Plywood Production Research Articles

Possibilities of using hydrolytic lignin in the production of wood-splicing materials

The problem of improving the environmental safety of the waste management system of chemical processing of biomass of wood is quite acute in every forest producing and timber processing region. Study of the possibility of using to investigate hydrolytic lignin as a modifier of phenol-formaldehyde resin for the production of plywood have been conducted. Used materials: phenol-formaldehyde resin SFZh-3013; technical hydrolyzed lignin. Mathematical models of the process of pressing glued plywood were developed and the optimal parameters for the production of plywood were determined based on the use of SFZh-3013 resin modified with hydrolytic lignin. The optimal mode of pressing is: the amount of injected hydrolytic lignin in the SFZh-3013 resin grade is 5-10 parts by weight; pressing pressure 1.6 MPa, pressing temperature 135 °C and pressing time 9-10 minutes. The introduction of regimes developed using regression equations, with a sufficient degree of accuracy describing the pressing process, will significantly improve the efficiency of plywood production by saving energy and material costs and preserving product quality.

Accelerated aging of WPCs Based on Polypropylene and Birch plywood Sanding Dust

Abstract A lot of researchers are closely related with natural, lignocellulose fibre containing bio-composites production and studies. Various of polymer matrices, mainly polyolefins, combinations with natural fibres as a reinforcement are used. Our studies are focused on polypropylene based bio-composites containing birch plywood production by-product sanding dust (PSD) accelerated weathering processes. The obtained results showed the following sight. After the aging the surface of all samples had faded, the changes of the gloss (decreasing) and of the whiteness degree (increasing) also had taken place, but microhardness of the surface of specimens significantly has decreased. The tensile strength and modulus of the samples after UV aging diminished about 30–35%. That indicates to the changes not only in the surface layers of polymer but also inside of the polymer structure. The FTIR measurements showed that during UV aging process occurs significant changes of chemical structure of the weathered surface of all samples. DSC measurements showed an increase of degree of crystallinity of the weathered polypropylene composites after the first heating due to the recrystallization process in the polypropylene matrix and a small decreasing after second heating. The melting temperatures of all composites after UV aging considerably diminish up to 30°C.

Analisis Penyebab Kerusakan Mesin Produksi Kayu Lapis

PT. Sama Al-Tanmiah is a company engaged in the semi-finished plywood production industry. Semi-finished raw materials are further processed according to the needs of the buyer, the cause of damage is due to poor maintenance and deteriorating component quality. This research was conducted to determine the origin of the causes of damage to the production machine at PT. Same Al-Tanmiah. Retrieval of data obtained by means of interviews, observation and requesting secondary data for 6 months of production, for data processing using Fault Tree Analysis and Failure Mode and Effect Analysis. The data obtained from the company enters into data management. The next stage will be a fault tree image analysis using Microsoft Visio and weighting to the three production machines using Microsoft Excel. The results of the researchers obtained the root of the fault tree and the value of the RPN with weighted machine damage. Improvement of management and standard operating procedures (SOP).

Utilization of woody biomass combustion fly ash as a filler in the glue used for plywood production

The feasibility of the effective utilization of combustion ash from a woody biomass power plant as a novel filler added to adhesives used in plywood production is investigated. For this, plywood was prepared with glues containing combustion ashes having different properties, and the adhesion performance of the glues was examined in detail and compared with that of a glue containing calcium carbonate powder as the filler. Through optical microscopy observations and analyses of the adhesive layer in the plywood, the relationship between the properties of the glue, the structure of the adhesive layer, and the adhesion performance was unraveled. Results revealed that the glue containing woody biomass combustion ash without the unburned carbon component shows a better and more homogeneous adhesion performance than that containing calcium carbonate powder. The adhesion performance could be enhanced more uniformly by decreasing the particle size of the filler. The study also indicated that the difference in the adhesion performance according to the kind of filler is not due to the difference in the chemical structure of the adhesive layer, but because of the difference in the denseness of the adhesive layer dominated by the viscosity of the glue. Thus, this study confirms that woody biomass combustion ash could be practically utilized as a filler substitute of calcium carbonate powder in glues for manufacturing plywood.

