- Email: [email protected]
Evaluation of surface characteristics of laminated flooring
ARTICLE IN PRESS
Building and Environment 41 (2006) 756–762 www.elsevier.com/locate/buildenv
Evaluation of surface characteristics of laminated flooring Hulya Kalaycioglua,, Salim Hiziroglub a
Department of Forest Products Engineering, Karadeniz Technical University, Trabzon,Turkey b Department of Forestry, Oklahoma State University, Stillwater, OK 74078-6013, USA Received 10 March 2005; accepted 15 March 2005
Abstract In this study, surface characteristics of commercially manufactured laminated flooring were evaluated. The surface roughness of samples consisting of high-density fiberboard (HDF) base and melamine resin saturated paper overlay was investigated. Here, 10 cm 10 cm samples of two types of panels were used for the experiments. A fine stylus technique was employed for the measurements. Three roughness parameters, namely average roughness (Ra ), mean peak to valley height (Rz ), and maximum roughness (Rmax ) were considered to determine roughness of the flooring panels. It was found that statistically significant difference existed between two types of samples as well as values taken along and across the sandmarks of the HDF and overlaid panels. Average Ra , Rz , and Rmax values for HDF were found as 2.73, 26.04, and 27.27 mm, respectively. Overlaid samples resulted in 15.6%, 26.0%, and 21.0% lower values of above parameters than those of HDF panels. r 2005 Published by Elsevier Ltd. Keywords: Laminated flooring; Surface roughness; High-density fiberboard; Melamine saturated paper
1. Introduction Laminated flooring has been widely used in Europe for over 20 years and recently it is getting popular in North America [1]. In general, laminated flooring consisted of four main elements which are bonded together in the form of a sandwich. High-density fiberboard (HDF) having a density above 0.85 g/cm3 (HDF) is one of the most commonly used wood composite panels for the core layer. A wear resistant decorative paper usually saturated with melamine base resin is located in the core layer. A clear cap sheet made of aluminum oxide saturated film and a balancing backing are also put on the top of decorative paper and on the back of the panel, respectively. The main purpose of aluminum oxide film is to protect the surface against any stain. Laminate flooring should be durable and have high wear resistance. Some of these flooring panels have Corresponding author.
E-mail addresses: [email protected] (H. Kalaycioglu), [email protected] (S. Hiziroglu). 0360-1323/$ - see front matter r 2005 Published by Elsevier Ltd. doi:10.1016/j.buildenv.2005.03.012
at least twenty times higher strength and durability than that of a typical laminated kitchen countertop. Pressure, temperature, press time, and the quality of press caul are some of the parameters influencing the overall quality of final products. Surface roughness of the core material, HDF also plays a significant role for a proper construction. Any surface irregularities on the core or substrate may show through the overlay films and papers resulting in lowquality bonding between the layers. Subjective methods such as visual observation which depend on sandpaper grit sizes are commonly used to get a general idea about the surface roughness of wood composites used as substrate for overlaying. An accepted quantitative method to measure the surface quality of wood composite panels including HDF has not been established. Several methods such as laser, pneumatic, acoustic emission, and microscopy have been used to measure surface characteristics of wood-based composites. [2–8]. The stylus method which is used to evaluate the surface of metal and plastic materials gains most attention among various techniques since it evaluates
ARTICLE IN PRESS H. Kalaycioglu, S. Hiziroglu / Building and Environment 41 (2006) 756–762
the surface quality in terms of well-established numerical parameters [9–12]. It is accurate, practical, repeatable, and quantitative roughness parameters can also be precisely calculated by this method. Variables such as the stylus tip radius, the surface force produced by the stylus, and cut-off length of the profile have important influence on the accuracy of the results [13]. Cut-off length which is a filtering parameter separates unfiltered actual profile into two profiles, namely roughness and waviness profiles. Based on the standard, cut-off length should be at least 2.5 times the peak-to-peak spacing of the profile roughness so that a minimum of two peaks and valleys can be included within each cut-off length [13]. In this study, all three roughness parameters, Ra, Rz, and Rmax were calculated based on the filtered roughness profile. The use of the stylus technique in evaluating surface roughness of wood composites has been discussed in past studies [14–18]. The objective of this study is to evaluate surface roughness of both flooring samples before and after they were overlaid with melamine resin saturated decorative papers using a stylus technique. Established initial data will provide numerical qualitative values about the surface characteristics of such flooring samples. Also it is expected that the data will lead to improvement in overlaying process of the substrate resulting in a better quality of flooring product.
