over castings produced by the green-sand route and for many features such as gasket surfaces and drilled holes. Furthermore, the improved dimensional control means a significant reduction in, or even the elimination of, machining. And this means a reduction in the use of coolants and lubricants, the largest environmental impacts in the metal industry! The lost foam process should be considered as a possible addition in a foundry modernization plan. Lost foam differs from other techniques primarily in the following ways: there are no cores and no parting lines, dry un-bonded sand is used sand, there is no mould wall movement and the tooling is not subjected to foundry wear. These differences result in the following advantages to lost foam over conventional foundry processes: l There is less energy needed; l There are less emissions, the waste is solid and relatively clean, and the sand can easily be recycled; l More complex shapes are possible and the surface is almost finished. This makes that there is less or no machining, less or no finishing and less or no assembly needed; l The financial advantages are that there is less labour and less capital needed. Furthermore, the lifetime of tools is extremely long. l Concerning the core: there are no related defects, shifts or fins, there is no core removal and there is no core equipment necessary, so no handling of hazardous core materials; l l Because of the close dimensional tolerances and the possibility of more complex shapes, the design freedom is larger; The employees' working conditions are improved. Successful Examples This paragraph provides some successful examples of industries, which switched from other casting processes, mainly green-sand, to the lost foam technology. The Saturn Division of General Motors Corporation utilises lost foam technology in the production of several of its key engine components. Three of these are a 1.9 litre, four-cylinder engine block and two different four-cylinder heads, a single overhead cam (SOHC) and a double overhead cam (DOHC). All are cast in 319 alloy and given a T5 treatment. The engine blocks, weighing about 20 kg each, are cast individually at 80 moulds per hour. Features such as the water pump housing and the starter motor brackets are 'cast-in', reducing assembly and eliminating gaskets The Aluminum Vortec block (left) is manufactured from adding a lost-foam model (right) into a mold and fasteners. Each of the two four-cylinder heads is poured at a rate of 40 moulds per hour. The SOHC version weighs 11 kg and the DOHC 13 kg. As with the block, the lost foam process offered some unique design opportunities with these heads that are produced from composite lost foam patterns, comprising five slices of foam. This enabled the engineers to cast-in all the water and oil ways, eliminating the need for gun-drilling operations. Some 4.8 metre of gun drilling was avoided. This resulted in a capital saving of $ 15 million through 03

6 the elimination of a machining centre. Saturn is also producing ductile iron crankshafts and differential cases via the lost foam process. The design of these parts also includes many 'as-cast' features resulting in increased value added, part weight reduction and improved performance. Another foundry that is using lost foam technology successfully is the Mercury Marine Corporation in Fondulac, Wisconsin. In 1990, Mercury began the production of a three-cylinder aluminium engine block for its 50 and 60 horsepower outboard motors. The approach Mercury took was to use the flexibility in design that lost foam offered to simplify the post-casting processing of the engine block. They were able to reduce a significant number of combined finishing and assembly activities over the die-cast engine block by combining three castings into one. The net result of Mercury's effort was a reduction in the overall assembled weight, reduced machining and assembly costs, improved engine efficiency through increases in engine water cooling and elimination of head gasket warranty claims. Not only companies in industrialised are profiting from the lost foam process, companies in developing countries also do. For instance Alexcon Foam Cast Limited and Gujarat Metal Cast Industries in India, ARBOMEX in Mexico and Anhui Jin Jong in China are applying the lost foam process. Source: Truck Oil Pump CBI Market Information Database URL: Special Coating for Aluminum Die Casting Improves Service Life of Dies Press Release Hilden, For suppliers to the automotive industry, the production of casted aluminum parts by means of gravity and low pressure die casting is of high technological and economic importance. With precisely these requirements in mind, ASK Chemicals coatings specialists - developed the semiinsulating die coating SOLITEC AD 901, a highly efficient water-based coating that offers major economic advantages in foundry processes thanks to its extremely long service life. In addition to ensuring that molds are filled completely, controlling the solidification of the cast part and protecting the mold surface, SOLITEC AD 901 offers another key benefit: The service life of the dies is more than 50 % longer than when other standard coatings are used. This prolongs the intervals required for die coating and maintenance and, therefore, increases the availability. The comparatively high graphite content of SOLITEC AD 901 also significantly reduces the ejection forces and hence the loads on the mold surfaces. Even production downtime lasting up to four hours does not have any negative impact on the quality of the coating or cast part. The economic impact of this is longer usage periods with reduced maintenance costs. At ASK Chemicals, more than 90 chemists, engineers and technicians on three continents are hard at work responding to the requirements of suppliers of aluminum cast parts. By combining theoretical knowledge with practical experience and by engaging in dialogue with our customers, our research teams working in state-of-the-art laboratories develop products that are as innovative as they are efficient and that set new industry standards time and time again. For further information on the complete range of products, please visit 04

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8 Energy Saving in the Foundry Industry by using the CRIMSON Single Shot up-casting Process M R Jolly, X Dai and B Zeng, Cranfield University, Milton Keynes, Bedfordshire, UK ABSTRACT Instead of using the traditional batch casting process, the CRIMSON (Constrained Rapid Induction Melting Single Shot Up-Casting) 1 method employs a high-powered furnace to melt just enough metal to fill a single mould in a closed crucible. The crucible is transferred to a station for computer-controlled counter gravity filling of the mould for optimum filling and solidification. The CRIMSON method therefore holds the liquid aluminium for a minimum of time drastically reducing the energy losses attributed to holding the metal at temperature. With the rapid melting times achieved, of the order of minutes, there isn't a long time at temperature for hydrogen to be absorbed or for thick layers of oxide to form. The metal is never allowed to fall under gravity and therefore any oxide formed is not entrained within the liquid. Thus higher quality castings are produced leading to a reduction in scrap rate and reduced overall energy losses. Keywords: Rapid Melting, Energy Saving, Life Cycle Analysis, Light Alloys INTRODUCTION Aluminium melting in metal casting industry is an energy intensive process where it is estimated that the energy consumption is in the order of 6,000-17,000 MJ per tonne in using crucible and 2 natural gas. The main energy resources for aluminium casting in US are natural gas, electricity 3 and coke. In UK, most of the foundry use electricity, gas and oil as the fuel in the aluminium melting 4 processes. Due to the pressure of rising energy price and the limitation of strict environment protection legislation it is confirmed that under the right socioeconomic conditions efficiency optimisation of industrial process can be an important step toward increased industrial 5 sustainability. In metal casting industry the energy efficiency of a casting facility depends largely on the efficiency of its melting and heat treating performance. In association with the two performances, over 60 % of the total process energy costs are represented in a typical casting 6 facility where there are huge opportunities for metal casting industry to adopt the best energy practices which will provide the great energy saving potential. To ameliorate the current processes for increasing energy efficiency will have a vital effect on reducing the production costs and promoting the competitiveness. For instance, by implementing some state of the art technologies such as the CRIMSON method in aluminium alloy casting will make use of such opportunities. Engineers at the University of Birmingham, England, with local company, NTec, have invented a new casting process that will reduce the energy costs of light-metal foundries. The technology, entitled CRIMSON, means that foundries need only heat the quantity of metal required to fill a single mould rather than large batches that use unnecessary energy and create waste. The complete concept of CRIMSON requires a change of philosophy in the approach to casting and requires the user to think holistically in order to reap the full benefits from the process. This paper will discuss the various aspects of energy wastage within the foundry sector and discusses the processes whereby the energy can be reduced. Primarily the authors focus on the aluminium sector but CRIMSON can be applied to many of the nonferrous "light" alloys. Ferrous materials and nonferrous "heavy" alloys can also benefit from some of the ideas but not necessarily directly from the application of CRIMSON. A research programme funded by the UK Engineering and Physical Sciences Research Council (EPSRC) has allowed the researchers at Birmingham to carry out some initial energy measurements to compare the CRIMSON process with some traditional processes. The results of these experiments are also presented and discussed in this paper. CONVENTIONAL PROCESSES The philosophy that has been used in the foundry sector for many hundreds of years has 06

