Improving the value chain for plantation-grown eucalypt sawn wood in China, Vietnam and Australia: sawing and drying

The project FST/2001/021officially commenced with a joint inception meeting with FST/1999/095 in Zhanjiang, Guangdong Province, China in November 2005. These two ACIAR projects are closely linked using the same plantations and timeframe for research.

The inception meeting was conducted immediately after the IUFRO/ITTO "International Conference on Plantation Eucalyptus - Challenge in Product Development" held in Zhanjiang. This conference was held as a final reporting session for a large ITTO project to develop processing of eucalypts in China. The inception meeting was attended by representatives of Ensis, CERC, FSIV, University of Melbourne, Queensland Department of Primary Industries, Forestry Tasmania, Forests NSW, Stora Enso, Guangxi Forestry Research Institute, Guangxi Dongmen Forest Farm, Hunan Provincial Department and Beijing University. The inception meeting identified / confirmed (partly through the experience of the ITTO Project) the technological limitations in sawmilling and wood drying systems in both China and Vietnam that was recognised during project development. These identified limitations highlighted the importance of introducing or developing suitable technology and developing tree growing and processing skills in China and Vietnam.

Ensis attempted to overcome the deficiency in sawmilling technology with the assistance of Karasaw Australia. This assistance was additional collaboration unforeseen during project development. Karasaw Australia supply equipment in Australia that has been developed by Kallion Konepaja Oy (Kara) in Finland. Scientists from China were invited to Brisbane, Australia to inspect potential technology that may be introduced into China and Vietnam to develop small-scale sawmilling industries processing small diameter eucalypt logs from farm-based woodlots. Vietnamese and Chinese scientists also participated in trials processing 15-25 cm diameter Eucalyptus fastigata logs at the Timber Training Centre, Creswick, Victoria to test the suitability of a Kara PPS 500 multi-saw system imported into Australia from Finland. The trials indicated that the system may potentially meet this need with modification of the saws and mill design. Karasaw Australia is currently modifying the mill for potential processing of small diameter eucalypts in small regionally based sawmills in Australia, China and Vietnam.

In April 2006, five scientists from China and Vietnam attended a training session at the Timber Training Centre in Creswick, Victoria to train/upgrade skills in eucalypt timber sawing and wood drying, and were introduced to processing research procedures. While in Australia the scientists visited the University of Melbourne's Centre for Advanced Wood Processing and the CRC-Wood Innovations and were introduced to the microwave pre-treatment technology in solid wood processing. They also visited industrial sites in Victoria and New South Wales and intensively managed eucalypt farm forests in southern and northern Victoria.

In June / July 2006 the first of the larger scale processing trials were conducted in collaboration with Forests NSW and N.F. McDonnell & Sons in Victoria. This trial used four provenances of E. nitens with measured peripheral growth strain levels to assess the potential for a HewSaw R250 (or similar technology) to process eucalypts with a range of growth strain levels, and the potential for genetic improvement in resources developed for this processing technology. The HewSaw R250 is one of a number of sawing machines developed by the Viesto Group that applies chippers and saws in modern sawmill designs with potential to alleviate stresses that cause processing difficulties in eucalypts. Unlike the Kara PPS 500 the HewSaw R250 is a high throughput mill suitable for large scale industrial processing.

Assessment of the SilviScan technology in application for improvement in eucalypt resources for solid wood processing end uses has largely been completed. This work included an assessment of wood microstructure in a University of Melbourne, School of Forestry and Ecosystem Science Eucalyptus globulus silvicultural trail located in eastern Victoria. The effect of thinning and fertilizer application on wood microstructure was assessed and processing trails conducted in trees that represented the range in the variation found. Two draft reports have been prepared and two papers published in Wood Science and Technology and the proceedings of the IUFRO/ITTO Conference held in Zhanjiang.

