Lathe check development and properties: effect of log soaking temperature, compression rate, cutting radius and cutting speed during peeling process of European beech (Fagus sylvatica L.) veneer

Abstract

Denaud. Lathe check development and properties: effect of log soaking temperature, compression rate, cutting radius and cutting speed during peeling process of European beech (Fagus sylvatica L.) veneer. AbstractThe depth of lathe checks and integrity of veneer have been shown to be critical factors affecting the bonding process but also affecting the mechanical properties of veneer-based products. This study shows how beech (Fagus sylvatica L.) veneer lathe checks interval and depths are affected by soaking temperature, compression rate, cutting radius and cutting speed during the peeling process in well-controlled conditions. Freshly felled European beech logs were soaked in a water tank at 50, 60, 70 or 80°C. Following soaking, the logs were immediately peeled with laboratory scale lathe (SEM S500) to 3.5 mm thick veneer at a cutting speed of 1, 2 or 3 m s -1 and pressure rates of 0, 5, 10 or 15%. The correlation between lathe check depth and frequency was validated using "Système de Mesure d'Ouverture des Fissures" (SMOF) device, which enables to measure check properties reliably on veneer ribbons. In a well-controlled peeling process, the strong correlation between check depth and interval was shown. At higher temperature, shallower and more frequent checks are created compared to lower temperature. However, the effect of soaking temperature (between 50-80°C) on veneer checking is much smaller than the effect of compression rate during peeling process, where the higher compression rate produced veneer with shallower and more frequent checks. The results of the study also show that the direction of lathe check propagation could be affected by the rays in beech veneer. Rays resist crack growth in tangential direction, but act as weak planes in radial direction.

The influence of veneer thickness and knot proportion on the mechanical properties of laminated veneer lumber (LVL) made from secondary quality hardwood

“…The lathe check properties of oak veneers have never been reported before. Unlike oak, beech lathe check properties have been studied more extensively (Denaud et al 2007;Pałubicki et al 2010;Daoui et al 2011;Rohumaa et al 2018). Figure 3 compares the veneer knot proportion (unweighted) on different positions in the log and different veneer thicknesses.…”

An image processing algorithm for detection and analysis of slicing checks

“…Rough estimates of CDR for plain-sliced veneers used in this study ranged from 40 to 50%, with the highest values represented by the lowest cutting thickness used: 1.5 mm. It can be inferred though, that the results were influenced by a number of uncontrolled factors such as varying cutting The results of the CF measurements (Table 4) indicate a negative effect of the veneer thickness on the CF, similar to the results on lathe checks (Denaud et al 2007;Palubicki et al 2010;Rohumaa et al 2018). However, this effect has limited industrial application since, for many finished wood products, an essential requirement is a "null check tolerance".…”

“…A method of automatic lathe check detection with focus on CF and CDR was presented by Palubicki et al (2010). Their method, also known as SMOF device, was further utilized and developed by Dupleix et al (2013), Pot et al (2015), and Rohumaa et al (2018). Antikainen et al (2015) presented a method for check detection based on trans-illuminance.…”

Investigating face veneer check development in decorative plywood panels: the impact of four common manufacturing factors

“…In future research this method should be employed to investigate the effects of other factors discussed in the rich literature of the subject in order to confirm or dismiss earlier hypotheses. This check characterisation methodology, particularly in combination with rapid veneer characterisation methods such as those demonstrated in Rohumaa et al (2018) and other useful assessment methodologies can help shed light on a greater range of potential check development factors, especially those related to the characterisation and quantification of pre-existing cracks which are hypothesised to contribute to the degree of checking in the final panel.…”

“…Lathe-check orientation is thought to be important because more pre-existing cracks are present on the loose-side. The severity of pre-existing cracks and the causes for them have been examined by many researchers (recently, Buchelt et al 2018;Rohumaa et al 2018). While research examining the causes and severity of pre-existing cracks exist, their association with the development of surfacing checking in products is limited to lathe-check orientation.…”