More than 130 people from around the world gathered in Oxford for FIRA International Ltd’s World Furniture Technologies conference in September. The three-day conference covered a variety of topics, all closely allied to issues raised in the recent 2020 Vision research and innovation strategy for the furniture industry.
The 2020 Vision report has resulted in an action plan, drawn up in consultation with more than 60 industry representatives and trade associations from all sectors – and has the support of the DTI.
The presentation-packed conference included a paper by Dr Lyndon Buck, field chair in product design and design technology at Buckinghamshire Chilterns University College, addressing the subject of furniture design with composite materials.
Between 1994-1997, the furniture department of the university carried out experiments to establish the effects of introducing fibre composites into laminated timber sections. It was hoped that the resulting increase in strength and stability would allow thinner sections to be used without any loss of structural strength, and would also lead to laminated sections having less ‘spring-back’ when they were removed from the mould.
Quality in decline
Dr Buck suggested that the need for this treatment had been amplified by the fact that the quality of available timber used in the furniture industry was in decline.
As he pointed out: ‘Further optimisation of timber is necessary to improve its viability against isotropic structural materials such as metals and polymers… The tradition of using timber for furniture construction is coming under threat from rising costs, dwindling availability and falling quality.
‘Laminated timber overcomes these problems by allowing the use of cheap low-grade wood laminations in areas of low stress (usually the core) and expensive, high-grade materials where higher stresses occur
(usually towards the outer surfaces), hence improving structural efficiency. By using fibre composite/wood laminates,’ Dr Buck went on to add that ‘the strength to weight and stiffness to weight ratios may be increased substantially, lighter members can perform the essential load-bearing function without undue deflection, and there is less reliance on wood quality, consistency and predictability.’
Experiments showed that by using composites in the form of woven fabrics, fibre directionality was lost, therefore the fibre reinforcement was not being used efficiently, but that may be offset by the gains in stability that woven fabrics may offer. Timber loses up to 50% of its tensile strength with a slope of grain of 10O, Dr Buck reported, therefore, that fabrics that exhibit good stability in the warp and fill directions, such as twill weave or satin woven fabrics, should reduce distortion in the laminate, while the bi-directional reinforcement will enhance impact resistance and damage tolerance.
In conclusion, Dr Buck said, the research showed there was a place for fibre reinforced laminates and that furniture designers ‘should take full advantage of a material with all the mechanical advantages of an engineering composite with all the aesthetic benefits of wood. It just remains for the furniture industry to embrace these new materials to produce new designs for workable, profitable pieces that are graceful, lighter, stronger, free from distortion and more damage tolerant than present laminated furniture’.
One material that can now boast a substantial share of the furniture market, rising from relative obscurity 25 years ago, is MDF. Geoff Rhodes and Dr John Guerin, of Willamette Europe Ltd, UK and Ireland gave an insight into some of the key quality parameters that have changed over the past decade as expectations have increased.
When MDF was introduced into European markets in 1973, only standard grade, in a relatively small range of thicknesses was available. It was taken up by reproduction furniture makers as a replacement for solid lumber and, in particular, where solid edge lippings were used in combination with particleboard. By 1985 new markets saw MDF as a substitute for other wood products, but also for plastics, metals and textiles.
It is estimated that two-thirds of all MDF produced in Europe is used in the furniture industry and that a high degree of value adding is evident. Almost two-thirds of European manufacturers produce cut-to-size panels and over half produce moisture-resistant grades. Thin and light and super-light grades are produced by more than a third and some manufacturers produce specialist grades such as exterior grade, flame retardant grade and high density grade.
Moisture-resistant MDF has been used successfully for kitchen and bathroom furniture and other areas where condensation occurs, and exterior grade MDF, while used primarily in non-furniture applications, has found a niche with some manufacturers of garden furniture.
Flame-retardant MDF has become a preferred option for specialist shop fitters and furniture producers, and common applications include floor to ceiling storage cupboards that double as partition walls that meet fire regulations.
Environmentally sensitive sites, such as museums and laboratories, are now able to specify zero-formaldehyde MDF (zero formaldehyde in resin) for their furniture and fittings.
