- Email: [email protected]
Conserving Resources in Production - Breaking New Ground
Available online at www.sciencedirect.com
ScienceDirect Procedia Manufacturing 8 (2017) 619 – 626
14th Global Conference on Sustainable Manufacturing, GCSM 3-5 October 2016, Stellenbosch, South Africa
Conserving resources in production - Breaking new ground D. Landgrebea,b, V. Kräuselb, M. Bergmanna*, M. Wernera, A. Rautenstraucha,b a
Fraunhofer Institute for Machine Tools and Forming Technology, Reichenhainer Straße 88, 09126 Chemnitz, Germany Professorship for Machine Tools and Forming Technology, Technische Universität Chemnitz, Reichenhainer Straße 70, 09126 Chemnitz, Germany
b
Abstract Many approaches focus on more efficient production processes, on avoiding waste and scrap and on more efficient use/operation of products within one life cycle, i.e. from raw materials to the end of use. All these approaches share the goal of an increase in resource efficiency. In contrast, the reProd® approach is characterized by a comprehensive view of cycles. By shortening the cycle process, a huge potential can be opened up for metal products regarding a reduction of energy requirements and CO2 emissions. Approx. 70% to 90% of the energy requirements and also of the greenhouse gas emissions are necessary for melting the metals and for the first processing stage. If secondary semi-finished products are obtained from used goods, energy-intensive processes are eliminated. Thus a decisive contribution for the energy turnaround and for protecting climate and environment lies in “non-destructive recycling” and “re-use without melting” 2016Published The Authors. Published by Elsevier B.V. ©2017 © by Elsevier B.V. This is an open access article under the CC BY-NC-ND license Peer-review under responsibility of the organizing committee of the 14th Global Conference on Sustainable Manufacturing. (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of the 14th Global Conference on Sustainable Manufacturing Keywords: material cycle, recycling economie
1. Introduction The availability of raw materials has increasingly become a strategic factor for industrial nations with few raw material deposits and high export rates due to economic and social reasons [1]. Industrial manufacturers are faced with increasing challenges in the following areas: materials used in the product, material availability and missing material logistics chains, flexible production on the global market with short innovation cycles, cost for resources and energy, resource consumption in production and instruments for holistic management of sustainability in order
* Corresponding author. Tel.: +49-371-5397-1302 49; fax: +49 371 5397-61302 E-mail address: [email protected]
2351-9789 © 2017 Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of the 14th Global Conference on Sustainable Manufacturing doi:10.1016/j.promfg.2017.02.079
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to optimize process chains. Resource management, resource efficiency and recycling are main elements of global and political strategies and models regarding sustainable development for a growing global population. The European Union and the Federal Republic of Germany have each developed a strategy for sustainability and raw materials with resource management playing a major role. In Germany several networks and platforms are active in the identified leading market of “recycling” [2]. “Green economy” is the future scenario of the report on the environmental economy 2011 by the Federal Environment Agency. In 2008 companies of the manufacturing industries had an average proportion of the cost for raw materials, indirect materials and operating supplies of approx. 45% of the gross production value, which was more than double the proportion of the cost for wages, which amounted to 18% in 2008. In sectors that are particularly depending on raw material prices such as the automotive industry or the mechanical engineering industry, the cost for materials is already above 50% of the gross production value. However, the focus lies on labor productivity: While material productivity in Germany increased by a factor of 2 between 1960 and 2005, labor productivity increased by a factor of 4 within the same period of time [3]. By opening up potentials of resource efficiency associated with cost reduction, competitiveness of small and medium-sized companies can be boosted on the domestic and export market. Furthermore a relevant contribution can be made to save resources, also regarding developing future technologies [4]. Typical sectors of application include sheet metal processing industries, automobile manufacturers and suppliers, building technology and facade engineering, power engineering and manufacturers of application products (e.g. IT components). In 2008 raw materials with a total worth of Euro 126.7 bn were imported into Germany, of which the share for metals was 22% (without noble metals). Potential estimates for the year 2020 assume that increased recycling rates and optimized material exploitation can avoid greenhouse gas emissions of up to 10 million tons of CO2 equivalent compared to 2006 [5, 6]. 2. Circular economy 2.1. Material cycle The technical material cycle describes the cycle of successive product life cycles, starting with product development and ending with disposal. In this context three principles of today’s society shall be described in further detail. The principle of the “throwaway economy” corresponds to a cycle only to a limited extent. The term itself originates from the surplus or consumer society. This economic principle is characterized by the so-called throwaway mentality and pursues production that is not oriented towards sustainability. Often repairable or completely usable goods are disposed in favor of new goods. This principle is based on surplus production and on production of unnecessary or short-lived items in a society whose behavior is guided by the possibilities of consumption rather than necessity [7]. The cost of the throwaway economy is huge. The United Nations estimate that cities and communities worldwide spend an average of 20% to 30% of their budgetary funds for collecting and disposing of waste [8].
