# Category: Self-tapping screws - [NONOX stainless “Opel-head” self-tapping screws in practice](https://menet-trend.hu/en/nonox-world/nonox-stainless-opel-head-self-tapping-screws-in-practice.md) — The head is formed as if a washer sat under it, except that it is one piece. It bears over a large surface and — the detail rarely mentioned — already grips when only half-tightened, which is exactly what slotted holes and adjustable cladding need. Where the environment is wet, stainless earns its place. - [Opel screws in practice – through the eyes of a set designer](https://menet-trend.hu/en/nonox-world/opel-screws-in-practice-through-the-eyes-of-a-set-designer.md) — Thirty-three years among glue, paint and sawdust. A set has to be carried, pushed and fixed in the dark, and if something does not hold, that is not an aesthetic question. A set designer explains why wide-headed flat screws — the ones people call Opel screws — earned a place among her favourites. - [The self-drilling bi-metal screw that saves you time and money](https://menet-trend.hu/en/nonox-world/the-self-drilling-bi-metal-screw-that-saves-you-time-and-money.md) — A hardened carbon steel tip welded to a stainless steel body: the bi-metal self-drilling screw drills and fastens in a single operation, with no pre-drilling, while keeping its corrosion resistance at the surface. Why a plain stainless self-drilling screw cannot do the job, and where the bi-metal version pays for itself. - [Bi-metal*, self-drilling, NONOX self-tapping screws](https://menet-trend.hu/en/nonox-world/bi-metal-self-drilling-nonox-self-tapping-screws.md) — Ideal for mounting steel or aluminium profiles and sandwich panels onto steel or aluminium structures, with no pre-drilling. An A2 stainless body friction-welded to a hardened steel drill point, a flanged hexagon head, and a captive conical spring washer with a vulcanised EPDM seal that keeps the fixing watertight. - [Self-drilling bi-metal*, NONOX self-tapping screw, for thin sheets](https://menet-trend.hu/en/nonox-world/self-drilling-bi-metal-nonox-self-tapping-screw-for-thin-sheets.md) — Drilling, thread forming and fastening in one step, even into stainless sheet. The bi-metal NONOX self-tapping screw pairs an A2 stainless body with a friction-welded hardened steel point that forms the thread without cutting chips, giving 50% more holding force and needing fewer fixing points. - [Guide to determining the pre-drilling needed for self-tapping screws](https://menet-trend.hu/en/nonox-world/guide-to-determining-the-pre-drilling-needed-for-self-tapping-screws.md) — The diameter of the pre-drilling always falls between the core diameter and the nominal diameter of the screw. Sheet thickness, sheet material and the drilling technology all shift it. Always carry out a trial before beginning mass production. --- HTML: