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ТЕХНИЧЕСКИЕ НАУКИ
UDC 621.791-027.3 DOI 10.12737/5719
THE IMPORTANCE OF WELDING AND JOINING TECHNOLOGY IN A MODERN INDUSTRIAL STRUCTURE. SOME REMARKS ABOUT TRENDS IN WELDING AND JOINING*
D. von Hofe, K. Middeldorf
The term Insert cross-sector technologies for the cohesive bonding of materials are summarized, such as welding, gluing, and soldering, without which modern technical products will no longer be displayed. Examples from different industries are considered. The economic significance in exemplary countries of Europe and the world is pointed out. The required personnel qualification and the international standardization are discussed.
Keywords: cross-sector technologies, standardization and certification, personnel qualification, competence management.
1. Introduction: Development of joining technology as a production process. Joining, i.e. the connection of individual components in order to form one unit, is a problem which has concerned people since time immemorial and has stimulated them to very diverse creativity. Just think of the insertion of a handle into a stone with holes in order to manufacture the first hammer, the tying of a stone tip to a wooden shaft in order to increase the effect of an arrow, the weaving and sewing of fabrics and the joining of stones or pieces of wood in order to create whole building structures.
One particular type of joining relates to the so-called material-locking joining of components (as opposed to so-called positive-locking joining) in which the components are joined with each other in such a way that they can no longer be easily separated from each other once again, e.g. by means of adhesive bonding, brazing or, as always, welding.
Today, the industrial production of technical goods, particularly of investment goods, is hardly conceivable without joining technology. Welding, brazing and adhesive bonding are used for the manufacture of household appliances, vehicles of all kinds and electrical and electronic devices as well as for building structures in the private and industrial sectors. Today joining technology accounts for a substantial proportion of the entire manufacturing process of investment goods. Examples are specified on Table 1.
Table 1
Proportion of the value added by welding in some sectors as examples
Sector Value added by welding
Construction of metal and plastic pipelines approx. 3 %
Metal construction approx. 5 %
Vehicle construction (motor and rail vehicles) approx. 7 %
Shipbuilding approx. 8 %
Aerospace construction: (including allied joining technologies) approx. 8 %
(according to internal calculations by DVS / GSI in 2012)
*
The research is done within the frame of the independent R&D.
2. Significance of welding and joining technology today
2.1 Welding as a joining process — Diversity of processes. Similar welding is a peculiarity amongst the joining processes because, in the case of this process, the parts are joined with each other in such a way that continuity is created between the materials to be joined. However, dissimilar welded joints are also possible in order to join different materials or using dissimilar filler materials if the utilised materials are capable of forming alloys. For the definition acc. to ISO 857 see Fig. 1.
An operation which unites material(s) by means of heat or pressure, or both, in such a way that there is continuity in the nature of the material(s) which has (have) been joined. Filler metal (material) the melting temperature of which is of the same order as that of the parent metal (material) may or may not be used.
Fig. 1: Definition of welding according to ISO 857: 1990 [1]
As far as the welding of metals is concerned, a fundamental distinction is today made between pressure and fusion welding (Figs. 2a and 2b) [2]. Pressure welding designates welding processes in which the parts to be welded are heated up to the necessary welding temperature at the welding points and are subsequently pressed together using mechanical pressure. This results in a strong joint between the individual parts. In this respect, the necessary heat is supplied either by a current flow through the welding point or by mechanical friction. Correspondingly, the processes are called resistance pressure welding and friction welding. The best-known variant of the resistance pressure welding processes is spot welding which has a widespread reputation, e.g. from the automobile industry. Friction welding is utilised in order to weld rotationally symmetrical parts, e.g. cardan shafts [3]. Fusion welding is a welding without application of external force in which the faying surfaces have to be molten; usually, but not necessarily, molten filler metal is added [1]. In this case, narrow zones of the parts to be joined are melted at the contact points. The joint is brought about in the region of the weld by the liquid materials flowing into each other [4]. The most widespread process is metal arc welding in which the utilised heat source is an electric arc which, as a rule, burns between a consumable or non-consumable electrode and the work piece in the atmosphere or in a shielding gas.
