BA URA René /KDNDV, DF TU Zvolen, Slovak Republic/ INTERNATIONAL FURNITURE EXHIBITION MILAN 2006

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1 BA URA René /KDNDV, DF TU Zvolen, Slovak Republic/ NTERNATONAL FURNTURE EXHBTON MLAN 26 BARBOUTS oannis, VASSLOU Vassilios / AU,FFNE,DHTFP, Thessaloniki, Greece/ EXPRESSON PROBLEMS OF SCREW WTHDRAWAL USED N FURNTURE ECCENTRC JONTS CAPACTY ERDL Yusuf Ziya, GUNSEL Ugur / DWSFD, FTEMU, Turkey/ TECHNOLOGY EDUCATON AND WOOD PRODUCTS EDUCATON N TURKEY GAZO Rado, KODZ T. Emmanuel Jr. / Wood Research Laboratory, Purdue University, USA / MASS CUSTOMZATON N FURNTURE NDUSTRY HAPL Wolfgang /KDNDV, DF TU Zvolen, Slovak Republic/ DESGN? WARUM? WOZU? FÜR WEN? UND VON WEM? HAVAROVA Eva, GAZO Rado / Wood Research Laboratory, Purdue University, USA / TEACHNG FOREST PRODUCTS AND FURNTURE DESGN; ADDRESSNG EMERGNG FURNTURE DESGN SSUES AT WOOD RESEARCH LABORATORY, PURDUE UNVERSTY CONTRBUTONS

2 SEDLA K Ján, KOLLÁR Milan / DF TU Zvolen, Slovak Republic / TECHNOLOGY OF PRODUCTON OF UNCONVENTONAL FREZES BY GLUNG OF WASTE DMENSON TMBER ŠMEK Milan / ÚNDB, LDF MZUL Brno, Czech Republic / DSMOUNTABLE FURNTURE JONTS AND CAE SVOBODA Jaroslav, TAUBER Ji í / ÚNDB, LDF MZUL Brno, Czech Republic / ONS AND THER CONTRBUTON FOR LVNG SPACE TESA OVÁ Daniela / KZD, FLE ZU Praha, Czech Republic / HEDONC NFLUENCE OF VOC EMSSONS NTO MAN AND THE MEASUREMENT BY THE OLFACTORY METHOD VASSLOU Vassilios, BARBOUTS oannis, / AU,FFNE,DHTFP, Thessaloniki, Greece/ BENDNG STRENGTH OF CORNER JONTS CONSTRUCTED WTH BSCUTS VESELOVSKÝ Juraj / KDNDV, DF TU Zvolen, Slovak Republic / DESGN OF OFFCE FURNTURE FOR PEOPLE WTH DSABLTES CONTRBUTONS PROCEEDNG OF PAPERS FROM NTERNATONAL CONFERENCE OF NÁBYTOK 26 Reviewers: Prof. Dr. Georgi Kyuchukov, University of Forestry - Sofia, Bulgaria Prof. Wolfgand Haipl, Austria Assoc. Prof. Rado Gazo, FNR, Purdue University USA Prof. van Petelen, PhD., FA STU v Bratislave Prof. ng Štefan Schneider, PhD., TU vo Zvolene Assoc. prof.. ng.pavol Još ák, PhD., TU vo Zvolene Asssoc. Prof. Juraj Veselovský, PhD., TU vo Zvolene Editor: Asssoc. Prof. Juraj Veselovský, PhD., TU vo Zvolene Graphic arrangement: Rudolf Szabó dipl.ng. Edition: 1st Year of Edition: 26 Number of Copies: 9 Format: CD Papers did not passed language correction. Faculty of Wood Science and Technology, Technical University in Zvolen SBN COLOPHON

