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AIR
Directory of Non-Destructive Testing Methods for the Wood-Based Panel Industry (AIR3-CT94-2077) |
Introduction
This directory has been produced by a group of
experts within the Concerted Action project
(
AIR3-CT94-2077), which was
funded by the Commission of the European Communities during the period
1994-97. Non-destructive testing (NDT) and assessment of both raw material
and panel properties, contribute to reducing start-up time after change of
batch recipe, minimising the amount of product sub-quality and reducing
production costs. There are many different kinds of NDT systems available
in the market. It is the aim of this DIRECTORY to inform the potential
user of such systems about the physical principles of these systems. The
descriptions detail the relationship between the measured values and the
targeted properties, the effect of influencing factors and boundary
conditions under which the NDT systems can be used. It has been edited for
a wide audience, including technologists in the panel products industries,
companies designing and supplying process control equipment, students and
teaching staff.
Background
NDT systems which are capable of in-line
monitoring of raw material and panel properties are helpful tools for
plant operators and quality controllers. The information resulting from
such systems really becomes valuable when they are integrated into an
overall production control concept. In such a case the interaction between
raw material and panel properties and production parameters may be taken
into account by complex process models, that, after a tuning period ,
facilitate very close control of the production process leading to
optimised quality and cost reduction.
During the last three decades, the European wood-based panel industries have shown a continuous growth from 10 to 30% in the market place. Starting with the production of particleboard in multi-opening presses, a rapid development led to the introduction of new production techniques, such as single opening and continuous presses. Furthermore a wide range of wood-based panel products was developed, often tailored to meet the requirements of the furniture and building industry.
Particleboard and Medium Density Fibreboard (MDF) are the principle board types. There is currently a strong development in Europe directed towards increased OSB production. For many years the wood-based panel industries have experienced increasing pressure from their customers on aspects of quality and just-in-time delivery. This has led to the introduction of ISO 9000 quality management systems in the European wood-based panel industries.
Nowadays a close and accurate control of the production process is an indispensable requirement in modern plants. Operator skill and experience are still very important in order to manage the complex interactions between raw material properties, production parameters and end product properties. However, the drive towards ever increasing speeds of production and the necessity to produce a wide range of different panel products in smaller batches requires in-line process control.
Use of the Directory
The objective of this directory is to
provide manufacturers of wood-based panels with a reference guide to
non-destructive testing (NDT) techniques for use in the manufacture of
wood-based panels. A technical description of some of the equipment
available to perform the required measurements is also included.
The directory consists of six major chapters:
From the flow charts the user will get an overview of the locations in the wood-based panel production line where NDT systems are already being used. The coding systems used in the specific descriptions of the different NDT systems enable the point of application of the systems in the production lines to be determined.
Each NDT description has the same structure. Each description is identified with a commonly accepted title for the method on which the NDT system is based. This is followed by a description of what the method is capable of measuring in terms of the production process and a reference code is used for indexing.
The actual physical parameters measured by the NDT technique are specified. The next section describes the physical principles on which the method is based. This section may contain diagrams of the measurement set-up or apparatus involved, as well as elementary theoretical background information useful for a better understanding of the method.
The next section gives a description of how the physical parameter measured relates to the property under investigation. This may include the presentation of equations and graphs.
The next boxes describe the "quality" of the measured values in terms of duration, resolution, measuring frequency and range. For the wood-based panel production in particular, the elapsed time between a measurement and the presentation of the result is very important. Resolution in terms of accuracy is a very sensitive piece of information, because it is often greatly dependent on correct calibration. It should be noted that absolute values are not necessary in all cases; comparative values, indicating a shift of properties, may also be valuable tools for controlling a process.
The measuring frequency can either be characterised as batch-wise/off discontinuously/in-line or continuously/in-line. The range of measures indicates in which range of the measured properties valid and reliable inform, can be achieved by using the NDT method.
The information on boundary conditions and interference by other factors refers to possible limitations of the specific system. Furthermore the current state of application of the NDT method is specified. The methods described, may already be applied in industry or in research laboratories. Some of the methods are under development, but have potential for being used in industrial application the near future.
For each NDT method a list of suppliers is given. A full listing of company names and addresses can be found in the supplier index. In some cases the system provided by individual suppliers may differ to some extent. In this director generalised description of the principles involved has been given. It is recognised that a specific solution of a given suppliers may be quite different to that of others. The list of suppliers has been compiled based on the information collected during the production of the directory. This does not imply that the list is exhaustive.
Most NDT descriptions end with some literature references, which might be used if the reader needs more specific information.
The index at the end of the directory can be used to identify NDT systems for a specific purpose or where in the production process a specific NDT system may be applied.
Contents
The directory is divided as follows:
Acknowledgements and disclaimer
The group received
assistance from many suppliers of NDT systems, who provided background
information about their products and the principles involved. Their
contribution is gratefully acknowledged.
This directory is by no means claimed to be complete or free of errors. The reader should consider that there is a continuous development in the field of NDT systems. Information collected yesterday on NDT systems may easily be overtaken tomorrow by new developments and findings.
The inclusion of products in this directory does not imply that these products are approved by the editorial group or that they have been especially selected or are preferred over others. Similarly, those products which have not been included in this directory have not been intentionally omitted; either the editorial team was not aware of the specific products, or no information was available to them during the preparation of the directory.
Publication details
This material was reproduced from the
publication of the Office for Official Publications of the European
Communities (1998), ISBN 92-828-4381-5, EUR 18489 EN. Copies may be
obtained from Dr J Welling at BFH or the Non-Food Secretariat,
DG XII, Belgium.
Contacts
Contact
Coordinator
EC Scientific Officer
OOPEC
Participant
© Copyright 2006 Policy Statements
Updated
by CPL Press:
03/07/2007
- biomatnet@biomatnet.org
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