D. Landgrebe et al. / Procedia Manufacturing 8 (2017) 619 – 626
Fig. 1. General procedure - scheme of material recycling [9]
Material recycling of metals currently comprises processes for recovering or manufacturing metallic secondary products, see Figure 1. Several processes are passed for material recycling, starting from dismantlement and mechanical treatment, to sorting and homogenization (usually melting process or using chemical processes, depending on the metal properties), up to separation of impurities and manufacturing of recycling products (e.g. metal blocks, metal powder etc.) [9]. The described recycling of metallic products can be assumed to take place in virtually closed cycles in Germany. The recirculation of the metallic materials is characterized by an energy consumption of 23 GJ/t for steel production all the way up to semi-finished products, see Figure 2 [10].
Fig. 2. Energy consumption of steel process
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2.2. Cradle to Cradle Raw materials have become rarer and environmental awareness has risen. These reasons started a rethinking process. The idea of a cycle is the core of any economically and ecologically sustainable economy. The “cycle economy” stands for a system of waste and economy where natural resources are limited to a minimum. Instead raw materials are used as efficiently and as long as possible or they are recycled energetically. Ideally the materials are in a permanent cycle of recycling and only a minimum portion ends up in landfills [8]. The production principle “from cradle to grave” is replaced by Baungart’s principle “from cradle to cradle”. In this case the materials are selected very carefully for the production process in the first place: only materials are selected that are either 100% biodegradable (cycle of consumption) or that can be recirculated into the production process at 100% (technical cycle), see Figure 2 [11].
Biological cycle for consumables
Technical cycle for non-consumables
Fig. 3. Cycles for consumables and non-consumables [11]
2.3. reProd® approach Currently, in the recycling of old products like end-of-life vehicle or electronic waste down-cycling take place. Down-cycling is an inefficient use of material properties. A new solution demonstrates the reProd® approach. The reProd® approach describes the direct recirculation of products into new production cycles and utilization cycles, see Figure 3. Thus the conventional recycling process is shortened by using existing products or product components as secondary semi-finished products for producing new, different or differently designed products with significant benefits or a high level of added value. Shortening the cycle of reusable materials implies the elimination of sorting, processing and melting down. As a consequence, resource savings are achieved as regards reducing energy requirements and emissions by up to 70%. This approach differs distinctly from the current recycling of products, parts or materials. The term recycling of products or parts is defined as the reuse of products or parts. The shape of the product remains mostly the same and the existing product function is used again. Furthermore the following differentiation applies: x Reuse - Recycling during product use (example: reuse of car clutches) and x Further use - Recycling of old parts/old materials (example: further use of computer components in children’s toys). Material recycling is defined as utilization with the shape of the product being dissolved in order to use the product material again. This utilization can be differentiated as follows: x Reutilization – Recycling by production return (example: melting down metals) and x Further utilization - Recycling by raw material extraction (example: utilization of “scrap rubber” as filler material).
D. Landgrebe et al. / Procedia Manufacturing 8 (2017) 619 – 626
The reProd® approach has the objective to utilize components of products as secondary semi-finished products after their use phase. A possible example, which was selected for a feasibility study, consists in using a car component (roof) as a secondary semi-finished product for manufacturing a chair-back.
