WORKING LIFE OF PLOUGHSHARE RENOVATED BY HARD FACING

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1 WORKING LIFE OF PLOUGHSHARE RENOVATED BY HARD FACING RADOVAN SOSKA, PETER CICO, RASTISLAV MIKUS Department of Quality and Engineering Technologies Slovak University of Agriculture in Nitra Tr. A. Hlinku 2, Nitra SLOVAKIA Abstract: The aim of this paper is to emphasise the possibilities of lifetime improvement of working tools of agricultural machinery and especially to increase the abrasion resistance of the surface layer The life expectance was extended by welding of new cutting edge and hardfacings on functional areas of these new cutting edge (facet). I were used two technologies of surfacing by means of flame and an electric arc in the tests. The measurements were carried out over 40 ha and 80 ha of work tools in the soil. Key Words: tool wear, renovation, weld deposit, metal powders, soil tillage tool. INTRODUCTION The wear of cutting edges of agricultural tools in operating conditions significantly affects the quality of the work and energy demands of soil tillage processes. Traction force and fuel consumption increase significantly, while the work intensity and depth of tillage decrease with the greater thickness of the cutting edge of ploughshare. The quality of tillage decreases significantly with the greater thickness of the cutting edge of ploughshare. Therefore, when renovating particular tools, the possibilities of wear resistant cutting edge and self-sharpening effect achievement are researched. The latter can be reached by proper thickness of the coating and hardness ratio of the base and surfacing material. The size and intensity of wear can be measured using quantitative method, monitoring linear dimensions change per path unit in laboratory and operating conditions. (Votava 2014, Paulíček et al. 2011, Kotus 2010, Kotus 2009, Pulíček et al. 2014). Agricultural users look for alternative methods to extend the lifetime of these tools. An application of hard layer to the tool' functional zone is one of the possibilities. Manual metal arc welding using hard facing electrodes is one of the most common ways of agricultural tool renovation. However, the flame oxi-acetylene technologies became an alternative for hard facing recently, with application of tube hard facing wires or metal powders. It's a low-tech method by which it can be achieved minimal mixing of base material with weld deposit and good wear resistant properties. (Viňáš et al. 2013, Kolenič et al. 2007). High wear resistance and significant savings are achieved using this method, as evidenced by the work of authors. (Daňko et al. 2011, Bujna et al. 2008). The structure of the weld deposit very significantly influences the weld deposit characteristics, weight losses and wear resistance ratio. (Tolnai and Čičo 2001). The current trend of increasing operating speeds, reducing the consumption of materials and prolong service life is associated with the problem of wear resistance. They are parts which are important for quality in technological process. (Votava and Ščerbejová 2007) MATERIAL AND METHODS An indexable seven ploughshares of plough Lemken EURODIAMANT was used in field tests. All the twelve worn ploughshares were renovated by cutting the worn ploughshare blades and replacing with the plates of size 490 mm 50 mm 8 mm welded to the ploughshare body to get the original shape and size (Figure 1a). The facets welded were made from STN steel. Than were made preventive hard weld deposit in the top of ploughshares (Figure 1b). 928 P age

2 Figure 1 Modifications of ploughshare Legend: a) preparation of facet and ploughshare; b) weld deposit and cutting edge modification Completely were used three kinds of additional material. The results of their arithmetical mean of chemical composition were obtained by the SPECTROMAXx arc/spark OES (Optical emission spectroscopy) of weld deposits (Table 1) E 520. Table 1 Chemical composition of additionals materials Additional Chemical composition (wt %) made by optical emission spectroscopy materials C Si Mn Cr B Fe Ni W P S E < NP 60 WC <0.001 <0.001 NP > <0.001 Every kind of additional material was used for four ploughshares including two left-site and two right-site ploughshares. Two kinds of additional materials are metal powders of the NiCrBSi base. The metal powders are very similar to the application from chemical aspect. However metal powder called NP60WC20 should contain 20% tungsten carbide as small grains. When is used surfacing technology by flame this small grains of tungsten carbide will not melted, they will remain in the matrix. They were plotted by using oxyacetylene burner called NPK-3. It was used neutral flame during the hard facing to did not chemically influenced the weld deposit. The last type of additional material is called ES20. It s coated electrode for MMA. The hardfacing parameters with coated electrode: Diameter of electrode = 3.2 mm, electric current = 95 A, electrical voltage = 28 V. The last two ploughshares were used as etalons. The etalons were original and new ploughshares with the same geometrical dimensions and shapes which had renovated ploughshares. RESULTS AND DISCUSSION Field tests were realized in Kolíňany. The first measurement was done after ploughing of 40 ha and the final one after 80 ha. When measuring the wear, the ploughshares were removed and evaluated based on the loss of linear dimensions, since these describe the wear rate more reliably; the width of ploughshare plays an essential role in the quality of tillage in compare with the weight losses of ploughshares. The measurement locations on the ploughshares were strictly defined and marked. The measurement locations on the ploughshares were strictly identified, as shown in (Figure 2). Figure 2 Positions of wear measurements The ploughshares linear decrease after 40 ha of work is graphically illustrated in (Figure 3). The ploughshares linear decrease after 80 ha of work is graphically illustrated in (Figure 4) Field tests were 929 P age