Project FST 2001/021 continued to develop joint activities with FST 1999/091 by conducting processing trials using plantation material assessed in the field by FST 1999/091. This also involved engagement of industry in China, Vietnam and Australia. Major contributors were N. F. McDonnell & Sons (Victoria), Forest Enterprises Australia, the Dongmen veneer factory (China), Pisico (Vietnam), Raute (Singapore) and Veisto Oy (Finland). During the reporting period preparations were made for 3 processing trials (1 each in China, Vietnam and Australia) and 3 others (1 in China and 2 in Australia) were commenced or completed.

A report on the first of the processing trials has been completed. This was a sawing trial with ~135 logs conducted in collaboration with Forests NSW and N.F. McDonnell & Sons in Victoria using 4 provenances of E. nitens (17 y old plantations located near Tumut NSW) with measured peripheral growth strain levels, acoustic wave velocity (AWV) and Pilodyn measurements. The aim was to assess the capacity for these measurements to predict log and sawn board behaviour during harvest log handling and sawing. Sawing was conducted with a HewSaw R250. This machine is a single pass sawing machine developed by the Viesto Group in Finland that applies chippers and saws more-or-less simultaneously. The chippers which profile the cants appear to remove sufficient high stressed wood to allow sawing to proceed with little difficulty. The major findings from this research was that growth strain was only moderately useful in predicting growth stress related log and board behaviour, AWV was found to be a good predictor of log and board end splitting and could be used to predict recovery of sawn boards after docking end splits. Bow in sawn boards was the only important board behaviour characteristic related to growth stress release during sawing. Generally, this was of limited extent and not sufficiently severe to prevent major problems during transport and stacking of the boards. There was some provenance variation detected in log and board end-splitting and bow in sawn boards suggesting some potential improvement in performance.

A second report has been prepared for a trial conducted at the Dongmen Forest Farm, Guangxi Province, China. This trial was a departure from proposed work because adequate sawing equipment could not be located in this region of China. To overcome this difficulty logs were peeled and peeled veneer sheets kiln dried using standard processing methods for the production of internal grade veneer at the veneer factory in Dongmen. The trial used ~160 logs from a single clone of 12 y old E. urophylla x grandis from a spacing trial located in the Dongmen Forest Farm testing 6 spacing treatments. Growth strain, AWV and a number of other standing tree measurements were assessed for their potential to predict veneer recovery and quality. The main findings were that growth strain was a moderate predictor of log end splitting. On this occasion AWV was not a significant predictor of log end splitting. There was a significant effect detected for spacing treatment on recovery and value of veneer that was related to diameter growth. Models were developed that could predict recovery and product value based on log external features that could be used to value logs. Simulations suggest that there are likely to be substantial improvements in product quality with pruning as branch related defects were clearly the major grade limiting factor. Even greater improvement in product quality and value may be achieved with the production of appearance grade veneer. In addition to pruning trees a number of changes to processing methods would be required such as the application of pre-heating of logs, conveyors to transport veneer and veneer restraint in driers to prevent buckling and splitting of veneer. Log end splitting may also need to be reduced if appearance grade veneer were produced, however, this was not specifically tested in this research.

A third trial conducted with the Hewsaw R200 at the FEA sawmill in Tasmania with ~480 logs from a Forests NSW E. pilularis family trial (10 y old plantations located near Port Macquarie, NSW) has been completed. A subset of ~160 logs were intensively measured to examine log and board behaviour as for the E. nitens trial above so that comparisons can be made between trials. Product quality and value, board shrinkage and major grade limiting defects have been recorded for all logs. Financial modelling of the processing will be conducted using the financial analysis methodology in CSIROMILL using a module developed specifically for the HewSaw R200. Veisto Oy in Finland have been engaged to assist with input data to develop this module of CSIROMILL.

A processing trial is currently being planned for thinned 11 y old E. urophylla from a family trial at Ba Vi in northern Vietnam. This will be conducted at the Pisico sawmill at Quy Nhon in central Vietnam. Sawing will be undertaken with a horizontal band saw followed by application of sheltered air drying, steam reconditioning and kiln drying. This trial will apply standard sawing patterns for teak and a modified cutting pattern to assess the potential to reduce board end splitting. This project will also be conducted jointly with a project funded by MARD to compare a number of drying strategies for E. urophylla from central Vietnam. As with the completed processing trials growth strain and AWV from standing trees or logs will also be assessed for their potential to predict log and board behavioural characteristics with growth stress release.