9 been that it is more efficient to melt large volumes of metal than to melt only the exact amount required for each mould at the time when you need it. This has led to large melting furnaces and holding furnaces albeit becoming more and more energetically efficient over the years but still essentially wasting large amounts of energy. Recent 7 research by Tharumarajah has investigated the mass flows within aluminium high pressure die casting processes including looking at the impact that different levels of recycled scrap have on CO2 content of the process. His work investigates electrical and gas inputs, as well as water flows and waste flows and process losses. However his methodology does not come up with an energy burden per mass of good castings shipped. Such figures have been produced in the past by 4 analyzing the usage of energy in the foundry, however this ignores the energy burden of the incoming materials. The analysis in this paper attempts to put some figures against the processes used. A typical light-metal foundry usually melts anything from 100 kg to several 10s of tonnes of alloy in a range of furnace types. The liquid metal will then be held at a superheat of about 100 C (about 700 C for aluminium) in a second "holding furnace", before transferring it into a ladle and finally pouring into the casting mould. This may be a batch or semi-continuous process. The charge metal for the furnace comes from a number of sources. It can be high energy content virgin aluminium in the form of foundry ingot or direct chill (DC) cast billets. It can also be so-called "secondary" metal with an energy content corresponding to only 5% of virgin stock. This is metal which has been recycled from scrap and has been refined using similar processes to virgin alloys. The third source of material for a foundry is its own in-house recycled material arising from manufacturing process of the casting and from in-house machining processes, if they exist. Most foundries have in-house guidelines as to how much in-house scrap they recycle. Some have a policy of sending the material out for toll re-melting at a secondary alloy plant. It can take up to 8 hours for all the liquid metal in a batch to be used. Any leftover unused metal is poured off to be used again in-house, or scrapped to go for re-melting and refining in a secondary reprocessing plant. QUALITY OF ALUMINIUM Quality issues arise with the absorption of hydrogen from water in the atmosphere. Degassing by gas purging, or degassing additives on smaller quantities of metal, prolongs the time at temperature. Dross, a mixed metal oxide combined with small amounts of other compounds and some metallic aluminium, is created and scraped off, and either sent to landfill or, sometimes, for metal recovery. Added to this is the reaction of the metal with oxygen and water from the atmosphere, creating an oxide surface layer at every stage of the process. During pouring, this becomes mixed in, resulting in tiny particles or films of metal oxide, reducing the quality of the liquid metal and eventually leading to reduced mechanical properties of the solidified castings8,9. Furthermore, if the alloy specification is changed between batches, the furnaces and ladle are required to be flushed with more molten metal of each type before a new batch of the new metal type is used for production. MELTING AND HOLDING The traditional casting method uses energy to melt and subsequently keep a batch of metal at temperature (holding furnace), heat the pouring ladle, manage the problems associated with having kept molten metal hot (i.e. degassing and oxide formation), and melt unused metal, which is then recycled and/or scrapped, depending on quality. Figure 1 is a schematic of the foundry process and indicates the losses at each stage with the associated energy penalty for each stage, resulting in an overall energy cost per tonne of aluminium castings produced. The final figure of a massive GJtonne considers the worst case for every stage and indicates the potential for energy savings within this industry. This was calculated forward by taking the theoretical energy of melting 4 aluminium. Figures published in 1997 suggest that on average aluminium in the UK is produced using approximately 40 GJtonne-1. In high-pressure diecasting foundries this ranged from 26 to 52-1 GJtonne. For sand foundries the range was from 30 to 130 GJtonne-1. However, although these 07

10 seem quite wide variations aerospace investment casting foundries are not featured and the embedded energy of the materials is not considered. Embedded energy being defined as the energy that energy used to produce the raw materials, in this case the virgin and recycled aluminium charge, the energy for producing resins and steel for dies for example. The energy for producing aluminium from ore, that is the embedded energy within virgin aluminium, is of the order of 55 GJtonne -1 (10). The following sections are a breakdown of the Melting and holding processes and give some theoretical values which contribute to the huge amount of embedded energy within the castings produced. Melting The theoretical quantity of energy required to raise one tonne of pure aluminium to its melting point, melt it and raise the temperature to a superheat of 100 C, can be calculated as 1.1 GJ. The major alloying elements of Si, Cu and Mg seldom total more than 15% by mass of most alloys. Table I gives some published figures of heat capacity and latent heats of fusion for a number of alloys showing that there is little difference in the calculated total energy to raise the temperature and hold at a suitable superheat for casting. In fact looking across most of the engineering metals with the exceptions of Cu and Zn the energy requirement to take the metal to C superheat is always approximately 1 Gj. Most furnaces achieve efficiencies between 50 and 60 % and often the industry assumes the 12 conservative figure of 50 % (p119). These data are confirmed by investigating furnace manufacturer's specifications 13. A 1 tonne crucible furnace rated at 126 kw can melt at a rate of 295 kg.h -1. Published figures state that they can achieve 80 % efficiency if a lid is employed, thus the melt rate becomes 236 kg.h -1. Using these figures the energy to melt 1 tonne can be calculated as 1.92 GJ. Thus for a tonne of pure aluminium the efficiency is about 56 % and for the alloys ranging from 50 to 52 %. Alloy Designation US/UK Pure Al 356/LM25 336/LM /LM4 Data from 14,15,16 Major Alloying elements NA 7%Si 0.3%Mg 11%Si 1%Cu 1.2%Mg 1%Fe 0.5%Mn 5%Si 0.8%Fe 3%Cu Many foundries will use tower furnaces as they produce a constant supply of liquid metal. A typical example may be a tower furnace rated at 6.6 t.h -1 with an efficiency of 50%. 2.2 GJt -1 would be expected to be used to melt. However, there are also losses in oxidation and volatilization of certain elements which it is estimated make up about 2% by Table 1. Energy to raise 1 tonne of Al alloy to a superheat of 100 C Solidus (Ts) Liquidus (Tl) Heat 25 C mass of any melt. Therefore producing 1 tonne of good aluminium requires an estimated GJ of energy Holding Latent heat of melting point C C Jkg K- kjkg Calculated total energy to raise 1Mg to Tl C Melting large volumes of metal inevitably requires it then to be held. Foundries often use more MJ

11 energy for holding than for melting 4. Making the assumption that a shift is 8 hours then every tonne melted in a shift is held on average for 4 hours if all the metal is used over that period. Holding usually has similar losses to melting which are estimated at about 2% per unit mass 12 and will be affected by things such as the amount of stirring, the atmosphere and whether the melt is covered. Alloy composition will also affect the losses experienced. It would seem logical to assume losses are increased per unit mass the longer the melt is held for however it is not easy to find any good data in the literature that can be used to estimate melt losses as a function of holding time. It has been proposed that holding as little metal as possible for as short a time as possible at the lowest possible temperature is the best solution. Some have even proposed that metal should not be held at all and used as soon as melted 4 p 21. The current research programme at the University of Birmingham has provided some data on metal holding. Degassing and Cleaning. Degassing of aluminium has become an essential part of most foundry practice. The majority use rotary degassing as an efficient and environmentally friendly method. The losses can be as high as 5 % in terms of mass. Energy is also consumed by the rotor and there is embedded energy in the nitrogen or argon gas used as it will have been compressed into the cylinders. A midrange rotary degassing unit might be powered by a 3.5 kw motor and be used for 15 min. The amount of gas used each campaign would at 20 L min -1 would be 300 L. Thus the energy of N 2 or Ar embedded would be about 0.5 MJ. Combined with the energy for the rotor this means each campaign has an embedded energy of approximately 2 MJ. This might be carried out 4 times during a shift giving at total of 8 MJ. Cleaning usually refers to the removal of oxides. This is accomplished by either incorporating the process with the degassing by injecting a powdered flux though the lance or rotor, or by fluxing, rabbling the surface and "drossing-off". The production of dross results in melt losses and there is again inevitably embedded energy in the cleaning products used. The embedded energy in flux products is something that has not been investigated as far as the authors are aware. Assuming flux is added at a rate of 0.5 % per tonne of aluminium and assuming the flux is a K or Na fluoride then the energy for melting is MJ/kg and 1.6 MJ/kg 16 respectively and heating and melt losses of 5 % equate to 5.1 and 8.8 MJ/tonne of aluminium, respectively. MOULD, DIE AND CORE MAKING All foundries require a cavity for the liquid metal to be poured into. These can be made from a variety of different materials all with different energy burdens of their own. For consumable mould processes there will be the energy burden in the sand or ceramic materials from the mining and the transportation. These materials also use binders, organic or inorganic each with an energy content. Sand moulds could be formed with a wooden or steel pattern each with a very different energy. Ceramic investment shells are formed around a polymer material which has been injected into a steel die and then the polymer is removed using steam. The energy content of this process could potentially be extremely high. For non-consumable processes like die-casting the steel or cast iron dies have an energy content that would be of the order of those published by Brimacombe et al. 17 for steel products. FINISHING PROCESSES Finishing processes have a massive effect on the overall process efficiency. Fettling. It is at this point that in the process that the so-called "method" (rigging in the US) is removed. These are the extra bits of metal that enable the casting to be manufactured i.e. the feeders, risers and running system. In a good foundry producing general engineering or automotive castings a figure of about 50 % may be achieved. In a high precision aerospace investment foundry this figure could rise to 90%, implying that only 10% of the metal cast ends up in the black casting. Grinding and machining. In order to extract the casting for the die or moulds, there is often a taper or draft angle added 09