Effect of glueline treatment using tobacco stalk and leaf midrib additives on the bond strength and termite resistance of urea-formaldehyde bonded plywood

ABSTRACT Stalk and leaf midrib particles with size <74 µm from the native (Batek) tobacco (Nicotiana tabacum) were used as an additive to replace wheat and coconut shell flour in urea-formaldehyde adhesive formulations. Control and formulated glue-mixes with tobacco particles additive were used to bond Falcataria moluccana veneers into 3-ply plywood. The effect of varying amounts of tobacco particles (4, 8 and 12%) in the glue-mixes on shear strength, wood failure and subterranean termite (Microcerotermes losbañosensis) resistance of the plywood was examined. An increase in shear strength and wood failure up to 8% tobacco particles loading was observed compared with plywood that used commercial glue formulation. Based on shear strength and wood failure, panels containing 4–8% tobacco particles would pass the requirements of PNS ISO 12466-2. Termite resistance at 12% tobacco particles improved by 43% compared with the control. Thus, tobacco particles can be considered as a more beneficial alternative glue-mix additive in plywood production.

Physical mechanical properties of plywood made from lesser known wood veneers bonded with phenol formaldehyde adhesive

Indonesia plywood production becomes the third-largest after wood particle and pulp production. However, this production is not supported by the continuous availability of wood as raw materials, so the use of less-known wood species such as mempisang wood can be considered as alternative raw materials for plywood. This study aims to develop plywood from mempisang wood and investigate the effect of glue spread on the physical and mechanical properties of plywood. The plywood consisted of three veneers glued with various glue spread of phenol-formaldehyde resin (250 g/m2, 275 g/m2, dan 300 g/m2) using single spread method. The plywood was hot-compressed at 130°C for 5 minutes with specific pressures at 10 kg/cm2. Physical-mechanical properties of plywood were carried out based on JAS 233-2003. The higher of glue spread slightly improves the physical and mechanical properties of the mempisang plywood. The Moisture Content (MC), and Shear Strength (SS) values of the plywood satisfied the requirements for the JAS 233-2003 standard. The best level of glue spread of the plywood glued with 300 g/m2 phenol-formaldehyde.

Fracture Toughness of Medium Molecular Weight Phenol Formaldehyde (MMwPF) Plywood

Currently in Malaysia, most of the plywood industries are using tropical hardwood veneer with combination of rubberwood to form plywood. The used of rubberwood has actively reduced the cost of plywood production but recently the price of rubberwood logs has increased due to the shortage of the supply. Due to the demand from other timber industries such as furniture and medium density board thus, alternative raw material which is not focuses on lignocellulosic material only but also on the residue can be offered. Oil palm stems (Elaeisguineensis Jacq) need to be explored as these stems are abundant after falling from plantations which have not been fully utilized due to their poor properties. The main drawback of oil palm is its low dimensional stability found in the stem parts. Therefore this study investigated the 100% oil palm stem (OPS) plywood denoted as PTA by optimizing the pre drying process of the veneer by using roller pressing machine, steam dryer and platen press machine. After the OPS veneers have been pre-dried, they were treated with Medium Molecular Weight Phenol Formaldehyde (MMwPF) resin before fabrication of OPS plywood. The product could be promoted as concrete foam, light weight partitions, wall panel and floor slabs. The fracture toughness of OPS plywood developed in this study denoted as PTA was investigated. These properties were compared with the properties of another two types of commercial OPS plywood denoted as PTB and PTC which were manufactured using OPS veneer with tropical hardwood veneer for face and back veneer and control plywood denoted as PTD which was manufactured using 100% tropical hardwood veneer. The highest value of plain strain and energy release was showed by PTA compared to commercial plywood. The failure was more prominent in wood which showed by the crack propagated line in the veneer layer.

Systematic assessment of wheat extenders in condensation resins for plywood production: Part I - physico-chemical adhesive properties

ABSTRACT The use of additives for resins modification is common practice in wood-based panel industry and wheat flour has been one of the most widely used extenders for decades. The amount of wheat flour to be added is determined through a sense of proportion, mainly based on experience, as systematic scientific studies on the effect of its individual components are limited. In this study, we added wheat flour, wheat starch and wheat protein as extenders in various quantities to urea (UF) and phenol formaldehyde (PF) resins and analysed their structure, pH value and buffer capacity through closely examining their interaction with the resins as well as their effect on viscosity and bonding strength development. As a result, wheat protein proved to be the most effective on both resins. Despite influencing adhesive properties in uncured state, no effect on the curing behaviour of the resins could be observed.

