6 1 20 110 o o o x

7 1 12。5 110 o o o x

8 1 5 110 o o o x

9 1 12。5 120 o o o x

10 1 5 120 o o o x

Nomenclature。

o, successful result。 x, goal no achieved。

Table 3

Hypothesis tests of proportions for annealing process by CFHA。

Sampling Defects Trial Proportion P-value

No CFHA 194 528 0。36742424 0。0000

CFHA 1 797 0。00125471

4。 Conclusion

The presence of residual stress in injection molded parts is a particular concern due to its negative impact on the performance of assembled products like headlights which have to fulfill legal regulations FMVSS 108, based on destructive   tests。

A successful DOE was applied in the manufacture of PCLs, achieving relaxation of the microstructural ordering of polycarbonate, and by this method its service life in headlights is assured under different environmental conditions。 This thermal treatment in conjunction with the photoelasticity technique can be an alternative way of solving and analyzing this undesired characteristic when applied effectively during IMP in a plant as product quality  control。

Analysis by chemical attack and photoelasticity shows a good correlation of the results shown in Fig。 10, and can be adopted as a methodology to determine the residual stresses in transparent or translucent materials by performing the following steps: 1) analysis by the photoelasticity model (a) or (b), 2) identification of zones of high concentration of isochromatic lines, 3) estimation of residual stress by the selected test medium and 4) correlation of the results of nondestructive and destructive    techniques。

Acknowledgments

The authors wish to acknowledge the National Council on Science and Technology (CONACYT) for its financial support during the development of this project under registration number  216985。