12 to the final component shape. This may or may not need to be machined or ground off. Any such process uses energy thus the less finishing machining that is carried out the lower the energy content of the final component. The energy involved in machining and fettling will be measured in the new research programme at Birmingham. Scrap. Any component that contains porosity in locations that will affect the component performance, or that have unacceptable surface finish, or contain inclusions such as oxides, will be Fig.2 Image of the CRIM part of CRIMSON process scrapped. These materials will go back to the melting stage, to the secondary re-melter or toll remelted in any case the embedded energy is everything that had been carried out on the casting at the stage. Estimates of the level of embedded energy are considered in the section on Life Cycle Analysis. THE CRIMSON PROCESS The Crimson route for casting should enable foundries to save energy at various process stages. Aluminium will be provided in a pre-alloyed, clean and degassed condition from the metal supplier. The metal is heated rapidly with an induction coil and used immediately. This will obviate all the holding and degassing losses and will reduce melting losses. Induction melting is also a much more efficient melting method than either radiant, gas or oil fired furnaces. The equipment at the University of Birmingham comprises a 350 KW induction furnace which is expected will melt up to 10 kg of aluminium alloy in about 90 s. DC cast billets of the selected alloy are cut to weight and placed within the crucible. Power is turned on and the metal is constrained within the furnace to obviate the problem of ejection of the metal (Figure 2). When the metal is molten the crucible is transported to the up-casting unit (Figure 3). The crucible is quickly indexed into the casting position as soon as the safety inter-locked doors are closed. The software controlling the motor is then activated automatically and applies the correct displacement cycle to the screwed injector of the up-caster. The base of the crucible moves up through the crucible and is sealed against leaking by a gasket. LIFE CYCLE ANALYSIS (LCA) There are a number of different methodologies for dealing with Life Cycle Analysis and sometimes known as Life Cycle Inventory analysis (LCI). For the aluminium foundry sector it is probably best to use those that have been used in the steel industry and adapt them for the differences 17. Within the foundry sector the amount of recycling and levels of scrap that exist are highly dependent on the product and end market. Thus in general, the yield and scrap rates in the aerospace sector are respectively low and high, whereas in the automotive sector these tend be higher and lower than in the aerospace sector. Both of these factors have an effect on the total effective recycling efficiency of the process and thus the effect of the burden of the energy of the virgin and recycled aluminium used. There are a number of different ways carrying out an LCA but in this paper the focus is on two methods. One is the Multiple Recycling Concept and the other is the Closed Loop recycling 18 as described by ISO BOUNDARIES AND PROCESS MEASURES One of the most important things to decide on when carrying out an LCA are what are the process boundaries. In the study by Tharumarajah 7 the boundaries are limited to the inflow of aluminium, gas, electricity, water and die lubricant coming on site and aluminium, water and waste leaving the site. However the intrinsic embedded 10

13 energy content of these material flows is not considered. The study only considers the 1st pass material efficiency which is reported as 93.9%, waste is reported as 6.1%. This is equivalent to the 17 process yield (Y) discussed by Brimacombe et al.. However using an Operational Material Efficiency (OME) also known as True Yield4 i.e. the percentage of good metal shipped as a proportion of metal melted, the picture is changed somewhat, as this is 47.7%. This operational material efficiency is a good measure of the quality of the process and even though in this scrap material is recycled internally the level of scrap is high and thus the OME is poor. In this paper the embedded energy of the materials input is also considered and the effect of multiple recycling calculations is discussed. However the area that neither 7 Tharumarajah nor this paper studies in detail is the energy burden of the mould, die or core materials. The current research programme at the University of Birmingham will hope to address this issue in the future. MULTIPLE RECYCLING METHOD In order to estimate the embedded energy using this method it is important to measure or estimate a number factors described in the following sections. Figure 3: Photograph of the up-casting unit at Birmingham University Process Yield (Y). This factor is a number, usually less than 1, that is calculated by taking away the true mass losses in the process from unity. In the case of the aluminium foundry the true mass losses are those from melting, holding and degassing as these are oxidation losses. The other "losses" can be recycled in the process. Using the estimates above the real mass losses come to a total of 8.8 %. The process yield, Y, is therefore or 91.2 %. Recovery Ratio (RR). This is the figure that considers the scrap that is recycled from the process as a percentage of the material put in. Taking a foundry in the automotive or general engineering sector it can be estimated that the worst case RR is about 0.64 (64 %). For an aerospace foundry this is potentially higher as the proportion of good castings is much lower. It could be as high as 0.86 (86 %) but very often in this sector only virgin aluminium is used and thus RR would be zero (0 %). Recycling Efficiency (r). This parameter represents how efficient the process is over one cycle. It is the product of the Process Yield and the Recovery Ratio. Thus: r = RP X Y Eq.1 Calculating LCI for complete systems. To calculate the LCA using Multiple Recycling the following equations are required. The total mass passing through the chosen number of cycles, M M=1+r+r r n-1 Eq.2 The total energy content for the chosen number of cycles can be calculated using equation 3. Total energy content = Xpr+rXre+r2Xre+...+rn-1Xre Eq.3 Where Xpr is the energy from the primary process and Xre is the energy for the recycling process. Combining these two equations we can now get a Life Cycle Inventory (X) defined by equation 4. LCI for the whole system: Xpr+rXre+r2Xre+...+rn-1Xre X= 1+r+r rn-1 Eq.4 This can be reduced to: X= (Xpr-Xre) (1-r) Eq.5 (1-rn) The energy for each cycle can be plotted and it can be seen that the curve is asymptotic to a value that can be n n given by equation 6 as n and r 0 and (1-r ) 1. X = Xpr+r(Xre-Xpr) Eq. 6 11

14 Suggested values of Y, RR, Xpr, Xre and r for aluminium foundries in the automotive/general engineering market, and aerospace sector, with and without recycling, are given in Table 2. Figure 4 is a plot of the energy burden for each cycle until it reaches the asymptote. CLOSED LOOP RECYCLING Closed loop recycling is easier to apply and essentially can be applied where there are no inherent changes to the materials. This is the methodology recommended in such cases in ISO This can therefore be used for aluminium castings. The same result is obtained and it is a much simpler to apply. There are two stages for the calculation. The first stage of the calculation is to estimate the energy burden of the scrap. The method is clearly shown by Brimacombe et al. 17Error! Bookmark not defined. for steel. The second is to carry out the LCA for the recycling route. These calculations are shown in Tables 3 and 4 for a general/automotive type foundry and for an aerospace foundry. Table 5 is for the CRIMSON route. X, Energy Burden (GJ/tonne) 60 x x LCI: Auto LCI: Aero X : Auto X : Aero recycle x x x x x x x x x xxx x x x x x x x x x x x Cycle number, n Figure 4: Energy burden per cycle for aluminium castings in various market sector foundries DISCUSSION OF LCA The melting of metals and subsequent use of the liquid in manufacturing shapes has enabled man to develop some incredible technologies including the silicon chip and the single crystal turbine blade which is now ubiquitous in the modern jet engine. The down side of this old but enormously valuable technology is the large amount of energy required to achieve this outcome. In the current era of sustainability and reduction of CO2 emissions that have accelerated climate changes on the planet it is incumbent upon any such energy-hungry industry to identify how it can respond to the situation by reducing energy usage and being efficient with the energy that it uses. In this section Life Cycle Analysis (LCA) using both infinite recycling and closed loop methods has been applied to try to understand the energy 12

