Wood Heating Research Articles

Effects of wood flour content and heat treatment on the dynamic mechanical and impact properties of LDPE/red balau (Shorea Dipterocarpaceae) composites

Red Balau saw dust was heat-treated at 180 °C and 200 °C for one hour and compounded with low-density polyethylene, LDPE, at 9, 20 and 37 wt%. The compounded materials were injection moulded into test specimens. Charpy impact assessment of the notched samples of the composites revealed that the peak load, P, and the critical stress intensity factor, Kc, increased with wood content and treatment temperature. While the energy to failure, W , and the critical strain energy release rate, Gc, decreased with wood content, the values were highest in composites made from wood flour treated at 180 °C and reduced in 200 °C treated wood composites. This behaviour revealed that heat treatment of wood flour at the 200 °C resulted in poorer impact properties of the composites. Dynamic mechanical analysis showed an increase in storage and loss modulus of composites made from untreated wood flour relative to the heat-treated ones. Tan delta values were also found to reduce in the heat-treated wood composites as a result of decreased damping. Heat treatment of wood flour at appropriate temperature enhanced both the mechanical and dynamic mechanical properties of the composites.

Exposure to household air pollution over 10 years is related to asthma and lung function decline

We investigated if long-term household air pollution (HAP) is associated with asthma and lung function decline in middle-aged adults, and whether these associations were modified by glutathione S-transferase (GST) gene variants, ventilation and atopy. Prospective data on HAP (heating, cooking, mould and smoking) and asthma were collected in the Tasmanian Longitudinal Health Study (TAHS) at mean ages 43 and 53 years (n=3314). Subsamples had data on lung function (n=897) and GST gene polymorphisms (n=928). Latent class analysis was used to characterise longitudinal patterns of exposure. Regression models assessed associations and interactions. We identified seven longitudinal HAP profiles. Of these, three were associated with persistent asthma, greater lung function decline and % reversibility by age 53 years compared with the "Least exposed" reference profile for those who used reverse-cycle air conditioning, electric cooking and no smoking. The "All gas" (OR 2.64, 95% CI 1.22-5.70), "Wood heating/smoking" (OR 2.71, 95% CI 1.21-6.05) and "Wood heating/gas cooking" (OR 2.60, 95% CI 1.11-6.11) profiles were associated with persistent asthma, as well as greater lung function decline and % reversibility. Participants with the GSTP1 Ile/Ile genotype were at a higher risk of asthma or greater lung function decline when exposed compared with other genotypes. Exhaust fan use and opening windows frequently may reduce the adverse effects of HAP produced by combustion heating and cooking on current asthma, presumably through increasing ventilation. Exposures to wood heating, gas cooking and heating, and tobacco smoke over 10 years increased the risks of persistent asthma, lung function decline and % reversibility, with evidence of interaction by GST genes and ventilation.

A review on life cycle assessments of thermally modified wood

AbstractThis review compiles various literature studies on the environmental impacts associated with the processes of thermal modification of wood. In wood preservation field, the wood modification by heat is considered as an ecofriendly process due to the absence of any additional chemicals. However, it is challenging to find proper scientific and industrial data that support this aspect. There are still very few complete studies on the life cycle assessment (LCA) and even less studies on the environmental impacts related to wood heat treatment processes whether on a laboratory or on an industrial scales. This comprehensive review on environmental impact assessment emphasizes environmental categories such as dwindling of natural resources, cumulative energy intake, gaseous, solid and liquid emissions occurred by the thermal-treated wood industry. All literature-based data were collected for every single step of the process of wood thermal modification like resources, treatment process, transport and distribution, uses and end of life of treated wood products.

