Evaluation of the quality of the machined surfaces of Pinus elliottii Engelm. and Eucalyptus grandis W. Hill decks

Name: ANDRÉ PRATA VILLAS-BOAS MACIEL

Publication date: 28/02/2019
Advisor:

Name	Role
DJEISON CESAR BATISTA	Advisor *

Examining board:

Name	Role
DJEISON CESAR BATISTA	Advisor *
GRAZIELA BAPTISTA VIDAURRE	Internal Examiner *

Summary: The production of wood floors in Brazil is relevant in the world, especially those produced with native wood. Therefore, it is important to diversify the production and search for alternative species, due to environmental and supply issues. The main objective of this work was to evaluate the quality of the machined surfaces of Pinus elliottii and Eucalyptus grandis decks. Tangential boards with nominal dimensions of 30 x 100 x 3,000 mm (thickness x width x length) were used, sampled from the company stock WHERE the work was carried out. The boards were classified by apparent density and moisture content, both at two levels. An S4S planer molder was used for the production of the decks, which had five axes and a nominal rotation frequency of 5,200 RPM*min-1. The feed speed (Vf) was analyzed in three levels: 15, 20 and 25 m/min for Pinus elliottii and 3, 6 and 9 m/min for Eucalyptus grandis. Twelve treatments resulted from the interaction among the factors apparent density, moisture content and feed speed, with 15 repetitions. The quality of the machined surfaces was evaluated by the methods: i) roughness with surface roughness stylus tester (parameters Ra, Rz, and Rt); ii) visual-tactile analysis and; iii) measured advance per tooth (fz). The analysis of variance (&#945;= 0.05) in a factorial arrangement was applied to the quantitative roughness data, and the interaction among the factors apparent density, moisture content, and feed speed was verified. The grades (discrete data) of the visual-tactile and fz analysis were transformed into scores and analyzed by the Kruskal-Wallis H test (&#945;= 0,05). For the roughness of both species, there was no significant interaction (double or triple) between the tested factors (P-value>0.05). The effect of the moisture content was not significant (P-value>0.05); on the other hand, the effect of the apparent density was significant (P-value<0.05). The effect of the feed speed was significant (P-value<0.05) for Eucalyptus grandis and, for Pinus elliottii, only for Ra. The company is recommended to produce decks with the highest tested levels of apparent density and feed speed. In order to evaluate the quality of the machined surfaces, it is suggested to adopt the visual-tactile analysis, with experienced workers.

Keywords: wood floor, surface roughness, visual-tactile analysis, advance per tooth (fz).

Access to document