Laser technology has joined forces with the textile and soft furnishings business to create a hugely successful stitchless joining process.
TWI is involved in a DTI funded project, Furnitureweld, to assess the Clearweld ® process for the production of textile seams within the furniture industry.
Laser-welded seams and demonstrator items have been produced in a range of furniture fabrics with a performance that compares favourably with their stitched counterparts.
The Clearweld process, which has been patented by TWI and commercialised by the Gentex Corporation, offers a solution for laser-welding thermoplastic components including textiles. A low visibility laser absorbing fluid is appliedto one or both of the fabric surfaces, or to a polymer film, which is then inserted at the joint. An infrared laser beam is then directed along the seam line. The beam passes through the fabric, heats the absorber and generates a weld,which seals the interface. The use of an absorber restricts melting to the interface between materials, rather than through the full thickness. This results in a joint that has a greater flexibility and softer feel than is made withother welding processes hence its suitability for textile applications. The outer texture of the fabric is also retained.
The recently completed 15-month project was led by the Furniture Industry Research Association, FIRA. A survey to identify the fabrics and current stitching techniques commonly used within the furniture industry was undertaken.Welds were made in a variety of synthetic fabrics and the strength of welded seams was assessed with promising results. An equipment specification was developed to inform potential users of the most appropriate automated laser systemfor the furniture industry. Cost analysis, health and safety implications and sustainability issues associated with the uptake of the technology were also evaluated. The practical feasibility of the process was assessed through theproduction of demonstrator articles containing laser-welded seams.
A dedicated laser-welding system was set up at TWI by partners, Laser Lines and Motoman Robotics. Furniture manufacturing consortium members, Silentnight Beds and Knightsbridge Furniture Productions have provided invaluable input to'real life' applications.
Three manufacturing operations within the bedding industry were selected to act as demonstrators:
- Attachment of the label to the mattress
- Joining the mattress border
- Welding the fabric to the wood laminate to cover the divan drawers
Silentnight Beds constructed a bed from the laser welded demonstrator components. The bed was subjected to an industry standard testing programme and survived the tests with no visible deterioration of the welded seams.
Alongside this, a basic fully upholstered healthcare chair was made where the critical seams in the chair back cover were laser-welded. The particular model selected contains a semi-circular 'handle-hole' at the top of the chairback, which has been identified as a site of potential infection. Laser welding offers a reduced risk of infection compared with stitched seams and therefore provides a benefit in this application.
Fig.2. The label attached to the mattress using the Clearweld process
The potential benefits of Clearweld technology within the furniture industry include:
- Lower manufacturing costs
- Improved quality and reproducibility
- Less reliance on skilled labour
- Faster production times
- Greater design flexibility
- Improved aesthetics
For further information on Furnitureweld and laser welding of plastics contact Ian Jones. E-mail: Ian.Jones@twi.co.uk. More details on the Clearweld process can be found at www.clearweld.com.