Research review of material prediction and quality control of heat-treated wood

As an environmental-friendly wood physical modification method, wood heat treatment can not only improve the dimensional stability and biological durability but also effectively improve wood color, and is widely used in the functional improvement of fast-growing wood. Some representative research achievements on heat treatment technology are discussed. The traditional processes of wood heat treatment are summarized, and the future research is prospected. The present research on wood heat treatment mainly focuses on the following aspects: (1) the influence mechanism of high temperature heat treatment on such properties as wood dimensional stability, color and crystallization; (2) effects of high temperature environment on the content of the main chemical components, the volatile evaporations and degradation process of wood extraction; (3) changes and reactivity of phenolic hydroxyl and surface free radicals in lignin; (4) effects of heat treatment on wood permeability, paint film adhesion and durability. On this basis, the correlation between changes of wood characteristics (mass or surface chromaticity index) before and after heat treatment and heat treatment intensity is further analyzed. The characteristic parameters of wood such as mass loss rate, color difference of treated wood and the ratio of oxygen to carbon elements are important parameters to predict the properties of heat-treated wood. The future research on wood heat treatment should focus on the relation of micromechanical properties at the cell level and the macro-mechanical properties, and the development of catalysts to reduce the energy consumption of wood heat treatment. The biological durability, environmental and mechanical properties of heat-treated wood can be predicted rapidly and accurately based on the content or proportion of the main elements, surface color and other characteristics. On the other hand, the main parameters of heat treatment process are determined by using the prediction model according to the application environment and requirements, which can provide reference for the follow-up study. [Ch, 48 ref.]

The Effect of Short Time Thermal Treatment on Swelling of Field Maple (Acer campestre L.) and Fir (Abies alba Mill.)

From the immemorial time wood is highly abundant and well-performing material. Further one due to practical use the wood heat treatment, as a process for improving its properties has been enhanced in the recent tim. Abies alba Mill and Acer campestre L. are among the most wide spread species in Albanian forest and among the most useful types of wood in Albanian wood industry. The objective of this study is to investigate the influence of short time heat treatment on dimensional stability and the mass loss of these two species. Wood samples are treated in three different temperatures (180 ℃, 200 ℃, 220 ℃) and two different time durations of 15 and 30 minutes. After the heat treatment, the mass loss is determined for treated samples. Treated and untreated samples are immersed in water and the swelling is determined. According to the results obtained, wood swelling undergoes a considerable reduction in the case of wood treatment at a temperature of 220 ℃ for the longest time duration of 30 minutes. The higher percentage of weight loss after the thermal treatment (9.66% for the maple and 10.77% for the fir) was measured in the samples treated in a 220 ℃ for 30 minutes. The results of both treated and untreated wood were given for comparative purposes.

Health Impacts of Ambient Biomass Smoke in Tasmania, Australia.

The island state of Tasmania has marked seasonal variations of fine particulate matter (PM2.5) concentrations related to wood heating during winter, planned forest fires during autumn and spring, and bushfires during summer. Biomass smoke causes considerable health harms and associated costs. We estimated the historical health burden from PM2.5 attributable to wood heater smoke (WHS) and landscape fire smoke (LFS) in Tasmania between 2010 and 2019. We calculated the daily population level exposure to WHS- and LFS-related PM2.5 and estimated the number of cases and health costs due to premature mortality, cardiorespiratory hospital admissions, and asthma emergency department (ED) visits. We estimated 69 deaths, 86 hospital admissions, and 15 asthma ED visits, each year, with over 74% of impacts attributed to WHS. Average yearly costs associated with WHS were of AUD$ 293 million and AUD$ 16 million for LFS. The latter increased up to more than AUD$ 34 million during extreme bushfire seasons. This is the first study to quantify the health impacts attributable to biomass smoke for Tasmania. We estimated substantial impacts, which could be reduced through replacing heating technologies, improving fire management, and possibly implementing integrated strategies. This would most likely produce important and cost-effective health benefits.

Warming with wood: Exploring the everyday heating practices of rural off-gas households in Wales

Rural off-gas households, the highest carbon emitters in the UK, have largely been overlooked in energy scholarship and policy, resulting in limited understanding of the ways in which the socio-material inequalities shape their likelihood of moving into fuel poverty. This paper sets out to fill this knowledge gap by developing a better understanding of the role that non-standard heating technologies play in the thermal comfort practices of rural off-gas households in Wales. Specifically, this paper focuses on ‘traditional’ wood or biomass heating – open fires, enclosed stoves and range-ovens – that are popular and commonplace throughout the UK, particularly in rural households, where they may be utilised for primary or supplementary heating. Findings show that traditional wood/biomass heating, as part of a rural off-grid heating-mix, enables households to respond to financial tensions in meaningful ways that are perceived to make their circumstances better. Additionally, insights highlight the importance of considering the potential conflicts between sustainability agendas that inform contemporary energy policymaking, as well as understanding the existing dynamics of rural off-gas thermal comfort for informing just low-carbon transitions.

Influence of cooling rate on the physical properties, chemical composition, and mechanical properties of heat-treated rubberwood

Abstract This study aimed to reduce the loss of mechanical strength in heat-treated rubberwood by rapid cooling. Heat-treated rubberwood specimens were prepared by controlling their cooling rate during the cooling phase of the heat treatment. The effects of cooling rate on the physical properties, chemical composition, and mechanical properties of heat-treated rubberwood were evaluated. Results indicated that cooling rate significantly influenced mass loss (ML). ML in heat-treated rubberwood cooled at 6 °C min−1 decreased by 23% relative to that in heat-treated rubberwood subjected to natural cooling. Compared with the heat-treated rubberwood subjected to natural cooling, the heat-treated rubberwood that was cooled at 4.5 °C min−1 increased in modulus of rupture (MOR), surface hardness, and screw withdrawal strength (tangential section) by 26, 8, and 16%, respectively. The cool rates exerted less effects on the dimensional stability, surface color, modulus of elasticity (MOE), compressive strength parallel to grain (CS), and screw withdrawal strength (radial section) of the heat-treated rubberwood. The application of rapid cooling to wood heat treatment could efficiently shortened the heat treatment period, thus increasing productivity.

Investigation of real-life operating patterns of wood-burning appliances using stack temperature data

ABSTRACTA study was undertaken to identify patterns of consumer use of outdoor wood boilers or outdoor wood furnaces (technically referred to as outdoor wood-fired hydronic heaters (OWHHs)) and indoor wood stoves (IWSs) to inform the development of performance testing protocols that reflect real-life operating conditions. These devices are manually fed, and their usage protocols are a function of a number of variables, including user habits, household characteristics, and environmental factors. In this study, researchers logged the stack wall temperatures of 4 OWHH and 20 IWS units in the states of New York and Washington over two heating seasons. Stack wall temperature is an indicator of changes in combustion modes. Two algorithms were developed to identify usage modes and cold and warm start refueling events from the stack wall temperature time series. A linear correlation analysis was conducted to evaluate the effect of heat demand on usage patterns. The results and methods presented here will inform the cataloging of typical operational patterns of OWHHs and IWSs as a step in the development of performance testing procedures that represent actual in-home usage patterns.Implications: Current US regulatory programs for residential wood heating use a certification program to assess emissions and efficiency performance. Testing under this program uses a test that burns 100% of a single, standardized wood fuel charge to assess performance at different steady-state load conditions. This study assessed in-field operational patterns to determine if the current certification approach accurately characterized typical homeowner use patterns. The data from this study can be used to inform revisions to testing methods to increase certification test comparability between lab and field performance.

‘Simple’ surface-fire heat treatment significantly improves silcrete flake quality and flaking efficiency

Intentional stone heat treatment is a key marker for prehistoric behavioural variability. Yet, the relationship between differences in heat-treatment strategies and variations in stone tool-making processes remains heavily debated and poorly understood. We report on two experiments testing wood fuels and heating strategies applied to silcrete nodules from ~60 km south of Diepkloof Rock shelter in South Africa with early evidence for intentional silcrete heat treatment. We flaked the heated silcrete nodules to maximize miniaturized flake production. The resulting cores and flakes were compared in terms of their utility (flake cutting edge to mass) and cutting edge quality (cutting edge angles) in addition to quantifying woody residues and heat induced fracture rates. Our results show that ‘simpler’ surface-fire heat treatment strategies provide significant increases in miniaturized core utility and flake quality over unheated silcrete nodules. Some of these effects were obtained without more specialized knowledge than is required to maintain fires for cooking and other utilitarian purposes. Our results show that rapidly heating silcrete to modify rocks for miniaturized stone tool production is efficient at relatively low levels of technological investment.

Effect of press temperature on some properties of cement bonded particleboard

It is known that there is a correlation between hydration heat and physico-mechanical properties of wood based cement panels. Cement hydration is affected by many variables, such as chemical composition, water/cement ratio, wood/cement ratio, wood chemical properties, mineral additions and producing conditions. This study mainly aimed to investigate the effects of press temperature on some properties of three-layer cement bonded particleboard made from the particles of spruce (Picea orientalis) and poplar (Populus tremula). For this purpose, a total of 16 experimental board groups with 1200 kg/m3 target density and 1/3 wood-cement ratio were produced at the press temperatures of (20, 30, 40, 50, 60, 70 and 80) °C. As cement curing accelerator, CaCl2 was used at a rate of 5 % (cement weight basis). The physical, mechanical and thermal properties of the boards were determined. The results indicated that the press temperature substantially affected the properties of cement-bonded particleboard depending on the wood species. In the light of this study, the optimum temperatures in producing of cement-bonded particleboard were found as 40 °C for poplar wood and 60 °C for spruce wood.

