Line balancing for sewing is more complicated than that for assembly lines because the layout of the sewing lines can be organized in many different configurations. The quality of the line balancing will determine not only the throughput, but also the efficiency of the sewing line. Another important aspect that must be taken into account is maintaining the lean flow of products over the line. There are two possible approaches that may be employed while balancing a sewing line, namely, identifying the line balancing alternatives while targeting a certain takt time and identifying the line balancing alternatives for a given range for the number of operators. While line balancing is a very important planning activity for profitability in this industry, the short lead time between design and manufacturing phases makes it very difficult to collect reliable time study data, which in turn, makes generating reliable line balancing plans to be acted upon very difficult before the first manufacturing run.

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Line balancing provides only the theoretical structure of the sewing lines – the groups of operations to be assigned to operators. Another important aspect is to determine the most suitable operator assignment for each line for each shift to each operation group which may change due to absence or changing skill sets of operators. Hence, operator assignment is a problem that must be solved for each shift. While it is important to maintain a pool of operators with cross skill sets to ease the severity of the operator assignment problem, it may not be always possible to have a pool with a uniform skill set. In such cases, maintaining best possible operator assignments shift-in- shift-out is very important to maintain an acceptable quality level. Operator assignment process requires line balancing solutions to be available to have access to operation groups. Furthermore, it also requires skills and associated levels to be maintained for each operator in addition to the skills required by each operation. Again, maintaining operator skill data and required skills data for each operation with the very short available lead time make it very difficult to generate realistic operator assignment plans before the first manufacturing run.

 

Scheduling for garment manufacturing is mainly driven by scheduling products over sewing lines but this process must also consider the preceding spreading and cutting in addition to succeeding washing, finishing and packaging processes. Some products may only be manufactured during specific shifts. Raw material arrival times and due dates must be taken into account. Synchronization between different lines such as jacket and pants lines for suits is also important for properly managing the succeeding processes before and after sewing. One final important aspect is smoothing out the changeovers between different products sewed on the same lines. While much of the sequence is dictated by the tight deadlines, there may still be some degrees of freedom left to smooth out the changeovers to reduce lost times while changing the configuration of the line.

 

The output of these planning processes can sometimes be very difficult interpret with all their implications. NovaLab’s planning software, xS Planner, provides interactive raw material requirements plan view in addition to warnings related to various aspects of the plan such as late orders and a dashboard for KPIs.