2. Materials and methods A total of 20, 10 HDF and 10 laminated flooring samples in 11 cm 11 cm 0.7 cm were randomly cut from commercially manufactured panels. HDF samples were sanded with a sequence of 120- and 180-grit sand papers during the manufacturing. Mixed hardwood furnish was the raw material for the HDF base. Fig. 1 illustrates the construction of the overlaid samples. All of the samples were conditioned in a room with a temperature of 20 1C and relative humidity of 65% prior the measurements. Surface roughness of the samples was quantitatively evaluated at initial dry condition, and
Fig. 1. Schematic illustration of overlaying of the flooring sample.
757
sequentially as they were soaked in water for 2-h, 24-h, and 15 days. Direction of the sandmarks on the sanded HDF panels were identified using the China marker when they were dry and a total of 20 roughness measurements were taken from the surface of samples both along and across the sandmarks at each exposure. Overlaid HDF samples were commercially produced using continuous press lines having a speed of 240 mm/s. Full-size panels were laminated using a pressure of 38 kg/cm2 pressure at a temperature of 203 1C for 27 s. The surfaces of the laminated samples were also embossed during the overlaying process to emphasize rays, and grain orientation to imitate natural appearance of solid wood. Similar to HDF samples, 20 measurements were also taken from the surface of such laminated samples along and across grain orientation of the melamine-impregnated papers based on visual identification. Measurements were repeated at the same locations after the samples were soaked in water for 2-h, 24 h and 15 days. A portable stylus profilometer, the Hommel Tester T-500 unit was used for the roughness measurements. Fig. 2 shows the profilometer on a flooring sample. The profilometer consists of main unit and pick-up which has a skid-type diamond stylus with 5 mm tip radius and 901 tip angle. The stylus traverses the surface at a constant speed of 1 mm/s over 15 mm tracing length. The vertical displacement of the stylus is converted into an electrical signal by a linear displacement detector before the signals are amplified and transferred into digital information. Roughness parameters can be calculated from the digital information. Three parameters, Ra, Rz, and Rmax were considered to evaluate the surface characteristics of the flooring samples. The specifications and definitions of the three roughness parameters are discussed in previous studies [4,5,19]. Figs. 3A–C depict typical roughness profiles of HDF and laminated samples as dry, 2-h, and 24-h, water soaked, respectively.
Fig. 2. Surface roughness profilometer.
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Fig. 3. Typical surface roughness of the samples at :(A) dry condition, (B) 2-h soaked, and (C) 24-h soaked.
ARTICLE IN PRESS H. Kalaycioglu, S. Hiziroglu / Building and Environment 41 (2006) 756–762
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sanding and embossing processes. Tables 2–4 display statistical analysis of the experiments (Fig. 4). Overall surface roughness of both HDF and overlaid specimens had comparable values when they were conditioned at 65% relative humidity and room
3. Results and discussion Results of the surface roughness of the samples are displayed in Table 1. Both HDF and overlaid samples resulted in significant differences as a function of the
Table 1 Average roughness measurements of the flooring samples Roughness Exposure parameters (mm) condition
Ra
HDF panels
Dry
Rz Rmax Ra
2-h soaking
Rz Rmax Ra
24-h soaking
Rz Rmax Ra
15 day soaking
Rz Rmax
Overlaid panels
//
/
2.38 (0.10) 19.08 (0.12) 26.04 (0.22)
3.08 (0.18) 23.00 (0.15) 28.51 (0.24)
4.89 (0.21) 32.05 (0.24) 40.09 (0.18)
5.49 (0.25) 37.15 (0.22) 46.77 (0.23)
5.68 (0.25) 36.46 (0.24) 42.25 (0.19)
5.92 (0.19) 38.06 (0.22) 47.92 (0.18)
7.03 (0.21) 41.47 (0.18) 50.02 (0.22)
7.16 (0.24) 42.30 (0.23) 51.33 (0.21)
Average 2.73 21.04 27.27 5.19 34.60 44.93 5.80 37.26 45.08 7.09 41.88 50.67
//
/
1.63 (0.19) 10.54 (0.23) 14.49 (0.22)
3.09 (0.21) 22.85 (0.25) 30.51 (0.21)
1.75 (0.21) 11.47 (0.17) 15.45 (0.18)
3.18 (0.24) 19.35 (0.19) 26.25 (0.22)
2.27 (0.17) 14.59 (0.19) 19.06 (0.23)
3.05 (0.16) 18.46 (0.21) 24.96 (0.25)
1.79 (0.23) 11.48 (0.20) 16.01 (0.23)
3.25 (0.22) 19.63 (0.18) 26.13 (0.25)
Average 2.36 16.69 22.50 2.65 15.41 20.85 2.66 16.25 22.01 2.52 15.55 21.07
Values in parentheses are COV.