Characterization of Residential Woodsmoke PM2.5 in the Adirondacks of New York

ABSTRACT Although woodsmoke from residential wood heating can be the dominant source of winter PM2.5 in rural areas, routine monitoring is done primarily in urban or suburban areas. To obtain data on elevated woodsmoke concentrations from nearby sources, the PM2.5, black carbon at 880 and 370 nm, particle-bound polycyclic aromatic hydrocarbons (PAHs), and wind speed and direction were measured during winter at three residential locations in Saranac Lake, New York. A paired-site design enabled the identification of local sources relative to larger spatial scales. With the exception of occasional regional PM events, the hourly measurements of this pollutant between the paired sites exhibited poor correlations, suggesting that local woodsmoke was responsible for the observed increases in PM values. One location that was adjacent to a residence with a wood stove, which was 40 meters from the monitoring site, experienced repeated episodes of elevated PM2.5 concentrations, with a maximum 3-hour average of 150 µg m–3, a maximum 24-hour rolling average of 64 µg m–3, and a maximum midnight-to-midnight average of 46 µg m–3. Despite these PM events, the data indicated that this location was likely in compliance with the current U.S. EPA National Ambient Air Quality Standards (NAAQS) for PM2.5. The daily PM2.5 concentration peaked and troughed during the nighttime and the daytime, respectively, at all of the sites, which is consistent with local ground-level pollution sources, such as woodsmoke; this diel pattern was also confirmed by Aaethalometer Delta-C (DC) data, a woodsmoke PM indicator. The particle-bound PAH data was less specific than the DC data to the PM in the woodsmoke, partly because the instrument for the former also responds to traffic pollution. One site repeatedly displayed the influence of 2-cycle engine snowmobile exhaust during the early evening hours, with very high PAH concentrations but only modestly elevated DC concentrations. Subsequent tests showed that fresh 2-cycle small engine exhaust produces a somewhat weaker response than woodsmoke in the DC in terms of the concentration per unit of PM.

Effects of extractives on degradation characteristics and VOCs released during wood heat treatment

Eucalyptus was applied to investigate the influence of extractives on thermo-degradation of wood during heat treatment. Degradation characteristics, specifically the thermal degradation kinetics and volatile products during the heat treatment, were studied. A kinetic analysis was performed based on the Arrhenius equation and the time-temperature superposition principle. A devolatilization analysis was then conducted according to the chromatography identification. The results showed that the extractives facilitated the thermo-degradation and initiated the degradation at a lower temperature. An earlier degradation starting point was detected, and a lower activation energy of 65.7 kJ/mol was calculated for the non-extracted Eucalyptus. The VOCs collected in this research were primarily acetates, furans, terpenes, and other compounds. The non-extracted specimen released more VOCs than the extracted specimen. Compared with extracted samples, further hemicellulose degradation was identified for the non-extracted samples at the whole stage of 180 °C and a temperature-elevating period of 200 °C, as well as lignin decomposition at the temperature-holding section of 220 °C. However, only hemicellulose degradation was observed in extracted samples. This research could be helpful for the mechanism explanation of wood heat treatments and to promote the process to be more efficient and environmentally friendly.

The effect of heating rate, particle size and gas flow on the yield of charcoal during the pyrolysis of radiata pine wood