Ефективність виготовлення фанери, склеєної термопластичною плівкою

Досліджено ефективність виготовлення фанери, склеєної термопластичною плівкою. Ефективністю виготовлення фанери вважали сукупність економічної та екологічної ефективностей за результатами економії грошових ресурсів способом порівняння затрат під час виготовлення фанери, склеєної термопластичною плівкою, замість традиційної фанери. Встановлено, що застосування термопластичної плівки у виробництві фанери збільшує затрати на фанерну сировину на 100,8 грн/м3 та клейовий матеріал на 1874,0 грн/м3. З'ясовано, що основними відмінностями під час виробництва досліджуваних видів фанери є затрати на потреби в електроенергії, у гарячій воді на дільницях приготування клею і нанесення його на поверхню шпону та збори за викиди небезпечних сполук у навколишнє середовище. Встановлено, що найбільше споживання потреби води здійснюється на дільницях приготування клею та нанесення його на поверхню шпону. Відповідно затрати електроенергії на цих дільницях теж є значними. З'ясовано, що одним з вагомих факторів у виробництві фанери є викиди небезпечних сполук у навколишнє середовище, причиною якого є застосування термореактивних клеїв. Застосування термопластичних плівок у виробництві фанери відкидає потребу у становленні очисних споруд та щорічному збору за викиди формальдегіду та аміаку. Порівняння статей затрат на фанерну сировину (кряж) та клейові матеріали у виробництві традиційної фанери та фанери, склеєної термопластичною плівкою ПЕНГ, показує, що затрати коштів збільшуються в 1,4 раза під час виготовлення фанери, склеєної ПЕНГ. Однак, враховуючи затрати на потреби в електроенергії та у споживанні гарячої води, економія коштів становить 492337,56 грн. Незважаючи на затрати виробництва на фанерну сировину та клейовий матеріал, виготовлення фанери, склеєної термопластичною плівкою, є економічно вигіднішим за виробництво традиційної фанери. Окрім цього, екологічність отриманого продукту підвищує його конкурентоспроможність над традиційною фанерою. Запропонований спосіб виготовлення фанери підвищує продуктивність виготовлення завдяки відсутності трудовитратних операцій, гарантує високий ступінь чистоти атмосферного повітря для забезпечення якісних умов роботи працівників та екологічність готової продукції, яка навіть під час експлуатації є нетоксичною, що цим самим розширює можливості подальшого застосування.

Adhesion Investigations of Systems Based on Birch Plywood and Wood Plastic Composites

One type of birch plywood production by-product: plywood sanding dust (PSD) and virgin polypropylene (PP) composites adhesive activity was investigated. To improve of the WP (PP+40 wt.% PSD) composites sheets as overlay bonding strength against birch plywood surface and water resistance of these laminated systems the industrially produced WPC material was modified with maleated polypropylene wax (MAPP) additives. These studies showed possibility of the usage of presented by-product as an excellent reinforcement for PP based wood plastic composites and addition of the coupling agent (MAPP) gives the considerable increase of adhesive activity of the used WPC. Due to the presence of MAPP (up to 4%) significantly increases not only adhesive strength of the laminates but also water resistance of the laminated sandwich specimens. As the example adhesive bonding strength could reach 2,74 N/mm2 and increases up to 4 times to compare with unmodified WPC adhesives.

A Multifunctional Mineral Binder for Plywood Production: The Effect of Manufacturing Parameters on Bonding Quality

Geopolymers show great potential for use as binders in developing and manufacturing multifunctional wood products. The objective of this study was to improve the bonding quality of a geopolymer binder, with wood veneers, using different manufacturing parameters. To this end, we produced five layered plywood panels treated with various lay-up times (1, 5, 10, 15 min), panel compressibility values during hot pressing (5%, 10%, 15%, and 30% compression), veneer roughness values (low, medium, and high roughness), press temperatures (120, 140, and 160 °C), and veneer layouts via changing the middle layer position of plywood relative to the surface layers. The results show that the shear strength and thickness swelling were negatively influenced by increasing the lay-up time of resinated veneers and panel compressibility. Increasing the veneer roughness significantly increased the panels’ properties. Furthermore, the panels produced with a pressing temperature of 140 °C showed the best performances. The veneer layouts also significantly changed the physical and mechanical properties of the plywood panels. Generally speaking, the results obtained in this study show that improving the bonding quality of geopolymer binders with wood can be done through the manipulation of plywood manufacturing parameters.