Fig.4. reProd® material cycle as approach for conservation of resources with minimum energy input, thus reduction of CO 2 emissions [13]
3. Feasibility study 3.1. Technical feasibility In order to verify the feasibility of the presented reProd® approach, a study was conducted dealing with the development of a new, shortened material cycle. The study was based on the motivation to considerably reduce the energy used for the process of melting down metals and to reduce the amount of carbon generated during this process. The existing recycling process was to be shortened by manufacturing secondary semi-finished products from existing products. Any secondary semi-finished product consists of a product with unknown original material. Thus no conclusions can be drawn as regards the forming potential. The latter was reduced during the primary production process and during further use in the product life cycle. Other aspects to consider include the dimension of the component and the resulting initial dimension of the secondary semi-finished product. These influencing variables have to be known or limited in order to allow for further processing. Requirements also have to be specified for the original product from which the secondary semi-finished product is manufactured. Furthermore a sufficient amount of the original product shall be available and a continuous supply of the same shall be ensured so as not to interfere with the production of the secondary semi-finished product. Within the framework of the feasibility study Fraunhofer IWU demonstrates the example of forming car components into chairs. The feasibility was verified using the example of the processing route from a car sheet metal roof to a chair component, the chair-back (see Figure 4). Secondary semi-finished products were manufactured by disassembly and processing of a car roof. Various characteristic values of components and materials such as characterizing the forming capacity were investigated in order to verify the requirements placed on the secondary semi-finished product. Tensile and bulge tests were performed to determine the forming limit diagram. After the suitability had been confirmed, the secondary semi-finished products were transferred to the manufacturing process chain. The object of investigation comprised the determination of an appropriate process chain. This investigation covered the following process stages, e.g. heat treatment, removing the coating of the blank
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and sheet metal hydroforming. It became apparent that cleaning of the components was necessary in the presented application example. However, literature research proves that forming of powder-coated semi-finished products is possible and can be implemented industrially [12]. The process stage of heat treatment, in particular annealing, can be eliminated for manufacturing the secondary product chair-back. In general the process chain depends on the boundary conditions of the original product and on the stages of further processing. Depending on the initial state of the secondary semi-finished product, process stages have to be added or eliminated, such as cleaning, straightening or annealing.
Fig. 5. Production chain of a secondary semi-finished product [13]
The results of the study showed that new products can be manufactured from secondary semi-finished products when considering the boundary conditions. The conducted investigations demonstrated the technological feasibility using a simple component, thus proving that the conventional recycling process can be shortened. Knowledge is required regarding the material group of the original product and its production history. Moreover, the requirements on the secondary semi-finished product shall permit a range of tolerance [13]. 3.2. Economic evaluation Furthermore, a speculative economic evaluation was conducted as part of the feasibility study. This evaluation is based on dynamic market prices, i.e. the underlying cost and prices are fair values that are strongly influenced by market fluctuations. Thus this evaluation presents a snapshot in time. Table 1. Calculated price. reProd® approach
conventional material recycling
Process steps
calculated costs €/kg
Process steps
calculated price €/kg
Initial product
0.06
Initial product
0.06
Dismantling
0.1
Recycling
0.17
Cutting
0.03
Steel making process
0,17
Cleaning
0.04
Semi-finished product
0.23
Semi-finished product
0.4
Using the performed cost analysis for resource-saving recycling of the secondary semi-finished products, the reProd® approach, a basic savings potential of approx. 42% can be presented. The cost-intensive process stage of
