Antonin Havelka

Tensile Properties of Sewing Thread and Sewing Needle Temperature at Different Speed of Sewing Machine

Needle heatup is a big issue for apparel industry especially for automobile industry seat covers where a lot of synthetic materials are used which get damaged by needle heat at high speed of sewing machine,in this article thermocamera and thermocouple are used to measure the precise temperature of needle eye and then 100% polyester 35x3 Tex thread is taken for sewing,the lockstitch sewing machine is run at 1000rpm,2000rpm and 3000rpm respectively and the both methods are used to obtain the accurate needle temperature and finally thread tensile properties are measured before the sewing and taking out the thread from the seam precisely to get the tensile properties of thread after 10,30 and 60 seconds of continuous stitching,the article is very helpful in predicting the exact temperature of needle in lock stitch machine and getting the damage to thread by the needle heat at different speeds and different stages of sewing process.

The transport phenomena of semi‐permeable membrane for sport cloth

Purpose – This paper aims to investigate the comfort properties of modern functional clothing, such as moisture and heat transport. Transport properties are evaluated for real barrier membrane clothes for sport application, under real weather conditions in Middle Europe.Design/methodology/approach – The different combination of functional clothing, with barrier membrane, were investigated under different temperatures and relative moistures inside and outside clothing layers. Water vapour permeability was measured under the steady‐state conditions, by sweating guarded‐hotplate test.Findings – This paper describes the theoretical analysis of moisture transport, and its influence on thermal conductivity; the paper investigates various barrier fabrics for sport apparel, and their ranges of water vapour transport ability under real weather conditions.Research limitations/implications – All received results are based on the transport of water vapour through a semi‐permeable membrane and are supposed to be condu...

Wrinkle free plaited knitted fabrics without pre-heat setting

Abstract Wrinkle free fabric at low cost is always a desirable aesthetic property. Different type of resins/finishes and pre-heat setting prior to processing are applied to avoid wrinkles in woven and hosiery, respectively. Current study is proposed to produce wrinkle free circular plaited knitted fabric by the elimination of a pre-boarding step. In this achievement, yarn covering parameters and compatibility of yarns with knitting machines are examined. Sock samples were analyzed for improved physical appearance (wrinkles) after various processes (pre-tumbling, dyeing, bleaching, and washing). Yarn specifications (sheath yarn fineness, sheath yarn texture i.e. shrink/un-shrink, covering air-knots) impact on socks physical appearance were also analyzed. The results clearly showed that by decreasing number of yarn covering air knots and sheath yarn fineness leads to prevention of wrinkle formation. The results also prove to be supportive for cost effectiveness by eliminating the pre-setting stage.

Review: Radiation Heat Transfer Through Fire Fighter Protective Clothing

A fire fighter garment is multilayer protective clothing with an outer shell, moisture barrier and thermal barrier, respectively. Fire fighters encounter different levels of radiant heat flux while performing their duties. This review study acknowledges the importance and performance of fire fighter protective clothing when subjected to a low level of radiation heat flux as well as the influence of air gaps and their respective position on the thermal insulation behaviour of multilayer protective clothing. Thermal insulation plays a vital role in the thermal comfort and protective performance of fire fighter protective clothing (FFPC). The main emphasis of this study was to analyse the performance of FFPC under different levels of radiant heat flux and how the exposure time of fire fighters can be enhanced before acquiring burn injuries. The preliminary portion of this study deals with the modes of heat transportation within textile fabrics, the mechanism of thermal equilibrium of the human body and the thermal protective performance of firefighter protective clothing. The middle portion is concerned with thermal insulation and prediction of the physiological load of FFPC. The last section deals with numerical models of heat transmission through firefighter protective clothing assemblies and possible utility of aerogels and phase change materials (PCMs) for enhancing the thermal protective performance of FFPC.

Effect of Perforated Polyurethane Foam on Moisture Permeability for Car Seat Comfort

Polyurethane (PU) foams are the most essential part of a car seat cushion. PU foams are durable and easily moldable according to the shape of the car seat, but they are poorly permeable to moisture. This impermeability of PU foam causes wetness of the microclimate between the person and car seat and makes it uncomfortable. In this research PU foams with two different thicknesses and three different hole sizes were obtained from industry by the moulding process. The foams were tested for moisture permeability by the standard cup method to determine the effect of the size of the hole on the overall moisture permeability. The foams were further tested with 11 of the most common top layer fabrics to check the effect of the top fabric layer on the overall moisture permeability of the car seat. All the top layers were first tested by means of a sweating guarded hot plate (SGHP) to measure the water vapour resistance (Ret) and then 4 materials with the minimum Ret values were tested with the most permeable foam. The results shows that the perforation of PU foam causes a significant increase in moisture permeability, whereas the top layer with the minimum Ret value decreases the overall moisture permeability and a maximum of 40g/m2 of moisture per hour is obtained with the most permeable foam with the least Ret value of the top layer. This research is an initial work on replacing the car seat with perforated PU-foams.