Table 2 Statistical analysis for Ra values Source Corrected model Intercept Dry-water soaked (A) Panel type (B) Measurement direction parallel–perpendicular (C) AB AC BC ABC Error Total Corrected total (***) ¼ highly significant. (*) ¼ 0.5% significant. a 2 R ¼ 0:890.
Sum of squares a
Degree of freedom
3,591.59 13,534.57 544.24 1,730.44 239.10
15 1 3 1 1
798.92 22.59 85.22 3.15 442.62 20,637.14 4,034.22
3 3 1 3 956 972 971
Mean square
F value
Significance
239,44 13,34.57 181.41 1,730.44 239.10
517.15 29,532.71 391.83 3,737.51 516.43
*** *** *** *** ***
575.18 16.26 184.08 2,270
*** *** *** *
266.30 7.53 85.22 1.05 0.463
ARTICLE IN PRESS H. Kalaycioglu, S. Hiziroglu / Building and Environment 41 (2006) 756–762
760 Table 3 Statistical analysis for Rz values Source Corrected model Intercept Dry-water soaked (A) Panel type (B) Measurement direction parallel–perpendicular (C) AB AC BC ABC Error Total Corrected total
Sum of squares a
Degree of freedom
Mean square
F value
Significance
12,7436.21 549,569.13 12,783.59 80,107.27 7,765.69
15 1 3 1 1
8495.74 549569.13 4261.19 80107.27 7765.69
507.93 32,856.94 254.76 4789.35 464.28
*** *** *** *** ***
19,541.89 607.13 2,303.05 171.44 15,990.16 822,118.68 143,426.38
3 3 1 3 956 972 971
6513.96 202.37 2303.05 57.14 16.72
389.44 12.10 137.69 3.41
*** *** *** *
(***) ¼ highly significant. (*) ¼ 0.5% significant. a 2 R ¼ 0:889.
Table 4 Statistical analysis for Rmax values Source
Sum of squares
Corrected model Intercept Dry-water soaked (A) Panel type (B) Measurement direction parallel–perpendicular (C) AB AC BC ABC Error Total Corrected total
17,5387,318a 899,391,52 18,754,10 103,858,26 13,550,60 28,808,82 881,52 3,454,46 388,40 37,097,61 1,306,787,30 212,484,93
Mean square
F value
Significance
15 1 3 1 1
11,692.48 89,9391.52 6,251.36 10,3858.26 13550.60
301,31 23,177.18 161,09 2,676.41 349.19
*** *** *** *** ***
3 3 1 3 956 972 971
9,602.94 293,84 3454.46 129.46 38.80
247.46 7.57 89.02 3.33
*** *** *** *
Degree of freedom
(***) ¼ highly significant. (*) ¼ 0.5% significant. a 2 R ¼ 0:825.