3 EXPRESSON PROBLEMS OF SCREW WTHDRAWAL CAPACTY USED N FURNTURE ECCENTRC JONTS oannis BARBOUTS Vassilios VASSLOU 1 Abstract: Many different insert fittings (s, s with plastic or metal s, metal or plastic cam fittings etc.) are used to connect MDF and particleboards in ready-to-assemble case furniture. According to EN 13446:22 the withdrawal capacity of fasteners must be determined in Newtons per square millimeter (N/mm 2 ). Research reported here indicates that face withdrawal strengths of the different insert fittings tested expressed in N/mm 2 do not correspond to the maximum loads which are practically of the main importance for the furniture construction. Furthermore, the expression of fasteners withdrawal capacity in N/mm 2 does not help the performance comparison of different insert fittings. t is concluded that the absolute value of the maximum load applied can express clearly the actual withdrawal capacity of these fasteners. Key words:, withdrawal capacity, eccentric joints, furniture, standards NTRODUCTON Many insert fittings (s, s plastic - metal, cam fittings plastic - metal) are commonly used in ready-to-assemble furniture construction both to obtain greater holding strength and also to facilitate the on-site erection of dismountable furniture. Although the resistance to withdrawal of different types of fasteners have been studied by many researchers in different wood species [2,3] and wood-based panels [1,4,,6,7,8], and limited information is available from the manufacturers of the insert themselves, it still remains the problem of obtaining comparable data and of selecting those fasteners with superior holding characteristics so that optimum joint strength can be obtained by end user. Withdrawal capacity of fasteners, according to EN 13446:22, must be determined in N/mm 2 whereas, according to ASTM D :199 it must be determined as the maximum load required to withdraw the fastener from the wood or wood-based panel. Researchers express their results either according to EN standard (4,) or according to ASTM standard (1,2,3,6,7,8). n order to obtain the information needed to compare different insert fittings performance and to select the fasteners with superior holding strength, withdrawal strength tests were carried out on a number of commonly used inserts, and the results were expressed according to both standards. MATERALS AND METHODS n this research, the face holding strength of most of the insert fittings which are commonly used for this kind of joints represented five () manufacturers: Hettich Germany, Häfele Germany, Lama Slovenia and two (2) unknown manufacturers, are studied (which are referred in the study as: manufacturer A, manufacturer B, manufacturer C, manufacturer D and manufacturer E). Totally, twenty insert fittings, belonging to seven basic insert types, were included in the test (Figure 1). NÁBYTOK 26 FURNTURE 26

4 2 Figure 1. The types of insert fittings (7 s and 3 s) used in the study. Table 1. Description of the insert fittings (s - s) used in the study Cod e Scre w type Hole diamet er (mm) Hole lengt h (mm ) Screw material Screw diame ter Thread length ( mm) (mm) Total Cylindr ical Socket use Socke t mate rial Socket diamete r (mm) Socket length (mm) MANUFACTURER A Α 1 13 Steel No Β 1 13 Steel No C 2 13 Die-cast zinc No D 4 13 Steel No Ε 13 Steel 7,8 6.2 No F 7 13 Steel 4 7,8 7.8 Yes Brass 7.8 G Steel No H Steel Yes 13 Steel Yes Plasti c Plasti c MANUFACTURER B Α 1 13 Steel No Β 1 13 Steel No C Steel No D 6 13 Steel Yes Plasti c 12 Ε Steel No F 6 13 Steel Yes Plasti c 12 G 7 13 Steel Yes Brass 8 H 3 13 Steel No Die-cast zinc No MANUFACTURER C Α 3 13 Steel No Β 3 13 Steel No MANUFACTURER D NÁBYTOK 26 FURNTURE 26

