What “self-tapping” means
Self-tapping screws cut or form a mating thread as they are driven. They are for sheet metal, plastics, and light wood — not for pre-tapped machine threads.
Pan head self-tappers
Pan head self-tapping screws leave a raised head above the panel — useful on electrical enclosures and appliance skins.
Countersunk self-tappers
Countersunk self-tapping screws sit flush after driving into a matching recess — preferred on outdoor panels and visible fascia.
Pilot holes
Always follow the sheet gauge / pilot-hole chart for your material. Oversized pilots lose pull-out; undersized pilots can snap tips or gall stainless.
FAQ
Q: Can I reuse a self-tap hole with a machine screw?
A: Not reliably. Formed threads are not the same as cut machine threads.
Q: Stainless into aluminum — stuck screws?
A: Galling risk rises with dry assembly; specify lubrication needs on the RFQ if joints will be serviced.