Common Types of Appearance Quality Defects and Their Impacts on Performance

(1) Pores: Under high‑voltage conditions, pores alter local electric‑field distribution and affect partial‑discharge magnitude.
(2) Shrinkage cavities and sink marks: Shrinkage cavities and sink marks cause uneven product surfaces and impair electrical performance. Polishing destroys surface epoxy resin layers, increasing moisture‑absorption and dust‑adsorption tendency and further degrading electrical performance.
(3) Yellow marks: Mainly aesthetic defects with basically no performance impact.
(4) Flow marks: Flow marks may disturb uniform electric‑arc propagation across surfaces.
(5) Impurities: Impair electrical performance. Tests indicate dense or large‑particle impurities trigger surface discharge and raise partial discharge magnitude for finished products.
(6) Scratches: Essentially local sharp burrs, which may trigger product discharge.
(7) Cracks: Cracks will degrade the voltage withstand performance, partial discharge performance and mechanical properties of finished products. Surface cracks imply potential internal hidden risks, and gas leakage may occur in terminal board products. It indicates that appearance quality defects are not merely cosmetic issues, but will affect the overall performance of complete equipment to a certain extent, which requires sufficient attention.