5 Α 2 13 Steel 13 1, No MANUFACTURER E Die-cast Α No zinc 3 The insert fittings were commercially available standard items and their complete technical description is shown in Table 1. The wood-based panels tested included particleboard (Pbd) and medium density fiberboard (MDF), of 16mm thickness. The mean density of the particleboard was.634 g/cm 3 and its internal strength.8 N/mm 2. The mean density of the MDF was.68 g/cm 3 and its internal strength.9 N/mm 2. Manufacturers recommendations were followed with respect to pilot hole size and the insertion of s, plastic and metal s. Pilot holes were drilled through the center of each sample by means of a drill in a direction perpendicular to the face of the specimen. All of the samples were conditioned to constant mass at a temperature of 2 o C and a relative humidity of 6%, prior to the insertion of the fittings. All of the tests were carried out on a Shimatzu testing machine according to the standard EN 13446:22. The withdrawal capacity was expressed: a) as the maximum load applied in Newtons (N), b) in Newtons per square millimeter (N/mm 2 ), based on the total thread length, and c) in N/mm 2, based on the cylindrical thread length, in order to have a performance comparison of the insert fittings tested. DSCUSSON OF RESULTS The results of the tests are shown in the following Table 2. Research reported here indicates that face maximum holding strength of the insert fittings differ both, from manufacturer to manufacturer and from one fitting type to another. n general, the higher holding strength values were achieved by the s with the longer cylindrical thread part without s, and the s with plastic s of long thread part. On the other hand the lower holding strength values gave the s with the shorter cylindrical thread part without s, and the s with metal s, correspondingly, in both particleboard and MDF. We know that the selection of the fasteners with the higher holding characteristics is based on the maximum load applied, which is of the main concern for the end user. When the holding strength is expressed in N/mm 2, based either on total or on cylindrical thread length of the fittings a different classification is derived, which does not correspond to the classification of the maximum load applied. Obviously, it would be the wrong way to make our selection of the fittings with the superior holding characteristics based on their holding strength expressed in N/mm 2. Table 2. Screw withdrawal capacity of the insert fittings (s and s) in particleboard and MDF nsert fitting item Α Β # max (N) Particleboard Total length (N/mm 2 ) Cylind. length (N/mm 2 ) Panel type MANUFACTURER Α (82.)* (1.) (1.) (26.1) (.47) (.47) max (N) (31.6)* 84.6 (47.7) MDF Total length (N/mm 2 ) 13.9 (.7) 1.4 (.87) Cylind.Le ngth (N/mm 2 ) 13.9 (.7) 1.4 (.87) NÁBYTOK 26 FURNTURE 26

6 4 C # D # Ε # F G H + metal + plastic # Α Β # C # D E F G H + plastic + plastic + metal # Α Β # Α Α 79.7 (87.3) (1.4) (1.4) (3.) (.88) (.88) (31.9) (.82) (1.3) (1.8) (1.66) (1.66) (26.7) (.81) (.99) (7.9) (1.7) (2.14) (47.4) (1.44) (1.76) MANUFACTURER B (1.2) (.93) (.93) (.7) (1.1) (1.1) (3.4) (.92) (.97) (27.) (.82) (.86) (.8) (1.69) (2.7) (78.) (2.36) (2.89) (6.6) (2.19) (2.34) (6.1) (1.) (1.41) (.3) (1.4) (1.4) MANUFACTURER C (7.3) (.96) (1.3) (2.9) (.88) (1.11) MANUFACTURER D (8.8) (1.32) (1.63) MANUFACTURER E (43.) (.79) (.79) 84.8 (61.2) 96.6 (37.4) 18.8 (4.) (49.9) 61.1 (37.6) (47.9) (43.2) 89.3 (.8) (76.4) (49.9) 622. (42.3) (3.) 46.9 (23.8) (6.1) (41.7).9 (26.8) (43.6) (63.3) (42.8) (72.6) 14.1 (1.2) 14.1 (1.2) 9.94 (.62) 9.94 (.62) 13.3 (1.1) (1.6) (1.4) 24.2 (1.4) 2.12 (1.31) (1.1) 1.2 (1.39) 22.2 (1.1) 18.8 (1.28) 18.4 (1.7) 16.7 (.72) (1.87) 11.8 (.69) 14. (.74) 11. (.73) 12.7 (1.) (.66) 13.4 (1.32) (1.4) (1.6) 22.6 (1.39) (1.77) 3.7 (1.6) (1.1) 1.2 (1.39) 23.9 (1.8) (1.34) (1.31) 2.26 (.88) 24.2 (2.) 1.64 (.98) 14. (.74) 16.3 (1.2) 16. (1.33) 16.8 (.81) 13.4 (1.32) * Mean values of 1 samples and standard deviation in parenthesis The differences between the three expressing methods which are attributed mainly to the compound NÁBYTOK 26 FURNTURE 26