15 burdens that are carried by aluminium castings in the automotive and aerospace sectors. The author is assuming that for the aerospace sector the majority of casting are produced using the investment casting process whereas for the other sectors it will be a mixture of mainly high and low pressure die and sand casting. LCA is notoriously complicated to carry out because of the difficulties in the definition of the process boundaries. An example of this can be seen in the aerospace sector. Generally, the aerospace sector uses virgin aluminium as feedstock for the casting process. There is often a high scrap rate which can be higher than 90 %. This is not all scrap from bad product it is made up of process scrap which comes from the methoding (rigging) and machining. This becomes waste in the aerospace sector but is a high quality, high energy content raw material for the rest of the aluminium foundry sectors. The question then is should that be included in the aerospace LCA to enable a complete picture to be obtained or excluded and just added into the other sectors? Looking at the energy burden estimated in each of cases from the LCA can be misleading unless one understands what this is representing. For an aerospace sector casting with no internal recycling the energy burden per kg of melted metal is approximately 55 MJ. However this kg of liquid metal may sometimes only produce 55 g of good castings! Thus the burden per kg of good castings could be as high as 1 GJ. The scrap which is -1 estimated to have a burden of about 48 MJkg is then fed back into the other aluminium sectors. If it was fed back into the aerospace sector and used as part of the charge material then because of the high scrap rate the energy burden would appear to be -1 reduced considerably to about 14 MJkg as less primary aluminium would be used. This is a reflection of the very considerably less energy required to re-melt aluminium compared with the energy required to electrolytically reduce it from its ore. However this may still only produce 55g of good castings so, although reduced, the energy burden per kg of good castings is still an enormous 258 MJ. It becomes very obvious from these calculations that the energy burden is heavily affected by the recycling efficiency (r) and the operational material efficiency (OME). So although the aerospace sector could have a recycling efficiency of 78 % because in practice the OME is so poor the energy burden per unit mass of good castings is very high. This information can be used by the industry in order to manage change within the sector. Taking a similar approach to the traditional methods for producing automotive castings it can be seen that, as the scrap rate is lower, the energy credit is not as high, so for each kg of liquid metal the energy burden is actually higher than in the -1 aerospace sector at about 25 MJkg which is still less than 50 % of the primary aluminium route. Using the same approach as in the previous paragraph and incorporating the OME it can be seen that for this sector an average energy burden -1 might be of the order of 90 MJkg. This figure is surprisingly similar to the energy measurements made in the 1990s and published by the UK government4. The energy levels published are for the energy used in the foundries so do not reflect energy burden of the materials coming into the process. Thus the only part considered in the calculation in this paper is the impact of the secondary melting at 2.8 MJkg -1 melted which is equivalent to 10 MJ for each kilogramme of good castings. It could be proposed therefore that to the figures measuring the use of energy by the foundries a further 80 MJkg -1 (80 GJtonne -1) could be added to truly represent the impact that aluminium castings have on the environment. So what effect can the CRIMSON process have on the foundry sector when it is apparent that effective methoding to improve the OME is one of the major ways of reducing the energy content, as long as recycled material from end of life castings is used as the raw, materials rather than virgin aluminium? An LCA for the CRIMSON process keeping everything equal except for the effect on the melting shows that the energy burden 63 Mjkg -1 with an OME of 30 %. This is a considerable reduction of the 90MJkg-1 for the traditional processes. With the improvements in scrap rates expected, as the material will be cleaner, but with no change of methoding then burden reduces by -1 very little to 62 MJkg and an OME of 34 %. Improvements to the OME by altering the methoding could change this dramatically and this may be where the biggest second opportunity arises. For example reducing the methoding by 50 % (i.e. improving the so-called box yield to 67 %) could bring the OME to close to 50 %. This has the effect of reducing the embedded energy per kg of good castings to 59 MJ. These calculations assume 13

16 that only supply of aluminium is the internal recycled scrap and primary aluminium. If the internal scrap is topped up with end of life scrap from other sources and the primary aluminium is kept to a level of about 30 % then the embedded energy drops dramatically to about 40 MJkg -1. Obviously traditional process can also raise their level of recycled materials to improve the situation with regard to embedded energy but the effect of the CRIMSON process in dropping the energy to 70 % of that traditional route by reducing melt losses and obviating holding and degassing losses is dramatic. E N E RG Y C O N S U M P T I O N O F CONVENTIONAL FOUNDRY AND THE NEW CASTING METHOD The second part of this paper presents some of the energy measurement results from a conventional foundry and compares this with results from the CRIMSON process. CONVENTIONAL MELTING PROCESS One of the foundries for producing high end casting components at Grainger & Worrall (G&W) Ltd. is currently using a combination melting and refining process (Figure 5) where the primary melting area functions like a tower furnace with gas as the fuel to preheat and melt aluminium ingot. The melted aluminium alloy then flows along an inclined channel into a refining area where an electric resistance furnace is used for holding. From here the Cosworth process is used. Filling is carried out using an electromagnetic pump to transfer molten alloy from the holding furnace to the mould cavity. In this foundry, there are two furnaces using this kind of combination melting process for producing two types of aluminium alloys A354 and A357. The capacity of both furnaces is 4 tonnes. The holding time for each furnace is up to 4-5 days. The superheat temperature of the A354 aluminium alloy is 760 C. The pouring temperature of the melted aluminium alloy is 700 C. CASTING SAMPLE A "Test bar" mould has been selected to use novel method to examine its energy consumption. The design of the "Test bar" with a runner system is shown in Figure 4 which has a profile of 530 mm length x 390 mm width x 100 mm height with a weight of 4 kg 19. G&W is currently using traditional sand casting processes to produce normal casting components and the Cosworth casting process is especially selected to produce high quality components. THERMODYNAMICS ANALYSIS OF THE FURNACE Aluminium melting processes in both crucible and induction furnace include complicated physicalchemical phenomena such as gas combustion, dross generation, phase change and heat transfer (radiation, conduction and convention). Some of the thermodynamic parameters can be measured easily such as temperature and pressure and in the mean time some parameters are difficult to measure such as the heat loss in the way of radiation and conventions. However, thermodynamic analysis of the energy balance during the melting process in a crucible or a furnace based on the experimental results is achievable 20. These experimental results and the related thermodynamic analysis can be a reference to help casting industry to improve the energy efficiency and decrease the waste emission. The schematics of energy balance in the aluminium melting furnace of G&W ltd. and CRIMSON are shown in Figure 6 and 7, respectively. The experiment and analysis of energy efficiency is based on the following assumptions: 14

