Methods of Defining Time of Machine-Hand Sewing Suboperations

Abstract

The process of work in sewing operations is performed on machines characterised by machine-hand suboperations, where man and machine work in the system together and simultaneously. In developing and defining adequate methods of work and time norms it is necessary to employ such methods for determining the time necessary to perform machine-hand suboperations that include and completely define the operation of sewing in question. Most such methods are based on the investigations of interactions of technical- technological conditions of work: nominal sewing machine stitching speed, overall seam length, stitch density and seam curvature radius. Contemporary methods of industrial engineering offer new techniques of determining and defining the time necessary to perform machine-hand sewing suboperations. Besides technical-technological principles, these methods also define and determine the impact of psycho-motorical abilities of the operator and his/ her skill, required accuracy of joining parts, as well as the method of transporting the workpiece, which defines the quality of the seam produced. This paper offers a survey of methods for defining machine-hand suboperations, based on the degree of sewing machine utilisation, joining accuracy, individual ability of the operator at the overall sewing speed achieved, ability to react and the required method of transporting the workpiece layers in the course of the sewing suboperation in question.