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the conventional material cycle is the steel production. It requires 42% of the entire cost of the conventional material cycle. In summary the presented savings potential is based on researched prices and assumptions and it has to be validated regarding its transferability into industry. 4. Obstacles 4.1. Recycling economy in Germany The recycling markets are characterized by a number of features making it harder to establish novel material cycles. In order to overcome these obstacles and to optimize the cycle management, specific instruments have to be developed. Significant impulses for recycling were provided by past technological innovations in sorting technology. A predominant problem in the German cycle economy is the oligopoly to monopoly type structure of the recycling markets. In the last decades, German waste management has developed material and thermal recycling of waste into a lucrative business. Consequently, a “fight for waste” has formed. This is demonstrated by the overcapacity of waste incineration plants (i.e. thermal recycling). With the beginning of the economic crises, this phenomenon caused a lack of materials required for material recycling. Additionally, a significant amount of material flows are directed abroad, for instance, waste electrical equipment or scrap cars. In order to counteract this tendency, however, suitable systems are missing for collecting and high-quality recycling of the contained metals. Moreover, further development of the legal framework is uncertain, for example announcing the introduction of a law on recyclable materials. As a result, the cycle economy receives low investments are for research and development [14]. 4.2. Implementation of the reProd® approach There are various challenges to be met in order to implement the reProd® approach. First of all, initial end of live products respectively components have to be identified and matched to target products. Regarding quantities and geometrical aspects, not all components could be used as a resource for the proposed approach. Another requirement consists in creating structures to ensure guaranteed availability of end-of-life products. This guarantee allows the manufacturer to apply dependable planning for manufacturing new products. Additionally, evaluating the quality of secondary semi-finished products is considerably more difficult than it is for primary raw materials. The supplier has to cover large expenses for determining the state, classification and processing of end-of-life products into secondary semi-finished products that meet the requirements. This directly influences the pricing. The customer cannot check the quality specifications unless he does so at his own expense. A comparison of all the information between the participants such as the specific requirements on the secondary semi-finished product, proof of quality, availability etc. is associated with transaction cost that has not yet been calculated. Thus this poses an uncertainty, especially for the supplier. The flexible manufacturing process chain designed according to the requirements is a challenge in terms of production technology. Integrating secondary semi-finished products is related to uncertainties and tolerances. In order to handle these obstacles, the manufacturer has to be able to react flexibly. All listed items have a potential for individual research. 5. Summary and outlook The presented reProd® approach describes a path to shorten the existing material cycle. It includes a considerable reduction of the existing recycling process, i.e. savings of approx. 70%. Within the framework of a conducted feasibility study, the direct recirculation of components into a new production cycle or utilization cycle was verified. Moreover, the calculation of economic efficiency results in a savings potential of approx. 42% for the reProd® approach compared to the existing material cycle. In order to demonstrate the previous results, further research activities are planned. Furthermore, extensive market analyses are conducted which shall indicate a possible integration of the reProd® approach into existing market structures. In addition, a business model for recycling companies is developed. It describes various recycling
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scenarios, i.e. various initial products are included which pass through different stages of recycling. The objective is to develop a concept for calculating the cost, meeting the new requirements of the reProd® approach.