17 Figure 6: Schematic of energy balance in the aluminium melting furnace at G&W ltd. Ø Ø Ø Ø Ø Ø Figure 5: Schematic of the aluminium melting furnace in G&W Ltd. The system assessed is at continuous steady state which includes fuel flow, air flow rate, melting rate, flue gas parameters and thermal conduction through furnace wall The fuel and combustion products behave as ideal gas mixtures The ambient temperature and pressure are taken as standard 25 C and 1 bar respectively The electric energy consumption is only applied to the part of electricity resistance heating or induction heating in furnaces, not applied to the motors and control devices which are neglected for the convenient calculation and simplicity The natural gas composition is considered as pure propane due to the small amount of N2, CO2, H2S and H2O included The metal lost during drossing is neglected for simplifying the calculations Energy balance at G&W The energy balance of the furnace at G&W in Figure 6 can be expressed following the methodology proposed by Rosen 21: E in = E out E in = Efuel + E ingot + E comb air E out = Emelt + Q = (E + E ) + Q _ Q = E E mis in al = E al / E fuel mis ingot al mis Where: E : is the energy input of the furnace system E in out : is the energy output of the furnace system Eq. 7 Eq. 8 Eq. 9 Eq. 10 Eq. 11 E fuel : is the energy generated from fuel combustion E ingot : is the energy generated from aluminium ingot, here E ingot = 0 E comb air : is the energy generated from combustion air, here E comb air = 0 E melt Figure 7: Schematic of energy balance in the induction furnace of CRIMSON : is the heat transferred to the melted metal; E Al : is the energy variation of the metal from ingot to Metal metal Q mis : is all the energy loss during the melting process in a furnace chamber : is the energy efficiency of the furnace at G&W CRIMSON energy balance The energy balance of the induction furnace of the new process in Figure 7 can be expressed in a slightly different way: equations 7 and 10 are the same; 8, 9 and 11 can be revised as follows: E in = Eelectricity + E billet Eq. 8* E out = Emelt + Q mis = (E bill + E Al) + Qmis Eq. 9* c = EAl / E electricity Eq. 11* Where: E E electricity billet : is the energy generated from electricity : is the energy generated from aluminium billet, here E = 0 billet c : is the energy efficiency of the induction furnace It should be clarified here that the conventional foundry is normally supplied with aluminium ingot having a trapezoidal cross section from the primary and secondary industries. The quality of this kind of ingot is usually poor due to the harsh and turbulent flow behaviour of pouring during the primary production process. The new process requires the billet with circular cross section and in good quality in order to better suit for the crucible of the induction furnace in the new process. At current stage, it is impossible for the suppliers to provide this type of billet due to the small amount of requirements. However, after contacting several suppliers of the direct chill billet in UK, it is possible for them to provide the circular cross section billet with required diameters and sound quality if the ordered amount is proper. The compromising 15

18 method in this project is that the scrap and ingot are re-melted and recast into circular billet with the required chemical composition. The energy consumption incurred as a result of this stage is not audited in this paper. E X P E R I M E N T R E S U L T S A N D DISCUSSION The energy consumption at G&W where the Cosworth process is applied was investigated where both gas (propane) and electricity are included and the usages are recorded in Table 6. It should be noticed that power measurement may be connected with the day or night rate. During the investigation, only the energy consumption (kj.kg-1or MJ.kg -1) is measured and the cost which linking with the rate is not considered. From Table 6, the total actual energy consumption E Al for melting A354 Al alloys in G&W can be calculated as E Al =44.80 MJ. kg -1. The thermal efficiency of using the LPG for melting the alloys is 1 = 10.4%. The thermal efficiency of using the electricity for holding the melt is = 6.14% 3. Experimental parameters for casting the "Test bar" mould in the new casting facility are given in Table 7 The theoretical energy consumption E Al for heating the A354 alloy to 729 C is E = 318kWh.T -1 Al. The energy consumption measured during the melting is 1.98 GJ.t -1 (550 kwh.t -1) (Table 2). The thermal efficiency of the induction furnace can be calculated from these two figures and is = 57.8% 3. The thermal efficiency of the melt furnace at G&W for gas is 1 = 10.4% and for electricity is 2 = 6.14%. The former 1 is near the normal thermal efficiency of crucible furnace using gas (13 %). The latter 2 is far less than the normal thermal efficiency (59~76 %) of an induction furnace using electricity. This implies that there is large energy loss for the current melting process at G&W due to the long holding time. This would suggest that if the current long melting and holding process at G&W were replaced by the new single shot melting method, the thermal efficiency will be increased up to 40 %. When melting the same weight of the Al alloys, G&W used about 23 times more energy than the new casting facility. It is estimated that 42.8 GJ.t -1 (11.9 MWh.t -1) can be saved for producing every tonne of A354 casting alloys when using the new process. Thus, to use the new process, the melting cost will be drastically decreased. c 2 More reasons for recommending the new method instead of using crucible furnace at G&W are: although a crucible furnace is cheap method for melting Al alloys which is popular in foundry due to its easy for tapping and charging different alloys, the thermal efficiency of the crucible furnace is far lower (7~19 %) than the new method (57.8%) and the temperature of the liquid alloy is difficult to control. It has been proved in this investigation that the thermal efficiency of furnace at G&W is only 10.4 %. Furthermore, the new method uses a rapid filling method as soon as the alloy is heated to the required temperature, avoiding using holding furnace for holding long time and thus reducing the potential energy wastage. In the mean time, due to the quick melting and filling processes, the opportunity of generating the oxide film on the surface of the liquid alloy and the potential time for hydrogen absorption are drastically reduced. The quality of the casting can be secured accordingly. CONCLUSIONS High scrap rates and low operational material efficiency in the aerospace sector leads to an extremely high energy burden per tonne of good castings estimated to be in the region of 1 TJ. If the aerospace sector were to recycle its own scrap internally the energy burden per tonne of good casting could be reduced by 75% to approximately 250 GJ based on the assumptions used in this paper. Table 6: Actual consumption of gas and electricity in G&W Ltd when Cosworth process is used Energy type LPG (propane) Electricity Energy consumption (0.7 m3.t-1) kj.kg-1 (2800 kwh.t-1) MJ.kg-1 Energy density by mass (MJ.kg-1) Table7:. Experimental parameters for the "Test bar" in the new casting process facility Experiment parameter Value Note Weight of metal charge 4 kg Thermocouple Melt temperature 729 C reading Melting time 2 mins Injection time of up-caster Holding time Solidification time Measured energy consumption for melting the charge 10 s 20 s 28 s 7.92 MJ (2.2 KWh) In the general and automotive aluminium foundry sectors the energy burden is estimated to be of the order of 90 GJ.t

19 Applying the CRIMSON process to the general and automotive sectors has the effect of reducing the melting losses and obviating holding and degassing losses. This has a positive effect on the -1 energy burden by reducing it to about 63 GJ.t of good castings. Keeping primary aluminium content to 30% and improving the running systems could reduce this -1 energy burden to a level of 40 GJ.t of good castings shipped The experimental investigation on melting efficiency of both conventional and new melting processes has revealed that the new method is an innovative method for saving energy in the casting industry. If the conventional foundries could use the novel melting method instead of their traditional melting method, the estimated energy savings could -1-1 be of the order of 43 GJ.t (11.9 MWh.t ) for A354 alloy. This would drastically reduce the -1 production cost by about 904 t (when a cost of p.kwh is used). This could be crucial in the rigorously competitive market of casting industry. FUTURE WORK The other issues of the energy efficiency for the foundry will be further considered in the next stage of the project where not only the melting process is included other relevant processes should be considered. Work is underway with an aerospace investment casting foundry: the results of this study are to be published shortly. Work is also underway investigating the mechanical properties of castings produced using the CRIMSON process with parallel castings on gravity poured material from the same melt process. ACKNOWLEDGEMENTS This research project is funded by the Engineering and Physical Sciences Research Council (EPSRC) of the UK under the grant of EP/G060096/1. Acknowledgement will be given to the Grainger & Worrall Ltd. for providing the experimental data of their current production process. REFERENCES 1 Patent Patent Pending P306306GB. 2 U.S. Department of Energy, "BSC, Incorporated, Advanced Melting Technologies: Energy Saving Concepts and Opportunities for the Metal Casting Industry," U.S. Department of Energy, M. R. Jolly and X. Dai, "Potential energy savings by application of the novel CRIMSON aluminium casting process," Applied Energy, December UK Department of the Environment, Transport and the Regions, "ENERGY CONSUMPTION GUIDE 38, Nonferrous foundries (Second edition)," HMSO, London, B. Klaasen, P. T. Jones, D. Druinck, J. Dewulf, P. Wollants and B. Blanpain, "Exergy-Based Efficiency Analysis of Pyrometallurgical Processes," August R. Eppich and R. D. Naranjo, "Implementation of Metal Casting Best Practices," U.S. Department of Energy, A. Tharumarajah, "Benchmarking aluminium die casting operations," vol. 52, p N. R. Green and J. Campbell, "Statistical distributions of fracture strengths of cast Al-7Si-Mg alloy," Mat. Sci. and Engineering, vol. A173, pp , J. Campbell, "Invisible macrodefects in castings," Journal de Physique IV, no. supplément au Journal de Physique III, Novembre World aluminium organisation, " [Online]. 11 M. Jolly, "Castings," in Comprehensive Structural Integrity, vol. 1, R. R. a. B. K. I. Milne, Ed., Oxford, Elsevier, 2003, pp Foseco, Non-Ferrous Foundryman's Handbook, J. Brown, Ed., Oxford: Butterworth Heinemann,, Nabertherm, " [Online]. 14 C. Smithells, Ed., Metals Reference Book, 5th ed., London and Boston: Butterworths, ASM Metals Handbook, 9th ed., Metals Park, Ohio: ASM, D. Lide, CRC Handbook of Chemistry and Physics, 74th ed., Boca Raton, Florida: CRC Press, pp L. Brimacombe, N. Coleman and C. Honess, "Recycling, reuse and the sustainability of steel," Millenium Steel, pp , International Organisation for Standardisation (ISO), "Life cycle assessment: Principles and framework, Geneva: International Organisation for Standardisation (ISO), J.-C. Gebelin, M. Lovis and M. R. Jolly, "Simulation of Tensile Test Bars: Does the filling method matter?," in Symposium on Simulation of Aluminum Shape Casting Processing, TMS Congress2006, San Antonio, March L. M. Hassan, K. Kuwana, K. Saito and P. King, "Performance of secondary aluminium melting: Thermodynamic analysis and plant-site experiments," Journal of Energy, vol. 31, no. 12, pp , September M. Rosen, "Exergy-based Analysis and Efficiency Evaluation for an Aluminium Melting Furnace in a Diecasting Plant," in Proceedings of the 4th IASME/WSEAS International Conference on ENERGY & ENVIRONMENT (EE'09), Note: "This paper was presented at the World Foundry Congress, Mexico, April 2012 and is published with the kind permission of the World Foundry Organization." 17