temperature. Average values of Ra, Rz, and Rmax for HDF and overlaid panels were found as 2.73, 21.04, 27.27, 2.36, 16.69, and 22.50 mm, respectively (Figs. 5 and 6). Based on analysis of variance (ANOVA), significant difference was found between average Ra, Rz, and Rmax values taken from the surface of both types of samples at the initial condition. When the samples were soaked in water for 2 h, surface characteristics of overlaid panels also did not show any deterioration resulting in increase in roughness parameters. In fact surface quality of the overlaid samples improved 9% based on Ra values. This can be related to release of embossed surface of melamineimpregnated papers as water penetrates into it causing flattening out of groves on the paper due to embossing. As soaking time is increased from 2 to 24 h, no change
on the surface quality was determined based on the numerical values of roughness parameters. However, when samples were kept for 15 days in water, Ra value even reduced from 2.66 to 2.52 mm which is a 5.5% improvement of the surface roughness. This finding also suggests that the surface quality of the overlaid samples improved as a function of the soaking time. When HDF specimens were kept in water for 24 h, their surface quality adversely influenced resulting in an increase in the average Ra values from 2.73 to 5.19 mm. The other two parameters, namely Rz and Rmax also increased similarly to Ra. The amount of increase in Ra was only 10.5% as the soaking time was changed from 2 to 24 h. When the HDF samples were kept in water for 15 days, their surface quality was significantly affected having an Ra value of 7.09 mm. Based on the results of ANOVA,
ARTICLE IN PRESS H. Kalaycioglu, S. Hiziroglu / Building and Environment 41 (2006) 756–762
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Fig. 4. Average Ra values of the samples.
Fig. 5. Average Rz values of the samples.
water exposure time was found to be a significant parameter that influences the surface quality of the samples in terms of the three roughness parameters as can be seen in Tables 2–4.
4. Conclusions This study investigated the surface roughness of HDF and laminated panels using a fine stylus technique.
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Fig. 6. Average Rmax values of the samples.
It appears that the surface quality both along and across sandmarks and embossed grain orientation of laminated samples of such panels can be quantified by numerical parameters obtained from stylus-type profilometer. Water soaking did not influence the surface quality of overlaid samples; however, HDF panels had rougher surfaces than those of dry samples when they were soaked in water for three exposure times. Further studies of additional roughness parameters could give a better understanding to evaluate influence of water exposure on surface quality of the samples. Also determining density profiles of the specimens would be desirable to attain a detail information effect of vertical density variation as function of water soaking exposures. References [1] Tanritanir E, Akbulut T. Plywood industry and general situation of plywood trade. Laminart 1999(9):122–32. [2] Faust TD. Real time measurement of veneer surface roughness by image analysis. Forest Products Journal 1987;37(6):34–40. [3] Funck JW, Forrer JB, Butler DA, Bruner CC, Maristany AG. Measuring surface roughness of wood: a comparison of laser scatter and stylus tracing approaches. Proceedings of the Society of Photo-Optical Instrumentation Engineers, vol. 1821. Washington: Bellingham; 1992. p. 173–83. [4] Hiziroglu S. Surface roughness analysis of wood composites: a stylus method. Forest Products Journal 1996;46(7/8):67–72. [5] Hiziroglu S, Jarusombuti S, Fuengvivat V. Surface characteristics of wood composites manufactured in Thailand. Journal of Building and Environment. 2004;39:1359–64.