Charcoal derived from sustainable grown wood is a potential source of fuel and reductant for iron and steel making and a potential way to decrease the net CO2 emissions from the steelmaking industry. However a modern charcoal making process is likely to be required to supply the iron and steel industry with the required amount of charcoal to make significant difference to greenhouse gas emissions. The design of such a process requires fundamental knowledge on the effect of process variables on charcoal formation and yield during pyrolysis.The effect of biomass heating rate, purging gas flow and particle size on the yield of charcoal from pine wood was quantified in a series of pyrolysis experiments using a thermo-gravimetric apparatus. Temperature-time curves obtained during the heating of biomass showed the pyrolysis reactions became exothermic at about 350 °C. Increasing the flow of inert carrier gas through the biomass sample resulted in a decrease in charcoal yield and a faster rate of biomass decomposition. At zero gas flow the charcoal yield is independent of particle size. As gas flow through the sample is increased the yield of charcoal is increasingly dependent on increasing particle size.Increasing the wood heating rate from 0.11 to 10 °C/min, resulted in decreased charcoal yield. The period of fast biomass decomposition shifted to higher temperatures and the start of decomposition occurred at higher temperatures. These results indicate that low temperature reactions of charcoal formation are favoured by low heating rates and the initial charcoal acts as a catalyst for primary biomass decomposition. Lower heating rates are also associated with increased retention of pyrolysis vapours in the biomass which results is increased production of secondary charcoal and increased charcoal yield.

Thermal decomposition fundamentals in large-diameter wooden logs during slow pyrolysis

Charcoal has several applications on both small and industrial scales. Nevertheless, its parallel production of approximately 70% in coproducts during the slow pyrolysis process is still considered a challenge, especially for producers in emerging countries. However, the Brazilian production model stands out positively compared to the other producing countries, considering that Brazil is the world’s largest charcoal and sole pig iron producer from a renewable natural resource. The aim of this work was to analyze the thermal behavior of wood during the thermochemical process and the macro-thermogravimetry of large wood samples in different moisture and diameter conditions, similar to those found in the production units in Brazil. The slow pyrolysis was performed using 30-cm-long logs. The highest temperature gradient of 280 °C was observed in the 14-cm-diameter and 40 wt% moisture logs. The wood heating rate during carbonization was nonlinear. The presence of water in the wood delays the charcoal production reactions by up to 50% and contributes to the formation of different thermal profiles in the wood. Thus, due to the nonlinear thermal profile of the transformation of wood into charcoal, thermal curves are an important tool to help the control systems of the charcoal production units.

CO2 Efficiency Break Points for Processes Associated to Wood and Coal Transport and Heating

This paper aims to deal with CO2 emissions in energy production process in an original way, based on calculations of total specific CO2 emissions, depending on the type of fuel and the transport distance. This paper has ambition to set a break point from where it is not worthwhile to use wood as an energy carrier as the alternative to coal. The reason for our study is the social urgency of selected problem. For example, in the area of public sector decision-making, wood heating is promoted regardless of the availability within the reasonable distance. From the current state of the research, it is also clear that none of the studies compare coal and biomass fuel transportation from the point of view of CO2 production. For this purpose, an original methodology has been proposed. It is based on a modified life cycle assessment (LCA), supplemented with a system of equations. The proposed methodology has a generalizable nature, and therefore, it can be applied to different regions. However, calculation inputs and modelling are based on specific site data. Based on the presented numerical analysis, the key finding is the break point for associated processes at a distance of 1779.64 km, since when that it is better to burn brown coal than wood in terms of total CO2 emissions. We can conclude that, in some cases, it is more efficient to use coal instead of wood as fuel in terms of CO2 emissions, particularly in regard to transport distance and type of transport.

Preparation and applications of electrically conductive wood layered composites

This paper presents simple, inexpensive and industrially-viable methods of creating electronically-active carbon nanotube and graphene-based coatings for wood, capable of bringing a wide range of new functionalities to traditionally passive wood-based construction elements, including furniture and flooring. The coating methods are tested against the surface properties of wood/wood-based materials and specific application requirements. Furthermore, a set of examples of wood-based electronic applications potentially useful in a wood industry context is demonstrated/tested. These include liquid, pressure and temperature sensors for such applications as flood, occupancy or fire detection, as well as nano/microthin heaters for residential heating or drying of moist construction wood.

Air Quality Impacts of Smoke from Hazard Reduction Burns and Domestic Wood Heating in Western Sydney

Air quality was measured in Auburn, a western suburb of Sydney, Australia, for approximately eighteen months during 2016 and 2017. A long open-path infrared spectrometer sampled path-averaged concentrations of several gaseous species, while other pollutants such as PM 2.5 and PM 10 were sampled by a mobile air quality station. The measurement site was impacted by a number of indoor wood-heating smoke events during cold winter nights as well as some major smoke events from hazard reduction burning in the spring of 2017. In this paper we compare the atmospheric composition during these different smoke pollution events and assess the relative overall impact on air quality from domestic wood-heaters and prescribed forest fires during the campaign. No significant differences in the composition of smoke from these two sources were identified in this study. Despite the hazard reduction burning events causing worse peak pollution levels, we find that the overall exposure to air toxins was greater from domestic wood-heaters due to their higher frequency and total duration. Our results suggest that policy-makers should place a greater focus on reducing wood-smoke pollution in Sydney and on communicating the issue to the public.