References [1] Angerer G, Erdmann L, Marscheider-Weidemann F, Scharp M, Lüllmann A, Handke V, Marwede M. Rohstoffe für Zukunftstechnologien Einfluss des branchenspezifischen Rohstoffbedarfs in rohstoffintensiven Zukunftstechnologien auf die zu-künftige Rohstoffnachfrage, Stuttgart: Fraunhofer IRB Verlag, 2009. [2] Selection URL: http://www.deutsche-rohstoffagentur.de, http://www.vdi-zre.de/, http://www.demea.de/, http://www.netzwerkressourceneffizienz.de/, http://www.efanrw.de/, 2015.12.15. [3] Deutsches Ressourceneffizienzprogramm BMU http://www.bmu.de/fileadmin/bmu-import/files/pdfs/allgemein/application/pdf/progress_bf.pdf, 2015.12.15. [4] Netzwerk Ressourceneffizienz- http://neress.de/fileadmin/media/files/Progress/ProgRess-Entwurf_Version_3.0_final.pdf, 2015.12.15. [5] Bundesverband der Deutschen En-tsorgungs-, Wasser- und Rohstoffwirtschaft e. V. BDE (Hrsg.): Recycling stoppt Treibhausgase - Der Beitrag der Kreislauf- und Wasserwirtschaft zum Klimaschutz, Kurzfas-sung, erstellt durch ifeu und Öko-Institut, 2010. [6] Dehoust G, et al. Klimaschutzpotenziale der Abfallwirtschaft - Am Beispiel von Siedlungsabfällen und Altholz, FKZ 3708 31 302 im Auftrag des Umweltbundesamtes, Januar 2010. [7] Reuß J, Dannoritzer C. Kaufen für die Müllhalde - Das Prinzip der geplanten Obsoleszenz. Freiburg: Orange Press, 2013. [8] Bundesministerium für Umwelt, Naturschutz und Reaktorsicherheit; Green Tech Made in Germany 2.0; München: Verlag Vahlen, 2009. [9] Martens H. Recyclingtechnik – Fachbuch für Lehre und Praxis, Heidelberg, Spektrum Akademischer Verlag, 2011. [10] Milford R L. The effects of yield on embodied energy and CO2 in four case study metal products,Wellmet 2050 working paper w8, 2011. [11] Cradle to Cradle® - http://epea-ham-burg.org/de/content/n%C3%A4hrstoffkreisl%C3%A4ufe, 2015.12.15 [12] Gedan-Smolka, M.; Edelmann, M.; Demmler, M.: Umformung pul-verbeschichteter Platinen als wirtschaftliche Alternative zur klassischen Stückgutbeschichtung. In: Journal für Oberflächentechnik 46 (8), 2006, p. 18 – 20. [13] Landgrebe D, Bergmann M, Kräusel V, Rautenstrauch A, Werne M, Laue R. Ressourcenschonende Produktion - Neue Wege bestreiten reProd®-Ansatz. ZWF - Zeitschrift für wirtschaftlichen Fabrikbetrieb, Jahrg. 110 (11), Carl Hanser Verlag, 2015, p. 2 – 5. [14] Wilts H, Lucas R, von gries N, Zirngiebl M. Recycling in Deutschland Status quo, Potenziale, Hemnisse und Lösungsansätze – Studie im Auftrag der KfW Bankgruppe, November 2014.
ScienceDirect Procedia Manufacturing 8 (2017) 619 – 626
14th Global Conference on Sustainable Manufacturing, GCSM 3-5 October 2016, Stellenbosch, South Africa
Conserving resources in production - Breaking new ground D. Landgrebea,b, V. Kräuselb, M. Bergmanna*, M. Wernera, A. Rautenstraucha,b a
Fraunhofer Institute for Machine Tools and Forming Technology, Reichenhainer Straße 88, 09126 Chemnitz, Germany Professorship for Machine Tools and Forming Technology, Technische Universität Chemnitz, Reichenhainer Straße 70, 09126 Chemnitz, Germany
b
Abstract Many approaches focus on more efficient production processes, on avoiding waste and scrap and on more efficient use/operation of products within one life cycle, i.e. from raw materials to the end of use. All these approaches share the goal of an increase in resource efficiency. In contrast, the reProd® approach is characterized by a comprehensive view of cycles. By shortening the cycle process, a huge potential can be opened up for metal products regarding a reduction of energy requirements and CO2 emissions. Approx. 70% to 90% of the energy requirements and also of the greenhouse gas emissions are necessary for melting the metals and for the first processing stage. If secondary semi-finished products are obtained from used goods, energy-intensive processes are eliminated. Thus a decisive contribution for the energy turnaround and for protecting climate and environment lies in “non-destructive recycling” and “re-use without melting” 2016Published The Authors. Published by Elsevier B.V. ©2017 © by Elsevier B.V. This is an open access article under the CC BY-NC-ND license Peer-review under responsibility of the organizing committee of the 14th Global Conference on Sustainable Manufacturing. (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of the 14th Global Conference on Sustainable Manufacturing Keywords: material cycle, recycling economie
1. Introduction The availability of raw materials has increasingly become a strategic factor for industrial nations with few raw material deposits and high export rates due to economic and social reasons [1]. Industrial manufacturers are faced with increasing challenges in the following areas: materials used in the product, material availability and missing material logistics chains, flexible production on the global market with short innovation cycles, cost for resources and energy, resource consumption in production and instruments for holistic management of sustainability in order
* Corresponding author. Tel.: +49-371-5397-1302 49; fax: +49 371 5397-61302 E-mail address: [email protected]
2351-9789 © 2017 Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of the 14th Global Conference on Sustainable Manufacturing doi:10.1016/j.promfg.2017.02.079