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21 Modern Sand Reclamation Technologies For Economy, Environment Friendliness & Energy Efficiency Aniruddha Ghosh, GM - The Wesman Engineering Co. Ltd Abstract Unlike green sand, chemically bonded sand cannot be used again and again without reclamation because in this system, the mixed sand gets it`s strength through chemical reaction which is irreversible in nature. Each sand particle is coated with this reacted chemical, which behaves like an inert element after usage once. This inert coating also called Dead binder needs to be removed from the used sand because it being brittle in nature gives rise to increased fines in the sand. Dead binder is present in the form of layers adhering to the surface of the sand grains. These layers if not removed changes the property of the sand and makes it totally unsuitable for further usage because proper strength would not be achieved even with higher chemical percentage. Sand grain modification is another important aspect of reclamation. During reclamation rubbing take place between sand grains and also against surfaces of the various equipment of the reclamation system at different stages. As a result sharp corners of the original sand (which is available from the nature) get rounded causing reduced surface to volume ratio, which ultimately reduce binder demand. This obviously reduces the chance of getting defective casting due to formation of gas. Main methods of Sand Reclamation are (1) Mechanical Attrition Reclamation and (2) Thermal Sand Reclamation. In Mechanical Attrition Reclamation rubbing of sand grains against each other take place by mechanical means like vibration, fluidization etc. This process cannot remove all the binder coatings. As a result about 10 to 20% fresh sand needs to be added with the sand to keep LOI value within limit. Generally such sand is reused for the same binder system. Thermal Reclamation is actually a combination of Mechanical Attrition Reclamation and Thermal Reclamation. In this process, mechanically reclaimed sand is heated to a temperature of about 800 degrees C. Heating takes place in a specially designed furnace where the sand is both fluidized as well as heated. Thus rubbing of sand against sand takes place here, too. Various equipment involved in a Thermal Reclamation System are Lump Reducer, Pneumatic Transporter, Screw Feeder, Combustor with Sand Preheater and Air Preheater, Fluidized Bed Cooler and Dust Extraction System. Of these equipments Combustor is the special furnace in which the mechanically reclaimed sand gets fluidized as well as heated. To utilize the waste heat both incoming sand as well as air is preheated with the help of waste flue gas coming out of the system. From the Screw Feeder mentioned above, mechanically reclaimed sand is fed to the Sand Preheater of the Combustor whereby the incoming sand to the furnace gets preheated. Afterwards, the sand is both fluidized as well as heated in the furnace itself. As a result rubbing of sand against sand as well as burning of dead binders, both are accomplished at the same place. Thermally reclaimed sand is better than mechanically reclaimed sand as well as fresh sand from various aspects as follows : (1) Thermally reclaimed sand undergoes lower thermal expansion causing better mould stability. (2) Thermally reclaimed sand is better than fresh sand because it is more rounded in shape causing lesser binder demand. (3) Irrespective of the binder system in the previous cycle, thermally reclaimed sand can be used with any chemical binder system in the subsequent cycle. 19

22 (4) As most of the sand is reused, almost no dumping is necessary resulting in safer environment. (5) Conserves natural resources by eliminating requirement of new sand. (6) This is a highly energy efficient process. 1) Introduction: In green sand clay bonded, process the sand is used over and over again after some treatment of the used demoulded return sand. The treatment includes sieving, removal of Iron particles, cooling, water and binder addition, mixing etc. But in case of chemically bonded sand system the mould / core strength is developed by chemical reaction or thermal process. Contrary to the green sand system binder in chemically bonded sand is set by irreversible process. It does not remain active and cannot take part in the bonding of sand in the next cycle. After the mould / core are set and casting is done the binder present in the system is totally dead and fresh binder must be added before the sand can be used in the next cycle. Reuse of sand this way, will result in accumulation of dead binder in the system making the sand totally unusable. The option, adopted by some, is to discard and dispose the used sand altogether after and start with new sand in every cycle. This is not a feasible proposition on economic and environmental consideration. The availability of dumping ground for used chemically bonded sand is becoming difficult day by day. Cost of dumping is also increasing exorbitantly. In addition to non availability of dumping ground and high dumping cost, the environmental problem is of critical concern. The dumped sand, being toxic, would pollute the atmospheric air as well as the ground water having long lasting effect on environment and plants. The government authority is becoming stricter on these issues. On the other hand, availability of new sand is becoming a problem these days. Local authorities are imposing restriction in mining / extraction of sand altogether. Therefore supply of new sand to foundries shall be very little or it may even stop altogether. Therefore they will be compelled to survive on sand obtained by reclaiming used /de-moulded sand. In addition to above compulsion, there are other good technical reasons for reclamation of chemically bonded sand for re-use. 2) TECHNICAL REASONS FOR RECLAMATION Removal of dead binder: The dead binder present in the used sand increases the fines in the system sand. The fines having more surfaces to volume ratio require more resin / chemical to achieve desired level of bond strength. The increase of fines in the system sand also contributes to deterioration of sand properties. These fines, therefore, are to be removed from the system. Majority of the dead binder, however, are present in the form of layers adhering to the surface of the sand grains. If these layers are not removed, the sand grain would be coated with multiple layers of such dead chemicals in subsequent cycles. This deposit, being brittle, changes the sand property and would make the sand totally unsuitable for moulding as proper strength would not be achieved even with higher percentage of chemical. The presence of residual dead binder in the system is a determining factor in arriving at the required chemical percentage in the next cycle. The amount of this dead organic binder, usually determined by Loss On Ignition (LOI), is very important in chemically bonded sand system. If the LOI changes in every cycle then percentage of chemicals to be added would also change in every cycle. This situation cannot be accepted as a good operating practice. In practical situation it is not possible to determine the required chemical percentage and add the same accordingly in every cycle. Therefore every attempt is to be made to keep the LOI figure more or less constant making the system stable. Stability means to attain the LOI figure of the reclaimed sand at the end of the cycle equal to the LOI figure of the sand before addition of binder in the beginning of the cycle. To attain this condition it often becomes necessary to add certain amount of NEW 20