[6] Hiziroglu S, Holcomb R, Qinglin Wu. Particleboard manufacture from Eastern Redcedar. Forest Products Journal 2002;52(7/8): 72–6. [7] Stumbo DA. Surface texture, measuring, methods. Forest Products Journal 1963;12(7):299–303. [8] Ostman BAL. Surface roughness of wood-based panels after aging. Forest Products Journal 1983;33(7/8):35–42. [9] ANSI. Surface texture surface roughness, waviness, and lay B46.1. New York: The American Society of Mechanical Engineers; 1985 43pp. [10] Akbulut T, Hiziroglu S, Ayrilmis N. Surface absorption, surface roughness, and formaldehyde emission of Turkish medium density fiberboard. Forest Products Journal 2000;50(6):45–8. [11] Lemaster RL, Beal F. The use of dual sensors to measure surface roughness of wood-based composites. Proceedings of the ninth International Symposium on nondestructive testing of wood. Madison, WI: Forest Products Society; 1993. p. 123–30. [12] Peters C, Mergen A. Measuring wood surface smoothness: a proposed method. Forest Products Journal 1971;21(7):28–30. [13] Mummery L. Surface texture analysis. The handbook. Germany: Hommelwerke. Muhlhausen; 1993 106pp. [14] Hiziroglu S, Graham M. Effect of press closing time and target thickness on surface roughness of particleboard. Forest Products Journal 1998;48(3):50–4. [15] Ho KS. The effect of planning variables on surface texture of Meranti. Research pamphlet no. 117. Kepong, Malaysia: Forest Research Institute; 1993 25pp. [16] Peters C, Cumming JD. Measuring wood surface smoothness: a review. Forest Products Journal 1970;20(12):40–3. [17] Pohl P. Pressure of the gauging point a contact profilometer exerted on wood surface. In: Proceedings of the second Medzinarodna Vedecka Knoferencia. Slovensko: Nitro; 1999. [18] Suchsland O. The swelling and shrinkage of wood. Madison, WI: Forest Products Society; 2004. [19] Drew WE. Surface texture measurement errors: stylus type instruments. Quality (October) 1992:41–4.
Building and Environment 41 (2006) 756–762 www.elsevier.com/locate/buildenv
Evaluation of surface characteristics of laminated flooring Hulya Kalaycioglua,, Salim Hiziroglub a
Department of Forest Products Engineering, Karadeniz Technical University, Trabzon,Turkey b Department of Forestry, Oklahoma State University, Stillwater, OK 74078-6013, USA Received 10 March 2005; accepted 15 March 2005
Abstract In this study, surface characteristics of commercially manufactured laminated flooring were evaluated. The surface roughness of samples consisting of high-density fiberboard (HDF) base and melamine resin saturated paper overlay was investigated. Here, 10 cm 10 cm samples of two types of panels were used for the experiments. A fine stylus technique was employed for the measurements. Three roughness parameters, namely average roughness (Ra ), mean peak to valley height (Rz ), and maximum roughness (Rmax ) were considered to determine roughness of the flooring panels. It was found that statistically significant difference existed between two types of samples as well as values taken along and across the sandmarks of the HDF and overlaid panels. Average Ra , Rz , and Rmax values for HDF were found as 2.73, 26.04, and 27.27 mm, respectively. Overlaid samples resulted in 15.6%, 26.0%, and 21.0% lower values of above parameters than those of HDF panels. r 2005 Published by Elsevier Ltd. Keywords: Laminated flooring; Surface roughness; High-density fiberboard; Melamine saturated paper
1. Introduction Laminated flooring has been widely used in Europe for over 20 years and recently it is getting popular in North America [1]. In general, laminated flooring consisted of four main elements which are bonded together in the form of a sandwich. High-density fiberboard (HDF) having a density above 0.85 g/cm3 (HDF) is one of the most commonly used wood composite panels for the core layer. A wear resistant decorative paper usually saturated with melamine base resin is located in the core layer. A clear cap sheet made of aluminum oxide saturated film and a balancing backing are also put on the top of decorative paper and on the back of the panel, respectively. The main purpose of aluminum oxide film is to protect the surface against any stain. Laminate flooring should be durable and have high wear resistance. Some of these flooring panels have Corresponding author.
