A new way of adhering woven textile to a nonwoven backing was explored, the end product in mind being a sound absorbent panel. Today a hot melt adhesive is sprayed on the nonwoven with woven decorating textile put on top before compression molding. This method results in an uneven layer of adhesive with the consequence of decorating textile detaching from the nonwoven and thereby a high number of discarded products. The report investigates the possibility of using a bicomponent fiber as the adhesive. This would guarantee an even layer of adhesive and make the manufacturing process one step shorter. A bicomponent fiber of core/sheath construction with a low melting polymer in the sheath was incorporated in the nonwoven upon fabrication. In the main bulk of the nonwoven a smaller ratio of bicomponent to normal polyester fiber was used, enough to stabilize the nonwoven. For the top layer of the nonwoven a higher ratio was chosen. As the nonwoven is then compression molded under heat together with the decorating textile, the low melting sheath of the bicomponent fiber will melt and create bonds within the nonwoven as well as to the textile. The ratio in the top layer was varied as well as the pressure in compression molding. The adhesion strength between nonwoven and decorating textile was tested, and the sound absorbing properties of the different manufactured samples were compared. The sound absorbing parameter of air flow resistance was tested and sound absorption was tested using impedance tube with transfer function method. Further, a way of testing transmission loss was developed by the manufacturing of a custom built impedance tube, which was then compared to the transfer function method. The results showed that a higher bicomponent percentage gave higher sound absorption in lower frequencies, but a lower sound absorption in higher frequencies. The thickness of the samples gave a positive effect on the sound absorption in all frequencies. The conclusion is to recommend a thicker material, and choose bicomponent according to which frequencies that should be absorbed and what adhesion strength is needed for end product. / Program: Textilteknik

Sontech International AB är ett företag som är specialiserade på ljudabsorbenter i metall och skum. De har tagit fram en ljudabsorbent i kartong med slitsar som går längs arket med ett avstånd på max 5 mm mellan dem. Denna produceras idag med en CNC-maskin och det tar 17 minuter per kvadratmeter att producera absorbenten med 5 mm mellan slitsarna. För att produkten ska vara lönsam behöver produktionstiden ned på en minut per kvadratmeter. Det är ett relativt litet företag med stora kunder och har därför inte tid eller resurser att lägga på att utveckla produktionen av den. Därför har författarna fått i ansvar att som examensarbete inom maskinteknik försöka utveckla och till sist presentera en färdig modell på en maskin för lösningen. Efter skisser, prototyper och val mellan tre färdiga modeller på föll valet på maskinen vid namn Krattan. Krattan drivs med två pneumatiska cylindrar som lyfter upp arket och drar vad som kallas krattan som består av 199 knivar tvärs över det. Produktionstiden uppskattas ha sjunkit till ca 20 sekunder per kvadratmeter kartongark. / Sontech International AB is a company that specializes in sound absorbents made of metal and foam. They have a new product that is a sound absorbent made of cardboard with cuts along the sheet of cardboard with a maximum distance between the cuts of 5 mm. This product is made with a CNC-machine and it takes 17 minutes per square meter to produce a sheet with 5 mm between each cut. To make the product viable the production time needs to come down to a minute per square meter. Sontech is are latively small company which is why they have not been able to spare the resources to develop a solution for manufacturing this product. The writers have based their thesis paper in mechanical engineering on developing and presenting a complete model of a machine as a method of production. After many sketches, prototypes and a selection between three different solutions they picked a machine that they refer to as ‘‘The rake’’. ‘’The rake’’ is powered by two pneumatic cylinders. One cylinder lifts the sheet of cardboard and either pushes or pulls ‘’the rake’’ part of the machine that is made of 199 blades. The production time is estimated to be about twenty seconds per square meter of cardboard.