23 sand in the system. The percentage of new sand required to be added to reclaimed sand generally varies from 10 to 20%. Sand grain modification: It is another important aspect in considering reclamation. During reclamation, due to grain-against-grain rubbing/abrading as well as grain rubbing against rubbing surfaces of various reclamation equipment at various stages of reclamation the sand grains get altered. The sharp corners get rounded, converting the sand grains from angular to sub-angular to rounded. This improves the desirable property of sand to a great extent. The surface to volume ratio gets reduced resulting in reduced binder demand. Due to this positive effect of reclamation the new sand, instead of adding to the system directly, is generally added in the lump breaking stage of the reclamation process so that grains are, to some extent, get modified before mixing and moulding. 3) HOW RECLAMATION IS DONE Sand Reclamation can be termed as the process of reconditioning of used / demoulded sand in a foundry without lowering its original properties, which are particularly required for foundry application. Reclamation may be done by various methods - namely: Ø Ø Ø Ø Attrition (Mechanical) Reclamation Thermal Reclamation Combination of the above Wet Reclamation Attrition Reclamation process is capable of converting, at economic rate, the used recycled sand with low binder content, without foreign material and with even grain size distribution - all that are required for producing good quality mould / core. The reclaimed sand is delivered at sufficiently low temperature useable for core / mould making. Attrition reclamation is done by wearing binders from the sand grain through a series of mechanical processes. Since all the binder is not removed by this process, in most of the cases about 10 to 20 % new sand is added to keep the LOI within limit. Attrition-reclaimed sand of certain binder system can generally be re-used for the same binder system only. It cannot be for re-used in other binder system, in most of the cases, or as new sand because of presence of residual binder. For such requirements the Thermal Reclamation process is the only means by which this can be achieved. Thermal Reclamation is the process in which the sand is heated to a temperature of about 800 deg. C, in a specially designed fluidized bed Combustor which is the main equipment of the thermal reclamation system. In the Thermal Reclaimer, the sand grains obtained from the lump breaker is generally preheated and fed into the combustor where it is fluidized by precisely controlled air flow at desired pressure. The fluidized bed also receives LPG / Natural gas at controlled rate which burns in the fluidized bed with oxygen available in the fluidizing air in the bed. The binder in the sand is totally burnt and hot reclaimed sand is obtained at the outlet of the Combustor. However in the Wesman Thermal Reclaimer, the sand grains obtained after breaking the lumps are preheated in a heat exchanger and fed into the Combustor at a pre-determined rate. Here it is fluidized by precisely controlled preheated air. The fluidized bed of sand receives controlled stream of flame and hot products of combustion from a specially designed combustion system. In this, apart from LPG / Natural gas, liquid fuel like LDO / HSD can also be used as source of heat. This is an added advantage as Natural gas is not available in many Foundry locations /clusters and LPG is very expensive, whereas LDO / HSD is available everywhere and are not as expensive as LPG. Following equipment are included in Wesman Thermal reclamation unit. 21

24 1. Lump Reducer Reduces the de-moulded sand lump in to sand grains in a vibrating unit fitted with unbalance motor. 2. Pneumatic sand transporter to deliver the de-moulded and reduced sand grains to the return sand storage silo. 3. Screw Feeder feeds this sand in to sand preheating unit. 4. Sand preheating unit, fitted at the inlet of the Fluidised bed combustor to preheat the incoming return sand by using waste heat in the flue coming out from the combustor. 5. Air preheater for further extracting waste heat from flue. 6. Fluidised bed combustor where the preheated sand is feed from the Sand pre-heater by a screw feeder and fluidised by preheated air. Preheated sand is further heated to about 800 O C by heat provided from the Wesman combustion system. The combustion system includes combustion air fan, Burner system suitable for Natural gas, LPG or liquid fuel like LDO / HSD, regulators and automatic controller. 7. Skip Hoist for transporting hot reclaimed sand in to hot sand silo at the inlet of the cooler in a particular model. In other models the hot reclaimed sand flows directly into the fluidized bed cooler. 8. Fluidized bed Cooler where the hot reclaimed sand is cooled to usable temperature by means of fluidizing air as well as cooling coil. 9. Pneumatic sand transporter for delivering the cooled reclaimed sand to the sand storage silo for reuses. 10. Dust extraction system having suction points at various stages of reclamation for removing dust as well as for classification of sand. The schematic of the Wesman Thermal reclamation process is shown below. For certain binder system further processing of the thermally reclaimed sand would be required. In these binder systems layer of burnt binder still remains adhered to the sand grains. Attrition / rubbing would be required for total removal of this burnt layer from the sand grain so that totally reclaimed sand, which is generally better than new sand, is obtained at the end of reclamation process. 4) ADVANTAGES Thermal reclamation process is, in many ways, better than attrition (mechanical) reclamation process for the following reasons: 22

25 1. New sand has higher thermal expansion. During pouring, the mould expands excessively and causes distortion, instability and dimensional inaccuracy. When sand is heated above 600 Deg. C, the same undergoes phase change which is permanent in nature. This phase-changed sand has lower thermal expansion and, therefore, all the problems mentioned above are less and casting of more accurate shape and dimension is obtained. 2. Unlike mechanical reclamation, 100% sand, except those reduced to dust, is reclaimed to betterthannew condition. 3. In majority of the cases thermally reclaimed sand, irrespective of the original binder system, can be reused in any system of sand green sand or chemically bonded sand with any chemical binder. Thermally reclaimed 4. Chemically bonded sand can even be used for green-sand system and vice-versa. 5. Though generally Natural gas or LPG is used as fuel, Wesman's Thermal Sand Reclaimer can be fired with Light oil which is available everywhere. This is a great advantage as most of the locations where Foundries are located / clustered do not have supply of Piped Natural Gas, CNG or CBM. If they have to use Gaseous fuel, they would be forced to use LPG which is comparatively more expensive. Whereas oil is available everywhere and only about 8 to 10 Liters of oil would be required for reclamation of 1 MT of sand. Wesman's Thermal Sand Reclaimer can be used for reclaiming Shell sand, Phenolic 2-part/3-part sand, Furan sand etc. Even Green sand may be reclaimed with additional downstream equipment. 5) CONCLUSION The thermal sand reclaimer eliminates air and ground water pollution from discarded sand which are chemically bonded and toxic. It also reduces / eliminates requirement for natural resource like new sand which is presently a scarce commodity. This would help conservation of natural resources. This is very important especially in view of restrictions imposed by Government for mining sand in some states. It may be mentioned that just for drying of 1 MT of new sand 8 to 10 Liters of oil is required in well designed Fluidized bed sand dryer. Ordinary rotary sand dryer consumes at least 10 to 12 Liters of oil for drying 1 MT of new sand. Whereas for reclaiming 1 MT of used sand only 7 to 9 Kg of LPG or 8 to 10 Liters of oil would be required. Therefore one can obtain better than new sand at a cost of drying alone for the same quantity of sand. This is a highly ENERGY EFFICIENT process. Thermal reclamation should be adopted by the foundry men as it 1. Is an economical proposition. 2. Eliminates cost of dumping of used sand. 3. Conserves natural resources by eliminating requirement of NEW sand. 4. Conserves energy spent in drying new sand as drying would not be required. 5. Conserves energy of transportation and eliminates related pollution. 6. Conserves natural environment by eliminating dumping of used toxic sand. 7. Is an ENERGY EFFICIENT process. 23

26 ELECTROTHERM

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28 Additive Manufacturing A BOON TO CASTING ENTREPRENEURS Muddassir Ahmed - Manager Trainings Muddassir@ktdmc.com - KTDMC 3D printed model of Eiffel TowerIt seems like science fiction come to life: a machine that rapidly manufactures almost anything you ask of it, from a pin to an aircraft part. 3-D printing, which is also known as Additive Manufacturing, because it creates an object by adding material in the form of powder or liquid, layer by layer, as opposed to traditional subtractive manufacturing. No matter what the shape and complexity of the part is, it just need the 3d format file to have the physical 3D printed part in your hand. The charismatic techniques of 3D printing helped many industrial sectors to boost up worldwide like Aerospace, Automobile, Medicine, Defense, Fashion etc. In Pakistan, Jewelry sector has experienced the magic's of Additive Manufacturing technology in the form of wax patterns of different ornaments which they are using directly for casting successfully. For local Casting Industry in Pakistan, benefits and application of Additive Manufacturing are summarized below. Benefits For CASTING INDUSTRY: ü ü ü ü ü ü ü Complexity to manufacture the part/ patterns/ mould/core is of no issue since the part built layer by layer through this technology. Shrinkage allowance could be accommodated directly in casting patterns Greatly helps in modification of casted parts/ patterns etc. Consistent quality Cost effective in many cases, especially when there is a high rate of material removal in machining required No high tech skills required Time efficient Specific Applications in Casting Industry: Sand Casting; MOLD and CORE can be directly printed, eliminating the need of pattern and core boxes as compared to traditional ways. Molten metal then directly poured into the 3D printed mold to get the casted part in hand. Patterns could also be produced directly from 3D printing and a best fit specially when: Ø Molds are intended for prototype or production use Ø Casting designs need verification Ø Gate and runner refinements are likely Ø Castings will be complex or large Investment Casting: Print the pattern for investment casting directly from 3D-printer. Shrinkage allowance could be accommodated directly in 3D CAD model which is giving advantage over the traditional way of producing patterns. 26