Pressure welding
Pressure Pressure Pressure Pressure welding Pressure Pressure weld- Pressure
welding welding welding using an electric welding using ing using the welding us-
using a using a using a gas discharge radiation movement of ing electric
solid liquid gas (arc, sparks or plasma) mass current
Fig. 2a: Pressure welding processes according to the German industrial standard DIN 8563-6 [2]
Fusion welding
Fusion welding using a liquid Fusion welding using a gas Fusion welding using an electric gas discharge (arc, sparks or plasma) Fusion welding using radiation Fusion welding using electric current
Fig. 2b: Fusion welding processes according to the German industrial standard DIN 8563-6 [2]
As far as the welding of plastics is concerned, a distinction is made between hot gas welding, direct and indirect heated tool welding, friction welding, ultrasonic welding, high-frequency (HF) welding, light beam extrusion welding and laser beam welding [5].
All these welding processes manufacture joints whose metallurgical properties at the joining point are identical or very similar to those in the base materials to be joined. This results in advantages over other joining processes, e.g. strength and corrosion properties in the welded joint which are identical or very similar to those in the base material, thus permitting weight-saving joints without any overlapping of the ends of the components. It is disadvantageous that, as a rule, the high heat input alters the properties of the base materials in the weld region and, during the cooling, leads to the build-up of residual stresses and the formation of distortion.
2.2 Other joining processes and examples of applications. Adhesive bonding and brazing have already been specified as other material-locking joining processes. The advantages of these processes are that no or substantially less heat is input into the materials for joining purposes than in the case of welding in order to avoid residual stresses and distortion altogether or partially and that even very different and even non-weldable materials can be joined, e.g. the adhesive bonding of glass with metal or of thermosetting plastics and the brazing of copper, steel and electronic components. The possible energy sources for brazing are the same as those for welding but at a substantially lower temperature since the base material is not melted completely.
2.3 Examples of applications of welding technology from various sectors. In principle, almost all processes are applied in all the sectors of the investment goods industry and of the skilled trades processing metals or plastics. To an absolutely crucial extent, the choice of the suitable welding process depends not only on the materials to be joined and the economic viability but also on the experience of the user. While manual joining processes are primarily utilised in single-item fabrication (such as manual metal arc welding), mechanised or automated processes are applied in series fabrication, frequently with robot support, e.g. spot welding in automobile manufacture, metal arc welding in metal construction and plant engineering, beam welding for the manufacture of precision parts or friction stir welding in aluminum processing.
In its publication entitled "Improving Global Quality of Life through Optimum Use and Innovation of Welding and Joining Technologies", the International Institute of Welding (IIW) provided a detailed description of the state of the art of joining in the most important industrial sectors and an outlook into the future [6].
2.4 Economic significance of welding and joining technology. With regard to the manufacture of investment goods in particular, welding technology and joining technology have not only technical significance but also outstanding economic significance. This is illustrated by an analysis which has been made on behalf of DVS — German Welding Society and has been updated for many years [7]. Joining technology creates value added on three levels:
during the manufacture of devices for joining, such as welding and brazing machines (Table 2),
during the manufacture of complementary goods and services for welding, brazing and adhesive bonding, e.g. filler materials, training of specialist personnel, protective facilities and auxiliary devices (Table 3),
during the application of joining technology for the manufacture of a product, e.g. a car, a pipeline or a computer (on this subject, Table 4 shows the value added and the number of people generating this value added).
