Zippers are manufactured as a continuous roll of tape with teeth on one side. However depending on use, zippers are cut to the required length, stoppers are fixed and sliders are inserted to make them ready for use. As the zipper length required for trouser fly is more or less fixed, conventionally cut-to-length zippers are used while attaching in trousers. In alternate method, continuous zippers are first attached separately with left and right fly pieces and then cut to finish.
StitchWorld published series of articles illustrating comparative advantages and disadvantages and economic viability of various technology levels for several operations like spreading and cutting, piped pocket making, motion and time study, dart making, shirt finishing and belt loop attaching in earlier issues. In this article Team StitchWorld discusses conventional method of attaching cut-to-length zippers vis-à-vis automated processing of endless zippers.
Be it fixing a metal zipper or a plastic zipper in a casual trouser or a formal, the continuous method of zip fastening or batch method, zipper attachment in the trouser fly requires a combination of several sewing and non-sewing operations which involve varied level of mechanization. But to meet quality standards and attain price advantage, an appropriate blend of technology has to be selected.
Conventional Processing (Cut-to-length Zippers)
The processing method of zipper attachment involves highly trained operators who are expert at zipper attaching operation. The quality of work depends on many factors and an accurate repetition of getting similar good results always cannot be guaranteed. If operators change because of illness, holidays, change of job, transfers, etc. the performance and the quality will not remain the same as they were earlier. The costs of the fixed cut-to-length zippers are a further negative aspect (as fixed cut-to-length zippers are made from continuous roll of endless zippers only. Additional cost towards cut to required length, stoppers are fixed and sliders are inserted for ready to use). Also the higher wages due to the use of standard machines cannot be disregarded.
From Table 1, (see next page) it is clear that conventional method has 10 different operations out of which 8 are sewing operations and 2 are ironing operations. Total standard minute value is 7.42 minutes. Four different types of sewing machines are necessary in the conventional method. The disadvantages of conventional process are high zipper costs, extensive storage and logistics, Fluctuations in production quality and high labour costs.
Automated Processing (Endless Zippers)
Using automated machines make the operation simple for the operators, reducing their skill requirements and saving up to 50% of personnel costs. This production method guarantees quality improvement combined with cost reduction. Other advantages of the automated processes are less labour cost and reduced SAM, leading to more and better quality production that too by using lesser number of machines requiring comparatively lesser floor area.
As against the conventional method where 10 operations are required to put to attach the zippers, the automated method requires only 8 different operations out of which 6 are sewing operations, one punching and one ironing operations. Total standard minute value is only 3.79 minutes, a reduction of nearly 50% from conventional method. To sew six operations six different types of sewing machines are necessary in the automated method.