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to optimize process chains. Resource management, resource efficiency and recycling are main elements of global and political strategies and models regarding sustainable development for a growing global population. The European Union and the Federal Republic of Germany have each developed a strategy for sustainability and raw materials with resource management playing a major role. In Germany several networks and platforms are active in the identified leading market of “recycling” [2]. “Green economy” is the future scenario of the report on the environmental economy 2011 by the Federal Environment Agency. In 2008 companies of the manufacturing industries had an average proportion of the cost for raw materials, indirect materials and operating supplies of approx. 45% of the gross production value, which was more than double the proportion of the cost for wages, which amounted to 18% in 2008. In sectors that are particularly depending on raw material prices such as the automotive industry or the mechanical engineering industry, the cost for materials is already above 50% of the gross production value. However, the focus lies on labor productivity: While material productivity in Germany increased by a factor of 2 between 1960 and 2005, labor productivity increased by a factor of 4 within the same period of time [3]. By opening up potentials of resource efficiency associated with cost reduction, competitiveness of small and medium-sized companies can be boosted on the domestic and export market. Furthermore a relevant contribution can be made to save resources, also regarding developing future technologies [4]. Typical sectors of application include sheet metal processing industries, automobile manufacturers and suppliers, building technology and facade engineering, power engineering and manufacturers of application products (e.g. IT components). In 2008 raw materials with a total worth of Euro 126.7 bn were imported into Germany, of which the share for metals was 22% (without noble metals). Potential estimates for the year 2020 assume that increased recycling rates and optimized material exploitation can avoid greenhouse gas emissions of up to 10 million tons of CO2 equivalent compared to 2006 [5, 6]. 2. Circular economy 2.1. Material cycle The technical material cycle describes the cycle of successive product life cycles, starting with product development and ending with disposal. In this context three principles of today’s society shall be described in further detail. The principle of the “throwaway economy” corresponds to a cycle only to a limited extent. The term itself originates from the surplus or consumer society. This economic principle is characterized by the so-called throwaway mentality and pursues production that is not oriented towards sustainability. Often repairable or completely usable goods are disposed in favor of new goods. This principle is based on surplus production and on production of unnecessary or short-lived items in a society whose behavior is guided by the possibilities of consumption rather than necessity [7]. The cost of the throwaway economy is huge. The United Nations estimate that cities and communities worldwide spend an average of 20% to 30% of their budgetary funds for collecting and disposing of waste [8].
D. Landgrebe et al. / Procedia Manufacturing 8 (2017) 619 – 626
Fig. 1. General procedure - scheme of material recycling [9]
Material recycling of metals currently comprises processes for recovering or manufacturing metallic secondary products, see Figure 1. Several processes are passed for material recycling, starting from dismantlement and mechanical treatment, to sorting and homogenization (usually melting process or using chemical processes, depending on the metal properties), up to separation of impurities and manufacturing of recycling products (e.g. metal blocks, metal powder etc.) [9]. The described recycling of metallic products can be assumed to take place in virtually closed cycles in Germany. The recirculation of the metallic materials is characterized by an energy consumption of 23 GJ/t for steel production all the way up to semi-finished products, see Figure 2 [10].
Fig. 2. Energy consumption of steel process
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2.2. Cradle to Cradle Raw materials have become rarer and environmental awareness has risen. These reasons started a rethinking process. The idea of a cycle is the core of any economically and ecologically sustainable economy. The “cycle economy” stands for a system of waste and economy where natural resources are limited to a minimum. Instead raw materials are used as efficiently and as long as possible or they are recycled energetically. Ideally the materials are in a permanent cycle of recycling and only a minimum portion ends up in landfills [8]. The production principle “from cradle to grave” is replaced by Baungart’s principle “from cradle to cradle”. In this case the materials are selected very carefully for the production process in the first place: only materials are selected that are either 100% biodegradable (cycle of consumption) or that can be recirculated into the production process at 100% (technical cycle), see Figure 2 [11].