Table 2
Production of and value added by devices and systems for joining in EURO million
in the EU in 2010
Germany Italy Netherlands France Great Britain Czech Rep. EU 27
2,880 876 27 518 213 76 7,950
36 % 11 % 0.3 % 7 % 3 % 1 % 100 %
2,551 1,169 29 323 160 7,504 (figures from 2007)
+ 13 % -25 % +/- 0 +60 % +33 % +6 % (comparison between 2010 and 2007)
Source: Moos, W. et al. (2013), calculation by DVS / GSI [7]
Table 3
Production of and value added by complementary goods and services for joining in EURO
million in the EU in 2010
Germany Italy Netherlands France Great Britain Czech Rep. EU 27
2,135 880 228 940 541 51 7,539
28 % 12 % 3 % 12 % 7 % 1 % 100 %
2,106 1,797 382 1,514 1,193 12,843 (figures from 2007)
+ 1 % -51 % -40 % -38 % -55 % -42 % (comparison between 2010 and 2007)
Source: Moos, W. et al. (2013), calculation by DVS / GSI [7]
Table 4
Value added by the application of welding technology and joining technology
Personnel Value added in 2010
1,124,200 EURO 60 billion
Germany 332,500 (30 %) EURO 18.8 billion (31 %)
Italy 211,100 (19 %) EURO 12.4 billion (21 %)
France 103,200 (9 %) EURO 6.4 billion (11 %)
Great Britain 86,400 (8 %) EURO 4.9 billion (11 %)
Netherlands 38,300 (3 %) EURO 2.3 billion (4 %)
Czech Rep. 31,900 (3 %) EURO 1.3 billion (2 %)
Others in EU 27 320,900 (28 %) EURO 12.2 billion (20 %)
Source: Moos, W. et al. (2013), calculation by DVS / GSI [7]
24
In order to estimate the worldwide value added by welding, reference must also be made to the market for products for welding outside Europe (Table 5). According to a conservative estimate, it can be derived from this that that value added by welding and joining worldwide is at least four times higher than that in Europe, i.e. EURO 250-300 billion per year. This illustrates the economic significance of welding and joining technology.
Another interesting factor relates to the consideration of the worldwide trade in devices and facilities for welding, cutting and surfacing which may be assessed to be over US Dollar 7 billion (Table 6) and of the scope of the Russian imports of products in this field which had a scope of US Dollar 963 million in 2012 (Table 7).
2.5 Quality assurance in welding and joining technology. However, joining technology has considerable significance from a different viewpoint as well. The reliability and safety of a lot of technical products is dependent on the reliability of the welds and the joints. The failure of a single weld may lead to the bursting of a pressure vessel or a pipeline, to the collapse of a bridge or a crane or to a car accident.
Table 5
World market for welding in 2012 / welding machines, welding robots and welding
consumables
Welding machines RES15 / ARC2) units Robots RES15 / ARC2) units Consumables kt
1 China 10,300 / 510,000 2,900 / 6,800 3,200
2 Europe 11,700 / 152,200 6,400 / 3,100 550
3 USA 7,900 / 120,000 6,900 / 4,000 450
4 Central/South America 4,900 / 67,000 700 / 700 220
5 Japan 5,800 / 75,900 3,470 / 3,300 283
6 India 2,600 / 71,000 600 / 650 270
7 Korea 3,000 / 52,000 1,500 / 2,400 240
8 Russia / CIS 1,700 / 63,300 200 / 300 230
9 Middle East / Africa 2,100 / 77,800 400 / 300 340
Total 50,000 / 1,069,120 23,070 / 21,550 5,783
15 Resistance Welding 2) Electric Arc Welding
Source: Japan Welding News for the World (2013) [8]
However, it is a very complicated process to test the quality of material-locking joints in particular without destroying them, if this is possible at all. Therefore, outstanding significance is attached to the competence of the manufacturers and operators of welded and joined products in joining and welding technology. This encompasses not only the manufacture of welded, brazed or adhesive-bonded parts but also the planning, designing, engineering and operation of them (Fig. 3). This necessitates the qualified training of the personnel responsible in each case.
Table 6
World markets for products related to machinery, plants and applications for welding, cutting and surfacing (2012),
key regions
Total input from the world into: US Dollar million
China 3,468
Russian Federation 963
India 699
Brazil 619
Source: UN 2013 / Messe Essen [9]
Table 7
Supply markets for products imported into the Russian Federation / "Top Five"
Products related to machinery, plants and applications for welding, cutting and surfacing (2012)
Total input from: US Dollar million %
Germany 172 18
China 171 18
Italy 101 10
USA 57 6
Rep. Korea 26 3
Source: UN 2013 / Messe Essen [9]
Fig. 3: Competence management in joining technology
2.6 Standardisation in welding and joining technology. Essential support with regard to the selection of the process suitable in each case and of the suitable quality assurance is provided by the national and international standardisation. If manufacturers and operators comply with this, they are also protected from rights of recourse to a great extent.