Formaldehyde and VOC emissions from plywood panels bonded with bio-oil phenolic resins

Pyrolysis bio-oil was used to partially substitute for phenol in reacting with formaldehyde for the production of bio-oil phenol formaldehyde plywood (BPFP) panels, with the phenol substitution ratio being 20%, 40%, or 60%. Emissions of formaldehyde and volatile organic compounds (VOCs) from the BPFP panels were studied using solid-phase micro-extraction (SPME) followed by headspace gas chromatography/mass spectrometry (GC/MS), and were compared to those from the phenol formaldehyde plywood (PFP) panels. The sources for VOCs were analyzed, and the health risks associated with the BPFP were examined. Results showed that at 80 °C: (1) Formaldehyde emissions from the BPFP panels were increased to about 4 times that of PFP; (2) VOCs emissions were significantly reduced by up to 84.9% mainly due to the greatly reduced phenol emissions, although the total number of VOCs was increased from 20 to 35; (3) BPFP presents greatly increased carcinogenic and non-carcinogenic health risks because of its much stronger emissions of formaldehyde, N,N-dimethylformamide, benzofuran, furfural, and many chemicals from the bio-oil. It is highly advisable that the health risks are properly taken care of before the wide application of BPFP, or similar bio-oil based engineered wood products.

Effects of Selected Parameters on the Bonding Quality and Temperature Evolution Inside Plywood During Pressing.

This research optimizes the process of plywood production to determine its effectiveness in reducing energy and adhesive consumption for more efficient production with the required quality. The influence of selected parameters including veneer treatment (non-densified and densified), plywood structure, temperature, time and pressure of pressing, on the bonding quality and temperature evolution within the veneer stacks during hot pressing was investigated. Rotary-cut, non-densified and densified birch veneers and phenol formaldehyde (PF) adhesive were used to manufacture plywood samples. The effect of pressure and time of pressing on bonding quality of the plywood was determined. Bonding quality was evaluated by determining the shear strength of the plywood samples. The temperature evolution inside the veneer stacks was measured for birch veneers for different pressing temperatures and pressures for different numbers of veneer layers. The heating rate of the veneer stacks increased as the pressing temperature increased and decreased markedly with an increasing number of veneer layers. At a high pressing pressure, the heating rate of the densified veneer stacks was faster than that of non-densified veneers at the same pressure. The use of densified veneers for the production of plywood can lead to a shorter pressing time (17–50% reduction), lower glue consumption (33.3% reduction) and a lower pressing pressure (22.2% reduction) without negatively impacting the bonding strength of the plywood.

Systematic assessment of wheat extenders in formaldehyde-condensation plywood resins: part II – mechanical properties of plywood panels

ABSTRACT Wheat flour is used as an extender for urea (UF) and phenol formaldehyde (PF) resins in plywood production. The addition of wheat flour is usually based on operational experience. Whereas flour quality parameters are important predictors for the bread production, fundamental scientific knowledge is hardly available for adhesive applications. Therefore, this work focusses on the separate investigation of the main components of wheat flour: starch and protein, as additives to UF and PF resins in different amounts. The resin batches produced were used for manufacturing 9-layered birch plywood panels. While part I focused on physico-chemical properties of the adhesives, in this present part panel performance was tested in accordance with EN 314-1 (2005) and by evaluating formaldehyde emissions using micro-chamber/thermal extractor. The UF-based panels were tested for class 2 covered exterior use and the PF panels for class 3 non-covered exterior use according to EN 314-2 (1997). Wheat protein showed the most promising wet shear strength results for both resins, the resulting high viscosity limits its addition to 30%. An addition up to 100% wheat flour and wheat starch to UF resins provided sufficient wet shear strengths. None of the extenders had an effect on formaldehyde emissions.

Wood and Veneer Properties of Fast Growing Species from Batai, Eucalyptus and Kelampayan

Anatomical, physical, chemical and veneer properties of wood are important aspect that affect applicability of wood based product. This study is focused on three fast growing species of Batai (Paraserianthes falcataria), Eucalyptus (Eucalyptus pellita) and Kelampayan (Neolamarckia cadamba). All trees were cut into three height portion (bottom, middle and top) and wood disc samples are taken for anatomical, physical and chemical determination from each part of height. Meanwhile veneer properties were determined for veneer sheet after peeling and drying process. Eucalyptus shows the highest number of vessel for 16 mm2 area and near pith has higher frequency of vessel occurrence than near bark. The highest specific gravity for Batai, Eucalyptus and Kelampayan were found in bottom portion, followed by middle and top portion. Percentages of moisture content for this tree species is increased going from bottom to top portion. Cold and hot water, alcohol toluene, ash content and lignin content were found to have significant differences for top, middle and bottom of tree portion. The highest of percentage of veneer shrinkage was shown by Kelampayan veneer. Meanwhile, Batai veneer exhibited the lowest contact angle. As the conclusion, species and tree portions were found to be significantly affected for the anatomical, physical and chemical properties. For veneer analysis, species were found to affect veneer parameters. The results are of importance in order to optimize the production of plywood from fast growing species in Malaysia.

A research on the design a bamboo powder drying machine

Bamboo is a sustainable and environmentally friendly material that has the potential to improve the global decline of natural resources. Bamboo is very popular in the countryside of almost all Southeast countries, particularly in Vietnam. Its ability can replace some kinds of wood in decoration and household goods. Bamboo grows up rapidly and can be harvested within 3 to 5 years of planting, in the meanwhile, the harvesting time of other hardwood trees must be from 8 to 10 years or longer. The inherent characteristics of bamboo are lighter than other wood materials and have a value in social and environmental benefits. Its advances in manufacturing technology have created high-value products such as bamboo flooring and bamboo furniture that can substitute for wood flooring and wood furniture. According to the biology studies, the bamboo has the characteristics that can replace the natural wood, but the direction of development from the stage of cultivation to the stage of finished products has not been exploited thoroughly. The production of bamboo plywood will become a great potential for the bamboo plywood industry in Vietnam. Generally, the fabrication of bamboo plywood depends on the following processes such as cutting, grinding to powder or pulp, drying, and pressing processes. In cutting and grinding processes, the trivial remains of bamboo after use, shoots… can be chopped and ground to a powder that is dried and pressed into bamboo plywood by a specialized machine similar to the production of artificial wood particleboard (PB). Bamboo powder drying machine plays a very important role in the production process of bamboo plywood. The function of the machine is drying bamboo powder to get the technical required appropriate moisture before pressing it into the standard bamboo boards. This article presents a design of bamboo powder drying machine with simple structure, long life, medium productivity, and price suitable for medium and small scale production of the Vietnam market. The first bamboo powder drying machine that was manufactured in DCSElab and its products is considered to respond to the technical requirements of customers.

A study on the design of bamboo grinding machine

Bamboo is a sustainable and environmentally friendly material that has the potential to improve the global decline of natural resources. Bamboo is one of the popular flora in Southeast Asia; it is also traditional plants that grow abundantly in Vietnamese villages from north to south. Its ability can replace some kinds of wood in decoration and household goods. Bamboo grows up rapidly and can be harvested within 3 to 5 years of planting, in the meanwhile, the harvesting time of other hardwood trees must be from 8 to 10 years or longer. The inherent characteristics of bamboo are lighter than other wood materials and have a value in social and environmental benefits. Its advances in manufacturing technology have created high-value products such as bamboo flooring and bamboo furniture that can substitute for wood flooring and wood furniture. According to the biology studies, the bamboo has the characteristics that can replace the natural wood, but the direction of development from the stage of cultivation to the stage of finished products has not been exploited thoroughly. The production of bamboo plywood will become a great potential for the bamboo plywood industry in Vietnam. Generally, the fabrication of bamboo plywood depends on the following processes such as cutting, grinding to powder or pulp, drying, and pressing processes. In cutting and grinding processes, the trivial remains of bamboo after use, shoots… can be chopped and ground to a powder that is dried and pressed into bamboo plywood by a specialized machine similar to the production of artificial wood particleboard (PB). The aim of this paper is a representation of a design, computing the structure of a version of a bamboo grinding machine that is sustainable, responds to technical requirements, and protection of the environment. The result of the design was applied for manufacture a typical bamboo machine in the CAD-CAM workshop of DCSELAB in the framework of a project between DCSELAB and PhuAn Village Corporation that has evaluated with satisfaction the real proof of the design. The machine has been in the session of initial testing and exploitation.

A Design of Bamboo Plywood Pressing Machine

Bamboo is very popular in the countryside of almost all Southeast countries, particularly in Vietnam. Its ability can replace some kinds of wood in decoration and household goods. Bamboo grows up rapidly and can be harvested within 3 to 5 years of planting; in the meanwhile, the harvesting time of other hardwood trees must be from 8 to 10 years or longer. The inherent characteristics of bamboo are lighter than other wood materials and have a value in social and environmental benefits. Its advances in manufacturing technology have created high-value products such as bamboo flooring and bamboo furniture that can substitute for wood flooring and wood furniture. Bamboo plywood presses play an important role in the production of bamboo plywood in the industry. The machine has the function of pressing bamboo powder, and binder has been mixed from the front to the bamboo plank to meet the technical requirements. This article presents a design of bamboo plywood pressing machine that combines the heating function for the blocking board and keeps that temperature during the pressing process to create a suitable size bamboo plywood according to customer requirements. The simulation results show that the complete bamboo plywood-pressing machine is appropriate and authentic to the initial design. The result of the design was applied to manufacture the machine in DCSELAB workshop via a collaboration project between Langtre PhuAn company and the DCSELAB. The system is installed a resistance flat plate capacity of 1KW, and 2 resistors flat plate with the capacity of 0.8KW. The first manufactured machine is now in the initial working session in Langtre Villige, Binh Duong province. The initial experimental products were accepted by the partner company, and we have recommended some measures to ameliorate time by time the quality as well as the productivity of the machine. There is really not yet an official statistic on the comparison with the products of a similar machine, and we are attending the response of the customers.

Hemp flour as a formaldehyde scavenger for melamine-urea-formaldehyde adhesive in plywood production

The possibility of using hemp flour as a filling material for melamine-urea-formaldehyde (MUF) adhesive was investigated for the process of manufacturing plywood. Adhesive mixtures were filled with various amounts of hemp flour and compared to rye flour as a reference mixture, and their properties were tested. The quantity of added filler had a significant effect on the resins viscosity. Moreover, the replacement of rye flour with the hemp flour resulted in acceleration of gel time and a slight increase in solid content. Due to the high proteins content, hemp flour led to a significant reduction of formaldehyde emission. Bonding quality of plywood made with hemp flour as a filling material for the adhesive mixture meet the requirements from the standard. Introducing it in an amount of 20 pbw and 25 pbw (parts by weight) allowed for the production of plywood characterized by equally good mechanical properties as that of reference plywood glued with an adhesive mixed with rye flour. In summary, the proper amounts of hemp flour can be applied as a filling material and formaldehyde scavenger for MUF adhesive without the deterioration of mechanical properties of manufactured plywood.

Effect of vacuum hot pressing on the bonding quality and heat transfer performance of plywood

Vacuum technology was applied to the hot-pressing technology of plywood production with phenolic resin (PF). For plywood with the same number of layers, veneers were hot-pressed with conventional and vacuum hot-pressing processes respectively at the same hot-pressing time. Varying layers (3, 9 and 15-layers) and spread quantities (220 g m−2, 260 g m−2, 300 g m−2) were applied. Heat transfer performance of the assembly, polymerization extent of PF, and bonding quality of plywood were examined by thermocouple and humidity sensors, Fourier transform infrared spectroscopy (FTIR), fluorescence microscope and bonding strength measurement. The results indicated that, compared to conventional hot pressing, the temperature of the central layer of the assembly vacuum hot-pressed was significantly increased by about 20–30 °C and the adhesive cured more quickly. The hot-pressing method had a significant influence on the bonding strength of plywood, with an enhancement of the bonding strength to wood failure ratio of 48.37% and 33.55%, respectively. The adhesive between adjacent laminates formed a continuously dense layer with more connection points, leading to excellent mechanical meshing and high bonding quality. In addition, vacuum hot pressing can eliminate the influence of adhesive position on bonding strength and make the mechanical properties of plywood tend to be uniform in thickness direction. Under the experimental conditions, the variable energy cost of 15-ply plywood with 1 m3 produced by vacuum hot pressing was 3.83% less than that of conventional hot pressing, and the plywood could still maintain good bonding strength at low spread quantity.