## 4 Discussion and Conclusions
### Conclusions  
ANOVA, with a level of significance \(\alpha=0.05\), was performed on the variables: durability, production, and scrap. These analyses demonstrated that there is a significant difference in the average duration between die-nozzle models. The Tukey test identified that the 1 DNL and 3 DND models have greater durability. The 3 DND model has average durability of 2.8 \(\pm\) 0.4 days. It was also verified that there is a significant difference between cable and scrap production of all die-nozzle models [29; 30]. With the results of the statistical analysis previously described, it is justified that the variables: durability, production, scrap, the color of the insulator, machine, and operator, are considered relevant for the calculation of the performance indicators due to the influence of the die-nozzle pairs, the 3 DND model is the best performer in terms of the generated scrap [38; 39]. Therefore, the results demonstrated that there is an effect of the model of die-nozzle on the variables. The performance is calculated individually with the method of the cable manufacturer, where the result indicates that the models 1 DNL = 81.2% and 3 DND = 80.2%, are those with the highest performance indicators [40]. The second phase was carried out applying formal tools of Total Quality Management: Benchmarking, Statistical Process Control and DOE. It was obtained that the 3 DND and 1 DNL models have a \(\sigma\) level of 3.79 and 2.08. Their indicators Cpk = 1.26, 0.73, Cp = 1.59, 0.80, and Pp = 1.09, 0.80 respectively, so these die-nozzle models are the most approach the references established by the norm, for that reason, they are the best in the capability of the process, in that order [41]. The indicators of performance under the criterion of the analysis of the company evaluate in percentages the factors considering a higher weight to three of the six: productivity, quality and time, obtaining like the result the following order of performance of the die-nozzle models 1 DND, 4 DNK, 2 DNV, and 5 DNS. The results of the Statistical Process Control and Six Sigma are based on the evaluation of the variability of the measurements of the finished product and the scrap volume generated, obtaining, as a result, the following order: 3 DND, 1 DNL, 2 DNV, 4 DNK, and 5 DNS, which It is different because different criteria are used. However, it is observed that the models with the best performance are those that have the highest indicators of processes capability. Therefore, the Manufacturing Company could be used the method of Statistical Control and DOE to evaluate the performance of the die-nozzle pairs [42]. Other authors have applied different statistical techniques and have proposed a routine for evaluated the failure rate and inspection intervals using the first-order reliability method (FORM + Fracture) to alleviate the computational cost of probabilistic defect-propagation analysis. The proposed method is one of the first applying reliability concepts to additive manufacturing (AM) components [1]. It is proven that significant improvements can be generated through the systematic application of the TQM process [2]. With the use and application of statistical analysis, reductions in manufacturing, inspection, materials or methods costs can be achieved [43]. The concept of additive manufacturing [7], will be very useful for the optimization of processes in all types of components. With the results obtained using the DEA model of Super Efficiency oriented to inputs with non-decreasing returns to scale, the same conclusions were obtained as those obtained through Statistical Process Control and DOE, so that the order of preference of the die-nozzle models is as follows: 3 DND, 1 DNL, 2 DNV, 4 DNK, and 5 DNS [32; 33]. The methods to optimize the design proposed in [1] were very useful for following work in the improvement of tooling and manufacturing processes. By an early control such as that proposed in [2], substantial improvements in the manufacture of electrical conductors and other products can be achieved.