Biological cycle for consumables
Technical cycle for non-consumables
Fig. 3. Cycles for consumables and non-consumables [11]
2.3. reProd® approach Currently, in the recycling of old products like end-of-life vehicle or electronic waste down-cycling take place. Down-cycling is an inefficient use of material properties. A new solution demonstrates the reProd® approach. The reProd® approach describes the direct recirculation of products into new production cycles and utilization cycles, see Figure 3. Thus the conventional recycling process is shortened by using existing products or product components as secondary semi-finished products for producing new, different or differently designed products with significant benefits or a high level of added value. Shortening the cycle of reusable materials implies the elimination of sorting, processing and melting down. As a consequence, resource savings are achieved as regards reducing energy requirements and emissions by up to 70%. This approach differs distinctly from the current recycling of products, parts or materials. The term recycling of products or parts is defined as the reuse of products or parts. The shape of the product remains mostly the same and the existing product function is used again. Furthermore the following differentiation applies: x Reuse - Recycling during product use (example: reuse of car clutches) and x Further use - Recycling of old parts/old materials (example: further use of computer components in children’s toys). Material recycling is defined as utilization with the shape of the product being dissolved in order to use the product material again. This utilization can be differentiated as follows: x Reutilization – Recycling by production return (example: melting down metals) and x Further utilization - Recycling by raw material extraction (example: utilization of “scrap rubber” as filler material).
D. Landgrebe et al. / Procedia Manufacturing 8 (2017) 619 – 626
The reProd® approach has the objective to utilize components of products as secondary semi-finished products after their use phase. A possible example, which was selected for a feasibility study, consists in using a car component (roof) as a secondary semi-finished product for manufacturing a chair-back.
Fig.4. reProd® material cycle as approach for conservation of resources with minimum energy input, thus reduction of CO 2 emissions [13]
3. Feasibility study 3.1. Technical feasibility In order to verify the feasibility of the presented reProd® approach, a study was conducted dealing with the development of a new, shortened material cycle. The study was based on the motivation to considerably reduce the energy used for the process of melting down metals and to reduce the amount of carbon generated during this process. The existing recycling process was to be shortened by manufacturing secondary semi-finished products from existing products. Any secondary semi-finished product consists of a product with unknown original material. Thus no conclusions can be drawn as regards the forming potential. The latter was reduced during the primary production process and during further use in the product life cycle. Other aspects to consider include the dimension of the component and the resulting initial dimension of the secondary semi-finished product. These influencing variables have to be known or limited in order to allow for further processing. Requirements also have to be specified for the original product from which the secondary semi-finished product is manufactured. Furthermore a sufficient amount of the original product shall be available and a continuous supply of the same shall be ensured so as not to interfere with the production of the secondary semi-finished product. Within the framework of the feasibility study Fraunhofer IWU demonstrates the example of forming car components into chairs. The feasibility was verified using the example of the processing route from a car sheet metal roof to a chair component, the chair-back (see Figure 4). Secondary semi-finished products were manufactured by disassembly and processing of a car roof. Various characteristic values of components and materials such as characterizing the forming capacity were investigated in order to verify the requirements placed on the secondary semi-finished product. Tensile and bulge tests were performed to determine the forming limit diagram. After the suitability had been confirmed, the secondary semi-finished products were transferred to the manufacturing process chain. The object of investigation comprised the determination of an appropriate process chain. This investigation covered the following process stages, e.g. heat treatment, removing the coating of the blank
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and sheet metal hydroforming. It became apparent that cleaning of the components was necessary in the presented application example. However, literature research proves that forming of powder-coated semi-finished products is possible and can be implemented industrially [12]. The process stage of heat treatment, in particular annealing, can be eliminated for manufacturing the secondary product chair-back. In general the process chain depends on the boundary conditions of the original product and on the stages of further processing. Depending on the initial state of the secondary semi-finished product, process stages have to be added or eliminated, such as cleaning, straightening or annealing.