3 continuously evaluated. The land had 17.5% and 16.8% of moisture during the processing 40 and 80 ha of land by loughshares. Figure 3 Changes in linear dimensions of ploughshares in particular zones after tilling 40 ha Every renovated ploughshares had increase wear resistance. Graphical illustration shows that best results had additional material called E520. His average wear for one ploughshare was 6.8 mm. The results for NP 62 and NP 60WC20 were nearly same. Their average wear was 8.4 mm and 9.6 mm. Worst results had etalons. The average wear for one ploughshare was mm. When compared etalons and renovated ploughshares with hardlayers made from E 520 it is 1.68 times higher wear after 40 ha. Figure 4 Changes in linear dimensions of ploughshares in particular zones after tilling 80 ha After 80 ha were results for renovated ploughshares still good. The worst results had etalons again whit arithmetic average of wear 21.7 mm. Results for weld deposit on the NiCrBSi base were nearly same again. Better result had metal powder NP 62. His average wear for one ploughshare was mm. Metal powder called NP 60WC20 had mm average wear. The best results had electrode called E520 with average wear mm. The etalons have 1.76 times higher wear after 80 ha than electrode E520.The structure of hard facing material plays a very important role in material wear resistance determination. Structure of basic material STN shows lamellar perlite and ferritic net at grain boundaries (Figure 5). 930 P age

4 Figure 5 Detailed structure of the basic material steel STN In this test the weld deposit with carbides in matrix NP62 (Figure 6) shows little bit worse wear resistance than the weld deposit on same based by NiCrBSi called NP60 WC20 (Figure 7). Figure 6 Detailed structure of the NP62 Figure 7 Detailed structure of the NP60 WC20 The matrix of weld deposit E520 is consist of ledeburit on the picture is shown also join weld on and basic material (Figure 8). Figure 8 Detailed structure of the E520 CONCULSION Ploughing is one of the most energy demanding operations in agricultural production; therefore, methods for energy demands reduction are searched. Worn ploughshares renovation is one of the methods. Hard facing is one of the most used one, applied to the new ploughshare in advance, or as a renovation method described in this paper. When surfacing, the majority of costs can be attributed to material, consisting of shielding gas and hard facing materials costs besides the labour costs. The hard facing renovation effect was technical life extension by 130% until 176% times if we notice even the renovation of the corrective dimension. REFERENCES Bujna, M., Čičo, P., Kotus, M., Kolenič, F Vplyv kompozitných práškových materiálov na zvýšenie úžitkových vlastností radličiek pri naváraní laserom. Acta mechanica Slovaca, (12): P a g e

5 Daňko, M., Čičo, P., Kotus, M., Pauliček, T Odolnosť materiálov vytvorených laserovým naváraním proti abrazívnemu opotrebeniu. In Kvalita a spoľahlivosť technických systémov. Nitra: TF SPU, pp Kolenič F. et al Vytváranie návarov laserom a elektrónovým lúčom a vlastnosti návarových vrstiev. Zvárač, (4): Kotus, M Tribologické skúšky oteruvzdorných materiálov. In Bezpečnosť Kvalita Spoľahlivosť. Košice: TU KE, pp Kotus, M Stanovenie odolnosti prídavných materiálov pri vytvorení jednovrstvových návarov, In Technická diagnostika strojů a výrobních zařízení 'DIAGO 2010'. Ostrava: Vysoká škola baňská Technická univerzita, pp Pauliček, T., Daňko, M., Kotus, M Vplyv umiestnenia radličky kompaktora na veľkosť abrazívneho opotrebenia. In Bezpečnosť Kvalita Spoľahlivosť. Košice: TU KE, pp Pauliček, T., Votava, J., Kotus, M Abrasive resistance of filler metals in laboratory conditions. Journal of Central European Agriculture, 15(1): Tolnai, R., Čičo, P Wear resistance of hard facing materials of a new concept. Acta Technologica Agriculturae, 4(4): Viňáš, J. et al Degradation of renovation layers deposited on continuous steel casting rollers by submerged arc welding. Journal of Engineering Manufacture, 227(12): Votava, J Usage of abrasion-resistant materials in agriculture. Journal of Central European Agriculture, 15(2): Votava, J., Ščerbejová, M Tepelné zpracování ADI litiny pro výrobu nástroju na zpracování pudy. In Kvalita a spoľahlivosť technických systémov. Nitra: SPU, pp P age