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Commissioned Reports - Scanning


Date: 2005
Title: To assess the operation feasibility of the WoodEye board scanner on UK Wood (CV3843)
Authors: Report commissioned from BRE
Full Report: BRE Digest 492 available from www.brebookshop.co.uk

Summary
Resulted in Seminar at BRE on timber scanning with speakers from grader/scanner manufacturers well attended by industry. Also BRE Digest 492 Timber Grading and Scanning detailing advances in these fields.


Date: 2005
Title: Study of application of timber scanning PhD (CV0038)
Authors: Report commissioned from BRE
Full Report: Awaiting electronic version

Summary
This project supports the PhD studies of Tim Reynolds at CTE on  Timber Quality & Scanning. The subject of this study is the application of optical scanning technology on both logs and sawn timber, with the aim of improving the utilisation of British-grown Sitka spruce. In order to determine what optical scanning techniques can be applied in industry, and in what manner, it is necessary to understand the effect of the characteristic being measured on timber performance. Using this knowledge, threshold values for processing decisions together with the overall effect of the sorting strategy can be determined. Technical and practical difficulties with the scanning processes can also be investigated.

Practical work completed to date: The main bulk of the practical work has comprised the testing and assessment of 500 battens obtained from four categorised forest stands.  Ninety logs were characterised with variables such as top and bottom diameter, whorl spacing and under-bark slope of grain beingrecorded. The logs were scanned by a 3D laser scanner prior to being converted.  Log shape variables such as sweep, ovality and taper were obtained from the scanner data. Pith eccentricity was manually measured from log disc images. The battens were machine stress graded and then conditioned to in-service levels of moisture content. Measurements were taken of distortion, knot size and position, knot area ratio, compression wood content, rate of growth, density, position relative to pith and slope of grain. Selected material was tested in bending to obtain Modulus of Elasticity (MOE) and Modulus of Rupture (MOR) values.

Around 100 small clear samples of Sitka spruce were subject to precise measurement of radial, tangential, and longitudinal shrinkage during drying. The samples were also tested in bending to obtain MOE and MOR values, and assessed for compression wood content. This work allowed the relationships between other measured variables such as rate of growth, distance from the pith, density and slope of grain to be explored. Microfibril angle measurements were made on sections taken from selected samples. Shrinkage measurements were also made on further sets of samples taken from selected curved logs containing compression wood.

Other material assessed for distortion characteristics included a batch of 100 battens which were noted to have significant compression wood content. These were grouped into compression wood categories and measured for distortion (bow, spring, twist and cup) after being dried unrestrained. Further material (around 200 battens) taken from the edge of a forest stand at Scotch Coultard with a high incidence of compression wood, was machine graded, measured for slope of grain and compression wood content, then tested in bending.

A database of around 100 machine grader rejects was also compiled, with the battens being re-graded to obtain detailed machine stiffness values. This material was also assessed for knot content, density, rate of growth and slope of grain. The battens were examined to classify the nature of the defect, or feature, at the lowest machine stiffness value along the length.
As well as the analysis of the inter-relationship of timber variables, a number of small scale experiments were performed to verify observations. These included a trial of a cutting pattern designed to reduce twist. Trials with scanning techniques based on the use of lasers, X-rays and image analysis techniques were also performed.


Date: 2002
Title: Evaluation of X-Ray grading machine (CV7501)
Authors: Report commissioned from BRE
Full Report: Awaiting electronic version

Summary
As part of the TIMGRAD project several new grading projects were investigated, the CTBA of France had produced an x-ray grading machine which had proved promising on a trial sample of 200 pieces of UK grown Sitka spruce. After the Dynagrade had been show not to function well with UK grown Sitka spruce it was thought appropriate that the X-ray grading technology should be investigated. To that end a significantly sized sample UK grown Sitka spruce was collectede. The material was passed through the BRE Cook-Bolinder to collect reference grading data and then shipped to the CTBA for passing through the X-grading machine.

The sample was broken in France and the strength, stiffness and density supplied to BRE with the X-ray grading data. However, France at that time used the global MoE (unlike the UK) and tested the timber at centre span rather than weakest section therefore the data  was unsuitable for direct comparison with grading based on the Cook –Bolinder. A relationship for UK grown Sitka spruce based on X-ray data was established but was inferior to results that would have been expected from a sample graded using a bending type machine, though direct comparison was not possible.
The outcome of the project was that no further action be taken with regard UK timber and the French grading machine. This machine was later superseded by the GoldenEye based on German x-ray grading technology.


Date: 2002
Title: Sawing and Scanning Research Literature Review (CV6668)
Authors: Report commissioned from BRE
Full Report: Awaiting electronic version

Summary
This was a literature review of advances in sawing and scanning technology.  The results were presented at a meeting with all the softwood saw millers.