Development of V-Shaped Compression Socks on Conventional Socks Knitting Machine

Abstract The aim of this study was to develop V-shape compression socks that should exert graduated lateral compression around the leg. For the development of socks, three types of yarns: main yarn (MY), plaiting yarn (PY) and inlaid yarn (IY) were used. Each yarn contained spandex yarn as the core. Machine adjustments were optimized to achieve the special V-shaped compression socks according to size of the wooden leg. Eighteen socks samples were developed and quantified for pressure exertion at ankle and calf portions using the MST MKIV, Salzmann pressure measuring device. Consequently, only two socks samples were accepted, which had the pressure exertion values of 21 mmHg and 23 mmHg with graduation percentage of 73% and 80%, respectively.

Effect of a Superabsorbent for the Improvement of Car Seat Thermal Comfort

The use of super absorbent polymers (SAP) for moisture absorption and comfort is still unexplored. The aim of this work was to observe the application of super absorbent fibres in car seats for comfort purposes. In this research the efficiency of different SAP fibrous webs were determined under different moisture percentages to examine the sorption and desorption efficiency. A SAP fibrous web with low thickness and high moisture absorption were tested with a multilayer sandwich structure of a car seat cover to determine moisture absorption through the cover material. The standard Cup method was used to determine the moisture permeability of different car seat covers with a superabsorbent layer closed with impermeable polyurethane foam. It was observed that the SAP fibrous layers are very effective in absorbing and desorbing water vapour under extremely high and low moisture percentages. In extreme humid conditions (95%RH), 20g of the SAP layer absorbs nearly 70% of its weight in water vapour, reaching the maximum absorption capacity in 6 hours.

Prediction of needle heating in an industrial sewing machine

In industrial sewing, needle heating is a key problem that limits the further increase of sewing speed, and hence the productivity. Heat is generated during the sewing process because of friction between the needle and the sewing thread as well as between the needle and the fabric. The high temperature of the needle affects the quality and productivity of the sewing. The problem of needle temperature rise due to friction heat generation is considered in this paper and a simple analytical model is developed to predict needle temperature. The predicted needle temperature is compared with the experimental results by the inserted thermocouple method. Some of the process parameters, used as input variables, were also measured experimentally and experimentally observed values of needle temperature were compared with the theoretical prediction. It was observed that the temperature of the needle increases significantly with the presence of the sewing thread. Both the theory and the experimental results show that the needle temperature increases linearly with the machine speed within the ranges studied.

The effect of sublimation print on thermal conductivity of layered sports textiles

AbstractSublimation print applied onto layered sports textiles can significantly change their functionality and properties, which were so significantly emphasised at production. One of the issues, we focused on in this article is measurement of thermal conductivity of membrane textiles before and after sublimation print application. To find out the effect of colouring on properties of the material, the sublimation process was applied by two methods—using colouring (printed transfer paper) and without colouring. Sublimation print onto examined textiles was applied in the temperatures ranging from 180 to 220/°C. Thermal conductivity was measured using the (C-THERM Cti) device. Results of the measurements imply that the value of thermal conductivity increases proportionally with rising temperature of the sublimation process.

The thermal insulation properties of hightech sportswear fillings

Purpose – The purpose of this paper is to deal with performance verification of thermal insulation fillings that are used for outer clothes into cold environments. Thermal properties of filling materials (down and three sophisticated fillings) were tested under condition approaching real weather conditions in Middle Europe. Design/methodology/approach – In the paper, modern method of thermal resistance Rct measurement, by Sweating Guarded-Hotplate system, was compared with method of Technical University of Liberec (TUL method). The TUL method shows good results and it is applicable even at ambient temperatures below zero, which fully corresponds to real application of the insulation filling. Findings – Evaluation of fibre battings were carried out even at temperatures below the freezing point, which is important for simulation of actual application of these filling structures. The highest thermal resistance of goose down confirm that natural materials have their irreplaceable position, especially in appli...