Fig. 5. Production chain of a secondary semi-finished product [13]
The results of the study showed that new products can be manufactured from secondary semi-finished products when considering the boundary conditions. The conducted investigations demonstrated the technological feasibility using a simple component, thus proving that the conventional recycling process can be shortened. Knowledge is required regarding the material group of the original product and its production history. Moreover, the requirements on the secondary semi-finished product shall permit a range of tolerance [13]. 3.2. Economic evaluation Furthermore, a speculative economic evaluation was conducted as part of the feasibility study. This evaluation is based on dynamic market prices, i.e. the underlying cost and prices are fair values that are strongly influenced by market fluctuations. Thus this evaluation presents a snapshot in time. Table 1. Calculated price. reProd® approach
conventional material recycling
Process steps
calculated costs €/kg
Process steps
calculated price €/kg
Initial product
0.06
Initial product
0.06
Dismantling
0.1
Recycling
0.17
Cutting
0.03
Steel making process
0,17
Cleaning
0.04
Semi-finished product
0.23
Semi-finished product
0.4
Using the performed cost analysis for resource-saving recycling of the secondary semi-finished products, the reProd® approach, a basic savings potential of approx. 42% can be presented. The cost-intensive process stage of
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the conventional material cycle is the steel production. It requires 42% of the entire cost of the conventional material cycle. In summary the presented savings potential is based on researched prices and assumptions and it has to be validated regarding its transferability into industry. 4. Obstacles 4.1. Recycling economy in Germany The recycling markets are characterized by a number of features making it harder to establish novel material cycles. In order to overcome these obstacles and to optimize the cycle management, specific instruments have to be developed. Significant impulses for recycling were provided by past technological innovations in sorting technology. A predominant problem in the German cycle economy is the oligopoly to monopoly type structure of the recycling markets. In the last decades, German waste management has developed material and thermal recycling of waste into a lucrative business. Consequently, a “fight for waste” has formed. This is demonstrated by the overcapacity of waste incineration plants (i.e. thermal recycling). With the beginning of the economic crises, this phenomenon caused a lack of materials required for material recycling. Additionally, a significant amount of material flows are directed abroad, for instance, waste electrical equipment or scrap cars. In order to counteract this tendency, however, suitable systems are missing for collecting and high-quality recycling of the contained metals. Moreover, further development of the legal framework is uncertain, for example announcing the introduction of a law on recyclable materials. As a result, the cycle economy receives low investments are for research and development [14]. 4.2. Implementation of the reProd® approach There are various challenges to be met in order to implement the reProd® approach. First of all, initial end of live products respectively components have to be identified and matched to target products. Regarding quantities and geometrical aspects, not all components could be used as a resource for the proposed approach. Another requirement consists in creating structures to ensure guaranteed availability of end-of-life products. This guarantee allows the manufacturer to apply dependable planning for manufacturing new products. Additionally, evaluating the quality of secondary semi-finished products is considerably more difficult than it is for primary raw materials. The supplier has to cover large expenses for determining the state, classification and processing of end-of-life products into secondary semi-finished products that meet the requirements. This directly influences the pricing. The customer cannot check the quality specifications unless he does so at his own expense. A comparison of all the information between the participants such as the specific requirements on the secondary semi-finished product, proof of quality, availability etc. is associated with transaction cost that has not yet been calculated. Thus this poses an uncertainty, especially for the supplier. The flexible manufacturing process chain designed according to the requirements is a challenge in terms of production technology. Integrating secondary semi-finished products is related to uncertainties and tolerances. In order to handle these obstacles, the manufacturer has to be able to react flexibly. All listed items have a potential for individual research. 5. Summary and outlook The presented reProd® approach describes a path to shorten the existing material cycle. It includes a considerable reduction of the existing recycling process, i.e. savings of approx. 70%. Within the framework of a conducted feasibility study, the direct recirculation of components into a new production cycle or utilization cycle was verified. Moreover, the calculation of economic efficiency results in a savings potential of approx. 42% for the reProd® approach compared to the existing material cycle. In order to demonstrate the previous results, further research activities are planned. Furthermore, extensive market analyses are conducted which shall indicate a possible integration of the reProd® approach into existing market structures. In addition, a business model for recycling companies is developed. It describes various recycling
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scenarios, i.e. various initial products are included which pass through different stages of recycling. The objective is to develop a concept for calculating the cost, meeting the new requirements of the reProd® approach.
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