E-mail addresses: [email protected] (H. Kalaycioglu), [email protected] (S. Hiziroglu). 0360-1323/$ - see front matter r 2005 Published by Elsevier Ltd. doi:10.1016/j.buildenv.2005.03.012
at least twenty times higher strength and durability than that of a typical laminated kitchen countertop. Pressure, temperature, press time, and the quality of press caul are some of the parameters influencing the overall quality of final products. Surface roughness of the core material, HDF also plays a significant role for a proper construction. Any surface irregularities on the core or substrate may show through the overlay films and papers resulting in lowquality bonding between the layers. Subjective methods such as visual observation which depend on sandpaper grit sizes are commonly used to get a general idea about the surface roughness of wood composites used as substrate for overlaying. An accepted quantitative method to measure the surface quality of wood composite panels including HDF has not been established. Several methods such as laser, pneumatic, acoustic emission, and microscopy have been used to measure surface characteristics of wood-based composites. [2–8]. The stylus method which is used to evaluate the surface of metal and plastic materials gains most attention among various techniques since it evaluates
ARTICLE IN PRESS H. Kalaycioglu, S. Hiziroglu / Building and Environment 41 (2006) 756–762
the surface quality in terms of well-established numerical parameters [9–12]. It is accurate, practical, repeatable, and quantitative roughness parameters can also be precisely calculated by this method. Variables such as the stylus tip radius, the surface force produced by the stylus, and cut-off length of the profile have important influence on the accuracy of the results [13]. Cut-off length which is a filtering parameter separates unfiltered actual profile into two profiles, namely roughness and waviness profiles. Based on the standard, cut-off length should be at least 2.5 times the peak-to-peak spacing of the profile roughness so that a minimum of two peaks and valleys can be included within each cut-off length [13]. In this study, all three roughness parameters, Ra, Rz, and Rmax were calculated based on the filtered roughness profile. The use of the stylus technique in evaluating surface roughness of wood composites has been discussed in past studies [14–18]. The objective of this study is to evaluate surface roughness of both flooring samples before and after they were overlaid with melamine resin saturated decorative papers using a stylus technique. Established initial data will provide numerical qualitative values about the surface characteristics of such flooring samples. Also it is expected that the data will lead to improvement in overlaying process of the substrate resulting in a better quality of flooring product.
2. Materials and methods A total of 20, 10 HDF and 10 laminated flooring samples in 11 cm 11 cm 0.7 cm were randomly cut from commercially manufactured panels. HDF samples were sanded with a sequence of 120- and 180-grit sand papers during the manufacturing. Mixed hardwood furnish was the raw material for the HDF base. Fig. 1 illustrates the construction of the overlaid samples. All of the samples were conditioned in a room with a temperature of 20 1C and relative humidity of 65% prior the measurements. Surface roughness of the samples was quantitatively evaluated at initial dry condition, and
Fig. 1. Schematic illustration of overlaying of the flooring sample.
757
sequentially as they were soaked in water for 2-h, 24-h, and 15 days. Direction of the sandmarks on the sanded HDF panels were identified using the China marker when they were dry and a total of 20 roughness measurements were taken from the surface of samples both along and across the sandmarks at each exposure. Overlaid HDF samples were commercially produced using continuous press lines having a speed of 240 mm/s. Full-size panels were laminated using a pressure of 38 kg/cm2 pressure at a temperature of 203 1C for 27 s. The surfaces of the laminated samples were also embossed during the overlaying process to emphasize rays, and grain orientation to imitate natural appearance of solid wood. Similar to HDF samples, 20 measurements were also taken from the surface of such laminated samples along and across grain orientation of the melamine-impregnated papers based on visual identification. Measurements were repeated at the same locations after the samples were soaked in water for 2-h, 24 h and 15 days. A portable stylus profilometer, the Hommel Tester T-500 unit was used for the roughness measurements. Fig. 2 shows the profilometer on a flooring sample. The profilometer consists of main unit and pick-up which has a skid-type diamond stylus with 5 mm tip radius and 901 tip angle. The stylus traverses the surface at a constant speed of 1 mm/s over 15 mm tracing length. The vertical displacement of the stylus is converted into an electrical signal by a linear displacement detector before the signals are amplified and transferred into digital information. Roughness parameters can be calculated from the digital information. Three parameters, Ra, Rz, and Rmax were considered to evaluate the surface characteristics of the flooring samples. The specifications and definitions of the three roughness parameters are discussed in previous studies [4,5,19]. Figs. 3A–C depict typical roughness profiles of HDF and laminated samples as dry, 2-h, and 24-h, water soaked, respectively.
Fig. 2. Surface roughness profilometer.
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Fig. 3. Typical surface roughness of the samples at :(A) dry condition, (B) 2-h soaked, and (C) 24-h soaked.
