Edge screw withdrawal resistance in conventional particleboard and OSB: Influence of the particles type

Abstract

This research was based on presumption that the changes in size and shape of wood particles are expected to have certain impact on the particleboard quality in general. Since the conventional particleboard (PB) and oriented strand board (OSB) were built of the quite diverse wood particles, they present interesting specimens in the comparison tests. In this work, the influence of the wood particles type on the edge screw holding performance of conventional particleboard and OSB was investigated. Those tests were obtained with the screw diameters of 4.0 mm, 4.5 mm and 5 mm. Depth of embedment was 30 mm for all tests and with the pilot-hole diameter kept in the range of 80-90% in respect of the screw root diameter. Additional tests of the thickness density profile and tensile strength perpendicular to the surface of the board were conducted. Since the middle layer structure of the particleboard embeds the screw body, both mentioned parameters are considered important in the aspect of the quality of the edge screw holding performance. In order to have further insight into the conformation of the middle layer the image survey was obtained on the split board section presenting the surface of the middle layer. Significant differences in the SWR performance of OSB and PB was recorded at all screw diameters. For the screw withdrawal tests parameters OSB samples showed 56-73% superior mean values then conventional PB. On the other hand, the OSB showed wider dispersions of measured withdrawal forces at all screw diameters, which might present some of the problems in certain engineering and project calculations.Ovo istrazivanje je zasnovano na pretpostavci da promene u velicini i obliku iverja mogu imati uticaj na kvalitet ploce iverice uopste. Posto su konvencionalna ploca iverica i ploca iverica od orijentisanog "strend" iverja (OSB) izradjene od sasvim razlictog iverja, predstavljaju interesantne predmete poredjenja. U ovom radu ispitan je uticaj tipa iverja na ivicno drzanje vijaka u konvencionalnoj i OSB ploci iverici. Ispitivanja su radjena uz upotrebu vijaka precnika 4,0, 4,5 i 5,0 mm. Dubina uvrtanja je iznosila 30 mm za sve testove, a vijcani otvori su imali precnik u opsegu 80-90% u odnosu na precnik korena vijka. Takodje, obavljena su i ispitivanja debljinskog profila gustine i zatezne cvrstoce upravno na povrsinu ploce, posto oba ova svojstva predstavljaju pokazatelje kvaliteta srednjeg sloja ploce u kome je smesteno telo vijka. U cilju boljeg uvida u strukturu srednjeg sloja obavljen je vizuelni pregled povrsinskog preseka uzorka. U radu su utvrdjene znacajne razlike izmedju otpornosti prema izvlacenju vijka kod konvencionalne i OSB ploce iverice, pri svim precnicima vijaka. Pri tome, uzorci OSB-a pokazali su 56-73% vece srednje vrednosti sile izvlacenja u odnosu na konvencionalnu plocu. Sa druge strane, OSB ploca je pokazala vece rasipanje rezultata za sve precnike vijka, sto moze dovesti do odredjenih problema prilikom projektovanja i izrade namestaja.