Nima uchun ko'r perchinlar mandrelni sindiradi va tortish mixining sinish nuqtasida emas?

1. Mandrelning tortish kuchi barqaror emas, sinish nuqtasi kuchi mandrelning tortish kuchiga juda yaqin yoki issiqlik bilan ishlov berilmagan va mandrel mo'rt.

2. Perchinlashdan oldin mandrel shikastlangan.

https://www.yukerivet.com/news/the-mandrel-of-the-rivet-has-been-completely-pulled-out-is-it-qualified-to-leave-a-penetrating-hole-in-the-rivet-body-after-riveting/