Opportunities opened up
|
“The aim of the project was to develop powder formulations for wood based substrates that would emulate the performance of coatings used in metal finishing and that would have additional environmental benefits” |
Thin MDF, available in thicknesses from 2.5-6mm, has opened up many opportunities for furniture designers and manufacturers. Traditional uses include furniture backs and drawer bottoms, but more recent products include elaborate curved work. In reproduction furniture, thin MDF is commonly used for mouldings and intricate fretwork, and affords the opportunity to build components to very precise tolerances.
Other speciality MDF products that are tipped for future growth are high density MDF for specialist applications such as high quality bedroom furniture and where increased panel strength is required, and light and super-light MDF for times when weight is a critical factor – such as in mobile homes, mobile exhibition stands and also in theatre scenery.
As the long-term trend for furniture production within the EU is one of low growth or even stagnation, said the Willamette presenters, developing new, innovative products such as these was of paramount importance. So too, was educating the market of the true potential of MDF.
The new internationally recognised EN6 standards would help promote the product as ‘these definitions give furniture makers and other end users a clear understanding of the suitability of a product for a particular application’.
One development which may take MDF further forward is the application of powder coating finishes, which Willamette anticipates ‘will gain wide market acceptance and market share in the years ahead for a variety of reasons including reduced cost and strong environmental characteristics. For example, it is anticipated that PVC foil overlays will lose share in the years ahead to competing finishes, including powder coating for environmental reasons’.
Two subsequent presentations discussed the subject: Dr Neil Strong, project co-ordinator for FIRA, discussed the practical implications of powder coating MDF and outlined initial research undertaken by FIRA which provided the groundwork for a proposal submitted to the European Commission’s Framework IV Co-operative Research (CRAFT) programme in 1996.
The aim of the project was to develop powder formulations for wood-based substrates that would emulate the performance of coatings used in metal finishing and that would have the additional environmental benefits of reducing volatile organic compound emissions by 100% and waste reduction, through reuse of powder, by up to 90%.
Initial developments in solvent-free coatings had concentrated on water-based systems, said Dr Strong, and while these had reached a level equivalent to solvent-based lacquers, their take-up had been slow because of the association of the use of water systems and the raising of the wood fibres.
Dr Martijn Antonisse of DSM Resins bv in the Netherlands said UV-curable powder coatings are a new, innovative way to coat heat sensitive substrates such as MDF. Previously the use of powder coatings was confined to metal substances due to the high temperature (10 minutes at 160-220°C) required to melt the powder and start the chemical cross-link reactions that result in the durable coating layer. The new UV-curable technology allows the much lower curing temperatures (<120°C) required by wood, MDF, paper or plastic and the first commercial applications on MDF were carried out this year.
Combination of advantages
UV-curable powder coatings combine the advantages of conventional powder coatings regarding coating properties, environmental friendliness and high application efficiency, with the possibility of low temperature cure of the UV coatings.
On MDF, good coating properties are obtained with regard to adhesion, hardness and chemical resistance, said Dr Antonisse. These compare very well to solvent borne or liquid UV coatings, and the coatings can be obtained in several colours and surface structures such as texture or semi-gloss.
Scientific research into the properties – specifically the electric properties – of solid wood were illustrated by Natasa Atanackov and Dr Petar Todorovic, both of Belgrade University in Yugoslavia. The purpose of the study into the different modifications of wood arose from the desire for its better utilisation. The general objective of increasing profit while meeting market demands under the conditions of a limited supply of high quality wood can be achieved by:
Ms Atanackov and Dr Todorovic’s research investigated the electric properties of samples of commercially available Yugoslav wood species, including spruce, fir, pine, beech, oak, ash, black locust and walnut. Ionising radiation treatment was performed by exposing samples to doses of 10kGy of 60Co gamma rays. The purpose of this was to provoke changes in the wood structure via the ionising effect. It had already been noticed that, as a result of this treatment, changes had occurred in the sense that wood fibres had decreased their ability to take up water.
The presenters concluded: ‘Results of these investigations are thought to be interesting regarding different application possibilities for which electric properties of wood are important.’
