Igor Petrunić

Investigation of the strength of ultrasonically welded sails

Purpose – Today when the newest high‐tech fibers and sophisticated material constructions are used for the production of sails, forming 3D sail shape from 2D sailcloth has still remained very primitive because classic sewing techniques are mostly used. Since, the clothing and technical textile industry has been recently using some of contemporary joining techniques (ultrasonic, thermal, high‐frequency) replacing classic sewing, this paper seeks to investigate the possibility of ultrasonic welding in the production of sails, and the strength of obtained bonds.Design/methodology/approach – Concerning the aim, sails were made employing the classic and modern (ultrasonic) joining technique whereby bonding parameters such as amplitude and welding speed, geometry of anvil wheels were varied. Objective quality evaluation of the bond made in such a way, was performed in order to be more exact about its strength.Findings – Based on the obtained results it has been concluded that ultrasonic welding may successfully...

Equipment and methods used to investigate energy processing parameters of sewing technology operations

Purpose – The equipment for computerised measuring of electrical power and energy is presented, adapted to the needs of investigating processing parameters of garment sewing operations.Design/methodology/approach – The method of measuring the energy necessary to run the sewing‐machine driving electrical motor is also presented, correlated to the stitching speed in joining a straight seam in a single, two, or three, segments. Electrical energy consumption is analysed as dependent on the stitching speed, varying the number of stitches in the seam.Findings – The investigations described have shown the impact of the method of work applied and the effect of the changes in garment sewing operation in processing parameters on the level of electrical energy consumed by the sewing‐machine drive electrical motor. A new measuring method has been introduced in garment engineering, aimed at predicting electrical energy consumption in garment sewing operations, thus opening a completely new field of investigation in th...