ARTICLE IN PRESS H. Kalaycioglu, S. Hiziroglu / Building and Environment 41 (2006) 756–762
759
sanding and embossing processes. Tables 2–4 display statistical analysis of the experiments (Fig. 4). Overall surface roughness of both HDF and overlaid specimens had comparable values when they were conditioned at 65% relative humidity and room
3. Results and discussion Results of the surface roughness of the samples are displayed in Table 1. Both HDF and overlaid samples resulted in significant differences as a function of the
Table 1 Average roughness measurements of the flooring samples Roughness Exposure parameters (mm) condition
Ra
HDF panels
Dry
Rz Rmax Ra
2-h soaking
Rz Rmax Ra
24-h soaking
Rz Rmax Ra
15 day soaking
Rz Rmax
Overlaid panels
//
/
2.38 (0.10) 19.08 (0.12) 26.04 (0.22)
3.08 (0.18) 23.00 (0.15) 28.51 (0.24)
4.89 (0.21) 32.05 (0.24) 40.09 (0.18)
5.49 (0.25) 37.15 (0.22) 46.77 (0.23)
5.68 (0.25) 36.46 (0.24) 42.25 (0.19)
5.92 (0.19) 38.06 (0.22) 47.92 (0.18)
7.03 (0.21) 41.47 (0.18) 50.02 (0.22)
7.16 (0.24) 42.30 (0.23) 51.33 (0.21)
Average 2.73 21.04 27.27 5.19 34.60 44.93 5.80 37.26 45.08 7.09 41.88 50.67
//
/
1.63 (0.19) 10.54 (0.23) 14.49 (0.22)
3.09 (0.21) 22.85 (0.25) 30.51 (0.21)
1.75 (0.21) 11.47 (0.17) 15.45 (0.18)
3.18 (0.24) 19.35 (0.19) 26.25 (0.22)
2.27 (0.17) 14.59 (0.19) 19.06 (0.23)
3.05 (0.16) 18.46 (0.21) 24.96 (0.25)
1.79 (0.23) 11.48 (0.20) 16.01 (0.23)
3.25 (0.22) 19.63 (0.18) 26.13 (0.25)
Average 2.36 16.69 22.50 2.65 15.41 20.85 2.66 16.25 22.01 2.52 15.55 21.07
Values in parentheses are COV.
Table 2 Statistical analysis for Ra values Source Corrected model Intercept Dry-water soaked (A) Panel type (B) Measurement direction parallel–perpendicular (C) AB AC BC ABC Error Total Corrected total (***) ¼ highly significant. (*) ¼ 0.5% significant. a 2 R ¼ 0:890.
Sum of squares a
Degree of freedom
3,591.59 13,534.57 544.24 1,730.44 239.10
15 1 3 1 1
798.92 22.59 85.22 3.15 442.62 20,637.14 4,034.22
3 3 1 3 956 972 971
Mean square
F value
Significance
239,44 13,34.57 181.41 1,730.44 239.10
517.15 29,532.71 391.83 3,737.51 516.43
*** *** *** *** ***
575.18 16.26 184.08 2,270
*** *** *** *
266.30 7.53 85.22 1.05 0.463
ARTICLE IN PRESS H. Kalaycioglu, S. Hiziroglu / Building and Environment 41 (2006) 756–762
760 Table 3 Statistical analysis for Rz values Source Corrected model Intercept Dry-water soaked (A) Panel type (B) Measurement direction parallel–perpendicular (C) AB AC BC ABC Error Total Corrected total
Sum of squares a
Degree of freedom
Mean square
F value
Significance
12,7436.21 549,569.13 12,783.59 80,107.27 7,765.69
15 1 3 1 1
8495.74 549569.13 4261.19 80107.27 7765.69
507.93 32,856.94 254.76 4789.35 464.28
*** *** *** *** ***
19,541.89 607.13 2,303.05 171.44 15,990.16 822,118.68 143,426.38
3 3 1 3 956 972 971
6513.96 202.37 2303.05 57.14 16.72
389.44 12.10 137.69 3.41
*** *** *** *
(***) ¼ highly significant. (*) ¼ 0.5% significant. a 2 R ¼ 0:889.