One processing trial in Lizhou, China using ~16 y old E. dunnii and one at the FEA mill in Tasmania with CCV from Queensland are currently being planned.

Assessment of the SilviScan technology in application for improvement in eucalypt resources for solid wood processing end uses has also been completed and a report submitted to ACIAR.

FST 2001/021 continued joint activities with FST 1999/091 during the reporting period. The work in FST 2001/021 comprised a series of sub-projects (processing studies) that evaluated solid wood processing performance in commercial mills located in China, Vietnam and Australia. The mills applied a range of processing technologies with a number of species of plantation-grown eucalypt logs supplied by FST 1999/091. The logs were obtained from trees evaluated in the field to assess silvicultural and genetic effects of characteristics likely to affect solid wood processing. Where possible, in addition to establishing critical limits to growth stresses, tension wood, branch related defects and log quality, the sub-projects in FST 2001/021 tested silvicultural and genetic effects on processing performance.

The processing studies that commenced, continued from the previous reporting period or were completed during the reporting period are listed below with comments on their contribution to project objectives:
A large processing trial with E. grandis x urophylla conducted in collaboration with the Dongmen veneer mill in Guangxi Province, China, was completed and the report circulated to collaborators and the final report submitted to ACIAR. This project utilised veneer peeling equipment and wood residue heated veneer driers because of the difficulty locating acceptable sawing technology for research in southern Guangxi. The inclusion of peeling was a modification to the project objectives that broadened the scope of FST 2001/021. As with the earlier inclusion of the multiple circular saw technology developed by Viesto Oy and Karasaw in Finland in sub-projects conducted in Australia, this modification required alteration to the project objectives and outputs. One of the main benefits of inclusion of peeling was the capability of making direct comparisons of financial viability of sawmilling and peeling of small diameter eucalypts in China and Vietnam.
A processing trial was conducted with northern Vietnamese E. urophylla in a saw mill located in central Vietnam. Sawing methods developed for teak using a Vietnamese built single horizontal bandsaw coupled with kiln drying methods for Acacia spp. were applied. Comparisons of processing performance and product quality and value were made with some experimental sawing methods that included log rotation. Experimental steam reconditioning treatments were also conducted on a sub-sample of boards sent to Australia. This experiment indicated that processors in Vietnam and China are likely to benefit from inclusion of a commercial steam reconditioning treatment before final drying. A draft report has been prepared for the Forest Science Institute of Vietnam. The final report will be submitted to ACIAR in 2008.
Two other sawing and drying trials have been completed in Australia with E. pillularis from northern NSW and Corymbia citriodora spp variegata from southern Queensland. These sub-projects were conducted in collaboration with Forest Enterprises Australia with the HewSaw R200 located in Tasmania. Reports are being prepared for circulation to all collaborators.
The final trial for FST 2001/021 is still in the planning stage because of delays to the project due to the severe cold weather that occurred in southern China early in 2008. This work will commence in July 2008 with E. dunnii logs in a mill in Liuzhou in northern Guangxi. The mill is equipped with a single vertical bandsaw and mill residue heated kilns for final drying. We will incorporate an evaluation of steam reconditioning which will require modification to existing drying equipment and drying practices at the mill. Protocols for evaluation of the drying performance of E. dunnii will also be established. At the conclusion of the experiments all major activities for FST 2001/021 will have been completed.

The modifications to the project scope and timing of some of the sub-projects required alteration to a number of project milestones and deliverables. However, given no further delays during 2008/2009 all of the milestones will be met and the project completed on time.

Specific outputs:
September 2007; report on peeling trials with E. grandis x urophylla submitted to ACIAR.
October 2007; paper presented at the Plantation Eucalypts for High Value Timber Conference, Melbourne.
November 2007; Invited paper presented at Sawtech 2007, Melbourne.
March 2007; draft report on processing E. urophylla prepared for Vietnamese and Chinese partners.