Linking past uses of legacy SVOCs with today's indoor levels and human exposure

Semivolatile organic compounds (SVOCs) emitted from consumer products, building materials, and indoor and outdoor activities can be highly persistent in indoor environments. Human exposure to and environmental contamination with polychlorinated biphenyls (PCBs) was previously reported in a region near a former PCB production facility in Slovakia. However, we found that the indoor residential PCB levels did not correlate with the distance from the facility. Rather, indoor levels in this region and those reported in the literature were related to the historic PCB use on a national scale and the inferred presence of primary sources of PCBs in the homes. Other SVOCs had levels linked with either the activities in the home, e.g., polycyclic aromatic hydrocarbons (PAHs) with wood heating; or outdoor activities, e.g., organochlorine pesticides (OCPs) with agricultural land use and building age. We propose a classification framework to prioritize SVOCs for monitoring in indoor environments and to evaluate risks from indoor SVOC exposures. Application of this framework to 88 measured SVOCs identified several PCB congeners (CB-11, -28, -52), hexachlorobenzene (HCB), benzo(a)pyrene, and γ-HCH as priority compounds based on high exposure and toxicity assessed by means of toxicity reference values (TRVs). Application of the framework to many emerging compounds such as novel flame retardants was not possible because of either no or outdated TRVs. Concurrent identification of seven SVOC groups in indoor environments provided information on their comparative levels and distributions, their sources, and informed our assessment of associated risks.

Дослідження процесу гнуття деревини бука у пресі з високочастотним нагріванням

Перспективною технологією виготовлення гнутих деталей із масивної деревини є використання пресів, обладнаних генераторами СВЧ. Нагрівання деревини в полі струмів високої частоти дає змогу швидко нагріти її до потрібної температури, за якої пластичні властивості деревини будуть найкращими. Час на повний цикл гнуття становить 20…40 хв, тиск – до 500 кг/см2, кінцева вологість заготовок – 6…8 %. Ця технологія істотно зменшує час на гнуття та підвищує продуктивність порівняно з іншим обладнанням та технологіями. Наведено методику та результати дослідження процесу гнуття деревини бука у пресах з високочастотним нагріванням, а також вплив технологічних параметрів безпосередньо на якість оброблених заготовок. Дослідження проведено в умовах виробництва із застосуванням преса італійської фірми Italpresse, загальною потужністю 35 кВт. Експерименти проведено на шаблоні для гнуття із стрілою прогину 70 мм з використанням заготовок завдовжки 975 мм та поперечним перерізом 37×27 мм. Аналізуючи якість гнуття, визначено кількість придатних заготовок. Неякісною вважали заготовку, придатність якої є неможливою через наявність у ній тріщин, сколів, вм'ятин, потемніння та інших дефектів, що унеможливлює її використання з естетичних чи фізико-механічних вимог у виробництві меблевих виробів. За результатами досліджень отримано три групи графіків залежності частки виходу якісних заготовок від часу витримки, напруженості електромагнітного поля та тиску пресування. На основі аналізу отриманих графічних залежностей зроблено такі висновки: 1) збільшення тиску пресування до межі 100 кг/см2 призводить до зменшення частки якісних заготовок, а за тиску 120 кг/см2 – частка якісних заготовок зростає і є більшим, ніж за 80 кг/см2; 2)збільшення часу витримки до межі 20 хв призводить до зростання частки якісних заготовок, а за межі 30 хв – до зменшення частки якісних заготовок; 3) із зростанням напруженості електромагнітного поля частка якісних заготовок зменшується. Для знаходження оптимальних параметрів процесу гнуття букових заготовок виконано оптимізацію, за результатами якої можна стверджувати, що найбільшу кількість якісних гнутих заготовок (98,63 %) можна отримати за найменшої напруженості електромагнітного поля та за найбільшого значення тиску пресування, і витримки заготовок під тиском упродовж 20 хв 40 с.