Plants which manufacture investment goods and process metals or plastics attach outstanding significance to the standardisation in joining technology and particularly in welding technology. The experience and research results from all sectors are incorporated into this standardisation which allows the
know-how to be passed on to the next generation across different sectors. Product standards supply additional information about product-specific details or peculiarities.
Essential standardisation fields of welding technology and examples of international standards are portrayed on Fig. 4.
Fig. 4: Essential standardisation fields for quality assurance during welding and examples
3. Outlook. Megatrends which influence joining technologies the most are globalisation, demographic change, individualism and sustainability [10]. The requirements on joining technology will also alter due to these megatrends and with advancing technology and changing resources of energies and raw materials. Multimaterial design will be applied right down to single components, depending on the individual needs of the ultimate consumers and on the stressing, availability (prices) and reusability of the compatible materials. The surfacing of components for corrosion or wear protection is already customary today. The composite construction method with aluminium and steel is being utilised in the automobile industry to an increasing extent. Glass as a load-bearing element is conceivable even in the construction of buildings. The objective is to use fibre-reinforced plastics in the material-locking joint with metals. The various joining processes will stay in continuous competition for application. Joining is knowledge-based. Joining processes are increasingly based on and driven by knowledge and science [10]. In this respect, interdisciplinary links are just as indispensable as the corresponding training and further education of the specialist personnel at universities and in the plants. For many years, the Don State Technical University in Rostov/Don has been active in this field and has established international links. In this sense, the authors congratulate DSTU Rostov on its 85th anniversary and wish it a lot of success in the future as well.
References
1. ISO 857:1998. Welding and allied processes — Vocabulary — Part 1: Metal welding processes. Date of publication: 1998-12.
2. DIN 8593-6:2003. Manufacturing processes joining — Part 6: Joining by welding — Classification, subdivision, terms and definitions. Date of publication: September 2003.
3. Definition acc. to "Metalltechnik Lexikon", www.metalltechnik-lexikon.de.
4. Definition acc. to "Techniklexikon", www.techniklexikon.net.
5. Fertigungstechnik 2 Bd.2, Hrsg. v. Willy Schal, Verlag: Handwerk Und Technik (Germany).
6. Smallbone, C., Kogak, M., eds. Improving Global Quality of Life through Optimum Use and Innovation of Welding and Joining Technologies, First Edition 2012. IIW, A World of Joining Experience. www.iiwelding.org. — White Paper, 2012.
7. Moos, W., u.a. Gesamtwirtschaftliche und sektorale Wertschopfung aus der Produktion und Anwendung von Fugetechnik in Deutschland und Europa, SCHWEISSEN UND SCHNEIDEN 65 (2013) Heft 9 (Germany).
8. Japan Welding News for the World (2013).
9. Calculations by DVS and GSI, based on figures by United Nations Report 2013 and Messe
Essen.
10. Joining Sub-Platform SRA, Consultation Document, February 2013. Материал поступил в редакцию 14.07.2014.
Значение технологии сварки и соединения в современной промышленной структуре. Несколько комментариев о тенденциях в сварке и соединении*
Д. фон Хофе, К. Миддельдорф
Статья посвящена анализу современного состояния и перспективам развития технологий соединения материалов, таких как сварка, пайка, склеивание в европейских странах и в промышленно развитых странах мира. Показано, что темпы роста сварочного производства в различных отраслях достигают 8 % в год. По объёмам выпуска сварочного оборудования, роботизированных комплексов и сварочных материалов в лидеры выходит Китай. Значительный прирост объёмов сварочного производства наблюдается в развивающихся странах Азии, Африки и др. Большое внимание в статье уделено тенденциям развития стандартизации и сертификации в сварочном производстве, проблемам квалификации персонала.
Ключевые слова: межотраслевые технологии, стандартизация и сертификация, квалификация персонала, эффективность управления.
*
Работа выполнена в рамках инициативной НИР.
