A flange nut gives a constructed-in washer (flange) that distributes the clamping load about a broader space than an everyday lock nut. The design doesn't need a flat washer which is the higher choice for an oversized or slotted hole. Partially Threaded has an unthreaded space just beneath the flange https://highperformancevectorvari43085.eedblog.com/28298461/details-fiction-and-flange-nut