Metallics JFM31 5-40 x 1/2 in. Flat Head Slotted Machine Screws - Steel Zinc - Each

Yes. The Metallics JFM31 is a 5-40 screw cut to the ANSI/ASME B1.1 thread standard with 40 threads per inch in UNC form, so it mates with any standard #5-40 tapped hole or nut. Thread form is the thing that decides this, not the head style, so the flat slotted head does not change the fit.

That is what a flat head is for, and the JFM31 follows ASME B18.6.3-1998 for head geometry: head width runs 0.215 to 0.237 in. and head height 0.062 to 0.075 in. If your countersink is cut to the standard 82 degree flat-head profile at that diameter, the screw seats flush. A hole bored straight with no countersink will leave the head proud.

The JFM31 is zinc-plated carbon steel, made from AISI 1006 to 1022 material. Zinc plating is a mild indoor corrosion coating, so these are meant for dry interior work: enclosures, device plates, panel and electronics assembly. For damp, wet, or exterior locations, specify a stainless machine screw in the same 5-40 x 1/2 in. size instead.

470 lb minimum tensile, with a hardness of Rockwell B70 to B100. That is ordinary low-carbon fastener strength, fine for holding plates, brackets, covers, and electronics hardware. It is not a graded structural fastener, so do not substitute it where a drawing calls out a grade or a specific proof load.

They ship in a jar of 100, which is the order minimum (100 CT). Jar weight is 0.21 lbs. If you need a different count or another length in the FM and FMP series, other sizes and quantities are available by request.

The JFM31 is flagged as both ARRA compliant and Buy American compliant, with country of origin China. On a federally funded project, hand both of those to your specifier, because the compliance pathway that applies depends on the contract clause your job is written under.

The JFM31 runs 1/2 in. of overall length, and because it is a flat head the head sinks into the countersink, so effectively the full 1/2 in. is working length through your material and into the tapped hole or nut. Stack up your plate thickness plus the thread engagement you need: if that total tops 1/2 in., move up to a longer length in the FM and FMP series.

Use a machine screw like the JFM31 when the hole is already tapped or you are pairing it with a nut: it has a straight UNC thread at 40 TPI and does not cut its own threads. A sheet metal or self-tapping screw is the right call only when you are driving into un-tapped thin stock. Putting a machine screw into an untapped hole gets you nothing to bite.