Table 4 Statistical analysis for Rmax values Source
Sum of squares
Corrected model Intercept Dry-water soaked (A) Panel type (B) Measurement direction parallel–perpendicular (C) AB AC BC ABC Error Total Corrected total
17,5387,318a 899,391,52 18,754,10 103,858,26 13,550,60 28,808,82 881,52 3,454,46 388,40 37,097,61 1,306,787,30 212,484,93
Mean square
F value
Significance
15 1 3 1 1
11,692.48 89,9391.52 6,251.36 10,3858.26 13550.60
301,31 23,177.18 161,09 2,676.41 349.19
*** *** *** *** ***
3 3 1 3 956 972 971
9,602.94 293,84 3454.46 129.46 38.80
247.46 7.57 89.02 3.33
*** *** *** *
Degree of freedom
(***) ¼ highly significant. (*) ¼ 0.5% significant. a 2 R ¼ 0:825.
temperature. Average values of Ra, Rz, and Rmax for HDF and overlaid panels were found as 2.73, 21.04, 27.27, 2.36, 16.69, and 22.50 mm, respectively (Figs. 5 and 6). Based on analysis of variance (ANOVA), significant difference was found between average Ra, Rz, and Rmax values taken from the surface of both types of samples at the initial condition. When the samples were soaked in water for 2 h, surface characteristics of overlaid panels also did not show any deterioration resulting in increase in roughness parameters. In fact surface quality of the overlaid samples improved 9% based on Ra values. This can be related to release of embossed surface of melamineimpregnated papers as water penetrates into it causing flattening out of groves on the paper due to embossing. As soaking time is increased from 2 to 24 h, no change
on the surface quality was determined based on the numerical values of roughness parameters. However, when samples were kept for 15 days in water, Ra value even reduced from 2.66 to 2.52 mm which is a 5.5% improvement of the surface roughness. This finding also suggests that the surface quality of the overlaid samples improved as a function of the soaking time. When HDF specimens were kept in water for 24 h, their surface quality adversely influenced resulting in an increase in the average Ra values from 2.73 to 5.19 mm. The other two parameters, namely Rz and Rmax also increased similarly to Ra. The amount of increase in Ra was only 10.5% as the soaking time was changed from 2 to 24 h. When the HDF samples were kept in water for 15 days, their surface quality was significantly affected having an Ra value of 7.09 mm. Based on the results of ANOVA,
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Fig. 4. Average Ra values of the samples.
Fig. 5. Average Rz values of the samples.
water exposure time was found to be a significant parameter that influences the surface quality of the samples in terms of the three roughness parameters as can be seen in Tables 2–4.
4. Conclusions This study investigated the surface roughness of HDF and laminated panels using a fine stylus technique.
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Fig. 6. Average Rmax values of the samples.
It appears that the surface quality both along and across sandmarks and embossed grain orientation of laminated samples of such panels can be quantified by numerical parameters obtained from stylus-type profilometer. Water soaking did not influence the surface quality of overlaid samples; however, HDF panels had rougher surfaces than those of dry samples when they were soaked in water for three exposure times. Further studies of additional roughness parameters could give a better understanding to evaluate influence of water exposure on surface quality of the samples. Also determining density profiles of the specimens would be desirable to attain a detail information effect of vertical density variation as function of water soaking exposures. References [1] Tanritanir E, Akbulut T. Plywood industry and general situation of plywood trade. Laminart 1999(9):122–32. [2] Faust TD. Real time measurement of veneer surface roughness by image analysis. Forest Products Journal 1987;37(6):34–40. [3] Funck JW, Forrer JB, Butler DA, Bruner CC, Maristany AG. Measuring surface roughness of wood: a comparison of laser scatter and stylus tracing approaches. Proceedings of the Society of Photo-Optical Instrumentation Engineers, vol. 1821. Washington: Bellingham; 1992. p. 173–83. [4] Hiziroglu S. Surface roughness analysis of wood composites: a stylus method. Forest Products Journal 1996;46(7/8):67–72. [5] Hiziroglu S, Jarusombuti S, Fuengvivat V. Surface characteristics of wood composites manufactured in Thailand. Journal of Building and Environment. 2004;39:1359–64.
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