Metallics JFMP65SS 5/16-18 x 1 in. Flat Head Phillips Machine Screws - 18-8 Stainless - Each

It's a 5/16-18 UNC thread cut to ANSI/ASME B1.1, so it runs into any standard 5/16-18 tapped hole or nut. 18 threads per inch is the coarse series, which is what most sheet metal boxes, strut nuts and tapped enclosure bosses use at this diameter.

Yes, if the countersink is cut to the 82 degree flat head standard. The head measures 0.556 to 0.597 in. across and 0.165 to 0.191 in. high, built to ASME B18.6.3-1998, so it seats flush in a hole countersunk for a standard 5/16 flat head screw. Gaging diameter is 0.539 in. If your plate is only punched with a straight clearance hole and no countersink, the head will stand proud, use a pan or hex head instead.

These carry a 3150 lb minimum tensile and run Rockwell B85 to B95 hardness. That's softer than a hardened grade 5 or grade 8 steel screw, so for a high-torque structural connection stainless is not the right pick. What you get instead is corrosion resistance and better strength retention at elevated temperature. Note that there is no national performance standard for stainless machine screws, so treat the hardness and tensile figures as guides.

18-8 stainless is specified for general atmospheric corrosion resistance and is used in food processing machinery and refrigeration equipment, so exterior enclosures, damp mechanical rooms and washdown environments are within its range. It is not a marine-grade alloy, so for constant salt spray exposure specify 316 instead.

No. The JFMP65SS is flagged not Buy American compliant and not ARRA compliant, with multiple countries of origin. If your contract carries a domestic sourcing clause, these will not satisfy it.

A #4 Phillips. The recess is 0.358 in. across and 0.205 in. deep, which is deeper than most cordless-driver bits are used to, so seat the bit fully before pulling the trigger. Stainless cams out more easily than plated steel, so keep axial pressure on it.

They come in a jar of 100, and 100 is the order minimum. The packed jar weighs 2.08 lbs. For a crew stocking a van or a shop bin, that's one container per size rather than loose counts.

Machine screws like the JFMP65SS have a straight machine thread, not a self-tapping point, so they need either a tapped hole or a mating 5/16-18 nut. They will not cut their own threads in sheet metal. Nuts and washers are not part of the jar, order those separately.

Metallics lists this one for the electrical, plumbing, heating and air conditioning industries. Typical uses are fastening covers, plates and brackets where the head has to sit flush and the fastener will see moisture, plus food processing machinery and refrigeration equipment where the stainless matters.