29 For Design Validation of Casted Parts: Ø Ø Print the part directly from 3D software to verify the aesthetics of design Check the fits and forms of the part before starting serial production For Functional CASTED Parts of Low Volume: Ø Ø Address limited number of functional parts directly from 3D printer without investing heavily on tooling. It is possible to redesign casted parts with relatively thin skins that include internal lattice/mesh structures instead of solid material throughout, which can substantially reduce the amount of material, weight, and build time. It is also possible to redesign parts using topology optimization methods of letting mathematics decide where to put the material to optimize the strength to weight ratio. For Pressue Die Casting Moulds: Print the "insert of pressure die casting mould", especially when: Ø The machining is too complex Ø 3D conformal cooling channels are required to increase the part production rate Ø There is a high rate of material removal is required- since there is no wastage of material in 3D printing There is a gold rush of patents in 3D printing. Out of them SLS (selective laser eintering), SLA (stereo-lithography), DLP (digital light 3D cooling channels for "Pressure Die Casting Mould" processing) and FDM (fused deposition modeling) are the most beneficial technologies and fortunately present in Pakistan. A list of material options is available with related technologies. Following is the chart summarizing different technologies of Additive Manufacturing: S. No Patent Name FDM SLS DLP 3D Printing Manufacturer Stratasys 3D systems EnvisionTech 3D systems (Z corp.) Availability in Pakistan In 2012, sales for all the 3D printing products and services worldwide grew 60% to $2.2 billion, as compared to 2010, but still there is a lot need to do in this field. Experts throughout the world are using this technology synergistically. In Pakistan, it is needed to bridge the gap between the casting industry and the service providers of 3D printing through proper awareness program. We also have experts at doctorate level in Pakistan who had participated in the developments of these patents abroad. Now they are willing to do something for local industry. This will open the new frontier for the casting industry and keep the local expertise and investments pledged for this technology away from dearth. Yes Yes Yes Yes Materials Equivalent to ABS Equivalent to P-20 ( Medium Carbon Steel), ABS Equivalent to ABS 04 SLA 3D systems Yes Equivalent to ABS 05 SLS EOS No Steel Alloys, Titanium, Aluminum Alloys etc. 06 DLP 3D systems Yes Equivalent to ABS Composite material, Elastomeric, Cast 27

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32 CBI's project for Metalworking sector Pakistan and Memorandum of Cooperation CBI's project for Pakistan is one of the four projects of the program for the Metalworking Sector Asia. On January12, 2013, in the 1st Coordination Meeting CBI local expert Mr. Imtiaz Rastgar and Mr. Zaheeruddin Dar elaborated the whole idea and expressed the hope that outcomes of this program will have far reaching constructive impacts especially on the SME of Pakistan. Stakeholder meeting was conducted on October 11, 2013 for a discussion on Export Coaching Program. The Engineering Development Board hosted this meeting in its Conference Room. Trade Development Authority of Pakistan, Engineering Development Board, Small and Medium Enterprise Development Agency, National Productivity Organization, Pakistan Association of Auto parts and Accessories Manufacturers and Pakistan Foundry Association are the six organizations who participated in the meeting and acknowledged their efforts positively by enrolling themselves into the program. CBI proposed, a "Memorandum of Cooperation" and was signed by the stakeholders of six Pakistani BSOs, CBI and Mr. Robert Dresen -First Secretary/ Head Economic affairs to run joint export promotion programs by.. Ø Joint planning and execution of export promotion programs for engineering and metal working industry. Ø Support each other in export promotion of engineering and metal working products by combining organizational strengths and resources. Ø Run joint Export Coaching programs on the lines of the programs offered by CBI. It is a fact that the above-mentioned organizations want to avoid duplication and wastage of resources, effort and time through cooperation. The common objective is to develop Pakistan through export boost of engineering goods from Pakistan can only be met through mutual cooperation, support to each other and coordinated efforts to achieve efficiency, effectiveness and synergy EDB, TDAP, NPO, PFA, PAAPAM and SMEDA have agreed to join hands. 30

33 Veteran Foundrymen and Genius say Goodbye Mohammad Shareef, Chairman and founder of Hi-tech Foundry. As a child, while living in a village of Ludhiana, India, he read the blue prints of a wind turbine and, with sparse resources, successfully fabricated a working windmill that generated electricity. A polymath who played with mathematics, electrical, civil, and mechanical engineering, science was his greatest passion. After the day's work, he would return home to his private workshop and sanctuary that he had built on a very tight budget to make his own aero engines, machines, and model aircraft His Picture Mohammad Shareef ( ) While visiting friends he could teach their children how to make radios from kits, fool's gold, or simple electronic components and inspire them to have a passion for science. He started his career in All India Radio as an internee and rose to head the Equipment Production Unit of Radio Pakistan. During WW-II, when a shipment of recording media went missing, he singlehandedly and on a emergency basis, developed his own recording disc from scratch for All India Radio and presented it to the British Chief Engineer to whom he reported. From a humble radio engineer he went on to start his own metal casting business; his own foundry after retirement. After a rough, sweaty, and exhausting field day in his foundry, he would find time to sit down for his nocturnal prayer rituals. After that he would retire to his bed and while still holding a meditative state and counting his prayer beads, allow himself to gradually glide into a dream state. Despite humble schooling of a village, he would express his deepest emotions so immaculately in English poetry that he would be published for local journals and English newspapers. Some of Allama Iqbal's famous works too were translated by him and this part time passion of his is arguably one the best in preserving the essence of Iqbal's transcendental message. Those who had the pleasure of knowing him can safely say that today we lost a genius who served Pakistan and his fellow men to the best of his abilities. His is life worth remembering, emulating and celebrating. (Imtiaz Rastgar) Mian Sultan Noorani, CEO of Noorani Industries (Pvt Ltd) left us on this 13th Aug, He was man of great vision and energy. In Textile sector his contributions were enormous he was the PIONEER in Pakistan for locally manufacturing and exporting Textile Processing, Dyeing & Finishing machinery. He had developed Import Substitution machinery. In Agriculture sector his work was remarkable, he developed Water and Resources Conservation Tec hnologies and was first to introduce locally manufactured Drip Irrigation System in Pakistan. H e wa s o n e o f f ew industrialist of the country who developed strong linkage between industry and academia. He helped University of Agriculture, Faisalabad, researchers in their assignments related to farm machinery and developed lot of new innovations in agri sector. In education sector his efforts were commendable, he was one of founder member for TEVTA and PVTC BOM and played huge role and developed practical and industry oriented course outline and syllabus for many disciplines for students. He was District Governor of Pakistan for Lions Clubs International, USA in the year He was very active member of Pakistan Foundry Association. His other assignment/activities were: MEMBER, ACADEMIC ACTIVITIES UNIVERSITY OF AGRICULTURE, FAISALABAD EXECUTIVE MEMBER,B.O.M PVTC MEMBER,B.O.M TEVTA CHAIRMAN, TECHINICAL & HIGHER EDUCATION STANDING COMMITTEE, FCCI FAISALABAD. CHAIRMAN, TEXTILE MACHINERY STANDING COMMITTEE, FCCI FAISALABAD. CHAIRMAN, PAMIMA (FOR ) PRESIDENT,FOUNDRY OWNERS TRADE GROUP (FOR 3 YEARS) VICE PRESIDENT OF TEXMAP His activeness and enthusiasm is inspiration for generations to the come. We pray to Allah SWT for his eternal salvation and for his family to carry forward his life's work. For Condolences please contact His Son Mr. Zeeshan Ali Noorani

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