An X-ray tomography approach to calculate air volume present in an insulation system sewn with lockstitch and spacer stitch

Abstract

PurposeSewing is the most widely used and preferred method for manufacturing clothing products for extreme weather conditions and other industrial insulation systems. Multiple layers of functional fabrics in combination with insulation materials are used to thermally insulate precious body heat from its surrounding cold environment. The sewing process fixes the insulation material between the fabric layers. During conventional sewing, the insulation material is compressed along the stitch line. With the compression of the insulation material, entrapped air is forced to leave the insulation material internal structure, and heat loss occurs along the entire length of the stitch line. It results in the deterioration of thermal properties of the end product along the stitch line.Design/methodology/approachThe amount of air, which is a decisive factor for thermal properties of any insulation system, was investigated at the level of a unit stitch length of a lockstitch. Conventional microscopy methods are not suitable to study the compression along the stitch line. With the help of X-ray tomography, the three-dimensional data of a stitch was taken and studied to measure the volume of air. The samples were prepared with conventional lockstitch sewing and a newly developed innovative sewing method “Spacer Stitching.” The results are compared with each other in terms of the amount of air present in a unit stitch length.FindingsCalculations based on X-ray tomography images of lockstitch and spacer stitch revealed that, in the case of lockstitch, a unit stitch has a 15% of its volume made up of material and 85% of its volume by air. In comparison, the spacer stitch with the same sewing and fabric parameters has a material volume of 4.6 % and an air volume of 95.4% in a single stitch.Practical implicationsThe research can positively improve the thermal properties of sewn material made for insulating purposes of conventional clothing as well as of industrial insulations.Originality/valueThere is no literature available which investigates and calculates the amount of air and material present along with a stitch line.

Joining High Thickness Materials by Sewing – first Modelling Steps of the Stitched Place

“…Although using alternative joining methods and especially ultrasonic welding are reported from time to time, these have the priority in thick membrane structures for architecture where a homogenous layer of thermoplastic material is available [5]. Using sewing threads allows adjustment of the seam thickness and the product visual appearance, and can can lead to improved thermal insulation of the final product [6,7].…”