These might be related to high-frequency wood drying, high frequency assisted gluing, or the use of wood as a dialectric material. The latter can be of particular economic interest in terms of making better use of wood waste and production rejects.
|
“It allows the trade to promote perhaps the one key advantage that timber has over plastic, concrete and steel: that timber is endlessly renewable, infinitely variable, uniquely versatile and, without question, the most environmentally friendly material available today” |
|
Alasdair McGregor |
A paper presented by Sue Calver of FIRA in the absence of its author Dr Frimpong-Mensah also dealt with the issue of treating inexpensive wood in order to improve its appearance. Dr Frimpong-Mensah is with the Department of Wood Science and Technology at Ghana’s Institute of Renewable Natural Resources and his paper evaluated chemical staining as a wood furniture finish.
There is a long tradition of staining of wood furniture in Ghana using the three conventional stains of oil, water and non-grain raising, but there are a number of constraints associated with the use of these on Ghanaian wood species.
These include the non-uniformity of colour, bleeding, solubility in the top coats, penetration, grain raising and drying rate. Some tropical species contain agents that can make their surface finishing difficult by preventing the stains from drying and having a good adhesion, he said.
There are also some reservations among furniture manufacturers about chemical stains as wood finishes, Dr Frimpong-Mensah said, and this resulted in his nationwide survey in which a sample of 67 producers were selected to represent the Ghanaian furniture industry.
Variety of methods
Results showed a variety of methods of stain application, which ranged from the most widely used method of spraying, through to hand brushing, cloth or rag application or ‘other methods’. The number of coats also varied from three down to one and many respondents said they mixed the stain with a sanding scalar, a top coat or thinner.
‘Staining is a process which enhances the appearance of sub-quality wood surfaces and improves furniture components for marketing,’ said Dr Frimpong-Mensah. But he concluded: ‘The Ghana furniture industry has a large percentage of producers plagued by an inadequate knowledge of wood stains… Often the ana-tomy and chemistry of the wood species are not considered in the selection of suitable stains.’
Dr Stuart Walker, of the University of Calgary in Canada, presented a paper on the implications of sustainability for furniture design and manufacturing.
‘The effects of contemporary industrial infrastructures and systems on the environment are manifold and many of them, it seems, are negative,’ he told delegates. ‘There is a natural environment which is exploited, depleted and commonly regarded as a resource to be ‘harvested’. The effects of this exploitation can be harmful not only to ecosystems, but also to humanity.
Dr Walker continued: ‘There is also the created environment, the places of human habitation, work and recreation. Our industrial systems are also frequently in conflict with these.’
He said it was a moot point whether the natural world could continue to absorb both the depletion of resources and the production of waste, and he said sustainable development sought to manage environmental, social and economic imperatives simultaneously.
‘We must consider a significant shift in our ways of thinking about and implementing manufacturing so that mass-production and local-scale approaches become more integrated and interdependent,’ he said.
Dr Walker suggested that progress towards sustainability would require a greater emphasis on localisation which could have economic, environmental and social benefits. ‘Manufacturing a variety of products in relatively small quantities, for local markets using local designers, materials and labour can create employment opportunities, reduce transport requirements, utilise local skills and processes and create a material culture that is significant to place and community,’ he said.
Alasdair McGregor of FIRA sister company BM TRADA Certification, also addressed the issue of sustainability, this time in the wider context of the global resource.
Bringing delegates up to speed with the progress of forest management certification schemes and the eco-labelling of timber and paper products, Mr McGregor highlighted the work of the Forest Stewardship Council, the WWF 1995 Plus Group, the Pan European Forest Certification Council and national certification bodies. He also discussed chain of custody certification.
Forest management certification was now a fact of life, Mr McGregor told delegates. ‘For the moment market demand is growing. Timber’s time as the pre-eminent environmentally friendly building and furniture material has arrived and we have a wonderful window of opportunity to attack the market,’ he said.
Promoting responsibility
‘Forest management certification is an enabling process,’ he continued. ‘It enables companies to promote the fact that the forests are managed responsibly and that products can be produced that people can feel justifiably good about buying.
‘It is probably the most powerful marketing mechanism that the timber trade has had in a generation. It allows the trade to promote perhaps the one key advantage that timber has over plastic, concrete and steel: that timber is endlessly renewable, infinitely variable, uniquely versatile and, without question, the most environmentally friendly material available today and for endless future generations to come.’
Related Files
Furniture Consumption in Western Europe 1998
Comparison of Furniture and Non-Furniture Uses of MDF in Europe