7 effect of the insert fittings' characteristics (diameter, total length, thread length, shape, etc) are shown more clearly in the following Figures, for each manufacturer's fittings, separately. n Figure 2 we see the differences of the manufacturer's A insert fittings in Pbd Figure 2. Withdrawal capacity of manufacturer A insert fittings in Pbd, expressed as max. strength (N) [], and based on total [] and cylindrical [] length of the (N/mm 2 ) According to the first classification () more than 7 N holding strength have the fittings, C, H, B and A, and the lower holding strength have the fittings G and E, whereas, according to the second classification () more than 2 N/mm 2 holding strength have the fittings and H, and the lower value has the fitting D. n Figure 3 are given the corresponding differences of the manufacturer's A insert fittings in MDF, where we can see that according to the first classification () the fitting B has the higher and the fitting F has the lower holding strength, whereas, according to the second classification () the fitting has the higher and the fitting D has the lower holding strength Figure 3. Withdrawal capacity of manufacturer A insert fittings in MDF, expressed as max. strength (N) [], and based on total [] and cylindrical [] length of the (N/mm 2 ) n Figure 4 are shown the differences of Manufacturer's B insert fittings in Pbd Figure 4. Withdrawal capacity of manufacturer B insert fittings in Pbd, expressed as max. strength (N) [], and based on total [] and cylindrical [] length of the (N/mm 2 ) According to the first classification () more than 7 N holding strength have the fittings A and B, NÁBYTOK 26 FURNTURE 26

8 and the lower holding strength has the fitting, whereas, according to the second classification () round 2 N/mm 2 holding strength has the fitting G, and the lower holding strength have the fittings H and. The corresponding differences of the manufacturer's B insert fittings in MDF, are given in Figure, where the differences are similar to the previous observed in Pbd Figure. Withdrawal capacity of manufacturer B insert fittings in MDF, expressed as max. strength (N) [], and based on total [] and cylindrical [] length of the (N/mm 2 ) The differences of the rest manufacturers' C, D and E insert fittings in particleboard are given in the following Figure 6 and their corresponding differences in MDF are shown in the next Figure C-A C-B D-A E-A C-A C-B D-A E-A Figure 6. Withdrawal capacity of manufacturers C,D,E insert fittings in Pbd, expressed as max. strength (N) [], and based on total [] and cylindrical [] length of the (N/mm 2 ) C-A C-B D-A E-A C-A C-B D-A E-A Figure 7. Withdrawal capacity of manufacturers C,D,E insert fittings in MDF, expressed as max. strength (N) [], and based on total [] and cylindrical [] length of the (N/mm 2 ) According to the third classification () based on EN standard when we express the holding strength in N/mm 2 on the basis of the cylindrical thread length only, a new classification is derived, concerning especially the fittings with conical shape, almost similar to the second classification (). CONCLUSONS The withdrawal capacity of insert fittings used in furniture eccentric joints can be determined and NÁBYTOK 26 FURNTURE 26

9 expressed either as the absolute values of the maximum loads applied in N or according to EN 13446:22 standard in N/mm 2 of the total or cylindrical thread length. The three expressions correspond to different classifications and for comparable reasons of selecting those fasteners with the superior holding characteristics the values of the maximum load applied must be used. References: 1. Cassens, D.L. and C.A.Eckelman Face holding strength of threaded metal inserts in reconstituted wood products. Forest Products Journal. Vol. 3(3): Eckelman, C.A Screwholding performance in Hardwoods and Particleboard. Forest Products Journal. Vol. 2(6): Eckelman, C.A. and D.L.Cassens Holding strength of metal inserts in wood. Forest Products Journal. Vol. 34(6): Mihailova, J., G. Kyuchukov and N. Yosifov. 22. Comparative data and norms for resistance during removing s from furniture boards. NABYTOK 22 (CD-ROM): Technicka univerzita. SBN Örs,Y., Özen, R. and S. Doganay Screw holding ability (strength) of wood material used in furniture manufacture. Turkish Journal of Agriculture and Forestry. Vol. 22: Rabiej, R.J Factors affecting the load-bearing capacity of MOD-EEZ connectors. Forest Products Journal. Vol. 43(9): Vassiliou,V. and J. Barboutis.24. Holding strength of insert fittings of the eccentric joints in particleboard and MDF. Proceedings th nternational Furniture Symposium. October 21 st - 23 rd, Zvolen, Slovakia. 8. Vassiliou, V. and. Barboutis. 2. Screw withdrawal capacity used in eccentric joints of cabinet furniture connectors in Particleboard and MDF. Japanese Journal of Wood Science. Vol. 1: Author's addresses: oannis Barboutis and Vassilios Vassiliou Aristotle University, Faculty of Forestry and Natural Environment, Department of Harvesting and Technology of Forest Products, Box 243, Thessaloniki 4124 Greece jbarb@for.auth.gr, vass@for.auth.gr 7 NÁBYTOK 26 FURNTURE 26