McGuire Glossary of Fastener Terminology

H - 12 terms

HALAR(R) (ECTRE) (PLASTICS) - Ethlene-chlorotrifluoretlhylene copolymer exhibits better mechanical properties thanmany other fluoroplastics. But like other floroplastics, its flame retardance, chemical resistance and low dielectric constant remain constant over a wide temperature range. These qualities make it suitable for use in such products as electrical insulation, monofilament, tank linings, housings, and electrical components. It may be usefully employed at temperatures from the cryogenic range to about 330F

HALF HEX - A style of blind threaded insert in which the shank has a hex shape for roughly half of the entire part length. The hex portion is adjacent to the head and typically is the same length as the counterbore, followed by a transition to a round shank in the thread area. The hex shank is designed to be installed in a hex hole and offers improved spim-out resistance. The need to orient the part in the mounting hole during installation is generally considered a disadvantage.

HAND SPRAY - The word spraying generally refers to coating processes that use a spray of particles or droplets to deposit a material onto a substrate. At the substrate surface, the particle droplets form 'splats' or 'platelets' that interlock and build up to give the coating.

HAND TORQUE - 2 to 5 in. lbs initial installation only. Removal torque for reference only. Parts to be assembbled/dissembled by hand/fingers.

HARD METRIC - A term applied to a mounting hole scheme for inserts with metric threads in which the specified mounting hole sizes are in whole millimeter increments.

HEAD CHAMFER - The chamfer at the O.D. or the head, Primarily applied to type S and similar style nuts.

HEAD COUNTERSINK - The countersink on the head end of the part.

HEAVY TORQUE - 3/3 of initial installation value i.e. MIL spec., plus requirement of removals and clamp load.

HEIGHT of FUNDAMENTAL TRIANGLE/ V HEIGHT - Thread height that would be present if there were no truncations and both the root and crest had a sharp V profile. The design profile for unified and metric threads has a height of .625 times the height of the fundamental triangle. H denotes this height.

HISTORICAL - Version of a standard containing older content.

HOT MELT ADHESIVES - Thermoplastic materials that solidify at room temperature and melt quickly when heated. Excellent bonding strength and fast setting time.

HYDROGEN EMBRITTLEMENT RELIEF - ASTM F1941 recommends hydrogen embittlement relief for fasteners of 40 HRC or above. Fasteners are to be baked within 4 hours after electroplating at temperatures of 350 to 450 degress F. Fasteners with a specified maximum hardness of 34 HRC and below have a very low susceptibility to hydrogen embrittlement and do not require baking.