Effect of Core Stack Integrity on the Quality of Vacuum Pressure Impregnated Stators

The performance and reliability of electrical machines are strongly affected by the mechanical integrity of the stator core. In motor and alternator stators, uneven resin distribution during Global Vacuum Pressure Impregnation (GVPI) has been associated with irregular resin layer on the stator core and dimensional deviations. Investigations revealed that these inconsistencies arise not from the GVPI process itself, but from the loss of axial compressive stress in the lamination stack prior to shrink-fit assembly. To address this issue, a modified assembly procedure was developed, incorporating mechanical clamping to maintain continuous axial compression throughout frame installation. Experimental evaluation confirmed that preserving stack integrity significantly reduced resin diffusion between laminations and prevented the formation of a resin layer on the stator core which can provide inner diameter stability. Moreover, the knife-test assessment verified that the laminations of stator core are held together tight enough. This approach requires no alterations to the resin system or GVPI parameters and can be readily incorporated into existing manufacturing workflows. The results highlight the critical importance of sustaining axial compressive stress from lamination stacking through final assembly to achieve uniform impregnation, enhanced mechanical robustness, and consistent production quality in electrical machine stators.

کلیدواژه ها:

Stator Core ، Lamination Stack Integrity ، Global Vacuum Pressure Impregnation (GVPI) ، Resin Diffusion